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YOUR BEET

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If your application includes fundamental features like login, registration, password reset/recovery, resend confirmation links, and other specific functionalities requiring server requests, it's crucial to implement mechanisms against brute force attacks and the generation of a substantial load on your service. Without such mechanisms, your application may be vulnerable to various threats, including sending an excessive number of emails/OTPs to users, potentially leading to financial and reputational damage. Many lack adequate rate-limiting measures, relying solely on the limitations imposed by their business logic, such as restricting the number of requests based on a payment model. Some applications, however, do incorporate rate limits, particularly for operations like login attempts, registration, and other critical functionalities. These implementations often depend on the X-Forwarded-For header for IP address tracking. web applications To illustrate a simple example, I came up with this code snippet on Flask from flask import Flask, request, jsonify
from flask_limiter import Limiter
from flask_limiter.util import get_remote_address

app = Flask(__name__)
limiter = Limiter(
    app,
    key_func=get_remote_address,
    storage_uri="memory://",)

def get_ipaddr():
    # Retrieve the client's IP address from the request
    # X-Forwarded-For header is used to handle requests behind a proxy
    ip_address = request.headers.get('X-Forwarded-For', request.remote_addr)
    return ip_address

# Rate limit to 5 requests per minute per IP
@limiter.limit("5 per minute")
@app.route('/')
def index():
    ip_address = get_ipaddr()
    return ip_address In the following sections, I'll explain various approaches to testing and attempting to bypass rate limits in your application. To efficiently test your app for this type of vulnerability, automation is a powerful tool. You can achieve this by employing scripts, such as those in Python (as I often do), or using tools like Burp Suite (btw a great tool for testers and cybersecurity professionals). Also, tools like Postman might be used to automate checks relatively easily. Testing Rate Limit Changing IP value in X-Forwarded-For header X-Originating-IP: 127.0.0.1 Use different IP values in every request you send. Use double X-Forwared-For header. X-Forwarded-For:
X-Forwarded-For: 127.0.0.1 Try the same with different headers. X-Originating-IP: 127.0.0.1
X-Remote-IP: 127.0.0.1
X-Remote-Addr: 127.0.0.1
X-Client-IP: 127.0.0.1
X-Host: 127.0.0.1
X-Forwared-Host: 127.0.0.1 Change other headers Try changing the user-agent, content-type, accept-language, etc, or cookies, anything that could be used as a user identifier. If there is a rate limit of 3 tries per IP, every three tries, change the IP value of the header (or other headers or params in your requests). Add blank chars in params Try adding to the params you send %00, %0d%0a, %0d, %0a, %09, %0C, %20 For example param1=value1%%0d%0a 
param2=value2%00 For example, if you are requesting OTP for email verification and you only have 3 tries, use the 3 tries for example@email.com
example@email.com%00
example@email.com%0d%0a
And so on Use similar endpoints If you are testing, for example,/API/v1/signup endpoint, then try to perform brute-force to /Signup, /SignUp, /sign-up. Try adding blank chars (from the above) to the original endpoints. Adding extra params to the requested API endpoint If the limit is on the requests of /api/v1/resetpassword endpoint, try brute-forcing it by adding some query params - once the rate limit is reached, try, for example, /api/v1/resetpassword?param1=value1 Logins matter It might be the case that an app has flawed logic - if you log into your account before each attempt/series of attempts, the rate limit is reset for your IP, and you can continue your password brute-force attack. If you are testing a login feature, you can do this in Burp Suit with a Pitchfork attack in the settings (or you can write your own script for this) for each attempt/series of attempts. Here is my example of how I automated a simple check for the X-Forwarded-For header just to get a POW: from random import randint
import requests
import json


url = "https://yourapp.net/api/v1/regconfirm-resend"
data = {
   "email": "yourtest@mail.com"
}

N = 100


def generate_random_ip():
   return '.'.join(
       str(randint(0, 255)) for _ in range(4)
   )


for _ in range(N):
   headers = {
       "Host": "yourapp.net",
       "Content-Type": "application/json",
       "X-Forwarded-For": generate_random_ip()
   }
   response = requests.post(url, headers=headers, data=json.dumps(data))
   print(headers)
   print(f"Status Code: {response.status_code}, Response: {response.text}") Restoring original visitor IPs A possible solution might be the use of Cloudflare and its mechanisms. A detailed explanation can be found here . I will provide only a brief overview of its defense mechanisms. restoring-original-visitor-ips If you use applications that depend on the incoming IP address of the original visitor, a Cloudflare IP address is logged by default. The original visitor IP address appears in an appended HTTP header called CF-Connecting-IP. By following our web server instructions, you can log the original visitor IP address at your origin server. If this HTTP header is not available when requests reach your origin server, check your Transform Rules and Managed Transforms configuration. If Pseudo IPv4 is set to Overwrite Headers - Cloudflare overwrites the existing Cf-Connecting-IP and X-Forwarded-For headers with a pseudo IPv4 address while preserving the real IPv6 address in CF-Connecting-IPv6 header. Remember, when implementing such a defense mechanism, perform thorough testing. This approach might be subsequently applied to the entire cluster and could adversely affect certain functions and microservices where it is unnecessary. In a nutshell, while fixing a security breach, be cautious, as it could potentially impact the entire application. Analyze which part of your system might be affected negatively and test everything before shipping changes to the prod env. NOTE: Also published . here

Defending Your Web App: A Guide to Rate Limiting and Brute Force Attack Prevention

আপনার ওয়েব অ্যাপকে রক্ষা করা: রেট লিমিটিং এবং ব্রুট ফোর্স অ্যাটাক প্রতিরোধের জন্য একটি নির্দেশিকা

Verteidigen Sie Ihre Web-App: Ein Leitfaden zur Ratenbegrenzung und zur Verhinderung von Brute-Force-Angriffen

Defendiendo su aplicación web: una guía para limitar la velocidad y prevenir ataques de fuerza bruta

Défendre votre application Web : un guide sur la limitation du débit et la prévention des attaques par force brute

अपने वेब ऐप का बचाव: दर सीमित करने और क्रूर बल के हमले की रोकथाम के लिए एक गाइड

Web アプリの防御: レート制限とブルート フォース攻撃防止のガイド

웹 앱 방어: 속도 제한 및 무차별 대입 공격 방지 가이드

Defendendo seu aplicativo da Web: um guia para limitação de taxa e prevenção de ataques de força bruta

Защита вашего веб-приложения: руководство по ограничению скорости и предотвращению атак методом перебора

Web Uygulamanızı Koruma: Hız Sınırlama ve Kaba Kuvvet Saldırısını Önleme Kılavuzu

Bảo vệ ứng dụng web của bạn: Hướng dẫn giới hạn tỷ lệ và ngăn chặn tấn công vũ phu

保护您的 Web 应用程序：速率限制和暴力攻击预防指南

Introduction: In many collaborative environments, managing access to specific data in Google Sheets is critical for maintaining data accuracy and privacy. This article demonstrates how to create a system where users can edit specific cells only after providing their details. We'll achieve this using Google Apps Script, a powerful automation tool for Google Sheets. Setting Up the Google Sheet: To get started, create a Google Sheet, and structure it to include user details. For this example, we'll use columns for "Name," "Email," and "Details." The "Details" column will be used to indicate whether users have provided their details. The Role of Google Apps Script: Google Apps Script is at the heart of our solution. This scripting tool allows us to automate tasks in Google Sheets. In this case, it will help control cell access and track user edits. We'll begin by creating a script that checks if users have provided their details. This script will grant edit access to specific cells once a user's details are confirmed. Script to Manage Cell Access: function onEdit(e) {
  var sheet = e.source.getSheetByName("YourSheetName");
  var editedRange = e.range;
  var username = Session.getActiveUser().getEmail();
  var timestamp = new Date();

  // Check if user's details are in place.
  var detailsRange = sheet.getRange("B2:B10"); // Adjust to your specific details range.
  var userRowIndex = detailsRange.createTextFinder(username).findNext().getRow();

  if (userRowIndex > 0) {
    // Grant edit access to specific cells (e.g., columns C and D).
    var editRange = sheet.getRange(userRowIndex, 3, 1, 2);
    var protection = editRange.protect();
    protection.removeEditors(protection.getEditors());
    protection.addEditor(username);
  }
} This script, when triggered by an edit event, checks if a user's details are in the "Details" column. If found, it grants edit access to specific cells (e.g., columns C and D). Users can edit only after their details are confirmed. Making a Special Google Sheet With a "Lock Cells" Button Imagine you have a special Google Sheet where you want to let people fill in some information, but only after they tell us who they are. This article will show you how to do it, and we'll even add a "Lock Cells" button to make it easier! Step 1: Create Your Google Sheet First, open Google Sheets. Click on extensions Make a new sheet, and add some columns for names, emails, and other stuff. Step 2: Use a Magic Script (Google Apps Script) Google Apps Script is like magic for your Google Sheet. It can do things for you automatically. Here's a special script we'll use. It checks if someone has shared their name and email. THE NAME OF THE SHEET MUST MATCH WITH THE “YourSheetName“ IN THE CODE function onEdit(e) {
  var sheet = e.source.getSheetByName("YourSheetName");
  var editedRange = e.range;
  var username = Session.getActiveUser().getEmail();
  var timestamp = new Date();

  // Check if someone shared their details.
  var detailsRange = sheet.getRange("B2:B10");
  var userRowIndex = detailsRange.createTextFinder(username).findNext().getRow();

  if (userRowIndex > 0) {
    // Let them edit special cells (e.g., columns C and D).
    var editRange = sheet.getRange(userRowIndex, 3, 1, 2);
    var protection = editRange.protect();
    protection.removeEditors(protection.getEditors());
    protection.addEditor(username);
  }
} Step 3: Add a "Lock Cells" Button We'll make it even easier. Let's add a "Lock Cells" button to your Google Sheet. So, when someone wants to lock their cells, they just need to click the button. function onOpen() {
  var ui = SpreadsheetApp.getUi();
  ui.createMenu('Lock Cells Menu')
    .addItem('Lock Your Cells', 'lockYourCells')
    .addToUi();
}

function lockYourCells() {
  // This is where we lock the cells when someone clicks the button.
  // They can only click it after sharing their details.
} Here is the complete code if you do not want to create two separate codes. Save the script, and click on “Run.“ The system will give you the prompt below. The complete code: function onOpen() {
  var ui = SpreadsheetApp.getUi();
  var currentUserEmail = Session.getActiveUser().getEmail();
  
  if (currentUserEmail === "admin@example.com") {
    ui.createMenu('Lock Menu')
      .addItem('Lock Cells', 'showDialog')
      .addToUi();
  }
}

function showDialog() {
  var ui = SpreadsheetApp.getUi();
  var result = ui.prompt(
    'Lock Cells',
    'Enter the cell range to lock (e.g., A1:A10):',
    ui.ButtonSet.OK_CANCEL
  );

  if (result.getSelectedButton() == ui.Button.OK) {
    var rangeToLock = result.getResponseText();
    lockCells(rangeToLock);
  }
}

function lockCells(rangeToLock) {
  var spreadsheet = SpreadsheetApp.getActiveSpreadsheet();
  var activeSheet = spreadsheet.getActiveSheet();

  // Lock the specified cell range.
  var protection = activeSheet.getRange(rangeToLock).protect();
  protection.removeEditors(protection.getEditors());
  protection.addEditor(Session.getActiveUser());

  // Apply a background color to indicate locked cells.
  var lockedColor = '#e6e6e6'; // Light gray color.
  var range = activeSheet.getRange(rangeToLock);
  range.setBackground(lockedColor);
  
  // Create a time-based trigger to unlock the cells after 3 minutes.
  ScriptApp.newTrigger("unlockCells")
    .timeBased()
    .after(3 * 60 * 1000)  // 3 minutes in milliseconds
    .create();
}

function unlockCells() {
  var spreadsheet = SpreadsheetApp.getActiveSpreadsheet();
  var activeSheet = spreadsheet.getActiveSheet();
  
  // Define the range of cells to unlock, matching the locked range.
  var rangeToUnlock = "A1:A10";  // Adjust this to your specific range.

  // Remove the protection and clear the background color.
  var protection = activeSheet.getRange(rangeToUnlock).protect();
  protection.remove();
  activeSheet.getRange(rangeToUnlock).setBackground('');
} In this script: The admin can click "Lock Cells" to lock the specified cells and apply the background color. After locking, a time-based trigger is created to run the function after 3 minutes. unlockCells Set the background color after effectively unlocking the cells. Only the admin/you will see the LOCK MENU Replace "admin@example.com" With the Actual Admin's Email Address in the Code. Step 4: Make a Schedule You want the cells to lock themselves at a certain time, like bedtime. We'll use a special clock (time-driven trigger) to do that. Leave it as “Head.“ Step 5: Share the Sheet Now, you can share your Google Sheet with your friends or team members. They can use the "Lock Cells" button to lock their cells. Conclusion: With this magic system and the "Lock Cells" button, you can control who gets to edit your Google Sheet. It's like inviting friends to your party, but they need to tell you their names before they can play with your toys. I would be glad to help if you need any assistance.

How to Create a Custom Lock Menu in Google Sheets - The Magic of Automation

In the process of learning blockchain programming, whether it's the most popular on YouTube or the Alchemy's , content related to Hardhat is inevitable. This is not surprising as in the field of Web3 development, Hardhat is undoubtedly one of the most mainstream frameworks. However, I encountered the same pitfall in the process of learning these two courses, that is, after using Hardhat to deploy smart contracts, I could never succeed in the verification. The same error always occurred: video tutorial solidity bootcamp An unexpected error occurred:
ConnectTimeoutError: Connect Timeout Error
...... I searched on Google for a long time but didn't find a complete solution. Then I tried to ask GPT-4 but still failed to solve it. Eventually, I found some insights in this on GitHub. Now, in combination with the actual process of solving this problem myself, I will record the process of analysis and verification, hoping to help those who also encounter this problem. post Firstly, I want to analyze the causes of this problem： I'm using the WSL2 system. The proxy is set in the Windows environment, and the WSL2 system shares the proxy from the Windows environment. Therefore, the solution idea in the aforementioned post did not initially catch my attention. I originally thought that my WSL2 system had set up to share the proxy from the Windows environment, and that I could connect normally using the command, so the inability to use Hardhat's verify function should not be a problem with the proxy settings. curl http://google.com Moreover, my error message and the content in the aforementioned post were quite different, aside from the ConnectTimeoutError. Given that Hardhat itself frequently updates, I thought it was an issue with the Hardhat version or a problem with one of its dependencies. What's more, GPT-4 analyzed the situation in the same way at the time, which somewhat misled my thinking. I tried to upgrade and downgrade and adjust the versions of libraries and dependencies like Hardhat, @nomicfoundation/hardhat-verify, @nomicfoundation/hardhat-toolbox several times, and even tried to apply for multiple API keys on Etherscan, only to find it didn't help. In the end, I realized that although I globally shared the proxy from the Windows environment in WSL2, the verify plugin might not use the global proxy under the WSL2 environment when Hardhat is running due to some reason. Problem Solution and Contract Verification Process Environment configuration: I have a simple here, which deploys an upgradeable contract. You can refer to my package.json file. Many answers online are quite outdated, but my libraries are all up to date. Of particular note is the need to install the Undici library, which will be used to set the proxy for verification. example project Writing the contract and deployment script: This is a standard step and not the focus of this article. But if you are a beginner like me, you can also refer to the simple contract and deployment script in my aforementioned repository. After the writing is done, we can deploy the contract under the Hardhat localhost environment or on the testnet. However, only when deployed on the testnet or mainnet can we use Hardhat's verify plugin. Apply for an API key on the website, which is free. After application, create a new .env file in the root directory of the Hardhat project and paste into it. Then set it in the hardhat.config.js configuration file. You can also refer to the configuration method in this file in my repository. Etherscan ETHERSCAN_KEY=yourApiKey Use the command to view your IP address, assuming it's , then check the "LAN" corresponding HTTP port through the VPN client in your Windows environment, assuming it's yyyyy. Add the following content to your hardhat.config.js file: ip route | grep default | awk '{print $3}' http://xxx.xx.xxx.x const { ProxyAgent, setGlobalDispatcher } = require("undici");
const proxyAgent = new ProxyAgent("http://xxx.xx.xxx.x:yyyyy");
setGlobalDispatcher(proxyAgent); Please note that you should not use the IP address and port in the aforementioned GitHub post, because everyone's VPN client and IP are different. The post also mentioned looking at the DNS server IP using and adding it to the configuration. But if you, like me, share the Windows proxy in the WSL2 environment, then your DNS is likely set by yourself, such as 8.8.8.8. So using the method I mentioned in the fourth point above is the safest. Also, don't forget to turn on options like "Allow LAN connections" in your VPN client. If your client doesn't have this option, you may need to switch to another one. cat /etc/resolv.conf Use the command to verify the contract, or you can write an additional verification function in the deployment script, which will complete the verification immediately after deployment. npx hardhat verify --network yourNetWork CONTRACT_ADDRESS

Solving the ConnectTimeoutError When Verifying Smart Contracts with Hardhat

It’s important to have proper tooling that alerts you when your infrastructure isn’t performing as it should. When it comes to validators, the stakes (excuse the pun) are high, and so in this article, we’re going to show you how to create tooling that alerts you via Telegram if your node is jailed. Thanks to for his on creating bash scripts that interact with Telegram. @bogkonstantin article Creating the Telegram bot In order to send a message to a Telegram group or channel, the initial step is to establish your own bot. Simply launch the Telegram app, locate @BotFather, and initiate the conversation by typing /start. Proceed to follow the provided instructions for bot creation and acquiring the token necessary for accessing the HTTP API. Adding your bot to your Telegram channel Open your Telegram channel and add your newly created bot as a member. In order to get Channel Id, first, post any message to the Channel. Then use this link template to get Channel Id: <https://api.telegram.org/bot<YourBOTToken>/getUpdates> Here is a response you can expect. {
  "ok":true,
  "result": [
    {
      "update_id":123,
      "channel_post": {
        "message_id":48,
        "chat": {
          "id":-123123123, // this is your channel id
          "title":"Notifications",
          "type":"channel"
        },
        "date":1574485277,
        "text":"test"
      }
    }
  ]
} Create the shell script that checks if the validator is jailed and sends the alert. The following script runs a command using your zetacored binary to query whether your validator is jailed. Make sure to update your version of the script with your binary location, validator address, and Telegram details. It also logs details of the validator’s status to a log file each time the file is run. #Simple Script

cmd=$(/root/go/bin/zetacored query staking validator zetavalopercf4aqlv2l3g4i83f3w2mgdqjuiaxu2vkgg532mq | grep 'jailed: false' &> /dev/null )

if [[ $? -eq 0 ]]; then
   echo "Zetachain validator not jailed"
   echo $(date -u) "Zetachain validator not jailed" >> /root/JailedLog/val_jailed_log.txt
else
   echo "Zetachain validator is jailed!"
   echo $(date -u) "Zetachain validator is jailed!" >> /root/JailedLog/val_jailed_log.txt
   curl -X POST -H 'Content-type: application/json' --data '{"text":"Zetachain validator is jailed!"}' https://api.telegram.org/bot2486928301:cCfpaQlV2l3GII8af3W2mGdqJuiaXU/sendMessage?chat_id=-100447288104&text=Zetachain_validator_is_jailed
fi After creating the shell script, don’t forget to make it executable. chmod +x check_val_jailed.sh Setting up the cronjob that calls the script Finally, we use crontab to call the shell script on a regular time interval. Run to edit your crontab file. Add the following to your crontab file: crontab -e */15 * * * * /bin/bash -c "~/scripts/check_val_jailed.sh" This calls the bash script every fifteen minutes. Configure this as you please and update the file path above to the file path of your script. That’s it! Of course, ensure that everything is working as you intend. Thanks for reading.

Creating a Bash Shell Script That Alerts Via Telegram if Your Zetachain Validator Gets Jailed

Motivation Recently, we migrated our sub-project from to . During that migration, the main goal was to keep the previous behavior of setting and changing language in our app. react-localization i18next Storing language in a route path is a commonly used practice for the Nextjs framework. But for our project, that was an inappropriate solution. Our main application allows businesses to generate QR codes for their customers with a link to the sub-application where the end user can leave feedback regarding service quality and satisfaction. All QR codes had already been printed, and new ones would cost a fortune for the business. The previous version of the sub-app used to be built on the base of CRA, and only half a year ago, it was migrated to Nextjs. So, we were looking for library or libraries which could provide us with non-route-based internationalization and API similar to . We found . This is a library specifically designed for use with Nextjs. provides a simple and flexible way to add i18n functionality to Nextjs projects, including support for server-side rendering and other advanced features. react-i8next ni18n ni18n Basic Setup Let’s install all necessary dependencies to start working on our project. npm install i18next react-i18next ni18n The next step is to expand the existing with the default i18n config. next.config.js Basically, we need only a few fields for a quick start. is required to show all the locales we want to support in the app, and will be used when visiting a non-locale prefixed path (for us, it’s just the default language). locales defaultLocale // next.config.js
module.exports = {
	...yourNextConfig,
  i18n: {
    defaultLocale: 'GB',
    locales: ['GB', 'UA', 'PT'],
  },
}; Then we are required to create a new file in the root or utils/plugins/etc. directory named . - names which show us supported languages, and - namespaces, which we can use in some cases. ni18n.config.js supportedLngs ns // ni18n.config.js
export const ni18nConfig = {
  supportedLngs: ['GB', 'UA', 'PT'],
  ns: ['namespace-name'],
}; A few more things left. Our application requires , so let’s wrap the with the high-order component imported from . I18nextProvider App i18n It will initialize the instance and provide it as a context for all the children. i18next // pages/_app.jsx
import { appWithI18Next } from 'ni18n';
import { ni18nConfig } from '../ni18n.config';

const App = ({ Component, pageProps }) => <Component {...pageProps} />;

export default appWithI18Next(App, ni18nConfig); And the last preparation step before we started using translation into our components is a filling of translation files. The important thing - keep the following file structure. ./public
└── locales
    ├── GB
    │   ├── namespace-name.json  // { "key1": "Test" }
    │
    ├── UA
    │   ├── namespace-name.json  // { "key1": "Тест" }
    │
    ├── PT
		├── namespace-name.json  // { "key1": "Teste" } Finally, we’ve done with the setup and are ready to start integration of the i18n feature into components. Let’s take a look at the example in . ComponentName.jsx We extract the function from hook which will return translated string for the selected language. Looks simple, doesn’t it? t useTranslation // ComponentName.jsx
import { useTranslation } from 'react-i18next';

export const MyComponent = () => {
  const { t } = useTranslation();
  return (
		<div>{t('key1')}</div>
	);
}; If you store user language in DB, don’t forget to create a context with or any other solution to wrap pages and set the language in . Below, I’ll show you a simple snippet of how it could be implemented. React.Context useEffect // ContextName.jsx
const I18nProvider = ({ children, data }) => {
    const { i18n } = useTranslation();

    const { language = 'GB' } = data;

    useEffect(() => {
        i18n.changeLanguage(language);
    }, [language]);

    return (
        <I18nContext.Provider>
            {children}
        </I18nContext.Provider>
    );
}; That’s it. I hope it helped you to save some time, as always. In the future, we are going to migrate the existing i18n approach to route based. The reason is pretty simple - a unification of all our applications. I’ll definitely describe it in one of my next articles.

Implementing i18n in Next.js: A Guide to Non-Route-Based Localization

Nowadays every modern web application uses platforms that provide error monitoring in real-time. They have support for different languages and technologies. And that’s great because the quality of development grows every year. I’m a big fan of tools that help my team instantly react to bugs and crashes and fix them ASAP. It’s necessary when you are building a startup and trying to show your customers the best service. For instance, we used to monitor our frontend errors in and fixed repeated crashes for the mobile Safari browser. That was a big win because I had started to hate that issue (everyone faced that issue which cost him plenty of hours to find the solution). Recently, my team made the decision to migrate our front-end projects from Airbrake to . And like a big part of other developers, I was struggling with uploading source maps there. Airbrake Sentry I think the following solutions can help those who have and versions on their projects. ~Next.js@12 ~@sentry/nextjs@7.3+ Solution 1 If you see a notification similar to that in the picture below on an Issue page inside Sentry don’t fret. skipped the uploading of some source maps for Next.js generated files. In my case, those were errors that related to the framework/main files. @sentry/nextjs A little explanation: When Sentry is reacting to any error or event, it tries to get the source maps from the archive that it has uploaded. According to the GitHub issue conversation, the framework's code does not get uploaded by default anymore and Sentry doesn’t have access to all files for resolving stack trace. release Take a look at this note from Sentry manual setup documentation: If you find that there are in-app frames in your client-side stack traces that aren't getting source-mapped even when most others are, it's likely because they are from files in rather than . By default, such files aren't uploaded because the majority of the files in only contain Next.js or third-party code, and are named in such a way that it's hard to distinguish between relevant files (ones containing your code) and irrelevant ones. static/chunks/ static/chunks/pages/ static/chunks/ To make it upload everything, try to expand your current with the next properties. next.config.js // next.config.js
module.exports = withSentryConfig(
  {
	...yourNextConfig,
	sentry: {
	   widenClientFileUpload: true,
	}
  },
  {
	...yourWebpackSentryConfig,
	ignore: [],
  },
  yourSentryConfig,
); It helped me to resolve 2 of the 3 errors that I got. For the majority, it’ll solve 100% of problems with source maps. Solution 2 Let’s move on. The last problem was related to a square brackets notation for dynamic route values. If I catch an error on the client side(browser side), the stack trace paths are sent encoded but they’re not decoded when they reach the sentry server. Since the path is encoded and the string is not equal to , the source map is not matched/not found/whatever. When Sentry is sending the frames, it includes this encoded URL instead of the decoded URL. %5Bslug%5D.js [slug].js I’ve found the solution in rewriting StackFrame. Just follow the next instructions: Install package to expand your current client config. @sentry/integrations npm install --save @sentry/integrations I your add the next instruction sentry.client.config.js import { RewriteFrames } from '@sentry/integrations';

Sentry.init({
  ...yourSentryClientConfig,
  integrations: [
    ...yourSentryClientConfig.integrations,
    new RewriteFrames({
      iteratee: frame => {
        frame.filename = frame.filename.replace(distDir, 'app:///_next');
        // here we are decoding our square brackets []
        frame.filename = decodeURI(frame.filename);
        return frame;
      },
    }),
  ],
}); Great! I hope this solves at least one person’s problems! As new technologies constantly evolve, their versions get mismatched and make many developers cry. But god bless a huge programmer community that is glad to share their experience with others.

How to Upload Source Maps to Sentry with Next.js

David Copperfield: Chapter 24 - My First Dissipation

In this article, you will walk through the creation of a simple Bash shell script to send messages to Telegram messenger using the Curl command. Then you will use this script to send a notification on every ssh login into your server. Create telegram bot To send a message to Telegram group or channel, you should first create your own bot. Just open Telegram, find @BotFather and type . Then follow instructions to create bot and get token to access the HTTP API. /start Create Channel Create a new Channel in Telegram and . So your bot could send messages to the Channel. add your bot as a member In order to get Channel Id, first, post any message to the Channel. Then use this link template to get Channel Id: https://api.telegram.org/bot<YourBOTToken>/getUpdates Here is a response example: { : , : [
    { : , : { : , : { : , // this is your channel id : , : }, : , : }
    }
  ]
} "ok" true "result" "update_id" 123 "channel_post" "message_id" 48 "chat" "id" -123123123 "title" "Notifications" "type" "channel" "date" 1574485277 "text" "test" Script to send message In order to send a message we could use simple command: curl 'https://api.telegram.org/bot<YourBOTToken>/sendMessage?chat_id=<channel_id>&text=<text>' But in programming, it is good practice to hide the low-level implementation. So we will create a Linux terminal command and could send messages with this simple command. telegram-send Lets create file telegram-send.sh touch telegram-send.sh Then add script to this file. Set your group id and token in script. GROUP_ID=<group_id>
BOT_TOKEN=<bot_token> [ == ]; 0 [ -z ] 0 [ -ne 1 ]; 0 curl -s --data --data > /dev/null #!/bin/bash # this 3 checks (if) are not necessary but should be convenient if " " $1 "-h" then echo "Usage: `basename ` \"text message\"" $0 exit fi if " " $1 then echo "Add message text as second arguments" exit fi if " " $# then echo "You can pass only one argument. For string with spaces put it on quotes" exit fi "text= " $1 "chat_id= " $GROUP_ID 'https://api.telegram.org/bot' $BOT_TOKEN '/sendMessage' It is not a good practice to store your token in that place, but for now, it is ok. Also, you could limit actions your bot could do in the Channel only to send messages. To run this script we should add permission chmod +x telegram-send.sh Now you can test it ./telegram-send.sh "Test message" In order to use this script from everywhere and type instead add it to /usr/bin/ folder telegram-send ./telegram-send.sh sudo mv telegram-send.sh /usr/bin/telegram-send Owner of all files in /usr/bin is root user. So let's do the same with our script: sudo chown root:root /usr/bin/telegram-send Now you can test it telegram-send "Test message" Send notification on SSH login All files with .sh extension in /etc/profile.d/ folder will be executed whenever a bash login shell is entered or the desktop session loads. Let's add a new script to send the notification. touch login-notify.sh Add this code to script login_ip= login_date= login_name= message= $ $ $ telegram-send #!/bin/bash # prepare any message you want " " $(echo $SSH_CONNECTION | cut -d " " -f 1) " " $(date +"%e %b %Y, %a %r") " " $(whoami) # For new line I use $'\n' here "New login to server" '\n' " " $login_name '\n' " " $login_ip '\n' " " $login_date #send it to telegram " " $message Then move this script to /etc/profile.d/ folder sudo mv login-notify.sh /etc/profile.d/login-notify.sh Now re-login to your web server and check it works. Previously published at https://bogomolov.tech/Telegram-notification-on-SSH-login/

How to Create a Simple Bash Shell Script to Send Messages on Telegram

Cómo crear un script simple de Bash Shell para enviar mensajes en Telegram

Hi, I'm Valerio, software engineer from Italy and CTO at Inspector. To help you get faster in identifying which part of the application is in trouble, we have designed an easy and ready to use way to directly monitor your application controllers and methods. Many of us continue to discover bugs and errors in the applications thanks to direct reports by users. It’s too dangerous today, because when a user reports a problem it's just too late. For a user that report a problem there are many others that simply stop using our application silently, moving to another product that fits their needs better. Emerging software houses needs to hide bugs and bottlenecks from users eyes as much as possible to provide a better customer experience than the competitors. A real-time monitoring tool help developers to address this problem, but many tools out there need a lot of resources and time to be installed and configured, making the life of developers more complicated. Inspector is a composer package to add real-time monitoring in your Laravel application, it's very easy to install and use, and it takes less than one minute to get started. Install the composer package Install our package by running the command below in your terminal: composer require inspector-apm/inspector-laravel Configure the API key Get a fresh API key by signing up for Inspector ( ) and creating a new application, it takes just a few seconds. https://app.inspector.dev/register You'll see installation instructions directly in the app screen: Put the API key into your environment file: INSPECTOR_API_KEY = 13 c 37 c 434 XXXXXXXXXXXX Http Requests Monitoring To activate inspection when your application is executed by an incoming http request you can use the middleware. WebRequestMonitoring Thanks to the middleware you are free to decide on which routes you want activate execution tracing, based on your routes configuration or on your personal monitoring preferences. middleware works like any other Laravel middleware you are familiar to. WebRequestMonitoring Basically you can attach the middleware in the class in one or more of your predefined middleware groups: App\Http\Kernel …,
      \Inspector\Laravel\Middleware\WebRequestMonitoring::class,
   ], …,
      \Inspector\Laravel\Middleware\WebRequestMonitoring::class,
   ]
] /** * The application’s route middleware groups. * * @var array */ protected $middlewareGroups = [ 'web' => [ 'api' => [ Identify Controller/Method execution If you prefer to have a clear visibility of what controller and method are executed based on any HTTP request, you can use the code below inside the boot method of one of your ServiceProvider. Maybe the best place could be . EventsServiceProvider }
   });
} use Illuminate \ Routing \ Events \ RouteMatched ; /** * Register any events for your application. * * @return void */ public function boot ( ) { parent ::boot(); /* * Changes the way inspector reports transactions in your dashboard. */ Event::listen(RouteMatched::class, function ( RouteMatched $event ) { $name = $event ->route->getActionName(); if (inspector()->isRecording()) { inspector()->currentTransaction()->name = $name ; } else { inspector()->startTransaction( $name ); This will change the way Inspector reports transactions in your dashboard from to . GET /path/{id} YourController@yourMethod Conclusion Inspector is a simple yet powerful real-time monitoring tool, designed to easy understand how your application processes are performing and get alerted if something goeas wrong. Thank you so much for reading it, if you want know more about Inspector come on our website . https://www.inspector.dev Previously published at https://www.inspector.dev/laravel-real-time-controller-monitoring/

Laravel Real-Time Controllers Monitoring with Inspector - Laravel Package

ML.NET: Machine Learning framework by Microsoft for .NET developers Whenever you think of data science and machine learning, the only two programming languages that pop up on your mind are Python and R. But, the question arises, what if the developer has knowledge of other languages than these? We have a solution in the form of Microsoft’s recently introduced build 2018 of its own version of the machine learning framework especially for .NET and C# developers. The framework is open source and cross-platform and can also run on Windows, Linux, and macOS. The developers always wanted to have a NuGet package which they can plug in with a. Net application for creating machine learning applications. After the release of the first version, ML.NET is still a baby but it is already showing the capability to turn into a tech giant. In this version, we can perform several machine learning tasks such as classification, regression and much more with the help of advanced . We can also train the model and predict using models along with other basic MAchine Learning tasks and algorithms. ML algorithms ML.NET can be further extended to function with ML libraries like TensorFLow, Accord.NET, CNTK and many more. What is inside ML.NET? As we had seen how the framework can be extended to work with any third-party libraries for smooth functioning. It also consists of some awesome libraries as well. For tasks like regression and classification, both training and consumption are present in ML.NET. Other than this, it also supports core data types, extensible pipelines, data structures, tooling support, advanced performance math and etc. Let us learn how to add this NuGet package in yours.Net applications. First of all, you need to have installed .NET Core 2.0 or later versions as ML.NET currently runs in a 64-bit process. After you are done with this, open up your Visual Studio 2017 → Create New Project → Select Core Web application as shown in the picture. Click on Empty option for now: Start by creating your application and once it is done, add the required Microsoft.ML NuGet package. Proceed your search with ‘Microsoft.ML’ in NuGet Package Manager and then click on Install: After completing all the steps, your package is safely installed and ready to use. You can also get started with ML.NET NuGet by installing it from the CLI: dotnet add package Microsoft.ML Also, from package manager as: Install-Package Microsoft.ML Furthermore, you can create your framework directly from . GitHub What are the ML.NET core components? ML.NET framework has been launched as a part of the .NET foundation and today the repo consist the .NET C# APIs for both consumption and model training along with the variant transformations and learners are required for many popular ML tasks like regression and classification. ML.NET is aimed to provide E2E workflow for infusing ML into .NET applications across different specializations like pre-processing, feature engineering, modeling, evaluation, and operationalization. You can also create your own sample application that will demonstrate how to use the ML model in your app by using which can be directly utilized in your applications. ML.NET templates Things to know before starting with ML.NET Initialize your Model When working with machine learning, firstly, you need to pick the best fit ML algorithms as machine learning has methods like clustering, regression, classification, and anomaly detection modules. Train the Model You need to train the machine learning model as training is the procedure of analyzing input data by model to learn the pattern by saving it as a trained model. For instance, if you create a CSV file in your application and in the CSV file by giving stock details like ItemID, Location, InQTY, OutQTY, TotalStock quantity and many more. You are needed to give this CSV file as an input to the model which can get trained and analyze this data to predict the results. Once the model is trained, it understands the pattern of the input and the resultant model needs to be saved for predicting the result. Prediction The prediction is also known as score where it needs to have the same column as the trained model. The score helps to generate the results based on the trained model. Evaluation After the model training is completed, evaluate will be performed. It performs by comparing the model with the test data and predicts the final results. Creating a C# Console App in Easy steps Step #1: Create an app After installing all prerequisites, Select Visual Studio 2017 from Programs in Start → New Project → Click Visual C# → Windows Desktop → Console APP in dot Net framework. Input your project name and Select OK. Step #2: Push down Microsoft ML package By right-clicking on your project, select Manage NuGet Packages… Then, search for Microsoft.ML in the Browser tab. Select Install, Accept the policy and wait until the installation proceeds. You will see Microsoft.ML package gets installed and all the Microsoft.ML references have been inserted into your project references. Step #3: Create Training and Evaluating the Data Now, you need to create a Model training and evaluation for the dataset by adding two CSV files by making a new folder called data in your project to add it to CSV files. Add the folder of Data By right-clicking the project, Add New Folder named ‘Data’. Create Train CSV file On right-clicking the Data folder Select Add → New Item → Text file; name as ‘StockTrain.csv’. Click on properties for changing the Copy to Output Directory to ‘Copy always’. Add CSV file details as shown in the figure. Here’s a note to the users that you have to fix the label and the features. A label field is the one which we need to predict in our sample. — Product Item ID (Feature) ItemID — Warehouse Location (Feature) LocCode — Total Item arrived at location (Feature) InQty — Total Item delivered to the location (Feature) OutQty — ItemType “In” means local manufactured and “out” means outsourcing. (Feature) ItemType — Total no of item stock. (Label) TotalStockQty Keep in mind that you always need a minimum of 100 records of the data to be added to train your model. Similarly, you will have to add an another CSV file for evaluating by creating a new file namely ‘StockTest.csv’. Step #4: Create a class for Input Data and Prediction Now, you need to create a new class for Input Data and prediction by right-clicking your project and adding a new class as ‘ItemStock.cs’. You first need to import the Microsfot.ML.Runtime.API in your class as given: Further, we need to add all the columns in the same order as in the class and try to set the column as 0 to 5. Next, you need to create a prediction class to add your prediction column. It is noted that the prediction column needs to be renamed as ‘Score’ with the float as the data type. The scoring column contains the predicted results in the regression model. Step #5: Program.cs You need to open ‘program.cs’ file to work with ML.NET and import all the required references. Dataset Path You need to give the ‘StockTrain.csv’ path for the train data as the final trained model needs to be saved for evaluation and result productions. Set the model path as ‘Model.zip’ file and the trained model will be saved in the zip file during runtime of the program in your bin folder automatically. static readonly string _Traindatapath = Path.Combine(Environment.CurrentDirectory, “Data”, “StockTrain.csv”); static readonly string _Evaluatedatapath = Path.Combine(Environment.CurrentDirectory, “Data”, “StockTest.csv”); static readonly string _modelpath = Path.Combine(Environment.CurrentDirectory, “Data”, “Model.zip”); You can also change the Main method to async Task Main method like the code given below: Before that, you need to perform two crucial tasks to run your program successfully. First, set Platform Target as x64 as ML.NET runs in x64 and second is to run the program with async Task Main method, change the language version to c#7.1. Work with the Training Model Firstly, you need to train the model and later save it to the zip file which is your main method to call the prediction model and pass the ItemStock itemStockQtyPrediction class to return the model to the main method: In the method shown above, you need to add the function to train the model and save it to the zip file. In training, first of all, you will be working with the LearningPipeline() as it loads all the training data to train the model. Second, comes the TextLoader to get all the data from the train CSV file for training and set the use header to avoid reading the first row from the CSV file. The essential part is the predicted values to be defined in the training model. It needs numeric features to transform the categorical data and you have to add all the featured columns to be trained and evaluated. Adding Learning Algorithm In this code snippet, you are going to use FastTreeREgressor learner which has to get added to your pipeline. Finally, you need to train and save the model by the method given below: More to this, you need to evaluate the model by checking out the model with the test data and predict the final results. For doing so, you are required to call the Evaluate method from your main method and pass the trained model to this model. We pass the trained model in the Evaluate method with the sample CSV test data. Using text loader, load all the data from test data CSV file for model evaluation. Using RegressionEvaluator method we can evaluate the model with the test data and produce evaluation metrics by displaying both the Root Mean Squared (RMS) and RSquared metrics value. Final Prediction Results Now it’s time to produce the final results. Begin by creating a new Class named ‘ItemStock.cs’ and add values to it that are created and defined in the columns for Model training. You can also run the program and see the results in the command window as given below: After creating and running the program we can see the Model.zip file in the folder name ‘Data’ inside the application root bin folder to see our StockTrain and StockTest CSV file. The model gets trained with the help of this CSV file and the results will get stored in Model.zip file. Summing Up We can conclude ML.NET is an amazing framework for all the .NET developers who are looking forward to working with machine learning. In the present times, only the preview version of ML.NET is available but we cannot really wait for the public version to get released. If you are a .NET developer and not aware much about the machine learning framework then ML.NET is definitely for you. I hope you enjoyed reading this article. Keep Learning! Author Bio: HP Morgan working as a Tech analyst at Tatvasoft.com.au. A customer . In leisure time he likes blogging and also published his bylines at major publications. Software Development company in Australia <a href="https://medium.com/media/3c851dac986ab6dbb2d1aaa91205a8eb/href">https://medium.com/media/3c851dac986ab6dbb2d1aaa91205a8eb/href</a>

ML.NET: Machine Learning framework by Microsoft for .NET developers

In this tutorial I will go over how to easily integrate AWS DynamoDB with Flask, Python’s web development server. You will be creating a simple RESTful API that allows you to pull items from DynamoDB. DynamoDB DynamoDB is AWS’ answer to the NoSQL cloud database. Similar to other services, DynamoDB allows you to spin up databases for an application without having to worry about infrastructure, backups, and redundancy. You are able to interact with the database through the AWS console, or through the AWS API. In this tutorial we will be interacting with AWS using their command line package, as well as through boto3, a wrapper. Both of these methods make use of the AWS API. AWS Python Boto3 Boto3 is a Python package that acts as a wrapper around the AWS CLI. It is the recommended package for interacting with AWS using Python. Flask Flask is Python web framework. At the most basic level it provides a development server and debugger. Flask is highly extendable. Allowing the addition of other application features, such as: form validation, upload handling, and authentication. It will be used in this tutorial for it’s web server capabilities. Prerequisites This tutorial assumes that you have a basic understanding of the following: Linux CLI (bash) Python3 programming pip Flask AWS and IAM If you do not have Python3 already installed on your local machine please download the latest version . here , pythons package manager, should come with the Python installation. If for some reason it's not on your local machine go for instructions on how to install it. pip here If you do not have the AWS CLI installed run the following terminal command: pip install awscli --upgrade --user allows you to run AWS commands from the command line. With this package we are able to create EC2 instance, insert objects into an S3 instance, and delete items from DynamoDB tables, just to name a few examples. It's also a dependency allowing it to interact with AWS. awscli boto3 Next you need to configure so that it has access and permissions to your AWS account. awscli aws configure This should give you the following prompts: AWS Access Key ID [None]: ***PASTE ACCESS KEY ID HERE*** AWS Secret Access Key [None]: ***PASTE SECRET ACCESS KEY HERE*** Default region name [None]: ***TYPE YOUR PREFERRED REGION*** Default output format [None]: json The Access Key ID and Secret Access Key you enter here will define what kind of permissions will have when interacting with AWS. You will get this information from the IAM console. If you have no previous experience with AWS permissions please go for more information. awscli here You should also specify the default region. This will be the region on which your will run most of it's commands by default. A list of AWS available regions can be found . awscli here The default output format is set to json here in order to make it readable, but this can be changed. Creating a Test Table Since the only operation our API will expose is a very basic , you need to create a new DynamoDB table and populate it with a few items. This will be done using the AWS CLI. GET First, create a file that specifies the table schema. json Create a file through the terminal. create-table.json touch create-table.json And add the following code. {"TableName": "YourTestTable","KeySchema": [{ "AttributeName": "Artist", "KeyType": "HASH" },{ "AttributeName": "SongTitle", "KeyType": "RANGE" }],"AttributeDefinitions": [{ "AttributeName": "Artist", "AttributeType": "S" },{ "AttributeName": "SongTitle", "AttributeType": "S" }],"ProvisionedThroughput": {"ReadCapacityUnits": 5,"WriteCapacityUnits": 5}} This will tell AWS to create a new table named with string attributes and . It also specifies that both the and attributes will be used as the primary key. YourTestTable Artist SongTitle Artist SongTitle The key tells DynamoDB what to set the read and write capacities to. More information can be found ProvisinedThroughput here Next, create a file named . batch-write.json touch batch-write.json And insert the json code below: {"YourTestTable": [{"PutRequest": {"Item":{"Artist": {"S": "Bowie"},"SongTitle": {"S": "Life on Mars"}}}},{"PutRequest": {"Item": {"Artist": {"S": "Rolling Stones"},"SongTitle": {"S": "Paint it Black"}}}},{"PutRequest": {"Item" : {"Artist": {"S": "The Doors"},"SongTitle": {"S": "Light My Fire"}}}}]} The json file above will be parsed by when running a batch write command on our table. As you can see we are passing a list of three , which each contains an that consist of a dictionary of key/value pairs corresponding to our table attributes. awscli PutRequest Item Finally, we run the terminal commands to create and populate our table. aws dynamodb create-table --cli-input-json file://create-table.json 

aws dynamodb batch-write-item --request-items file://batch-write.json Should no error have occurred you should now have a new table that is populated. You can go to the AWS console to verify that the table is there. Note: The table will be created in the default region that was specified as part of the AWS configuration. Project Setup Now that your local machine has all of the dependencies installed you now need to create the root project directory. mkdir flaskdynamodb cd flaskdynamodb Since we will be installing python packages we need to create a virtual environment. Creating a virtual environment copies the Python executable to the package so that any calls to from the command line will run the virtual environments local Python executable. The virtual environment will also install packages to this same environment. Preventing package conflicts with the system-wide packages. python pip Note: In some linux distributions the python virtual environment module does not come pre-installed. In the case of Ubuntu and Debian distributions, you would need to install it with the following command **sudo apt-get install python3-venv** . If the commands below do not work on your system you might need to install **python3-venv** Create the virtual environment with the following terminal commands: python3 -m venv env source env/bin/activate The option tells to run the virtual environment module, and create a new virtual environment directory named . -m python env The command activates the virtual environment. This means that your system will now use the Python executable and pip packages installed within the virtual environment folder. source env/bin/activate Note: In the python command above is assumed **python3** is referring to Python3. This command might not work if you have **python** linked to Python3 on your system Installation Now that the project directory and virtual environment are setup it’s time to install and flask boto pip install flask pip install boto3 I will mention again that these packages are going to be installed to the virtual environment directory. If you were to look at the directory you would see the directories for and . env/lib/site_packages boto3 flask Flask Configuration Before any code is written you need to export the environment variable which tells what the main application file is going to be. flask export FLASK_APP=app.py As you might have noticed the file has not been created yet. Later on we will create this file, which will contain our Flask application code. app.py Application Code You will now create the files where the actual code is going to reside. touch app.py aws_controller.py Add the following code to the : app.py from flask import Flask app = Flask(__name__) @app.route('/')def index():return "This is the main page." @app.route('/get-items')def get_items():return 'TODO: Implement Functionality' if __name__ == '__main__':app.run() The above code creates a Flask app with two routes, and , exposed. At the moment these routes will simply respond with text. We will return to this file later in order to have return our call to AWS. / /get-items /get-items Note: If you are not sure how Flask works take a look at their quickstart guide . It’s time to implement the code that actually interacts with DynamoDB in the file. aws_controller.py import boto3 dynamo_client = boto3.client('dynamodb') def get_items():return dynamo_client.scan(TableName='YourTestTable') So what does the code above do? First the module is imported. boto3 creates a client that allows us to interact with the DynamoDB API. dynamo_client = boto3.client('dynamodb') The function runs a scan of the table name provided. In this case we are scanning . In DynamoDB a returns the entire table. This is in contrast to a operation, which searches a table based upon a primary key attribute value. In this case a is run in order to get the entire table. get_items YourTestTable scan query scan It’s time to go back and modify the Flask code in order for it to run the function. get_items Change the app.py file to contain the following code: from flask import Flask, jsonifyimport aws_controller app = Flask(__name__) @app.route('/')def index():return "This is the main page." @app.route('/get-items')def get_items():return jsonify(aws_controller.get_items()) if __name__ == '__main__':app.run() There are two things we changed in this file We imported the . This will give us access to the function. aws_controller.py get_items The route now returns the result from the function, but not before passing the result to which converts the object into the json equivalent which the client-side browser is able to render. /get-items aws_controller.get_items jsonify() Now that everything is setup you can start the Flask web server by running the following command in your terminal. flask run If Flask was able to bind to the correct socket the server should now be running and you should see the below output. flaskdynamodb$ run Serving Flask app "app.py" Environment: production Do not use the development server in a production environment. a production WSGI server instead. Debug mode: off Running on http://127.0.0.1:5000/ (Press to quit)127.0.0.1 - [12/Dec/2018 22:51:21] "GET / HTTP/1.1" 404 - - - [12/Dec/2018 22:51:21] "GET /favicon.ico HTTP/1.1" 404 - - - [12/Dec/2018 22:51:26] "GET /get-items HTTP/1.1" 200 - - - [12/Dec/2018 22:51:26] "GET /favicon.ico HTTP/1.1" 404 - (env) flask * * WARNING: Use * * CTRL+C - 127.0.0.1 127.0.0.1 127.0.0.1 Open your browser and go to the url specified in the output. This will be by default. http://127.0.0.1:5000/ Now enter the url for . . /get-items http://127.0.0.1:5000/get-items You should see a list of all the items from the table. That’s it! You now have a simple RESTful API that interacts with DynamoDB. Thanks for following along. GitHub Originally published at blog.albertoacuna.com on December 13, 2018.

Using AWS DynamoDB with Flask

A short article about Golang aimed for newer developers or those who have not spent much time researching the language and would like a short, concise, well thought-out, and original introduction. All code written is within a repl. Go is real cool, something that is extra cool about it is that it is the highest paying technology according to Stack Overflows 2017 dataset. The average pay for a Go developer is ~ : 110k a year this link right here! (Technology -> Top Paying Technologies on sidebar for verification) Hot damn! But, that is only a piece of the reason to learn Go. The main reason is this: Why? Well, is a well thought out modern language that utilises many of the best practices of languages created before it. learning it is only going to speed up your understanding of fundamental computer science topics. Golang programming It is also a language that was made by Google to take care of the massive amount of data and problems associated with handling their search engine that almost everybody uses. On another note, to fully learn Go is to learn how to build software that provides answers for low level problems. Another way to say it is software that provides services for other software. In a way, if you know Golang then you know how to build programs that touch the root of this field. Let’s delve into some code. The story begins as so: It is now, this time, as in, 2018. But suddenly time jumps… 240 years ahead. As if you were Austin Powers frozen all this time. And it is up to you to suddenly save the universe. With a twist at the end. I wrote a piece of code, around 150 lines, that tells the very short story in its entirety (lots of prints) which I will put at the end. I am going to go through the code from start to finish prior. Starts simple, then gets a bit dense. package main import ("fmt""time""strconv""io""strings") ? All Go source code is part of a package, and each file necessitates a package statement. is the file where the code runs. Other package files are modules imported into package main. The modules are reusable pieces of code to use or implement within . package main package main package main So, the imported modules contain source code which I will use within this file. type Aliens struct {species int} type NotEarthling struct {total intcentury stringthingamajig string} type Earthling struct {total intcentury stringname stringage int64} type WordSpaceship struct {health stringweapon string} type NumberSpaceship struct {health intweapon int} Multiple structs with different usages. ? It is how you create an object that can have different types for each value. The key is the word written, a string. Though, each key must have the specified type, it is not dynamic. What’s a struct The other major way to create objects is with a . Though, in that case every key must be a single type as well as the values: map all keys must be string, all values must be int make(map[string]int) So, in maps each key must be of one type and each value must be of one type. In structs, different types are allowed for each value. var you = Earthling{century: "21st", name: "you", age: 24} func main() {defer fmt.Println("Is this all a dream?") now := time.Now()  
nanos := now.UnixNano()  
fmt.Printf("Right now it is: %v! \\nPop! AHHHHH\\n\\n", now) The occurs in the global scope, so it must be initialised with the keyword. This is to initialise structs. Notice that I specified the key and set it’s value to the corresponding type written in the struct definition. Notice how I have not initialised every key/value (you not need to). variable declaration var one way ? This creates a last-in-first-out stack of function invocations to be called the completion of . I say a stack as can be called multiple times and each time it is called the last function pushed onto the stack is called first. defer after func main() {...} defer This is to say that the type will be figured out dynamically by the compiler. As in, when initialising a value to a variable in this way you do not need to specify the type, the only way to do so. :=, what is this? returns this: 2017–12–28 01:41:05.240081928 +0000 UTC time.Now() returns this: 1514425756675856179 which is the amount of nanoseconds that have occurred since the creation of Golang 8 years ago. now.UnixNano() allows logging out values in varying forms: Printf gives the default value %v gives the type of the value %T are two of the major forms. Still in the function main below. nanos = nanos + 7600000000000000000  

years := (nanos - now.UnixNano())/1000000000/31622400  

now = time.Unix(0, nanos)

fmt.Printf("And now it is: %v!\\nOh hell!\\n\\n", now) At the beginning one goes 7600000000000000000 nanoseconds into the future which is ~ 240 years. is a calculation, convert to seconds then to years. years will convert the nanoseconds to: 2258–10–29 00:55:56.675856179 +0000 UTC time.Unix(seconds, nano seconds) var e \[\]Earthling  
var ne \[\]NotEarthling

for i := 0; i < 70000; i++ {  
    e = append(e, Earthling{})  
}  

for i := 0; i < 44; i++ {  
    ne = append(ne, NotEarthling{})  
}  

aliens := Aliens{2}

futureEarthling := Earthling{len(e), "22nd", "The Future", 32141}  

futureNotEarthling := NotEarthling{len(ne), "99th", "Grok grok grok"} The keyword calls set a array (empty array) that can only be filled with the specified type. One cannot add ints, strings, etc. to this array. var zero valued In the following , I am to the arrays. for loops appending empty structs of the specified type There are only two alien species in this case. and . Earthlings NotEarthlings Notice, how is set to the struct without specifying the key, this is a shorthand, as long as you place the values in the corresponding order defined in the struct, in this case: , then the fields can be filled out in this way. futureEarthling Earthlings {int, string, string, int64} Now there is a function called attached to each object… lets check out that separate, not in main, function. Greet Earthling func (e *Earthling) Greet(y int64) string { century, \_ := strconv.ParseInt(e.century\[0:2\], 0, 64)

if century > 21 && century < 30 {

  age := strconv.FormatInt(you.age, 10)

  str := "Welcome to the future young Padawan, you are in the: " + e.century + " century. And I am: " + e.name + ". You are now... " + age + "years old. The world is under attack, and you have been revived to defend it! Big scary invader has something to say..."

  return str

} else {  
  e.age = e.age + y  
  return "Where am I???"  
} } Ok, so this corresponds to the existential crisis this person is going through, waking up so far into the future, and some random future guy that has something to say! Hmm… look at the top: . What’s this? Well, is going to be the instance of the object the method is called on. And the ? . I invite you to open the repl below, delete that and see what happens. (e *Earthling) e Earthling * This is a pointer * What it means is this: . If you do not, anything you do on will not alter the object within the main function. The pointer assures that the object can be altered. you.Greet(year) is creating a copy of _you_ unless you point at it’s memory address you We also have a new library in this code snippet… . This is the library to use when you want to change an int to a string, vice versa, or many other types. Go has so many data types… int, int8, int16, int32, int64. And all I named is int there, in other words, one can go on and on… type galore. strconv If you look closely, the entire reason I used a pointer was to alter the age of the young Padawan. numberShip := NumberSpaceship{100, 3}wordShip := WordSpaceship{"Read this to defeat me.", "Powerful words!"} wordAttack := make(chan int)finished := make(chan int) go func() {for {numberShip.health = numberShip.health - <-wordAttackif numberShip.health <= 0 {Extinction(&aliens)finished <- 0}}}() fmt.Println(Fight(&numberShip, &wordShip, wordAttack, finished)) Ok, first of all, the first parameter of both structs is their health. So, for the the health is 100, and for the the health is a sentence… …? I’ll go into that in the function at the bottom, , which uses what is called a . numberShip wordShip "Read this to defeat me" Fight Reader creates what is called a channel. A conduit to send/receive values. Sending is as so: , and receiving as: . make(chan int) <-wordAttack finished <- 0 is the creation of a When working with channels and goroutines in unison, the main thing to remember is that the goroutine continues So, let’s go check out where it is getting it’s values, the function. go func() {…}() goroutine. as long as the channel sends it values. Fight func Fight(ns *NumberSpaceship, ws *WordSpaceship, c, f chan int) string {x := len(ws.weapon)r := strings.NewReader(ws.health)b := make([]byte, ns.weapon)for {select {case c <- x:fmt.Println("Hit it!")case <-f:fmt.Println("He's finished!")return "\nYou saved time, space, eternity, everything!\n"}_, err := r.Read(b)if err == io.EOF {return "You failed, the universe is to end."}}} First, check out the function signature. The function was called by the variables memory address (with ). In the signature, the function expects a (ie. a variable) as the argument for both and . referencing & pointer referenced NumberSpaceship WordSpaceship Also, check out how both type is only written once. Parameter types can be grouped if they are next to one another and the same exact type. chan ints First, the library, this “implements simple functions to manipulate UTF-8 encoded strings.” In this function a will be created to read a string. strings reader Ok, the implementation of the string reader: returns a new that will read from s: . r := strings.NewReader(ws.health) Reader "Read this to defeat me" returns a byte slice of the length specified. is the value 3. b := make([]byte, ns.weapon) ws.weapon is more nuanced. can also be a variable name, let’s call it . If exists it means that the amount of bytes read by is to be returned to . But if left as is then one does not have to use the value returned. Otherwise, you have to, which is to say that So, for one, returns the amount of bytes read, and secondly it returns an error if and only if the entire string was read, in which case an (end of file) error is returned. Otherwise, it’s value is: . _, err := r.Read(b) _ n n Read n Go does not allow one to not use declared variables. Read io.EOF <nil> So, is the reader. is what the reading of the string is put into. is the function that is called to make that come about. r b Read So, to summarise the , and why it is being used, once the string is read the wins, and the loses. Very intense battle. Reader NumberSpaceship WordSpaceship A quick side note: is to say, do an infinite loop until the function returns. for {…} As for the attack of the . WordSpaceship is waiting on multiple communication operations, both channels, and . When one is ready to send out its data or receive data, it will continue to do so as long as the function does not return. select c f is to say, continually send the value of x to this channel. Then, going back to ’s goroutine, do this: to damage the ship. So, the channel is emptied of the x it just received. case <- x func main numberShip.health = numberShip.health — <-wordAttack channel receives a value and sends it out right after in the corresponding goroutine solely runs when f has a value associated to it and this only happens when this occurs in : , after the if statement. case <- f main finished <- 0 That’s the fight! And after the battle, whoever lost, well, their entire species goes extinct… this was how it was written, the logic is not combined in the real code as so though. type Aliens struct {species int} func Extinction(a *Aliens) {a.species = a.species - 1} func main() {aliens := Aliens{2}Extinction(&aliens)} Quite an intense bit of logic. And the entirety of what is logged out from the real code! Right now it is: 2017-12-28 21:40:35.066259304 +0000 UTC!Pop! AHHHHH And now it is: 2258-10-29 20:47:15.066259304 +0000 UTC!Oh hell! Where am I??? Welcome to the future young Padawan, you are in the: 22nd century. And I am: The Future. You are now... 264 years old. The Universe is under attack, and you have been revived to defend it! Big scary invader has something to say... Tord thaz geck hild quemp 240! He challenged you! You're the chosen one, so you must save the Universe! Jump on this spaceship. VRRRROOOOOOOOOOOOMMMMMMMM BOOM BOP BOOM BOP Hit it!Hit it!Hit it!Hit it!Hit it!Hit it!Hit it!He's finished! You saved time, space, eternity, everything! AHHH, the aliens left a bomb, the Universe is to disintegrate into nothingness! Some higher being sort of thing says: There are  0  sentient beings left alive. Was that all a dream? And the repl: _Powerful and simple online compiler, IDE, interpreter, and REPL. Code, compile, and run code in JavaScript, Python…_repl.it repl.it - GolangArticleFrozenSpaceGuy by @jerrymuzsik I highly recommend this if you are interested in learning more Go, great introductory documentation/practice problems! tour.golang.org A Tour of Go Thanks very much! You the best! Mr. Golang has a bit to say as well. I thanky thee muchee for readee thisee thingee, cheerees mee buddy

A Space Themed Intro to Golang

If you are an entrepreneur outside a mature startup ecosystem, reading this fun guide will increase your odds of surviving. ⚠️ Warning ⚠️ Reading this guide might increase your odds to survive and thrive. Not reading it won’t change anything, because you won’t know what could have changed. So, good luck with not reading it! In case you don’t know whether you’re in an emerging startup ecosystem, that’s because you are and you have no idea about entrepreneurship. No worries, you’ll be fine! Just read along. This is a fun guide and should be read as such. Nevertheless, you’ll find thoughtful pieces of advice for your venture’s success. If there’s anything you might share to help fellow entrepreneurs survive, please don’t hesitate to comment below. {🍑} Butt-Naked I know the story about this guy who’s a sleepwalker. He was visiting China for business and staying in a luxury hotel. He woke up from this weird dream in which he wasn’t able to open the bathroom’s door. He was standing in front of the door with his bladder about to burst. But hey, if you had a sleepwalking issue, I guess you would be wise enough not to sleep naked in a hotel room, right?? Well, he wasn’t. A bright, warm light on his head woke him up. He had locked himself outside his room, on the 80th floor of a luxury hotel in Shanghai. He was butt-naked! No cellphone, no room-key, just an unbearable need to empty the bladder. Think fast That’s when quick solutions must take place! In such large hotels, it wouldn’t take long for someone to show up. In China, walking naked in public spaces is sexual harassment. So, he sprinted, bare-naked, towards the EXIT sign. Please take a moment to visualize: a mid-aged man running naked through the long corridors of a five stars hotel. Quite a thrilling moment in life. He quickly walked through the fire exit door. Closing the door behind him, he finally took a breath. He found himself in a small room that separated the circulation area from the emergency stairways. Just like in a game, there he found all tools needed to “win the phase”. Leisure Suit Larry An intercom at the wall. A couple of empty laundry bags laying on the floor — those items must have been there on purpose. He tied two laundry bags together and wrapped them around the waist, covering his intimate parts and giving him a Tarzan look. Dial nine If you find yourself in the same situation one day, the only thing you need to remember is to . Nine is the universal number to reach the reception or an attendant — either should be able to provide help. dial nine The number nine is located on the second row starting from the bottom, to the right of the keypad — just in case for some reason your vision is impaired. Quite a life saver! Stay Cool Help came 10 minutes later. Upon opening the emergency exit-door, the front desk’s assistant jumped back with a surprised look while staring at the man’s odd outfit. Trying to act as casual as possible, the adventurous naked man followed calmly through the five stars hotel’s corridors back to his room. With a magic swipe of a master-key, the front desk’s assistant opened the door, putting an end to this unexpected adventure. A relief could never be so blissful! So much for a short but unforgettable experience in China. The butt-naked philosophy Being an entrepreneur in an emerging ecosystem is equivalent to being butt-naked in public space. It is not cool to be butt-naked in public areas. Knowingly, you need to act fast to find solutions to make your startup thrive. startup Stay unrestful until your startup starts generating revenues. Move quickly towards breakeven. When you reach it for the first time, remember to take a deep breath! Your venture has just begun, and you still have a long thrilling ride ahead. For better or for worse; Eventually, you will find the EXIT sign. **{🍑}_butt-naked**_think.fast 🤔⚡️_dial.nine 9️⃣_stay.cool 😎_butt-naked.philosophy 👳🏾 {🚽} Essentials In this section, I will introduce you to the idea of becoming a digital nomad. Becoming a digital nomad requires preparation in every sense. But most importantly, you’ll need to make sure that you have the correct equipment for your undertaking. Being a digital nomad First and foremost, you don’t talk about being a digital nomad in the first person. You shall never say “I’m a digital nomad”. Others might say “He’s a digital nomad”. You may acknowledge. It’s a title you’ll earn. Being a digital nomad is the synonym of preparedness. You must be mentally prepared to deal with the stresses of coffee lines, poor Wi-Fi, canceled meetings and last minute flights. Unconstrained access to coffee You must be aware of your survival needs, especially of the constant need for — and ways of obtaining — coffee. In general, an entrepreneur’s body cannot survive longer than three hours without a cup of coffee. So, you must rest sure that you’ll have open access to this fundamental source of energy. Along your way, you will find two primary sources of coffee: paid and unpaid sources. Unpaid sources of coffee are not to be found in the outdoors. You are likely to find them in conferences, supermarket tastings, and hotel receptions. Don’t be ashamed of providing yourself a free productivity boost. Laptop, the ultimate survival tool A LapTop is your most important survival tool. It must be chosen wisely and handled with care. It must be kept in perfect working conditions. Wrapping your laptop in tech stickers proves seniority and improves credibility. Each sticker represents a war-badge that will indicate your rank within the ecosystem. It is essential to learn how to read those badges, so you know if your fellow entrepreneur outranks you before engaging in heated discussions. Never carry sharp objects A digital nomad’s is to be 100% mobile. He or she must be ready to get on a plane at any time. The most humiliating situation a digital nomad may go through is being frisked at an airport’s x-ray. The digital nomad knows what to carry on and walks smoothly through the security check. raison d’être **{🚽}_essentials**_being.a.digital.nomad 🏃🏽_unconstrained.access.to.coffee ☕️_laptop.the.ultimate.survival.tool 💻🎖_never.carry.sharp.objects 🚫🔪 {👾} Strategy Whether on an elevator pitch or undergoing sleepless nights of due diligence — both may lead to a heart attack — the same disciplines and quick thinking are needed. The following strategies can significantly increase your chances of surviving. Time Warping The most valuable asset for an entrepreneur is time. An excellent expression of Silicon Valley’s success is its culture of efficiently managing time. Outsiders are often surprised by the fact that productive meetings won’t last longer than half an hour. Depending on the notoriety of the person you’re meeting with, a fifteen minutes meeting is a privilege for few. Be laser sharp. Objectiveness is an excellent skill to have. If you can adjourn the meeting five minutes earlier, do so. It means you have managed to bend time and you’re now a time-traveler. Allow the other party to decide whether to close the meeting earlier or not. That strategy generates a positive chemistry in a busy investor’s brain. Use this ability wisely in your ecosystem. With cultural adaptations, you’ll show a differential among entrepreneurs. Investors prefer sharp founders. Never be late Being on time is a critical factor in building trust. Unconsciously, a delay can be interpreted as lack of interest or worse, lack of respect. There are cultures, where delays are acceptable. You’ll never know how the other party will perceive it. It doesn’t matter if you’re pitching to an institutional investor or an angel. Investors are always in a hurry. Arrive at the latest five minutes before the meeting. Same day feedback It is crucial never to exceed the 24 hours limit to follow up on an investor’s meeting. Don’t wait until the next day to send a thank you note. Any symptoms of ADHD (Attention Deficit Hyperactivity Disorder) can sabotage that relationship you’ve spent valuable time building. Follow up immediately after the meeting. That’s a simple action that will save you time and show that you’re an organized and trustworthy entrepreneur. 2-Step Verification Also known as two-factor authentication, this extra layer of security has become a vital annoyance in our every-days. No matter if it’s from Apple, Facebook, Google, or other tech services, you just have to live with it. It ensures that you’re the only person who can access your account, even if someone knows your password. is all about networking. You meet people, who introduce you to people and vice-versa. Repeatedly introducing different people that may have productive business generates good karma and eventually leads to payback. So, network wisely and collaboratively. Venture Capital You can hack the 2-Step Verification of real life. Building trust in a one-hour meeting isn’t straightforward. More and more people tend to rely on common references to find endorsement. So, you shouldn’t wait for people to talk good about you! For every critical meeting find a common friend that can endorse you. Know your deltas Disciplined entrepreneurs usually do their homework and prepare a beautiful pitch presentation of their startup. Yet, the majority fail at knowing their numbers by heart. Knowing your revenues is an obvious advice. Most of the smart-investors aren’t concerned about your nominal terms. They are seeking for deltas and ratios that may reveal an exponential startup. Know your growth rates, customer acquisition costs, lifetime value of customers, burn rate, runway among other indicators. _time.warping ⏰👽_never.be.late 🕛_same.day.feedback 🗣_2-step.verification 👥_know.your.deltas 🤓 {👾}_strategy {⛅️} Climate & Terrain No ties Although these basic survival strategies and techniques apply to any emerging startup ecosystem, conditions vary widely around the world. You can use the following map to help you choose the appropriate clothing. As long as you’re not wearing a tie for your pitch, you’re doing good — hoodies are only for billionaires. Image courtesy of the UK Meteorological Office The Starbucks-meter If you haven’t yet figured out whether you’re in an emerging startup ecosystem or not, this sophisticated measuring tool will help you locate your startup. Besides the Bay Area and Israel, there are only two sorts of startup ecosystems. Those where you can find a Starbucks and those where you can’t. If you’re in the ladder, you’re a real deal emerging startup ecosystem entrepreneur. You’re a real survivor! Or, you’re the craziest person on Earth, and this guide was designed to support you. **{⛅️}_climate.&.terrain**_no.ties 🚫👔_the.starbucks-meter 🌟🌡 {🍖} Food As an entrepreneur, you shouldn’t need hunting skills. But in case you do, I advise you to reconsider the idea of starting your business wherever this is. So, let’s start from the assumption that you won’t be hunting for food anytime soon. Seven days to build You still have to worry about eating. Maybe you’ll be preparing food. But, assuming it takes 30 min to make one meal, let’s do the math: if you cook once a day for 365 days, it means that you spend more than seven days per year cooking. Christians believe that God built the Earth in six days and rested on the seventh. Taken from that perspective, imagine what you could do for your startup! So, you’d better find somewhere cheap to eat. “May I?” Here’s an integral part of your survival strategy. Politeness is never too much! When eating with prospective investors for lunch or dinner, it is essential to not be on your elbows chewing with open mouth. That’s your opportunity to show manners and make your parents proud. But manners can play in your favor — this advice is only valid when repeatedly performed— At the restaurant when the check arrives, don’t offer to split. Just ask: “May I?” Investors know you’re struggling every day to pay your bills. An incontrollable sentiment of parenthood will be triggered, and investors will do what they do best: Write checks! **{🍖}_food**_seven.days.to.build ⛪_may.I.? 🙄 {🏡} Camp Craft I have a good friend who became a hard-core serial entrepreneur that never succeeded. What also means that he never made enough money to pay for a satisfactory living. He developed ultimate survival skills, and his experience was crucial for drafting this guide. Trust your backpack During days of struggle, my friend and fellow entrepreneur moved twelve times in less than a year and never paid a penny for rent. He deserved a True Digital Nomad award. Living at different friends’ houses. Being 100% mobile. Not knowing where to go next. But always carrying your startup with yourself. You have to trust your backpack, your laptop, and your digital nomad instincts! Rely on friends Play hard, party hard. You may be a genius entrepreneur who can code and envision the future better than anyone. You still need friends to succeed. Family’s support, trustworthy relationships, and networking. You need to keep a life-balance. Anxiety may impair your vision of the future. Take a break. Enjoy life. Moments of productive procrastination lead to higher productivity. So, remember to stay close to your friends, they will be there no matter if you succeed or fail. **{🏡}_camp.craft**_trust.your.backpack 💼_rely.on.friends 👯 😷 Health Dodging a heart-attack I mentioned that you should find somewhere cheap to eat. Well, let’s focus on the idea of eating cheap while staying healthy. That leads to the thin balance, in which you eat cheap but still avoid a lifestyle that can lead to a heart attack. Not too long ago, I experienced the drama of having a close friend and entrepreneur suffer a heart-attack. Those were critical days for his startup. It was a life-changing event for his family. Fortunately, they all made it through! Success is a road After his heart-attack, some investors gave up on him; other stood firmly by his side. One year past, he managed to double his startup’s revenues. He is a real survivor. More than a friend, he is an inspiration. As we walked through the valley of shadows, investor, and entrepreneur, we knew many would fail us. We still have a long way, but we’re comforted by the knowledge that success is a road, not a destination. **{😷}_health**_dodging.a.heart-attack 💔_success.is.a.road 🏆 {🤑} Exit Exiting isn’t a purpose Some startups grow fast; other startups grow steady; many startups fail. I am not keen to advising founders to focus on finding ways to exit. A startup’s primary purpose is to develop indispensable products. Exit opportunities are a consequence of developing indispensable products. In emerging startup ecosystems, exiting is not as straightforward as it is in developed startup ecosystems. Dedicate yourself to building a startup that survives and thrives. Eventually, exit opportunities will knock at your door. **{🤑}_exit**_exiting.isn't.a.purpose 🔥🚪 Will you continue sitting there waiting for your startup to take off? Why are you still procrastinating and reading this stupid guide? Remember you’re butt-naked in a public space! ✅ TL;DR Thanks for reading this far, or not! What matters is you’re here. Print this cheat-sheet; it has been designed to fit in your pocket. Keep it handy; it may save you from the most unexpected situations. **{🍑}_butt-naked**_think.fast 🤔⚡️_dial.nine 9️⃣_stay.cool 😎_butt-naked.philosophy 👳🏾 **{🚽}_essentials**_being.a.digital.nomad 🏃🏽_unconstrained.access.to.coffee ☕️_laptop.the.ultimate.survival.tool 💻🎖_never.carry.sharp.objects 🚫🔪 _time.warping ⏰👽_never.be.late 🕛_same.day.feedback 🗣_2-step.verification 👥_know.your.deltas 🤓 {👾}_strategy **{⛅️}_climate.&.terrain**_no.ties 🚫👔_the.starbucks-meter 🌟🌡 **{🍖}_food**_seven.days.to.build ⛪_may.I.? 🙄 **{🏡}_camp.craft**_trust.your.backpack 💼_rely.on.friends 👯 **{😷}_health**_dodging.a.heart-attack 💔_success.is.a.road 🏆 **{🤑}_exit**_exiting.isn't.a.purpose 🔥🚪 Best of Luck Out There! is the co-founder and managing partner of . He writes and travels with the mission to help entrepreneurs thrive in emerging startup ecosystems. Derek L. Bittar IndicatorCapital Important DisclaimerThis story (or article) has been prepared for informational / entertainment purposes only, and is not intended to provide investment advice or any offer or sale of any investments. This story is the author’s opinion and is for information purposes only.

The Ultimate Survival Guide for Entrepreneurs in Emerging Startup Ecosystems

Meet Bond and ReactiveKit Mobile app consumers have raised the bar for their expectations while scrolling through an app. Nowadays, everyone wants to see smooth transitions, pixel-perfect apps, and fewer steps. Even a small visual distraction can make the user delete your app. In other words, . your app has to be perfect How do you handle your data changes? There is also another important thing, and that is . I have met tons of apps with poor handling of data changes. For example, you are pulling to refresh the table view content and suddenly the whole content disappears and reappears after 2–3 seconds. In most cases, you are getting the same results back as before the "pull to refresh", so nothing has really changed. Sounds familiar? how you handle the data changes to the UI Let's avoid this kind of situations, and handle data changes properly by using . 👇 bindings and reactive data sources Reactive Programming For those who aren't familiar with the term, reactive is an asynchronous programming paradigm concerned with and the propagation of change. For example, all changes to the model will be automatically reflected in the associated view. 📡 programming data streams If you are interested to find out more about reactive programming click here . Bind with Bond is a binding framework that takes binding concepts to a whole new level. It's simple, powerful, type-safe and multi-paradigm - just like Swift. It simplifies state changes by using bindings and reactive data sources. Bond Swift This library is in my all-time favorites. You can attach it to any component that you like. I will show you how to use Bond with few examples, so you can get the idea of how it's working. Installation For the installation, I am using . I highly suggest that you do the same. Just add the below code in your Podfile and run .👇 CocoaPods pod install target 'YOUR_TARGET' do use_frameworks! pod 'Bond', '~> 6.4.3' end I'm using the latest version of the framework from the day I wrote this post. For version changes, please check here . Add to the top of your class so you can use all the Bond methods. import Bond _Many iOS apps use Google Maps. This is a very common feature, so I have decided to prepare an ultimate guide on Google…_theappspace.com Google Maps SDK for iOS using Swift 4 - The App Space Events I will start by showing you how to get rid of the annoying process of and use the simplified approach from Bond instead. IBAction _ = yourButton.reactive.tap.observeNext { print("Button tapped.") } This will observe your button tap. It listens to because it's the most frequently used event. If you want to handle other events you can use: touchUpInside yourButton.reactive.controlEvents(.touchUpInside).observeNext { e inprint("Button tapped.")} Another example would be observing the text changes in a . Knowing that there is no native approach to this situation, Bond provides us with a simple solution. UITextField _ = yourTextField.reactive.text.observeNext { text inprint(text!)} Now, let me show you a simple binding of the typed text into a . The text will get transformed by using the closure and propagated to the label. is the typed string, so you can add any string transformation that you need. UILabel .map $0 yourTextField.reactive.text.map{ $0?.capitalized }.bind(to: yourLabel) Or, you can use the above example but provide a condition instead. Let's say you need to change the button enabled state as someone types in the text field. txtField.reactive.text.map { $0!.characters.count != 0 }.bind(to: yourButton.reactive.isEnabled) Observable Observables are signals and a typealias for the ReactiveKit type. Whenever the state of the changes, an observer will be notified. Property Observable let animal = Observable("Dog") animal.observeNext { value inprint("Hi \(value)!")} If you can see from the example, whenever the animal observable changes its value an observer will be triggered. To change the value just call . To bind an Observable with a UI component just use . animal.value="Cat" animal.bind(to: yourLabel) Bond also supports two-way binding by using . It means that if the view value changes, it will update the Observable value and vice versa. bidirectionalBind animal.bidirectionalBind(to: animalTextField.reactive.text) _This tutorial is about Instagram API Authentication using Swift and will teach you how to retrieve the ACCESS_TOKEN…_theappspace.com Instagram API Authentication using Swift - The App Space Reactive Data Sources By using reactive data sources, it allows us to easily observe changes in a table or collection view. That means whenever the array changes, the data source methods will update automatically. No need of adding on each array change, and it will update only the changes that were made. 🤘🤘🤘 reloadData() We need to use or that will observe for changes and pass the changes automatically to the data source methods. MutableObservableArray ObservableArray let array = MutableObservableArray([“John”,”Michael”,”Steven”]) I will now present you how easy and short it is to implement the data source of a table view. You don't need to connect the UITableViewDataSource with the table view, as Bond handles that for us. The mandatory and , are "packed" under the array method. In the closure, you can add your own cell logic. See the example below. 👇 numberOfRowsInSection() cellForRowAtIndexPath() bind() array.bind(to: tableView, animated: true) { dataSource, indexPath, tableView in let cell = UITableViewCell(style: .subtitle, reuseIdentifier: “cell”) cell.textLabel?.text = dataSource[indexPath.row] return cell } Now, let's say that the array needs to be updated. At this point, we need to , and forget about the table view and whether it's going to update or not. only focus on the array Here are some methods that you can use to make changes to the array. array.append("Brad") /* appends array with a new object */ array.insert("Brad", at: 2) /* inserts new object at the given index */ array.replace(with: [“John”,"Brad",”Michael”,”Steven”], performDiff: true) /* replaces the array but updates only rows that weren't present in the previous array (in our case index 1) */ array.moveItem(from: 1, to: 2) /* items in array will change places */ array.remove(at: 2) /* removes an item from the array */ array[1] = "David" /* replaces the value at the given index */ By using these methods properly, we provide the best user experience possible. The data will be updated, and the user won't get distracted in any way. I have presented just a few of the many features that Bond offers. Binding and the reactive paradigm can bring your app to the next level, so I would strongly suggest using this approach. If you want to spread the message, please don't forget to 👏 or share this story. Thank you for your attention! 🚀 Check out my latest project: _This app is only available on the App Store for iOS devices. Increase your profits by following our professional BET…_apple.co ‎VIP Sports Bet Tips & Scores on the App Store Read more of my writing on Medium: _Forget MVC, now!_hackernoon.com Introducing Clean Swift Architecture (VIP) _Many iOS apps use Google Maps. This is a very common feature, so I have decided to prepare an ultimate guide on the…_medium.freecodecamp.org Your ultimate guide to the Google Maps SDK on iOS, using Swift 4 _Custom UIView with XIB file is a very common practice in iOS Development. Custom UIView classes don’t contain XIB files…_medium.com SWIFT — Custom UIView with XIB file _A Swift tutorial that will make your app available in Spotlight search_hackernoon.com How to add Spotlight support to your iOS app _Understanding One-to-One and One-To-Many relationships_hackernoon.com Core Data Relationships _All you need to know about Auto Layout_hackernoon.com Understanding Auto Layout in Xcode 9 Subscribe to my Newsletter:

Reactive Programming and Binding in Swift

Back in 2010, an ambitious team, a great concept and big thinking around an innovative social commerce service This post summarizes the story of an ambitious social commerce project: plantobuy.com Based in Athens, Greece, at the peak of the financial crisis (or what we thought it was the peak), this project had an additional challenge to face: . extremely limited access to any form of funding THE IDEA What if consumers could anonymously publish their buying plans online? What if retailers could target specific buying plans with special, personalized offers? The core concept focused on allowing Then, benefit from highly targeted, personalized offers and social advice. The idea was to built an online platform to empower consumers to ‘ ’ while empowering retailers to perform intelligent, personalized or even 1–1 offerings. consumers to organize and publish their buying plans anonymously. tell the market about their buying plans A new communication channel enabling retailers to ‘talk to consumers’ who plan-to-buy what they sell or, in a more aggressive scenario, to those planning to buy competitive ones. Furthermore, retailers would benefit from a new capability, enabling . Retailers would use the platform to promote certain products to those consumers actually planning to buy them personalized offers directly to selected consumers Retailers no longer need to predict, estimate or guess what consumers need or looking for: they just define the target audience using as primary dimension the ‘buying plan’ Moreover, users would experience highly-related interactive ads with the ability to submit feedback to the advertiser anonymously. THE VISION To build a new SOCIAL COMMERCE platform enabling more effective communication between consumers and corporations THE PRODUCT A SHOPPING ADVISOR for consumers A free service for consumers offering a range of new capabilities, such as social advice and targeted, The offers would be driven by consumer buying plans, offering rich-media content, and in many cases ‘interactive’, feedback-enabled ads. personalized offers. A CAMPAIGNING platform for Retailers Advanced functionality for Retailers, enabling accurate Special functionality allowing retailers to get promoted via personalized offers, video ads and product sponsorships; to get feedback, insights & analytics on each promotional activity. customer targeting, based on explicitly stated buying plans. The ASK.YOUR.NETWORK feature The idea was to enable users, to ask advice from people they know and trust; to gather trustworthy hints, and recommendations regarding a significant, forthcoming purchasing decision. With a click of a button, from selected Facebook or Twitter connections and/or friends via e-mail. Feedback would then be presented to the user via an easy-to-read visualization of hints, and recommendations — as provided by user’s ‘ ’. a user could ask for a product advice circle of trust A continuous flow of social advice & ideas through the ask.your.network ™ concept: a social utility empowering consumers to gather opinions, comments & ideas from people they know and trust Personalized OFFERS In absolute contrast with the range of services, plantobuy.com was about personalized experiences, intelligent offers and content delivery. %deal% Plantobuy.com introduced highly targeted/ personalized offers on exactly what the user needed, timely and anonymously. Users were able to select the offers of interest and only then unveil their personal data to the retailers supported registration and administration of virtually any buying plan across a large number of heterogeneous categories. This allowed consumers to do for all personal, family and small business related expenses — a management tool for scheduling & administering spending. Plantobuy.com purchasing planning & budgeting RICH, INTERACTIVE ADS Users had access to an ‘endless’ feed of rich video content, including ads, all matching the selected buying plan: , ! Anonymously! highly-relevant ads interactive and also allowing the user to submit feedback to the advertiser plantobuy.com for Retailers — home page THE TEAM A small, but highly motivated and skilled team, with clear vision and remarkable expertise in software engineering, large-scale Information Systems design & Web-development, Data mining, Business Intelligence, Analytics and large Data store design. THE LAUNCH Following real agile engineering principles, we delivered a fully functional based on a highly engineered, scalable architecture using the latest tech stack available at the time — also leveraging cloud services and content delivery networks. MVP attracted attention and generated noise in the Greek market and appeared several times in major media channels — including Star Channel TV prime time News. Plantobuy.com THE REALITY Our ironically proved to be not really Viable nor Minimum: carried away by our passion for technological excellence, we over-engineered and possibly over-complicated particular components and processes. MVP , given the extremely limited resources, proved to be a critical factor for the success of the launch: Although there was remarkable interest from consumers and some tenths of thousands of users within the first couple of months, we failed to avoid the , the disconnect between the user base growth and retailer engagement. This had a significant opportunity cost which time gap This gap was the main reason for low user engagement which impacted all our major KPIs. By the time we achieved to on-board a few hundreds active retailers (a major achievement), we also had significant cash-flow issues along with extremely slow moving negotiations for funding. All the above combined with the financial crisis in Greece (+ the realization that the ‘crisis peak’ we have been experiencing was not really the peak) made service interruption the only meaningful option The service was discontinued back in Feb 2014 A stream of ideas as the driving force of innovation

Startup lessons: plantobuy.com

Almost two years ago let developers create bots quite painlessly. You can read an introduction about it . In this article we will create a simple bot in , it’ll be hosted in Azure using Bottle framework. The bot will not do anything fancy, consider it as a template for your python based bots. Telegram on Telegram website python Here are the things which we’ll cover: Registering your bot in Telegram app Creating a Bottle App in Azure Configuring Bottle server to run as HTTPS (which is required by Telegram) Creating an API endpoint for communication with Telegram After that, I will also introduce you to inline bots. Registering bot in Telegram app You can do it without leaving the Telegram app. Your contact person is, well, a bot named @BotFather. Start a conversation with him: He’s a really cool guy and I’m sure you’ll not have any problems with creating a new bot. Just write , then choose a name and username for it (the latter should end with ). /newbot bot If everything goes smoothly, you’ll receive your bot’s token, which we’ll use in the next step. Creating a Bottle App in Azure is a lightweight server framework for python. It’s available in Azure as a Web Application. In order to create it, open Azure Portal, look for „bottle” in new app search window. Bottle Click on it, then choose a name for your app and resource group. After about a minute, your app should be ready. You should be able to see it on http://APPNAME.azurewebsites.net Open it in azure, and search for “Deployment options”. By default azure bottle app is deployed from . Let’s create a local git repository just for your project. In , click and confirm. Then, click button, select and confirm. This action may take about a minute to reflect in the UI, after that you should see an address to your git repo in screen: this git repository Deployment options Disconnect Setup Local git repository Overview Copy that link, then switch to cmd/terminal, go to directory of your choice and clone your repo (I hope you have git installed!): git clone (repolink) You will be asked for user password, you can set it up in : Deployment Credentials Let’s take a look at the files: this file contains initialization of your bottle server app.py — it specifies logic which should be executed for API routes (and returns data) routes.py — all python dependencies have to be listed here requirements.txt — — if this file exists, azure will not proceed with full python deployment each time you commit (you should remove it for commits which add new dependencies) .skipPythonDeployment Other files and folders are less significant for this tutorial, you can figure out their importance by yourself (or ask in comments, I’ll be happy to help). Configuring Bottle server to run as HTTPS Telegram doesn’t support HTTP requests for bot API, so we need to make sure our method is reachable using HTTPS. Bottle doesn’t offer HTTPS server out of the box. To archive this, we need to create a ServerAdapter. You can use one of the implementations floating on the Internet, like . this Copy the code of server class and paste it into your file (right under the imports is fine): app.py class (bottle.ServerAdapter):def run(self, handler):from wsgiref.simple_server import make_server, WSGIRequestHandlerimport sslif self.quiet:class QuietHandler(WSGIRequestHandler):def log_request(*args, **kw): passself.options['handler_class'] = QuietHandlersrv = make_server(self.host, self.port, handler, **self.options)srv.socket = ssl.wrap_socket (srv.socket,certfile=' , server_side=True)srv.serve_forever() SSLWSGIRefServer server.pem' is a path to your server certificate. It’s easy to create it using by running the command below, you can provide empty input for all certificate fields except for , for it you have to use your domain address (APPNAME.azurewebsites.net): certfile=’server.pem’ OpenSSL Common Name openssl req -new -x509 -keyout server.pem -out server.pem -days 365 -nodes Place generated server.pem file in the root folder of your app. Now, let’s switch to using new class. Change your startup code to look like this and remember to use your app’s name: if __name__ == '__main__':app = bottle.Bottle()srv = SSLWSGIRefServer(host=" .azurewebsites.net", port=80)bottle.run(server=srv) APPNAME python-telegram-bot To communicate with Telegram API, we’ll use a wrapper called . python-telegram-bot This package is not available in your azure environment. In order to add it, you need to do two things: add line to requirements.txt python-telegram-bot==5.3.0 remove file .skipPythonDeployment Azure will make sure all package requirements are met during deployment (which happens after each commit). Communication between Telegram and our server can be done in 2 different ways:1. Our server can check for updates from Telegram in a loop using getUpdates method2. We can hook telegram to our server’s API method, so everytime there is some user message waiting, Telegram will send us an HTTPS POST request with details. In this tutorial we’ll use thesecond approach. Creating an API in Bottle Let’s open routes.py file. You can see many routes specified here, all of them useless for our use case, you can safely remove them. We will add two methods: will respond to telegram’s requests. Our bot will take the incoming message, assume it’s in format , split it into 2 ints and answer with the sum of these numbers. /botHook a+b will be responsible for hooking telegram to our API. You could move this logic to app.py file, so it’d be done with each deployment/server restart, but I prefer to have quick access to it this way. We’ll pass the address of the method. It will return a boolean value, which will indicate if the hooking was successful. /setWebhook /bootHook Here’s the full code for routes.py which you can use. Make sure to use your app name and bot token: from bottle import route, view, run, requestimport telegram TOKEN = 'TOKEN'APPNAME = 'APPNAME' ('/setWebhook')def setWebhook():bot = telegram.Bot(TOKEN)botWebhookResult = bot.setWebhook(webhook_url=' return str(botWebhookResult) @route https://{}.azurewebsites.net/botHook'.format(APPNAME)) ('/botHook', method='POST')def botHook():bot = telegram.Bot(TOKEN)update = telegram.update.Update.de_json(request.json, bot)bot.sendMessage(chat_id=update.message.chat_id, text=getSum(update.message.text, update.message.from_user.username))return 'OK' @route def getSum(query, userName):try:splittedBySum = query.split('+')if len(splittedBySum) != 2:raise ValueError('Too complicated stuff')return str(int(splittedBySum[0]) + int(splittedBySum[1]))except:return  "I'm sorry, {}. I'm afraid I can't do that".format(userName) Done! Now upload all our changes: git add .git commit -m 'Simple bot'git push origin master After the deployment is done, call webook method in your browser: https://APPNAME.azurewebsites.net/setWebhook If it resulted with , then everything should be ready to have your first conversation with your awesome bot, give it a try! True Inline bots We created a bot which answers with one result. Sometimes we’d like our bot to provide user couple of options. In Telegram it’s possible with inline bots. To see that multiple results you need to add your bot to some group conversation and start typing @botname query. To archive it, we need to activate this feature by talking to @BotFather. After switching it on with , it’s also required to provide text which will be shown to user after writing @YourBot in chat /setinline We also need to change /bootHook method (it has to support both normal messages and inline queries) and provide a small helper function: ('/botHook', method='POST')def botHook():bot = telegram.Bot(TOKEN)update = telegram.update.Update.de_json(request.json, bot) @route if update.message is not None:  
    bot.sendMessage(chat\_id=update.message.chat\_id, text=getSum(update.message.text, update.message.from\_user.username))  
elif update.inline\_query is not None:  
    results = list()  
    results.append(getArticleFromText("Just what do you think you're doing, {}?".format(update.inline\_query.from\_user.username)))  
    results.append(getArticleFromText(getSum(update.inline\_query.query, update.inline\_query.from\_user.username)))  
    bot.answerInlineQuery(update.inline\_query.id, results) return 'OK' def getArticleFromText(text):return telegram.InlineQueryResultArticle(id=text.upper(),title=text,input_message_content=telegram.InputTextMessageContent(text)) Here’s how it looks like in action: Conclusion It’s relatively easy to get your python code working as a Telegram bot. There are dozens of potential use cases for bots, so this knowledge may become handy one day for you. Also, check out other stuff which can be done with Telegram bots API, like different types of inline responses or games. If you have any questions, feel free to ask them. If you find this article helpful, also let me know! :)

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