Full stack Developer
Facebook, Google, Github, Netflix and few other tech giants have given a chance to the developers and products to consume their data through APIs, and became a platform for them.
Even if you are not writing APIs for other developers and products, it is always very healthy for your application to have beautifully crafted APIs.
There is a long debate going on the internet, about the best ways to design the APIs, and is one of the most nuanced. There are no official guidelines defined for the same.
The API is an interface, through which many developers interact with the data. A good designed API is always very easy to use and makes the developer’s life very smooth. API is the GUI for developers, if it is confusing or not verbose, then the developer will start finding the alternatives or stop using it. Developers’ experience is the most important metric to measure the quality of the APIs.
The API is like an artist performing on stage, and its users are the audience
The following are the most important terms related to REST APIs
Let’s write few APIs for Companies which has some Employees, to understand more.
/getAllEmployees is an API which will respond with the list of employees. Few more APIs around a Company will look like as follows:
And there will be tons of other API endpoints like these for different operations. All of those will contain many redundant actions. Hence, all these API endpoints would be burdensome to maintain, when API count increases.
What is wrong?
The URL should only contain resources(nouns) not actions or verbs. The API path
/addNewEmployee contains the action
addNew along with the resource name
Then what is the correct way?
/companies endpoint is a good example, which contains no action. But the question is how do we tell the server about the actions to be performed on
companies resource viz. whether to add, delete or update?
This is where the HTTP methods (GET, POST, DELETE, PUT), also called as verbs, play the role.
The resource should always be plural in the API endpoint and if we want to access one instance of the resource, we can always pass the id in the URL.
/companiesshould get the list of all companies
/companies/34should get the detail of company 34
/companies/34should delete company 34
In few other use cases, if we have resources under a resource, e.g Employees of a Company, then few of the sample API endpoints would be:
GET /companies/3/employeesshould get the list of all employees from company 3
GET /companies/3/employees/45should get the details of employee 45, which belongs to company 3
DELETE /companies/3/employees/45should delete employee 45, which belongs to company 3
POST /companiesshould create a new company and return the details of the new company created
Isn’t the APIs are now more precise and consistent? 😎
Conclusion: The paths should contain the plural form of resources and the HTTP method should define the kind of action to be performed on the resource.
HTTP has defined few sets of methods which indicates the type of action to be performed on the resources.
The URL is a sentence, where resources are nouns and HTTP methods are verbs.
The important HTTP methods are as follows:
GETmethod requests data from the resource and should not produce any side effect.
/companies/3/employeesreturns list of all employees from company 3.
POSTmethod requests the server to create a resource in the database, mostly when a web form is submitted.
/companies/3/employeescreates a new Employee of company 3.
POSTis non-idempotent which means multiple requests will have different effects.
PUTmethod requests the server to update resource or create the resource, if it doesn’t exist.
/companies/3/employees/johnwill request the server to update, or create if doesn’t exist, the john resource in employees collection under company 3.
PUTis idempotent which means multiple requests will have the same effects.
DELETEmethod requests that the resources, or its instance, should be removed from the database.
/companies/3/employees/john/will request the server to delete john resource from the employees collection under the company 3.
There are few other methods which we will discuss in another post.
When the client raises a request to the server through an API, the client should know the feedback, whether it failed, passed or the request was wrong. HTTP status codes are bunch of standardized codes which has various explanations in various scenarios. The server should always return the right status code.
The following are the important categorization of HTTP codes:
These status codes represent that the requested action was received and successfully processed by the server.
DELETE /companies/43/employees/2will delete the employee 2 and in return we do not need any data in the response body of the API, as we explicitly asked the system to delete. If there is any error, like if
employee 2does not exist in the database, then the response code would be not be of
2xx Success Categorybut around
4xx Client Error category.
These status codes represent that the client has raised a faulty request.
You can follow any casing convention, but make sure it is consistent across the application. If the request body or response type is JSON then please follow camelCase to maintain the consistency.
All of these actions are simply the query on one dataset. There will be no new set of APIs to handle these actions. We need to append the query params with the GET method API.
Let’s understand with few examples how to implement these actions.
GET /companiesendpoint should accept multiple sort params in the query.
GET /companies?sort=rank_ascwould sort the companies by its rank in ascending order.
GET /companies?category=banking&location=indiawould filter the companies list data with the company category of Banking and where the location is India.
GET /companies?search=Digital Mckinsey
GET /companies?page=23means get the list of companies on 23rd page.
If adding many query params in GET methods makes the URI too long, the server may respond with
414 URI Too long HTTP status, in those cases params can also be passed in the request body of the
When your APIs are being consumed by the world, upgrading the APIs with some breaking change would also lead to breaking the existing products or services using your APIs.
http://api.yourservice.com/v1/companies/34/employees is a good example, which has the version number of the API in the path. If there is any major breaking update, we can name the new set of APIs as
These guidelines are compiled on my experience of development. I would love to know your views on the pointers mentioned above. Please leave a comment, and let me know!
If this article helped you, then you can buy me a coffee 😊