API Development: A Complete Guide to Build Good API

APIs are those unsung heroes that play a significant part in winning the war, but they are not applauded for their efforts. Fast forward to today, APIs play a pivotal role in the development industry and help applications run smoothly, process with speed, and deliver results.

Expanded as Application Programming Interfaces, APIs help integrate third-party solutions, software, and systems with an application. And why do they do so? API function to exchange data between two entities. With so many third-party applications being developed for specific purposes, APIs are required to fulfill modern-day development.

Moreover, in a widely changing environment, APIs help build solutions that are adaptable, scalable, and resilient. Let’s explore some more about APIs in detail, how to build an API, and what are the best API development practices. Stay tuned to read an amazing guide to developing API.

Must Read: 7 Reasons to Choose Node.js for Web Application Development

What is an API?

Application Programming Interface (API) is a standalone software representing a set of instructions and standards. These instructions help utilize the features or services of another application, software, or platform.

The purpose of building an API is to increase the scope of services and improve the way applications or software communicate with each other.

Here’s the best example of an API.

We all, at one point (even if some people deny it), have played Candy Crush. Now when you see the “Connect to Facebook” button on Candy Crush, it integrates your game with your Facebook profile.

If you are playing from your phone, the game will automatically connect with your Facebook account without having to enter the login details. That is the power of using an API.

It speeds up the required services without having to let the user get distracted or close an application.

So, whenever it is about enabling communication between two applications, an API is used. It lets two software or application exchange data with each other to improve the user experience.

Developers can build an API for the application or solution they are building separately or use existing ones. Here their work is to connect the applications and make it possible for them to exchange data.

Another example of API working is when you choose to make an account on a website with Gmail or Facebook. This is called on-click sign-up. As you only have to click once from the given options, and your account on the website will be created instantly.

How Does an API Work?

To understand the background process of an API, we need to take an example. Let’s say you want to book a hotel and visit a website that supposedly shows all the hotels in the area you are searching for aligning with the dates you require.

After going to the website, you will enter the details of your requirements. You will enter the number of visitors, date of check-in, check-out, and the dates on which you will be visiting.

After submitting the details, you will get a list of all the hotels having vacant rooms during the selected dates. It will also show the price, additional services, and details of the same.

An API is used here to collect data from the website’s database and present the best possible options. Here the motive of the API is to collect and provide the required information to the users in a streamlined manner.

The API collects all this data either from the database or the hotel websites. Here the hotel website and the website you are using for booking act as endpoints.

To fully understand the working of an API development process, there are a few terminologies that you must understand.

Basic Terminologies Associated used in API Development Process

These are the terms that will be used when developers in an API development company are holding discussions on building APIs and developing similar systems.

SOAP and REST are also two important terms often associated with the API development process.

Here’s what they mean;

• SOAP: Simple Object Access Protocol or SOAP is referred to as the messaging protocol meant for sharing information. The structured information shared in this exercise represents the execution of web services in computing networks.
  SOAP is function-driven and uses XML only for sharing information and application layer protocols like HTTP and SMTP. For message format, HTTP uses HTTP, and for transmitting and negotiating the message, it uses the SMTP format.
• REST: Representational State Transfer or REST is the implementation of a program’s architectural system. The purpose of REST is to improve the efficiency of communication between two applications, devices, or systems. REST is used for a specific purpose and helps with making a particular set of data available only when requested.

How to Build an API?

An API development company follows a well-structured process to ideate and build an API. From the first step of initiation to the last step of launch, the API development process is an interesting thing to experience and practice. Here are the steps you need to know for standard and custom API development. 

• Identify the Goal for Building an API

  The purpose of identifying is the goal to ensure that the users and company requiring the API gets the value it intends to provide. In other words, you must establish your target audience and know their purpose of using the API solution.

  For instance, a private API is meant to be used by engineers inside an organization and the public APIs will be used by anyone with the API key. To identify and understand the target audience, start by asking the following questions.

  • What sort of users will engage with the API and what is their purpose of using the same?
  • What features will be required to fulfill the intended purpose of the API?
  • What functions are required to improve the user experience?

  Besides identifying the target audience, the developers must also select the tools required to build the API program. This includes the SDKs, development tools, documentation, etc.

  Based on the answers to these questions, you will get the functional and non-functional requirements of building the API. Functional requirements are the components you need to add to make the API work.

  Non-functional requirements are the ones that will be responsible for other components, including the UI, performance, speed, reliability, ability to scale, and API security.

• Create the API Design

  This step is about creating the API architecture, design, and overall structure. Yes, this is also an integral part of the API development process that every API development company must utilize.

  Here, we will address the non-functional requirements of API development, including security, reliability, scalability, testability, and usability.

  The design must be able to satisfy all these requirements. Between the client and the API or business logic, you need to limit the layers to three. These are;

  • Validation layer: This layer controls and oversees all the interactions within the application.
  • Caching Layer: This layer is responsible for sending caching-related instructions to the client.
  • Orchestration Layer: The third and final orchestration layer is tasked with combining data from multiple sources.

  The second thing you need to do for this step is select one architectural style. This includes choosing between SOAP and REST architecture. We have briefly discussed each of these styles above.

  In the development industry today, the REST approach to build the architecture is most popular. Developers prefer it for several reasons including higher performance, scalability, and the ease of work.

  However, working to build the architecture with REST requires fulfilling six constraints;

  • Uniformity of the Interface: This implies that no matter from the API request is sent, it should look uniform. Whether the request is coming from mobile, website, etc. they must pass through the Uniform Resource Identifier.
  • Statelessness: The servers involved in the API network do not store any information about the interactions. Hence, every API request should provide the necessary context to complete the transaction.
  • Code on Request: The responses generated by the API can include the executable code, but only if it is required.
  • Separation of Concerns: This one is important and regularly practiced in other development components as well. It highlights that the application’s backend must be developed independently from the user interface.
  • Multiple Communication Layers: For custom API development, the developers need to add multiple layers for communication between the server and the client.
  • Response Caching: Program the servers to inform the clients whether the response needs to be cached.

  Based on these six constraints, developers can implement a stable and efficient REST architecture. The last thing to work on in this segment is security. You need to identify the required security systems and add them into the API as well.

  There are four components in the security process;

  • Identification: Knowing who is accessing the API. This can be done with identifiers or API keys. Besides identifying, these APIs can also help detect any unlawful behavior.
  • Authentication: To allow users to confirm their identity, you can use OpenID or equally good systems. They can redirect the users to an authorization server to confirm their identity. The ID and password required for login in a part of this process.
  • Authorization: By using OAuth2, we can set accessibility limits and permissions to what a user can access.
  • Encryption: For security purposes, an API solution must have SSL/TLS level of encryption to protect the users from hacks and data theft. In addition to this, end-to-end encryption must also be used for protecting confidential information from getting leaked.

• Developing the API

  Now it’s time to build the API, and this process will take the longest time due to the multiple iterations required. The best strategy is to build the API one endpoint at a time. As you keep on building the endpoints, keep on adding the functionalities, adding them, and then creating their detailed documentation. 

  • Define the API Responses: The first step is to define what is a valid request and which request is not valid and what will be the response. The responses are codified;

  Code	Response
  200	Ok
  201	Resource Created OK
  202	Accepted
  400	Bad Request (Invalid Syntax)
  401	Unauthorized
  403	The user does not have access to the resource.
  404	Resource not found
  410	Missing or deleted data
  500	Internal error
  503	API is under maintenance

  • API Request Exceptions and Errors: In the next step, handle all the request exceptions. Plus, create the procedures to return correct HTTP status codes to the users. The motive is not to send generic error responses like 500: Internal error, etc.

  However, you should not go all the way in sharing specific information so as to provide the name of versions, classes, frameworks, SQL queries, etc. Sharing this information can put the application in a vulnerable position.

  A better way is using an API gateway, standardizing the responses, and sharing only the required information without exposing the internal systems. 

  • Building Endpoints: Build the endpoints, which represent one of the ends of a communication channel. To do so, you can adopt any of the five different HTTP methods. These are;
  1. 1. GET
     2. POST
     3. PUT
     4. PATCH
     5. DELETE

  Once you have built the endpoints, test them with unit and integration tests to ensure they are functioning as intended.

  • API Performance Analysis: It is necessary to make the API solution fast enough to handle multiple requests. They need to perform exceptionally well. This is essential when an API development company is building a solution for eCommerce stores. As these stores have to cater to multiple requests, their performance must be ensured.

  For this, try API pagination. This means splitting the API data into different pages, and each page must have its own URL.

  With this done, start analyzing the performance and make improvements as you go further. Here developers can use development concepts like HTTP compression to reduce the size of the large objects added in the API. Or they can combine compression with streaming to further improve performance and reduce latency. 

  • Work on Client-Side Caching: The next step in the API development process is storing data for subsequent requests. This must only be done if you need higher performance and save traffic load.
  • Create Documentation: Here, you need to create the API documents. This can be easily done with API documentation tools as they auto-generate the required information from the Open API definition layer.
  • Add Versioning: This step is required if, in the future, you want to expand the API’s functionality. At a time when these developments will be done, the API’s existing functions must not be hindered. Moreover, versioning is required when you want to create a public API.
  • Integrate Throttling: It is required to limit the number of requests an API can take and process. This is done primarily to protect the API against Denial of Service (DDoS) attacks. For this, the developers need to set the traffic quotas, spike arrests, and concurrent rate limits.

• Testing the API

  Right before launching, you must test the API to ensure that it performs as intended. We have talked about conducting the Unit and Integration test in the previous steps. Here, complete the testing procedure with the other three tests;

  • Functional Test
  • Reliability Test
  • Security Test

  Testing an API must be done with a designated process. This includes testing the API functions in isolation and using realistic data, which will only generate realistic results. Moreover, testing under different network conditions will help you identify the issues more precisely.

  Another good practice is to simulate errors and edge cases by instantly and quickly changing the responses.

  This completes the API development process. In the entire procedure, you must not steer away from the core purpose of building the API. After the API is launched and working, then begins the monitoring.

  The purpose of monitoring is to ensure that the API keeps on providing the services it is intended for. Plus, the API is always secure to find out when to scale. In the monitoring, you also have to check whether the API is completing all the goals. The goals can be;

  • Uptime
  • Handling the number of requests per month or week.
  • Attracting the monthly unique users.
  • Response time
  • Memory usage of the CPU and the Server
  • Time utilized on receiving the API key
  • Monthly revenue.

  This constant monitoring helps identify the improvements required, corrective measures, and other development-related work required to improve the API every day.

Which are the Best Tools to Build an API?

While we are on the topic, let’s take some more time to go through the list of tools for API development you can use to build an API.

Conclusion

API development process is an iterative procedure that resembles how we build software or an application. With an API, software and applications can become more agile, perform faster, and can help provide a better user experience. To build and understand the features to add in API, make sure to hire the best API development company.

While hiring, ensure to ask that your API developers are using the detailed development process we have highlighted above. Identify the key features of the API and its purpose to make the development exercise successful.