APIs form the backbone of modern app development , cloud services, identity management, and much more. With such a prominent role in today's digital landscape, it's critical to have good API development practices. In this article, we'll go over everything you need to know—from what an API is to how to develop an API the right way and why it's essential.
Let's get started with a quick primer on APIs.
What is an API?
API stands for Application Programming Interface. While that may sound pretty technically advanced, it's a simple concept. The easy way to think about it is that APIs allow computer programs to communicate with each other. An API is like a middleman between two apps, coordinating the sharing of data and services.
APIs have been around since the first computer programs were written. For an example from the early days of personal computing, imagine that you're writing a report in a word processor. You need to get a calculation from a spreadsheet and always need the latest figure in your report. Programmers could use an API to enable the word processor to grab that data from the spreadsheet. In this case, the API allowed two separate applications to share data.
With the rise of the internet, web service APIs have risen to prominence because they create new features and convenience. When you visit an eCommerce site, and it offers to let you log in using your Twitter account, that's a modern example of APIs in action.
The website's development team leveraged the Twitter API instead of coding a user authentication and identity management system. You enjoy the convenience of not having to create another username and password. The API took care of verifying your identity and telling the website it was OK to let you in.
REST APIs vs. SOAP APIs
Any discussion of web service APIs will lead to the question of REST APIs vs. SOAP APIs. Both are popular and serve more-or-less the same function, so which is better? That's a complex topic, but here's a quick overview of their similarities and differences:
SOAP (Simple Object Access Protocol) is one of the oldest web service APIs still in use today. Originally developed by Microsoft in the Web 1.0 era, SOAP is now an open standard as defined by W3C. SOAP first gained popularity because it delivers messages via HTTP (the web language) in the cross-platform XML language. When much of the web was built on proprietary technology, a SOAP API's ability to send and receive XML data across any platform and operating system was a breakthrough. SOAP remains in wide use today because of its tight security standard.
REST (Representational State Transfer) is an architectural standard for APIs. REST was developed as a response to what some see as SOAP's shortcomings—primarily SOAP's strict reliance on XML. REST APIs can send messages in various formats and languages, like CSV (comma-separated value) files to JSON (a JavaScript-derived language with similarities to XML).
SOAP is a web service API standard that follows strict criteria, including the WS Security protocol. REST, on the other hand, is an architectural style that is more lightweight and flexible than SOAP. Each has its place when it comes to using APIs.
Developers tend to use the RESTful architecture for its flexibility but will favor a SOAP API when strict security is needed.
The different types of APIs
There are four different types of APIs:
Open API: Also known as a Public API, this describes publicly available APIs. Access is open to all API developers and users on the internet.
Partner API: Unlike Public APIs, Partner APIs are not open to everyone. Developers need to be granted access to these APIs, which typically involves some sort of authentication workflow.
Private API: Also known as an Internal API, this category of API is restricted for use inside an organization only and is not available on the public internet. Private APIs typically exist to enhance employee workflows or share data amongst on-premise hardware.
Composite API: This type of API combines multiple APIs' different services and data into a single call. These APIs are seen as especially efficient for accomplishing multiple tasks at once.
Important API terminology
Here is a glossary of the most important API terms to know and understand:
API Key: An API key is a unique code passed between systems to authenticate the system making the API request.
Endpoint: The systems involved in an API transaction on each end are known as the endpoints.
JSON: JavaScript Object Notion (JSON) is a language and data format used for APIs to exchange data via web services.
GET: GET is part of the HTTP protocol and is a method that is used to request data from a server.
POST: POST is a method in the HTTP protocol used to send data to a server. It is used to create or update information on the server.
OAuth: OAuth is an authorization framework for APIs. It provides secure access to data to be used by third-party without the use of a password.
Latency: The time between processing an API request and sending the response is known as latency.
Rate Limiting: Rate limiting is the process of controlling the flow of incoming and outgoing traffic. It is typically defined by the number of requests an API server will handle at one time.
API Throttling: Rate limiting controls the usage of APIs at the network level. Whereas rate limiting concerns the number of requests an API will answer in a specific time frame, API throttling shapes network traffic to ensure peak performance.
Important features in API design
When creating an API, developers should keep some design philosophies in mind. Following these principles will simplify and speed up the development process:
Authentication and authorization
Consider which framework or specification you will use to implement API authentication. JRT and OAuth (or OAuth2) are some of the most commonly used methods.
Utilizing a cache can significantly speed up data transfer in APIs. The goal is to reduce in-memory requests to the server. Popular caching tools include Memcached and Redis.
Wrappers
API wrappers combine sets of API calls into one function. Wrappers often call multiple API calls at once and are seen as more efficient.
Error handling
Error handling in code helps developers identify problems more quickly, making debugging easier. Some common error-handling practices are the use of error codes and writing out an explanation of the error.
Validation
API data can be validated client-side or server-side. Client-side validation is usually handled by giving feedback on errors. Server-side validation follows typical programming error-handling practices.
Testing
Thorough testing is essential in all aspects of app development. That applies to all functions of an API—including the user experience, performance, reliability, and security. API testing is one of the most important practices in API design.
Common challenges when building APIs
As with any software development project, challenges in the API development process are not uncommon. Most of them have little to do with writing the API's code. Instead, it's all about the extra work and planning needed to ensure the API's successful adoption.
API Documentation
For an API to succeed, its user base needs a thorough reference guide available. Having excellent documentation can make the difference between an API being widely used or not. One of the most common practices in the industry is to have a developer portal on your website with ample documentation of every API. Users expect to see a complete list of features and how to leverage the API.
Versioning
Keeping track of changes as APIs are developed is essential. Users need to know which version of an API they are accessing, so they know which feature set they can access. Versions are often noted in an API's URI as such:
http://example.com/v1/users
Other approaches include version information in headers, although this can add complexity to development and implementation.
Governance policies
Like all IT services, APIs should be effectively governed. The best way to go about this is to develop policies that determine how an API can be used, how developers and engineers should use it, and specify what should not be done with it. Having these policies in place not only helps the development process but also helps to keep your organization in compliance with security regulations around the globe.
API orchestration
A small set of API endpoints are easily managed. But when you start to deploy APIs on a large scale, it can quickly become overwhelming and lead to chaos. Managing APIs at a large scale is known as API orchestration. The recommended solution is to use an API gateway. A gateway is like a middleman between two endpoints in an API, performing essential management tasks.
Security
As with anything on the internet, API security is a critical consideration. Utilizing an API gateway to enforce identity management and authorization policies is one of the best ways to ensure confidentiality and integrity when APIs are used.
Solutions for building your best APIs
Now that you have a solid understanding of APIs and the challenges around developing them, it's time to share some best practices to help you build the best APIs.
Craft a development methodology
Before delving into technology to solve your API challenges, a little homework is required. Having a robust methodological process will help you craft quality APIs.
Before creating an API, create a mission statement that clearly states what you hope to accomplish. Define who will use the API—whether it be customers, business partners, developers, or anyone on the internet.
Next, think of the problem you hope to solve and how the API will bring value to its users. Perhaps you want to allow your users to log in using the Twitter API or another authentication system. Or maybe you want to automate the delivery of financial reports internally. The critical part is clearly defining how you will improve the user experience.
Then quantify the value of the API to your organization. Will developing and deploying this API bring new customers and more revenue? Will it save internal costs? Once you can show the benefits, you are on your way to getting the internal buy-in and the resources needed to make the project a success.
Utilize an API management platform
Most organizations today will make use of an API management platform to ease the challenges of developing, testing, and maintaining APIs. API management platforms usually offer the following features:
API deployment: API management platforms ease the process of deploying an API and act as an API gateway, simplifying the development and management process.
Security: API management platforms ensure compliance with security policies and regulations. They are also useful for spotting problems that might expose data. API management platforms also allow you to control access to your code and other digital resources tightly.
Automation: API management saves development time, offering developers templates and the ability to automate API creation. Having all of your APIs together in one place gives you a library of sorts to see if code or functions already exist in your current APIs.
Reporting and analytics: APIs will typically log requests and responses, but humans do not easily read log files. Most API platforms will derive reports and usage analytics from those logs. From there, you can track which APIs are popular and diagnose any shortcomings.
Discover API development best practices with Codal
As you and your organization step into the world of APIs and microservice architecture, you will need a trusted partner. When you choose Codal, our team of experts will guide you every step of the way. We help you identify where APIs can help you meet your goals, timelines, and budget. We help you find and implement the tools and infrastructure for the best customer experience, creating more conversions, and increasing revenue.
