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Building an API – Here are the 5 things you need to know

(Image credit: Image source: Shutterstock/Wright Studio)

The term API, which stands for Application Programming Interface, is a kind of a language that lets a product/service, like Google Maps, exchange data with another, such as AccuWeather. It is also why we can view local weather trends on the interactive maps from Google!

In short, APIs can be used to combine the capabilities of different products, customise them according to our needs, or even create new ones.

Why do you need APIs?

APIs can help you improve the way you serve your clients through innovation. With their help, you can change things that aren't working as efficiently as they as should, and replace them with complementing functionalities that do.

Companies that run as closed systems, not embracing innovative solutions, will always be vulnerable to them. Just like the ice trade in 19th century went out of business when refrigerators and freezers were invented, your product/service could become obsolete too.

APIs offer you the technology that makes it easier not to remain in isolation. With newer APIs being simpler and more user-friendly, even non-coders can use them. Consider this example of the Twitter API being used to create a Google Spreadsheet. With its help, it is possible to monitor one’s social media outreach. Even scientists are finding the APIs useful and making them work for them!

The types of APIs

Essentially, there are four main types of APIs. The most commonly used APIs are called the north-south APIs. They are used to export data, communicate with external services, and take care of other communication between one computer and another.

A relatively newcomer to the field is the east-west API, which belongs to the second category. Today, individual functions in an application are implemented by separate microservices. APIs that make communication possible between such microservices are known as east-west APIs.

The third API category is used to make mobile apps work. Finally, there are those APIs that allow incorporation of external services into an app. Two examples of such APIs include Twilio, which is a cloud communications platform, and Stripe, which online businesses use for commerce.

API design

When building an API, here is what should go into its designing:

  • A blueprint or spec will be required. Use Spec-Driven Development to design a sustainable API and monitor glitches that arise so you won’t have any issues later on. The process is lengthy but worth the hassle.
  • An API modelling language, such as RAML, will be needed to build your spec. With its unique and interactive tools, RAML will make designing easier and consistent.
  • User feedback during the building of your spec is crucial since it will point you in the right direction. Developer/user interaction with the API prototype is possible through Anypoint Platform, Postman, and API Notebook.
  • Next, you will need to authenticate the API so that users may access it through their accounts.
  • The more resources your API has to offer to a client, the more durable your API would be. Therefore, make sure that you adhere to the best practices during the API designing process.
  • Lastly, you would need to decide which method of data exchange you will use for your API. Usually, that is a choice between the two standard formats, i.e. XML or JSON. Choose wisely!

API support

Quick implementation and user-friendliness are important aspects of good API building. Therefore, make your API more accessible to the client by providing informational documentation and return relevant data for a user’s call. Provide great support and developer experience, starting from the moment signups open to the provision of guides and references.

As mentioned earlier, user interaction is important and would require you to be actively listening and responding to them. Whether you communicate through a blog, email, or social media, your API must satisfy the needs of the user community/client. Don’t know how to hook the users? Quick and easy or no signups and free trial periods should do the trick!

API testing

Once all the rest is in place, you will have arrived at the final stage of building an API, i.e., testing! API testing isn’t needed just to discover bugs and inconsistencies. It will also keep the API relevant for your clients. That is why, testing can’t be a one-time thing.

Test your API continuously to ensure that it remains secure and merits the cost you pay each time to test it. APIs that don’t work seamlessly will remain un-adopted, no matter how many free trials you offer.

API testing can be challenging and cannot be based on just its individual functionalities but also the series or chain of functionalities. You need to be sure how it works from one end to the other. Your API should continue to offer value to an application and run efficiently.

When the API fails due to an error that you missed out during testing, so do all the applications connected to it, as well as, the business processes that are linked with those apps.

So, what do you need to look for when testing your API?

  • Ascertain that it does what it’s supposed to do
  • Make sure that it can handle the load sent its way
  • Identify every mistake that users can make and find a way around them
  • Check to see if it runs as smoothly across different operating systems, devices, and browsers
  • Calculate what you would pay if you don’t test it now

A thorough and continuous batch of tests will leave you with a healthier API. Testing APIs for one or two positive test flows isn’t sufficient, and neither is doing a positive and a negative test. For successful testing of your API, you will need to check for each unnecessary release risk. You don’t want to uncover a bug but miss out finding a variant that might arise later on.

Imagine an API that informs the users of newly released books based on the author’s name. If you run only a positive flow, you will have entered the name and date and decided that your API works. Think about what could happen when the date is right, but there is no book or when the author has a long name. Therefore, all the positive, negative, and edge cases must be tested out.

APIs are important in today’s world for several reasons. They can be used to create apps and software. Even if you are a user and not a developer, you will interact with them albeit in an indirect manner.

Secondly, companies can use them to share a select part of the information securely. This usually has a positive impact on your life. For instance, imagine travel websites that aggregate flight fares in one place for you to compare and choose great bargains!

Thirdly, APIs can be used to build businesses, such as the software Sprout Social founded via social media network APIs. Lastly, it can help businesses offer unique features to their clients to fulfil their needs better.

Mehul Rajput, CEO and co-founder, Mindinventory
Image source: Shutterstock/Wright Studio

Mehul Rajput
Mehul Rajput is the CEO and co-founder at Mindinventory, a leading mobile app development company specialized in android and iOS app development. He love to write on mobile technologies and app development.