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I bet you’ve already heard this three magic letters: API. What do they mean? Why you may possibly want to deal with API? How to approach this concept and make smart decisions dealing with API? Let’s start with the basics.
What is Application Programming Interface (API)
Let’s try to make a short definition of API first. Application Programming Interface is a set of clearly defined methods of communication between various software components.
APIs are exactly like user interface on your smartphone, except they are made for machines and software applications running on a computer. API is a contract that exists between two ends of the transaction.
API is a set of rules by which two software products interact with each other. It can be used by your smartphone, or it could be two servers talking to each other. Maybe you have email-responder talking through the network to Salesforce to exchange some information.
API terminology:
- A software application is often the “consumer” of the API. The “consumption” of API is usually called API integration.
- The service that offers the API is said to be the “provider”. The provider establishes the rules by which all app will talk to him. If you want my help – say “please”.
- If you’re using API to get information from the service (get Facebook ID) you make API calling. You make a call each time you say “please”.
Why would anybody develop an API or use it? What’s so cool about it?
As it turns out if you’re an app developer you can outsource certain requirements of your application to an API. So instead of coding entire Google Maps, you could outsource this to API with only one line of code. Just make a proper request and you’ll get the answer.
Examples of API Use
The most common example of API usage is transactions. If you want to execute a financial transaction, there are standard API for PayPal or Stripe. You don’t need to write a new payment gateway, you just make a call to PayPal’s API, name yourself and transaction destination.
Another really good example of API is social media plugins that you see on websites, such as news articles that embodies tweets, or pages with facebook comments under it, or facebook login button in an e-commerce store.
Also, you can integrate Instagram API into your website. This way you can automatically stream your photos from Instagram to the webpage. All you’ll need to do is make a certain API request.
How API is Used in Development
Whenever app you’re interacting with you’re in fact interacting with hardware. The software that you use can be thought as a cake, a stack of different programs, some of which sit between topping and bottom. Without these layers, software programmers and developers would have to code differently for every single hardware configuration on the planet. Fortunately, there are device drivers that standardize communication between software and hardware.
Now, with the technological advancements, the amount of layers have increased. We’ve got tons of complex services and software solutions. The question now is how do two different programming layers can interact with each other, without having tons of code in common. That’s where API is used.
API layer standardizes the coding process so that programs can interface with lots of different staff easily. API provides a simpler way for developers to interact with other kinds of software.
For instance, both Facebook and Twitter have their own APIs that they make available to web developers, making it easy to integrate Facebook and Twitter features into the web pages. Without these APIs, social media giants would have to share code directly with owners of other sites, which would be tedious, difficult and possibly give away certain trade secrets.
API allows business owners to share their software service without actually revealing trade secrets and code base.
On the other hand, developers don’t waste their time decrypting entire Facebook’s code base. You can just open documentation for Facebook API, find function you want to use, see the list of commands, insert those commands on your page, and that’s it. Your website now can talk to Facebook.
API Types
Internal API
This kind of API is usually used by large corporate apps in order to establish communication between inner services.
For example, your corporate app has an internal service that stores all contracts, invoices, legal agreements. On the other hand, you’re building a new email-service that will automatically send invoices to new clients. Those two services can be connected in a monolithic way, which will make your app highly intertwined and complex.
On the other hand, you can connect all your corporate services through the API, which will make them more agile, maintainable and scalable. Because, each service will be packed in its own container, or API. This is what’s called service-oriented architecture (SOA).
External API
These APIs are primarily available externally to consumers. PayPal API is an external API. Nowadays, most of APIs are written based on REST/JSON technologies. You may heard of RESTful API, an API built using REST architectural approach.
What is REST API?
First of all, you need to understand what is REST. REST (Representational State Transfer) is an architectural style which prescribes a specific way of interaction between the components of the distributed application in a network. REST is not a thing, it is an agreed set of constraints that are taken into account when designing a distributed system.
Thus, RESTful API is an API made with REST approach in mind. Here are signs of REST that API inherits:
- Client-server architecture – this an underlying principle of each API that represents the type of relationship between the consumer and provider.
- Statelessness – Because the calls are stateless, REST is useful in cloud applications. Stateless components can be redeployed if something fails, and they can scale to address load changes.
- Uniform interface – RESTful API usually use simple HTTP methods to communicate. They use GET to retrieve a resource; PUT to change the state of or update a resource; POST to create resource; DELETE to remove it.
- Layered system – RESTful API strives to break each operation in a number of small modules. Each module addresses a particular function or transaction. This approach grants a lot of flexibility in terms of design and scale.
- Cacheability – This way the consumer can cache responses of API and save states on their side, without contacting the server each time it makes changes on their side.
Why you may want to develop an external API for your corporate app? This way you could easily share required resources with partners and clients, without sharing viable data.
Moreover, external APIs boast a better scalability and performance, meaning you and your clients will get a better service and UX. The difference in performance of corporate app, with and without API, may hit up to 1 minute in terms of load time.
What is API Documentation
Basically, it’s a dictionary which contains all commands a certain API understands. Documentation describes how to do API work.
Documentation describes all use cases and actions that can be performed with the software by use of API. That’s why API’s documentation usually structured by the use cases of app functions.
API documentation size depends on the number of use cases the app can support. You can have a 2-page PDF-file or host a 12-page website with numerous use cases and integrations your service can support.
Bottom Line
APIs might not be the usual star of the show when you’re using a simple app on your smartphone, but they make it possible for all of our devices and software to work well with each other.
In addition, APIs enable massive amounts of quick communication and high-end services that we’ve got used to. If you’re building a corporate app you may already notice performance issues that arise along with the growth of your software infrastructure. Building an internal or external API will help you overcome this issue.
