As compared to the Simple Object Access Protocol (SOAP), REST technology is preferred worldwide due to its use of less bandwidth making it suitable for internet usage. The API helps form an articulate way for the developer to write the program requesting services from an operating system or other application. REST is being used to build APIs in powerful websites around the globe such as Google, Amazon, Twitter and LinkedIn, as it allows the users to interact and connect with the cloud services.
Furthermore, a REST API is based on representational state transfer technology and uses an architectural approach and style of communication in web services development. As REST API uses HTTP, any programming language can use and test it easily. By using some conventions, REST API, along with simple data transfer mechanism and authentication mechanism can help build a set of APIS to create, read, update and delete records in your system through a set of HTTP calls.
API Testing includes testing direct APIs and as part of end-to-end transactions that are integrated during testing. These transactions include multiple endpoints type that are web services, databases, ERPs, web UIs, ESBs, mainframes and RESTful APIs. This testing is used to determine multiple results such as response to a range of feasible requests, reaction to edge cases that could be failures and unexpected inputs, delivery of responses on time and respond to security attacks.
API Testing is considered more suitable than GUI testing for test automation and continuous testing because APIs are known to have a more stable interface to the system under test and tests at the API later have short release cycles with fast feedback loops and are easier to maintain.
REST or the Representational State Transfer is an approach used in web applications to define the roles of various components. It uses the standard database- Create, Read, Update, Delete and convert into HTTP verbs including Post, Get, Put, Delete. By following the convention and passing the right parameters, you successfully translate business logic into HTTP.
Why REST API?
As against SOAP that has to follow a number of rules, with REST, the development team can scale the product by reaching out to the other servers or make various changes in the database, given that the data from each request is being sent correctly. There is a separation between the client and the server which makes it possible to gauge the front as well as the back of different servers making the apps more flexible to work with.
Under the REST protocol, the user interface is totally separated from the server and the data storage. In this, the portability of the interface to other platforms is improved while increasing the scalability of the projects. This division helps the different components of the development to be evolved on an independent basis.
Since adaptability of REST APIs to different types of platforms is considerable, new environments can be changed or tested within the development. With the help of servers such as PHP, Python, Node.js or Java, REST APIs can be easily used. What is to be considered however is that the responses to the requests should take place in the same language that is being used for the information exchange in which case, it is usually XML or JSON.
You can create an API with REST that can be used by you or the users. Using the right HTTP actions on the resources, the API design and functionality can be clearly indicated to the clients. When the correct HTTP verbs are being used, an API is declared understandable from the perspective of the client.
Setting up REST-API
The REST API has the following features:
1. The Client has the front end and the server has the backend wherein both can be replaced independently of each other.
2. Between the requests, no client data is being stored on the server and the session state is stored on the client.
3. The clients can cache the response to help improve the performance.
The most important aspect while writing HTTP status codes is to know the correct status codes against the request being made. Whenever you make the HTTP request, the server will respond likewise, and you will get to know if the code was successful or not and how to move further.
Always consider using the key principles of REST that involve separation of APIs into logical resources. Use Nouns instead of Verbs and keep the URL format consistent and use a plural such as tickets, users, groups etc.
Since not all internet points are secure, use SSL as the web APIs can be accessed from anywhere in the world and are open to being hijacked. SSL guarantees encrypted communication which in turn simplifies the authentication efforts.
All the APIs should have proper documentation which are easy to find and are open to public viewing. You may add URLs that can be opened into a browser or a terminal. Also, any update should be communicated via either a blog or a mailing list or both.
Use lean URLs instead of complex ones.
Use Put, POST and DELETE methods instead of the GET method to alter the state. Do not use GET for state changes.
For better navigation through the API, use Hypermedia As The Engine Of Application State (HATEOAS) that hypertext links.
Let the API consumer be given the ability to choose returned fields as this will reduce the network traffic and the usage of the API will speed up.
Always give aversion to your API and do not release that API which is unversioned. Use simple ordinal number and avoid dot notation such as 2.5.
Though some HTTP clients only work with GET and POST requests, increase accessibility by overriding the HTTP method, i.e. accept a request header with a string value containing one of PUT, PATCH or DELETE.