As the world of software technology is exploding and new softwares are created frequently, it is becoming a challenge to adapt a software completely. The primary challenges are compatibility and scalability.

When an organization invests its revenues in a particular software, they expect that the software should suffice their requirements over a period of time but soon they get stuck with challenges where the software is not able to communicate properly to the legacy softwares. To enable these communications, software industry came up with the concept of Application Program Interface (API). An API can specify how the software components will interact with each other. With the emergence of the API concepts, it became easier for the software developers to ensure the components can communicate to each other in a well-defined way. An API can be created for web based system, database system, operating system, software library or even for the computer hardware.

The organizations faced another challenge soon, with the emergence of Internet. Companies were finding it difficult to establish the communication between the Internet and the computer systems using various softwares and operating systems. To overcome the roadblock, RESTful API was created.

RESTful API Design

Representational State Transfer

RESTful web services helped in establishing the interoperability between the computer systems and the Internet. RESTful API uses the HTTP requests for performing the actions GET, PUT, POST and DELETE. While designing these API, the following properties should be considered without any second thought:

  • Performance: The interaction between the API components should not create any performance issues.
  • Scalability: The API should be able to support large number of components and communication among these components.
  • Simplicity: The APIs should not be very complex.
  • Modifiability: To meet the challenges of constantly changing environments and requirements, the API should be easy to modify, to meet the requirement.
  • Portability: The API should be portable, so that script can be moved along with the data from one system to another system.
  • Reliability: The API should be reliable enough to avoid any kind of failure at the system level, in case there is any failure at the component or data level.

The above mentioned non-functional properties of the APIs can only be achieved if the APIs are developed based on the constraints. These constraints define the way in which a server will respond or process the requests from the client. Few of the these most critical constraints are:

Client-server architecture: This particular constraint helps keeping the interface concerns separate from the data storage concerns. By addressing this constraint, the developer adds the feature of portability to the API, as it gives the developer flexibility to use the same API across multiple platforms. The most significant benefit of this constraint is, the components can evolve independently which helps in meeting the scaling requirements.

Cache-ability: The APIs should be able to declare themselves as cacheable. This Will prohibit the clients from using expired or stale data. If the cache-ability is defined properly, it helps in reducing a lot of client-server communication, resulting improvement in the performance.

Layered System: If the API is developed to support the layered system, the performance of the server can be improved many folds by having a load balancing mechanism in place.

Uniform interface: This is one of the most fundamental constraints in REST API designing as it helps decoupling the architecture, which results in independent evolution of the components. The four variants of this constraint is:

a) Resource identification in requests

b) Resource manipulation through representation

c) Self-descriptive messages

d) Hypermedia as the engine of application state

designing a mobile platform

RESTful API Design Patterns

There are various API design patterns which the developers can follow, to build the API. Few of these patterns are listed below:

1) Statelessness: The last place where an API developer would like to store the state information is the application server. Hence, the application servers should always be kept state-free, so that they can be scaled effortlessly.

2) Content Negotiation:  If the developer wants multiple representation to be supported for the resources they can either use content negotiation or they can use separate URLs for separate representations. The other option they have is to use a hybrid approach and have the content negotiation resources being redirected to specific URLs.

3) URI Templates: Creating URI templates enables URL composition for the client. Also, it helps the end-users in documenting the URL access patterns.

4) Design for Intent: The developed APIs should not expose the internal business objects. Hence the APIs should be developed to ensure they meet the requirements of the user cases, provided and faced by the users.

5) Versioning: If an API is designed as per the requirement and it works as expected, nothing like that, but just in case the API does not work as expected, in that case the developer is expected to make the required modification to the existing version of API. Hence, it is always a good practice to add the version number in the API, to keep track of the API versions.

6) Authorization: The RESTful API Design should be able to assign and modify the authorization rights, to allow the read and write access to the resources based on the requirement. Hence, the API developer should ensure that the API should not provide all the users access to each and every objects present in the system.

7) Bulk Operations:  The API should be developed in such a way that it can support bulk operations. This is generally required to meet the requirements of the clients which will issue less requests but these few requests will perform multiple or bulk operations.

8) Pagination: API created with Pagination servers more than one purpose. Pagination helps in reducing the amount of data that will be delivered to the client.  It also helps the preventing the unnecessary computations to be performed on the application server.

9) Unicode: These days, for an API developer it is very important to ensure that the API supports more than English characters in the web service. If Unicode characters are used in a URL, it has to be considered while the API is developed.

10) Error Logging: This is a very crucial activity for bug identification and bug fixing. The API developer should ensure that the process of collecting the error messages are streamlined and well defined. It is very important to clearly distinguish between the errors that were caused by incorrect inputs by the clients and the errors which were caused by the API itself. Hence, it is very important to record these logs in separate log files.

developer working

Author Bio

Natasha is a Content Manager at SpringPeople. She has been in the edu-tech industry for 7+ years. She has been writing on web technologies, technology trends, corporate training which finds its way to various technology websites on World Wide Web. With a aim to provide the best bona fide information on tech trends, she is associated with SpringPeople. SpringPeople is a global premier training provider for high-end and emerging technologies, methodologies and products. Partnered with parent organizations behind these technologies, SpringPeople delivers