API Specifications - All You Must Know About It

API specifications are the basic understanding of how an API will behave and how API links one to another API. This will also help us understand how the API functions and expected results. It talks about the design layout of the API and the philosophy behind the design. The best example of an API specification is the OpenAPI specification on GitHub. The API specifications display many API objects, values, and guidelines, showing the relationship between the objects and their use. An API specification combines both API documentation and API definition to create a contract readable by people and software. One advantage of an API specification is that it increases adoption and limits the project’s completion time. APIs can be divided into several types based on their specifications, of which a few are listed below.

Remote Procedure Call (RPC)
Simple Object Access Protocol (SOAP)
Representational State Transfer (REST)

They aim to accomplish a set standard of data exchange between operating systems or languages, or technologies for smooth communication. Let’s go through an in-depth study.

Remote Procedure Call (RPC)

Web APIs might follow resource exchange principles based on a Remote Procedure Call that specifies the reciprocity between client and server-based applications. A client requests data and sends a query to the server, and it responds with the requirement. Well, to implement the Remote Procedure Call, one way is Service Object Access Protocol.

Service Object Access Protocol (SOAP)

As Microsoft has defined, this very lightweight protocol is for exchanging structured information in distributed, deconcentrated systems. SOAP calls for some set syntax rules to process the requests and response messages sent by web applications. Through this, APIs based on SOAP principles enable XML (extensible markup language) to establish communication between systems via HTTP or SMTP. SOAP uses XML format for storing data and allows exchanges over the internet and various other networks. It defines rules for encoding documents in a form that humans and machines can read. SOAP integrates high security of exchanged data with enterprise web-based applications, which is why it is preferable to providers of payment gateways, identity managers and CRM solutions, and financial and telecommunication service providers just like PayPal.

Representational State Transfer (REST)

REST is a software architectural style to build applications using HTTP like web services such as World Wide Web. It has six constraints, and the Web APIs with it is called RESTful. This is a fantastic alternative for developers who find SOAP complicated to work on, which involves writing hefty codes to complete the task. It represents each source with a unique URL, and one can request it by providing a URL. Therefore, we can say that API definition, API documentation, and API specification are all interrelated but different from one another. Each of them has an essential purpose in serving the developer. Documentation tells how to use the API; the specification provides the functionality of the API, and the definition is the consumption of the API. Hence, they are all essential for the overall success of an API.

Other useful articles: