The RESTful API design is meant to mainly take advantage of all existing internet protocols. Even though REST is one of those designs which can be used with any type of protocol it mainly is the most advantageous with HTTP for Web APIs. What this means is that developers are not required to install a separate set of libraries or even software to start taking advantage of the API. Originally defined by Dr. Roy Fielding in his doctoral dissertation in 2000, it is noted for being layered with flexibility. Since unlike other APIs the data isn’t tied with methods or even resources it has the ability to make multiple calls and return a number of different data formats. It can also be changed structurally by using hypermedia .

Why Choose REST over SOAP?
SOAP was the API design protocol of choice for APIs in the old days. It is still existent with many older APIs. However, what allowed REST to take over was flexibility. REST allows developers to design applications that meet the needs of a wide selection of customers. Also unlike older technologies like SOAP, it is not limited to just XML but rather can also use YAML and JSON. Plus, developers are not required to memorize different procedural names or parameters.

Drawbacks of RESTful Design
Like everything in technology or perhaps in the real world there are pros and cons. REST APIs do have their own set of cons. For instance, you can lose the ability to hold a state when in REST-like within a session. Also, implementing REST APIs is more difficult for beginner developers. There are also many limitations which make the RESTful API so-called restful, and these constraints need to be kept in mind when building the API.

The Client-Server Constraint
The RESTful API design client-server constraint works on the assumption that the server and client are different from each other, so they evolve independently and individually. What that means is that you can make changes to a mobile application without affecting the data structure of the server. Yet it should also be possible to modify that database or issue changes to the server application without it having any impact on the mobile device. If anything this constraint exists to create a sort of separation which lets every application grow and be scaled independently of each other.

Stateless RESTful APIs
REST APIs are meant to be stateless which means that they need to make calls independently from each other and everyone has data to complete the task successfully. REST APIs shouldn’t rely on stored data across sessions or servers to make sense of what to call instead it needs to rely on the data which is provided within the call. Every call has the required data within itself like the API key, user ID, access token, etc. If anything it helps to increase an API’s reliability because it has all the required data to issue that call instead of making a long series of callers to the server if an object needs to be created because that could result in partial failure. Also, to ensure scalability and reduce memory requirements RESTful APIs store their state on the client as opposed to the server.

The Cache
Since using a stateless API tends to increase the overhead regarding the handling of requests both outbound and inbound, the API should be designed with cache storage in mind. What that does is when data can be cashed it is cached for a specific time or in cases where data is required in real time it isn’t cached. Caching will help to significantly reduce the overall number of interactions with the API which in turn reduces the load on the server. Though on the other hand API users benefit from high speed with efficient apps.