This article will examine REST, or REpresentational State Transfer, clients. It will explain their definitions, REST characteristics, how they work, who uses them, why they are important, what you can expect from them, some examples of their use, their benefits, and how they compare to other data methods retrieval.
What is a REST Client?
A REpresentational State Transfer client is one of three components of the REST client-server web application architecture. The three components are the client application, the APIs, which ferry information back and forth between the client application and the web server, and the server upon which the data resides.
The Characteristics of REST
A REST architecture has the following constraints:
• It separates clients from servers. Separating the UI from the data storage improves the portability of the UI across platforms. It improves scalability through simplification of the server components. This separation enables the components to evolve independently.
• It is stateless. The state consists both of intrinsic state and extrinsic state. The resource state, or intrinsic state, is stored on the server. Application state, or extrinsic state, consists of data stored on each client that is dependent on the server’s context.
• It is cacheable. On the World Wide Web, clients can cache responses. Responses must, either implicitly or explicitly, define themselves as either cacheable or non-cacheable to prevent clients from providing stale data in response to further requests. Caching partially or completely eliminates some client-server interactions, thus improving scalability and performance.
• It uses a uniform interface. This simplifies and decouples the architecture, which allows components to evolve independently. The constraints for this uniform interface are resource identification in requests, resource manipulation through representations, self-descriptive messages, and hypermedia as the engine of application state (HATEOAS).
• It is a layered system. A client cannot typically tell whether it is connected directly to the server or to an intermediary. This means that if a load balancer or proxy is placed between the client and server, it will not impact their communications, and there will not be a need to update the client or server code.
• It is able to create code on-demand to meet the needs of the application, even if the application is running. (optional)
How Do They work?
Most of the documentation out there focuses on how REST APIs work rather than the client. This is because the client is simply the interface that initiates the REST API, which is actually the component that goes out and does the heavy lifting. The client is a user interface that requests and displays the information requested by the end-user.
HTTP Verbs Are Used to Make the Requests
There are four HTTP verbs used to request resources in a REST system:
GET retrieves specific resources or a collection of resources.
POST creates a new resource.
PUT updates a specific resource by ID.
DELETE removes a specific resource by ID.
Who Are They For Exactly?
REST is used by developers who wish to build mobile apps or user interfaces to interact with public APIs such as Google Maps and those listed on sites such as GitHub. REST is used for APIs that do not need to adhere to the older SOAP protocol utilized by many legacy systems.
Why Are REST Clients Important?
REST is important because it represents the future of the Internet. REST will continue to provide developers access to a wide variety of publicly available APIs accessing a huge amount of data.
What You Can Expect From REST Clients
More than anything else, the thing you can expect from a REST architecture is flexibility. By being so flexible and adaptable, REST provides developers with an elegant framework to build client-server applications. While the older SOAP (Simple Object Access Protocol) protocol offers a standard that interfaces with a large number o legacy systems, it requires XML messaging.
REST offers developers the ability to define lightweight clients that will interact with REST APIs to transfer data from the server to the client application.
In this example, the client is a ride-sharing app. The driver requests the location of the pick-up location through the app (client), and it then interfaces with the API provided by Google Maps to retrieve the location data on the Google Maps server. In this case, the simplicity of this method is obvious. The developer of the client (app) only has to worry about the interface design and how to invoke the API provided by the server the developer wishes to interact with.
An end-to-end solution would require a developer to not only code the client but the API as well, in addition to creating the server information that would be retrieved. Still, the primary responsibility of the client is to make the data request and display the resulting information.
What Are the Benefits of REST Clients?
The Benefits of REST include:
• REST is adaptable and works well with cloud computing.
• REST is cacheable and worse well with Search Engine Optimization.
• REST architecture allows a greater variety of publicly available APIs to interface with.
• REST provides better support superior performance to your server’s clients.
• REST is faster and uses less bandwidth.
How Does REST Compare to Competitors?
REST architecture’s primary competitor is SOAP. The primary difference between SOAP and REST is that SOAP is a protocol, and REST is not. Typically, APIs will conform to either REST or SOAP, usually dependent upon the preference of the developer.
SOAP is still adhered to by many legacy systems, while REST is a newer, more agile environment as it has fewer constraints than SOAP. REST APIs are lightweight and ideal for newer concepts such as the Internet of Things (IoT), mobile app development, and serverless computing. SOAP web services provide built-in security and transaction compliance that satisfy many enterprise needs, but that makes them heavier. Many public APIs, like the Google Maps API cited in our example above, follow the REST guidelines.
Learning to code a client using the REST architecture will allow developers to create a multitude of applications that access publicly accessible data in a wide variety of environments.