REST VS SOAP

SOAP and REST both allow you to create your own API. API stands for Application Programming Interface. It makes it possible to transfer data from an application to other applications. An API receives requests and sends back responses through internet protocols such as HTTP, SMTP, and others. 

Many popular websites provide public APIs for their users, for example, Google Maps has a public REST API that lets you customize Google Maps with your own content. There are also many APIs that have been created by companies for internal use.

There are significant differences between SOAP and RESTful web services. The bullets below break down the features of each web service based on personal experience.

REST

• RESTful web services are stateless. You can test this condition by restarting the server and checking if interactions survive.
• For most servers, RESTful web services provide a good caching infrastructure over an HTTP GET method. This can improve the performance if the information the service returns is not altered frequently and is not dynamic.
• Service producers and consumers must understand the context and content being passed along as there is no standard set of rules to describe the REST web services interface.
• REST is useful for restricted-profile devices, such as mobile, for which the overhead of additional parameters are less (e.g., headers).
• REST services are easy to integrate with existing websites and are exposed with XML so the HTML pages can consume the same with ease. There is little need to refactor the existing site architecture. As such, developers are more productive because they don't need to rewrite everything from scratch; instead, they just need to add on the existing functionality.
• A REST-based implementation is simple compared to SOAP.

SOAP

• The Web Services Description Language (WSDL) describes a common set of rules to define the messages, bindings, operations and location of the service. WSDL is akin to a contract to define the interface that the service offers.
• SOAP requires less plumbing code than REST services design (e.g., transactions, security, coordination, addressing and trust). Most real-world applications are not simple and support complex operations, which require conversational state and contextual information to be maintained. With the SOAP approach, developers don't need to write plumbing code into the application layer.
• SOAP web services, such as JAX-WS, are useful for asynchronous processing and invocation.
• SOAP supports several protocols and technologies, including WSDL, XSDs and WS-Addressing.

https://searchmicroservices.techtarget.com/tip/REST-vs-SOAP-Choosing-the-best-web-service