Rest API

REST APIs enable you to develop any kind of web application having all possible CRUD (create, retrieve, update, delete) operation.

REST is a short form of REpresentational State Transfer. Introduced by Roy Fielding, REST is an architecture style for distributed hypermedia systems. REST is not a standard but think of it as a set of constraints or principles which must be satisfied if we want to refer to an interface as RESTful.

HTTP GET Method

Use GET requests to retrieve resource representation/information only – and not to modify it in any way. As GET requests do not change the state of the resource, these are said to be safe methods. Additionally, GET APIs should be idempotent, which means that making multiple identical requests must produce the same result every time until another API (POST or PUT) has changed the state of the resource on the server.

HTTP POST Method

The HTTP POST request is most commonly used to create new resources. When talking strictly in terms of REST, POST methods are used to create a new resource into the collection of resources.Upon successful creation, an HTTP code 201 is returned, and the address of the created resource is also transmitted in the ‘Location’ header. 

HTTP PUT Method

Use PUT APIs primarily to update existing resource (if the resource does not exist, then API may decide to create a new resource or not). If a new resource has been created by the PUT API, the origin server MUST inform the user agent via the HTTP response code 201 (Created) response and if an existing resource is modified, either the 200 (OK) or 204 (No Content) response codes SHOULD be sent to indicate successful completion of the request.

HTTP DELETE Method

Use DELETE APIs to delete resources (identified by the Request-URI). A successful response of DELETE requests SHOULD be HTTP response code 200 (OK) if the response includes an entity describing the status, 202 (Accepted) if the action has been queued, or 204 (No Content) if the action has been performed but the response does not include an entity.

HTTP PATCH Method

HTTP PATCH requests are to make partial updates on a resource. If you see PUT requests also modify a resource entity, so to make more clear – the PATCH method is the correct choice for partially updating an existing resource, and PUT should only be used if you’re replacing a resource in its entirety.

SOAP and REST can't be compared directly since the first is a protocol (or at least tries to be) and the second is an architectural style. This is probably one of the sources of confusion around it since people tend to call REST any HTTP API that isn't SOAP.

A SOAP client works like a custom desktop application, tightly coupled to the server. There's a rigid contract between client and server, and everything is expected to break if either side changes anything. You need constant updates following any change, but it's easier to ascertain if the contract is being followed.

A REST client is more like a browser. It's a generic client that knows how to use a protocol and standardized methods, and an application has to fit inside that. You don't violate the protocol standards by creating extra methods, you leverage on the standard methods and create the actions with them on your media type. If done right, there's less coupling, and changes can be dealt with more gracefully.

SOAP Web Services

SOAP stands for Simple Object Access Protocol. It is a XML-based protocol for accessing web services.