RPC, SOA, REST- the most well-known types of web-services

The web services a simply a number of tools that can be used in many various ways. The most used ones are PRC, SOA and REST.

The Remote Procedure Call web services is a service familiar to a great variety of developers. It represents a distributed function call interface. The most well-know operation of RPC is WSDL. It is the first web service that was widely implemented, and therefore it is very wide deployed and supported. But, regardless of its wide implementation, it has been criticized for not being loosely coupled, because it is often implemented too tight with the language-specific procedures and methods, therefore being insecure in case of inaccurate usage. Nowadays, many vendors disprove RPC, therefore  it is now disallowed in the WS-I Basic Profile.

The Service-oriented architecture (SOA) concept is also widely used. In contrast with RPC, the basic unit of communication between the client and server is the message, rather that the operation. This is very often called “Message-oriented service”. The majority of software vendors and industry analysts support this web service because in SOA, loose coupling is more probable, as the main focus is not on the implementation details, but is on the “contract” that WSDL provides.

The last type of web-services are the REST type. They represent an effort of emulation of HTTP and other similar protocols, but by constraining the initial interface to a small set of well-known operations, standard for the industry, such as GET, PUT and DELETE. In such a way, the web-service is interacting with stateful resources, instead of working with messages or operations. The RESTful web-services are able of using WSDL for describing SOAP messaging over HTTP, which is the standard for the operations, or it is possible to implement it as an abstraction, on top of SOAP.