SOA that comply with REST constraints has recently enjoyed a surge in popularity. The main reason for this is that REST maximizes (by imposing a uniform 'application' interface) what is possibly SOA's greatest virtue, namely, loose coupling between service-provider and consumer systems, which gives rise to an almost infinite potential for evolving systems independently.
In the case of the Web services, the REST-style approach is simple. Indeed, given that HTTP (RFC 2616) is the Web protocol par excellence and that the principles on which its architecture is based are, in fact, the restrictions defined in REST, obtaining REST-style Web services is as straightforward as using HTTP as the application-level protocol (Figure 2), instead of using it just for transporting (ubiquitously) messages generated by a different, 'specialized' application level (Figure 1).
Thus, the REST approach makes Web services truly Web-based resources with which application-level interaction with their capabilities using HTTP protocol (GET, PUT, POST, DELETE). In this way (Figure 2), each Web service has one or more 'Web resources', each of which is identified with a URL (i.e., a uniform identification schema) and implements, with specific semantics, the interface predefined by the HTTP protocol (i.e., the uniform interface).
Safelayer's TrustedX platform incorporates an integration gateway that supports, among other things, accessing and linking platform functions to make them available as RESTful services for their flexible integration.