The WSO2 ESB has had support for exposing RESTful interfaces and mediating RESTful invocations from the beginning although it is primarily based on Apache Axis2, which is a SOAP engine. However, in ESB version
4.0.3, REST API support has been significantly enhanced.
Instead of mapping REST concepts to SOAP in handling REST calls with proxy services, developers can easily configure REST endpoints in ESB version 4.0.3 by directly specifying HTTP verbs, URL patterns (servlet styled), URI templates, HTTP media types and other related headers. They can define REST APIs and associated resources in the ESB by combining REST APIs with mediation features provided by the underlying messaging framework.
As depicted in the diagram below, core API management features such as API key management, user management, security and SLA monitoring are all provided by the solution itself.
Going forward, the API Management capability will be matured to support a comprehensive API management solution. This will be a complete platform for developing and exposing REST APIs, which users can simply subscribe and consume. This solution will also leverage the multi-tenant support in Carbon to operate seamlessly in the cloud. All these changes are to be expected in future releases of the WSO2 ESB.
Also refer to Introduction to REST API sample in the ESB.