RIDDL (Resource Oriented Interface Description and Declaration Language) is a language that makes it possible to formally describe any HTTP based webservice.  

The main goal of RIDDL is to supplement WSDL as main language for the description of Web Services while extending the scope from purely SOAP based Web Services to Services, that are based on the REST paradigm and other technologies. RIDLL was developed to overcome all shortcomings of the SOAP protocol while sacrificing the protocol agnostic approach of SOAP and relying on the HTTP protocol. As all popular SOAP implementations (ab)use HTTP as transfer protocol, this sacrifice does not reduce the scope of RIDDL in the common practice. 

 

Due to the flexibility of RIDDL it is also possible to easily describe existing Web interfaces using the RIDDL language. This will make it easier to develop applications that make use of the APIs provided by Web 2.0 services like Twitter, Facebook and the likes. 

 

RIDDL also solves the problem of sending binary data as part of a message. By leveraging the HTTP capability of sending multipart messages, a Web Service specified in RIDDL does not need any clumsy workarounds like SOAP Web Services. 

 

In the declaration part of RIDDL it is also possible to specify a Web Service workflow by defining filters, that are applied before or after the actual interface. These filters can be local or at another endpoint thus effectively allowing for Web Service orchestration and choreographies. By implementing the declaration on the client side a service consumer can take advantage of Web Services across different administrative domains without any need to change them. 

 

By allowing more that one interface description in one declaration it is also easily possible to augment existing services with additional features. Also this additions can be located at different administrative domains which allows for easy on the fly composition of existing Web Services. 

 

By leveraging the expressive semantics of HTTP, RIDDL defined Web Services can (but are not forced to) avoid a considerable part of the parsing overhead associated with SOAP messages.  

 

To achieve the critical mass, that is needed to put forward a project with such a big scope, it is necessary to provide easy-to-use tools and implementations for using RIDDL with the most popular languages. One focus of the RIDDL project will therefore lie on the creation of tools that make it easy to access or provide services based on a RIDDL interface description. 

To keep the definition simple, RIDDL makes extensive use of the semantics incorporated in the HTTP protocol. RIDDL therefore relies on a transport protocol, that supports at least the functional subset HTTP provides.  

 

Being a supplement for WSDL as description language for interoperable Web Services, RIDDL does not intent do be a description language for application specific protocols that focus on extreme performance.