Soap

SOAP solves an important problem that enterprise and e-commerce/e-business applications face everyday which is inter-application data exchange by exposing functionalities to other parties to use. While SOAP can be considered as a good alternative to protocols such as DCOM and CORBA there is something missing! A developer writing a program that will consume a SOAP Web Service needs to have some knowledge concerning that service and this is where WSDL comes into play. WSDL can be considered as the door of the SOAP Web Service and the latter being a closed room or a black box.

WSDL stands for Web Services Description Language and is described by B. Evjenet (2007) as “an XML document that describes the Web service and can be used by any consuming application.” A WSDL document exposes the available functionality to the client, it also describes their inputs and parameters along with their types and the output type in fact it acts just like say a Javadoc output where classes methods and parameters are described.

An API (Application Programming Interface) is “a set of functions you can use to work with a component, application, or operating system.” (Microsoft, n.d) Can we consider WSDL as a Universal API? In my opinion we cannot, as previously explained an API is an interface to the application itself, WSDL on the other hand just describe this interface and therefore cannot be considered as an API. We can assume that the SOAP Server is the API and WSDL being the documentation that comes with it.

Could a WSDL file be regarded as a design view? To answer this question let’s start by seeking what is a design view. From my understanding a design view is something more like the architectural design of an application describing how components fits and interact together. UML can be considered as the appropriate language to describe architectural design view and this let us with WSDL to do just one simple but important job which is describing a Web Service...