The IBM alphaWorks developers have released a Web Services Description Language (WSDL) Explorer to assist in analyzing candidate web services. It is available as an online viewer and as a standalone application. The WSDL Explorer "is a Web application that displays WSDL files, generates views of operations, allows invocation of operations, and allows viewing of sample message flow. It enables users to compare and contrast Web services without going through the time and trouble of importing them into a heavy development tool. WSDL Explorer provides the ability to browse WSDL files, and it offers immediate access to Web service operations. WSDL Explorer displays the port types and operations as a tree in a navigation frame, and it displays a form view for a selected operation in a content frame. Data may be put in the form view and the operation invoked. Formatted results are displayed in an output frame. WSDL Explorer also displays the actual request and response messages. The WSDL Explorer is an innovative application of dynamic HTML combined with JSP technology. WSDL files are analyzed on the server; however, all tree navigation and operation invocation takes place on the client using JavaScript. Because all SOAP requests come from the client, this approach prevents an organization's servers from unwittingly participating in a denial-of-service attack."
From the FAQ document:
WSDL is an XML format for describing network services as a set of endpoints operating on messages containing either document-oriented or procedure-oriented information. The operations and messages are described abstractly and then bound to a concrete network protocol and message format to define an endpoint. Related concrete endpoints are combined into abstract endpoints (services). WSDL is extensible in order to allow description of endpoints and their messages regardless of what message formats or network protocols are used to communicate.
Why should I use a tool like WSDL Explorer? If you plan to use externally developed Web services in a project, you will need a means of analyzing candidate services. You can use a UDDI browser tool to locate services and references to their WSDL files in a UDDI directory (or directories). However, once you locate a service, the task of analyzing its functionality requires more effort than simply reading the service's WSDL description. Ideally, you would like to be able to see available bindings, list and invoke operations on the service, and look at sample message flow. You would also like do this without any development investment: You don't want to import the service into your favorite development tool, create lots of artifacts, and spend time writing sample clients, only to find out that the service doesn't really meet your needs. WSDL Explorer allows you to see available bindings, list and invoke operations on services, and look at sample message flow for multiple services at once without having to import the services into your development tools.
WSDL Explorer's invocation logic is implemented in client-side JavaScript served down by JSPs. Invoking methods from your client saves the round-trip time of sending an invocation request to the server on which WSDL Explorer is hosted, thus improving performance by eliminating some network latency. Another consideration in the WSDL Explorer client-side invocation design relates to security. An invocation design in which service operations are invoked on the WSDL Explorer server can leave the server open to unwittingly participating in a denial-of-service attack on a Web service company.
