Working with Web Services

A Web service is a service offered via the web. The principle on which a Web service works is the following: a business application sends a request to a service at a given URL address. The request can use the SOAP protocol over HTTP. The service receives the request, processes it, and returns a response. An example that is most commonly used for a Web service is a stock quote service in which the request asks for the price of a specific stock and the response gives the stock price.

In an OOM, you design a Web service as a component (EJB, servlet, or standard component) that includes a Web service implementation class.

When you work with Web services in an OOM, you use the class, component and deployment diagrams. They allow you to do the following:

Create new Web Service component
Reverse engineer WSDL to create Web Service component
Browse UDDI to search WSDL
Generate WSDL from Web Service component definition
Generate server side Web Services code for Java (AXIS, JAXM, JAX-RPC, Web Services for J2EE)
Generate server side Web Services code for .NET (C# and VB .NET)
Generate client proxy for Java
Generate client proxy for .NET
Reverse engineer for Java and .NET

What Do You Need to Work with Web Services?

You need a Java, C# or Visual Basic .NET compiler.

For Java, you also need a WSDL-to-Java and a Java-to-WSDL tool to generate Java proxy code and JAX-RPC compliant server side code. The WSDL-to-Java and Java-to-WSDL tools are used by the extended model definition named 'WSDL for Java'. For example, the WSDP (Web Service Developer Pack) provides a XRPCC tool, Apache AXIS provides a wsdl2java and a java2wsdl tool.

The WSDP and the appropriate SDK can be downloaded from the Sun Java Development Site: http://java.sun.com/index.jsp.

Apache AXIS can be downloaded from: http://ws.apache.org/axis.

To generate client proxy code for .NET, you will need to use the WSDL.exe included in Visual Studio .NET and declare the path to the WSDL.exe in the General Options dialog box ( Tools > General Options ) when you create the WSDL environment variables.

Defining Web Services Tools
A Web Service is an interface that describes a collection of operations that are accessible on the network through SOAP messages.
Defining Web Services Targets
The following OOM languages support Web services:
Defining Web Service Components
A Web service is represented as a component that you can display in a component diagram. From a component diagram, you can display the Web service interface and implementation code, eventually, you can also deploy Web service components to nodes if you want to describe deployment of components into servers.
Managing Web Service Methods
You can define one or several methods as part of a Web Service. In PowerDesigner, you use operations to create Web service methods.
Defining Web Service Component Instances
The deployment diagram is used with Web services to model the Web services deployment. This diagram is useful if you want to deploy a Web service into one or several servers, and if you want to know which Web service is deployed where, as deployment diagrams can display network addresses, access endpoints and access types.
Generating Web Services for Java
You can generate client side or server side implementation classes, interfaces, deployment descriptor, JAR, WAR, or EAR from the Generate object language command in the Language menu.
Generating Web Services for .NET
The following items are generated in .NET languages (C# and VB.NET):
Generating Web Services for Sybase WorkSpace
You define a Web service from the component diagram or using the Web service wizard from the class diagram. You use the OOM to design the Web service implementation using the implementation class, however this implementation may be partial and you may need to use a web service editor to complement the Web service implementation.
Reverse Engineering Web Services
The process of reverse engineering Web services described in this section allows you to reverse WSDL for .NET and Java. This process is very similar to an import process, that is why it is introduced as the Import WSDL process.