“The power of Web services is interoperability. Thanks to
industry collaboration on the Web services technologies (SOAP,
WSDL, UDDI) and, more specifically, thanks to the work of the Web
Services Interoperability organization (WS-I.org), a Web service
can interact with any other Web service, no matter which platform
the Web service is developed and run on (such as Microsoft .NET or
IBM WebSphere). A Web service client can be of many types, such as
another Web service, a client written in a scripting language, a C#
client, a Java client, etc. This article focuses on Java clients,
which can be used to access any Web service conforming to Web
services specifications (not only Java Web services). Throughout
the article, you will see the Web service client code required to
invoke the same Web service using different lookup and access
methods. The example used is the ‘Hello’ Web service, which
provides a ‘getGreeting’ operation. This operation takes one String
parameter (for example, Jane) and returns a greeting: ‘Hello
Jane!’.“This section will describe the process of invoking Web
services. A Web service provider describes a Web service in a Web
Services Description Language (WSDL) document. The Web service is
typically published to a Universal Description, Discovery and
Integration (UDDI) registry. A Web service requester finds the Web
service in the UDDI registry, binds to the Web service, and invokes
it. The Web services roles are shown in Figure 1. This article will
focus on the horizontal arrow (bind) from the service requester to
the service provider. This article will call the requester a
client; it can also be referred to as a consumer…”