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Web services provide communication between programs based on industry standards, and are platform and language independent. Each Web service has an interface description that encapsulates its details in a form suitable for use by other applications. This interface description may be published in a repository, so that applications can find and utilize the Web service. The description is constructed using Web Services Description Language (WSDL).
Web services are typically based on SOAP (Simple Object Access Protocol), which is an XML-based message protocol that is transport protocol independent. Our sample solution uses the Web Services for J2EE support provided in IBM WebSphere Application Server V5.0.2; Web Services for J2EE support is provided using a standard defined in Java Specification Request (JSR) 109.
In our sample solution, the target EJB application is wrapped as a JSR 109-based Web service. The source application accesses the target Web service using proxy classes generated from the WSDL file for the target Web service.
The technologies used by J2EE application servers to provide Web services facilities are evolving very quickly. The Java community has recently adopted a set of standards to define the different aspects of how Web services can be supported in a J2EE-compliant application server. These standards are described in Java Specification Requests (JSRs).
The main JSR for Web services is JSR-109, Implementing Enterprise Web Services (also known as Web services for J2EE). It reached the final release status in November 2002.
The aim of JSR-109 is to define the programming model and runtime architecture for implementing Web services in Java. It federates the work done on several other JSRs. This JSR was led by IBM.
The Web services for J2EE Version 1.0 specification is an addition to J2EE 1.3. J2EE 1.4 requires support for Web services for J2EE Version 1.1. There are minor differences between the J2EE 1.3 Version (JSR-109 Version 1.0) and the J2EE 1.4 Version (JSR-109 Version 1.1).
Specifications have also been opened for defining APIs for specific parts of the Web services stack:
JSR 67: Java APIs for XML Messaging (JAXM)
JAXM provides an API for packaging and transporting business transactions using on-the-wire protocols being defined by ebXML.org, OASIS, W3C, and IETF.
JSR 93: Java APIs for XML Registry
JAXR provides an API for a set of distributed registry services that enables business-to-business integration between business enterprises, using the protocols being defined by ebXML.org, OASIS, and ISO 11179.
JSR 101: Java APIs for XML-Based RPC
JAX-RPC defines APIs to support emerging industry XML-based RPC standards.
JSR 110: Java APIs for WSDL
This JSR provides a standard set of APIs for representing and manipulating services described by WSDL (Web Services Description Language) documents. These APIs define a way to construct and manipulate models of service descriptions.
See the Java Community Process Web site for the JSR details:
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