Simplifying Web Service development with JSR-181

JSR 181 or Web Services Metadata for the Java Platform is a Java Specification Request that defines an annotated Java format that uses Java Language Metadata (JSR 175) to enable easy definition of Java Web Services in a J2EE container. To put simply, JSR 181 enables developers to create portable Java Web Services from a simple Plain Old Java Object (POJO) class by adding annotations.

This Web Service development model may be related to JSP model where a JSP file is translated into a Servlet that gets in turn compiled to a class file that finally runs inside the container. The JSP model frees the developers from manual compilation and deployment of Servlets into container. Similarly in this model too, Web Service developers defines only the annotated Java Web Service (JWS) file and leave the job of creating necessary deployment and configuration files to the vendor (who actually implements Web Services based on JSR 921 specification). For example, WebLogic application server provides an Ant task called jwsc to create the JSR 921 compliant Web Service implementations. As the generation of JSR 921 compliant Web Services is hidden to developers, they can focus on developing core business services rather than worrying on learning and implementing generalized APIs and deployment descriptors.

The annotated Web Service development model also provides fine-grained control over exposing the Web Services. It enables the developers to expose the entire class or only the selected methods as the Web Service. This feature may be of great help when the Java class contains core business methods bundled along with non-business methods and/or data service methods, which the developer might not want to expose as services. In this scenario, the developer may take advantage of the annotations to specify how a Web Service should be exposed to outside world.

Putting simply, JSR 181 is a specification to define standard and portable Web Services. It offers the following benefits:

* Provide a simplified model for developing Web Services
* Abstract the implementation details
* Achieve robustness, easy maintenance, and high interoperability