Articles : Web Services Metadata :

Web Services Metadata

Introduction

The web services metadata specification proposes a rapid and simple solution to define and develop web services. The specification introduces the concept of adding metadata to the implementation bean to define a web service. The metadata can be in the form of custom tags for the different elements in a web service. The metadata tags would not interfere with the normal working of the application but would allow a preprocessor to interpret the metadata tags and generate the appropriate code for web services. This reduces the amount of code the programmer has to write for making Java classes behave both as a regular application and as a web service.

To make this possible the web service metadata specification uses the "JSR 175 – A Program Annotation Facility for Java" specification. More information about the program annotation facility in Java can be found in the references section below.

Anybody familiar with the EJBGEN utility used in weblogic or the Xdoclet API would appreciate the web services metadata approach. The ideas of all these APIs are the same. Instead of making the developer create multiple configuration files, interface classes and mapping files, these application give the developer the flexibility to write the business implementation class and define custom tags with the same class. An interpreter will read these custom tags and create all the other supporting classes.

The same approach can work for web services, as a web service requires multiple files for it’s functioning. A web service developer usually would have to create several artifacts for defining a web service: a WSDL document outlining the interface to the web service, a service endpoint which is the Java representation of a web service interface, a service implementation bean which has the business logic for the web service and finally one or more deployment descriptors which link the WSDL document, the web service interface and the web service bean together. "JSR –181" alleviates all these problems by an annotation based web services generation solution.

It provides a facility to create web services by creating annotations in Java code.
It provides a common syntax for web service definitions, which can be used by developers and can be manipulated by custom tools.
It provides a standard and simple way to develop web services.
It makes it easier for developers to develop web services that conform to the standards of SOAP and WSDL.
It makes it easier to develop web services that work seamlessly with the core Java web services APIs.
This separation between the actual web service implementation and the web service definition helps to segregate the public web service APIs and the actual business implementations.

Sample:

import javax.jws.WebService;
import javax.jws.WebMethod ;

@WebService {
	name = “SampleWebService” ,
	targetNamespace = “http://javaboutique.com/sample/SampleWebService”  
}
public class SampleBean{
	@WebMethod
	public String webServiceMethod1(){
      	…..
      	return “Sample Method working”;
      }
      
      public void regularMethod1(){
      	…
      }
}

The above sample is a regular Java class that has been annotated with "JSR –181" web service annotations.

Home / Articles / Web Services Metadata / 1

Applet Index
(sorted alphabetically)
A B C D E F G H I J K
L M N O P Q R S T U
V W X Y Z #s

The Java Source
(applets w/source code)
A B C D E F G H I J K
L M N O P Q R S T U
V W X Y Z

How to Add Java Applets to Your Site

New on the Java Boutique:

New Review:

Time Management Made Easy with the Quartz Enterprise Job Scheduler
Why not just use the Java timer API? This open source scheduling API boasts simplicity, ease-of-integration, a well-rounded feature set, and it's free!

New Applet:

Reverse Complement
Reverse Complement is a simple applet that converts DNA or RNA sequences into three useful formats.