services should be described and bound by clients.
II. Universal Disc overy, Description and Integration
In order to use a service, a client must first locate that service
and retrieve information to use the service.
The Universal Discover, Description and Integration or UDDI
specification, defines a number of lookup services that allow
clients to look up and retrieve the required information to
access a Web Service. UDDI provides a mechanism for clients
to dynamically find other web services over the web. Using a
UDDI interface, businesses can dynamically connect to
services provided by external business partners.
UDDI actually provides three specific services:
• Traditional White Pages for looking up a Web Service by
• Traditional Yellow Pages for looking up a Web Service by
• Green Pages for more generic searches based on the
characteristics of a Web Service.
Vendors who provide UDDI services typically operate a service
known as a UDDI Business Registry, or UBR, which can be
accessed to both publish and request information about a
given Web Service.
III. Connecting It All Together With the Simple
Object Access Protocol (SOAP)
We have analyzed few things like defining, describing and
publishing a web service. Now we see the mechanism to
access a web service once we’ve found it.
Web Services become accessible through the SOAP protocols.
SOAP defines a way to perform remote procedure calls
(RPCs) using HTTP as the underlying communication protocol.
Typically, a SOAP call is packed as a body of an HTTP
request. SOAP is simple, easy to implement, and well supported
in the industry. Even a UDDI registry is accessed
through well-defined SOAP calls.
SOAP supports both synchronous and asynchronous call
semantics i.e. standard RPC as well as message-based. It
can also be used with a variety of protocols other than HTTP.
A SOAP message is an ordinary XML document containing
the following elements:
• A required Envelope element that identifies the XML
document as a SOAP message
• An optional Header element that contains header information
• A required Body element that contains call and response
• An optional Fault element that provides information about
errors that occurred while processing the message
AN INTERACTIVE WEB SERVICE WORKING
The Google Web APIs service package contains
• GoogleSearch.wsdl - the WSDL description
• googleapi.jar - a client java API library
and provides three operations for the Google database:
Developing Web Services with Java
The few essential tools for Java Web Service development:
• Apache AXIS (Apache Extensible Interaction System)
I a Java-based implementation of SOAP+WSDL
II largely allows the programmer to forget these technologies
III typically used together with Tomcat
IV Highly recommended!
• Sun’s Java WSDP (Web Services Developer Pack)
I support for SOAP, WSDL, UDDI, ...
II JAX-RPC maps SOAP/WSDL to RMI (Java Remote
III Java API for XML Pack (the so-called JAX Pack)
IV the JSP Standard Tag Libraries (JSTL) API
V Java Secure Socket Extension (JSSE) API
VI Jakarta Tomcat Web container
VII the Ant build tool
VIII the UDDI-based registry server
• Open-Source Java EE 5-compliant application server :
I Will feature a major transition from Java WSDP.
II Java WSDP Pack will no longer be developed as a
discrete release vehicle for the Web services and XML
III will provide latest state of development will be supported
that WSDP provides
IBM’s alpha Works’s EETK (Emerging Technologies
IV Support for SOAP, WSDL, UDDI and much more...