Web-Services in Java

Web-Services: Web-service is a service offered by an electronic device to another electronic device, communicating with each other via the World Wide Web, or (specific) a web service implemented in the particular technology or brand, W3C Web Services.

Or

Web services are an open standard (XML, SOAP, HTTP etc.) based Web applications that interact with other web applications for the purpose of exchanging data. Web Services can convert your existing applications into Web-applications.

Why WEB-SERVICES ??

    In a web service, the Web technology such as HTTP—originally designed for human-to-machine communication—is utilized for machine-to-machine communication, more specifically for transferring machine-readable file formats such as XML and JSON.

A complete web service is, any service that −

-Is available over the Internet or private networks

-Is not tied to any one operating system

-Is self-describing via a common XML grammar

-Is discoverable via a simple find mechanism

-Uses a standardized XML messaging system

Components of Web Services

           The basic web services platform is XML + HTTP. All the standard web services work using the following components −

     -SOAP (Simple Object Access Protocol)

     -UDDI (Universal Description, Discovery, and Integration)

     -WSDL (Web Services Description Language)

How Does Web service work?

          A web service enables communication among various applications by using open standards such as HTML, XML, WSDL, and SOAP.

You can build a Java-based web service on Solaris that is accessible from your Visual Basic program that runs on Windows.

        The main characteristic of Web-service architecture is service-provider software publishes its description its description in the directory.

Consumer software- makes queries o find what services are available & how to interact/communicate with Service-Provider.

The following diagram shows the working flow of web-services

                                                Fig [1]

The WSDL in the directory would help to form XML, then request/response is taken place in XML format.

Web Services Concepts:

Web-services provides mainly 2 concepts they are

•  JAX-WS
• JAX-RS

JAX-RS :

• It is Java API for RestFul web services.
• It is a spec that provides support in creating web-services according to REST architectural patterns.
• JAX-RS uses annotations [Annotations are used to map resources].
• It is used for development and deployment of web service to client & end-points.