Understanding web service in simple words

What is a Web Service ? :

• A webservice is a software function provided at a network address over the web

• It is supposed to be "always on"

• Web services are really nothing more than a request/ response mechanism that allows a client to remotely access/ modify data.

Types of Web Services :

1. Big Web Services  (Basically StateFull)

( JAX-WS provides the functionality for “big” web services )

• Big web services use XML messages that follow the Simple Object Access Protocol (SOAP) standard.

A SOAP-based design must include the following elements.

• A formal contract ,WSDL can be used to describe the details of the contract .

• The architecture must address complex nonfunctional requirements .

Examples include transactions, security, addressing, trust, coordination, and so on. For More on JAX-WS Refer this link 

Basic Component of State Full Webservices

What is WSDL?

•  Web Services Description Language

• based on XML

• describe Web services
• locate Web services

What is SOAP?

• Simple Object Access Protocol

• format for sending messages

• platform independent

• based on XML

What is UDDI?

UDDI is a directory service where companies can register and search for Web services.

 2)  RESTful Web Services (Stateless)

         (  JAX-RS provides the functionality for Representational State Transfer (RESTful) web services  )

         

REST is well suited for basic, ad hoc integration scenarios. RESTful web services, often better integrated with HTTP than SOAP-based services are, do not require XML messages or WSDL service–API definitions .

developing RESTful web services is inexpensive .

Appropriate for  following conditions .

1. The web services are completely stateless (A stateless server is a server that treats each request as an independent transaction that is unrelated to any previous request.) A good test is to consider whether the interaction can survive a restart of the server.

2. A caching infrastructure can be leveraged for performance. If the data that the web service returns is not dynamically generated and can be cached.
3. producer and service consumer have a mutual understanding of the context and content being passed along.