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Web services and SOA

What are Web services and Soa ? Normally, we think ,don’t know it but we use it every day and every time when we open our computer and do our working by pass
This system don’t know ourselves because of not interesting it is very vital for us job all day under this we can know one by one of two systems.

Web services describes a standardized way of integrating Web-based applications using the XML, SOAP, WSDL and UDDI open standards over an Internet protocol backbone. XML is used to tag the data, SOAP is used to transfer the data, WSDL is used for describing the services available and UDDI is used for listing what services are available. Used primarily as a means for businesses to communicate with each other and with clients, Web services allow organizations to communicate data without intimate knowledge of each other's IT systems behind the firewall.

Unlike traditional client/server models, such as a Web server/Web page system, Web services do not provide the user with a GUI. Web services instead share business logic, data and processes through a programmatic interface across a network. The applications interface, not the users. Developers can then add the Web service to a GUI (such as a Web page or an executable program) to offer specific functionality to users.
Web services allow different applications from different sources to communicate with each other without time-consuming custom coding, and because all communication is in XML, Web services are not tied to any one operating system or programming language. For example, Java can talk with Perl; Windows applications can talk with UNIX applications. Web services do not require the use of browsers or HTML.
Web services are sometimes called application services. Under point out of process of the web service work in system.




And SOA are based on a mesh of software services. Services comprise unassociated, loosely coupled units of functionality that have no calls to each other embedded in them. Each service implements one action, such as filling out an online application for an account, viewing an online bank-statement, or placing an online booking or airline ticket order. Instead of services embedding calls to each other in their source code they use defined protocols that describe how services pass and parse messages, using description meta-data.
The developer associates individual SOA objects by using orchestration. In the process of orchestration the developer associates software functionality (the services) in a non-hierarchical arrangement (in contrast to a class hierarchy) using a software tool that contains a complete list of all available services, their characteristics, and the means to build an application utilizing these sources.
SOA is an architectural style for building software applications that use services available in a network such as the web. It promotes loose coupling between software components so that they can be reused. Applications in SOA are built based on services. A service is an implementation of a well-defined business functionality, and such services can then be consumed by clients in different applications or business processes.
SOA allows for the reuse of existing assets where new services can be created from an existing IT infrastructure of systems. In other words, it enables businesses to leverage existing investments by allowing them to reuse existing applications, and promises interoperability between heterogeneous applications and technologies. SOA provides a level of flexibility that wasn't possible before in the sense that:
• Services are software components with well-defined interfaces that are implementation-independent. An important aspect of SOA is the separation of the service interface (the what) from its implementation (the how). Such services are consumed by clients that are not concerned with how these services will execute their requests.
• Services are self-contained (perform predetermined tasks) and loosely coupled (for independence)
• Services can be dynamically discovered
• Composite services can be built from aggregates of other services
For example, SOA uses the find-bind-execute paradigm as shown in Figure 1. In this paradigm, service providers register their service in a public registry. This registry is used by consumers to find services that match certain criteria. If the registry has such a service, it provides the consumer with a contract and an endpoint address for that service.

Figure 1: SOA's Find-Bind-Execute Paradigm
Reference:http://en.wikipedia.org/wiki/Service-oriented_architecture#SOA_and_Web_service_protocols
http://www.webopedia.com/TERM/W/Web_services.html
http://java.sun.com/developer/technicalArticles/WebServices/soa/.