Introduction:-
Web services are client and server applications that communicate over the World Wide Web’s (WWW) Hypertext Transfer Protocol (HTTP). As described by the World Wide Web Consortium (W3C), web services provide a standard means of inter-operating between software applications running on a variety of platforms and frameworks.
Web services are characterized by their great inter-operability and extensibility, Web services can be combined in a loosely coupled way to achieve complex operations.
Web services are open standard (XML, SOAP, and 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.
Web Services are self-contained, modular, distributed, dynamic applications that can be described, published, located, or invoked over the network to create products, processes, and supply chains. These applications can be local, distributed, or Web-based.
Web services are XML-based information exchange systems that use the Internet for direct application-to-application interaction. These systems can include programs, objects, messages, or documents.
Components of Web Services:-
The basic Web services platform is XML + HTTP. All the standard Web Services works using following components
- SOAP (Simple Object Access Protocol)
- UDDI (Universal Description, Discovery and Integration)
- WSDL (Web Services Description Language)
Web service Features:-
XML-based
Web Services uses XML at data representation and data transportation layers. Using XML eliminates any networking, operating system, or platform binding. So Web Services based applications are highly inter-operable application at their core level.
Loosely coupled
A consumer of a web service is not tied to that web service directly. The web service interface can change over time without compromising the client's ability to interact with the service. A tightly coupled system implies that the client and server logic are closely tied to one another, implying that if one interface changes, the other must also be updated. Adopting a loosely coupled architecture tends to make software systems more manageable and allows simpler integration between different systems.
Coarse-grained
Object-oriented technologies such as Java expose their services through individual methods. An individual method is too fine an operation to provide any useful capability at a corporate level. Building a Java program from scratch requires the creation of several fine-grained methods that are then composed into a coarse-grained service that is consumed by either a client or another service. Businesses and the interfaces that they expose should be coarse-grained. Web services technology provides a natural way of defining coarse-grained services that access the right amount of business logic.
Ability to be synchronous or asynchronous
Synchronicity refers to the binding of the client to the execution of the service. In synchronous invocations, the client blocks and waits for the service to complete its operation before continuing.
Asynchronous operations allow a client to invoke a service and then execute other functions. Asynchronous clients retrieve their result at a later point in time, while synchronous clients receive their result when the service has completed. Asynchronous capability is a key factor in enabling loosely coupled systems.
Supports Remote Procedure Calls (RPCs)
Web services allow clients to invoke procedures, functions, and methodson remote objects using an XML-based protocol. Remote procedures expose input and output parameters that a web service must support. Component development through Enterprise Java Beans (EJBs) and .NET Components has increasingly become a part of architectures and enterprise deployments over the past couple of years. Both technologies are distributed and accessible through a variety of RPC mechanisms. A web service supports RPC by providing services of its own, equivalent to those of a traditional component, or by translating incoming invocations into an invocation of an EJB or a .NET component.
Supports document exchange
One of the key advantages of XML is its generic way of representing not only data, but also complex documents. These documents can be simple, such as when representing a current address, or they can be complex, representing an entire book or RFQ. Web services support the transparent exchange of documents to facilitate business integration.
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