On the surface, Web Service is an application that exposure to the outside world, a call can be conducted through Web API. This means that the method can be used by programmers to implement a feature called Web applications.
Deeper point of view, Web Service is a new branch of Web applications, they are self-contained, self-describing and modular applications that can in the network (usually the Web) is described, publish, and through the web to call.
Web Service is a web-based, distributed, modular components; it to perform specific tasks, comply with specific technical specifications, these specifications enable Web Service is compatible with other components to interoperate. It can use standard Internet protocols, Web Service platform is a standard that defines how applications to achieve interoperability in the Web.
Web services is not necessarily on the existence and WWW, Web services can live anywhere in the network, the Internet or LAN will do.
Web service implementation, deployment platform, the details of the procedure and called the service has nothing to do. Web service API and by statement calling mechanism used. This Web browser and Web application server similar to the relationship between.
Web Service platform needs a protocol to achieve the creation of distributed applications. Any platform has its own data representation and types of systems. To achieve interoperability, Web Service platform to provide a standard type system for communication between different platforms, programming languages and component models of different types of systems. Currently these agreements include:
XML and XSD. Extensible Markup Language XML is a Web Service platform that the basic format of the data. In addition to easy to set up and easy to analyze things, XML is both a major advantage of platform-independent, it has nothing to do with the company. W3C XML is created at the same time, W3C has developed a standard definition of XML Schema data types, and gives a language to extend this type.
Web Service platform is to use the XSD as a data type system. When you use a language such as VB.NET or c #, java to build a Web Service, in order to comply with Web Service standards, all data types used must be converted to XSD types. If want it to be used in different platforms and different software transfer between different organizations, we must also use it to package up something. This thing is a protocol, such as the SOAP protocol.
SOAP, SOAP or Simple Object Access Protocol (Simple Object Access Protocol), which is used to exchange XML encoded messages lightweight protocol. It has three main aspects: XML-envelope for the description of the contents of the information content and how to deal with the definition of the framework; the program object code as the rules of XML objects; implementation of the Remote Procedure Call (RPC) of the agreement. SOAP can be run on any transport protocol.
Simple Object Access Protocol (Simple Object Access Protocol, SOAP) is a kind of passing messages between systems using the XML protocol. Before the advent of the SOAP, people in systems using CORBA, DCOM mechanism of interaction data, these mechanisms are used in humans can not recognize and read the binary data transfer message, it is difficult to develop and debug.
SOAP uses text format, open the XML document sent messages, you can use a hyperlink transfer protocol (HyperText Transfer Protocol, HTTP), File Transfer Protocol (File Transfer Protoclo, FTP) and other network protocol, and also help to promote a variety of heterogeneous distribution systems, various programming languages to achieve mutual cooperation between the. SOAP applications typically used to encapsulate the message communication packets, in the exchange of data between distributed systems, called heterogeneous system object. With the popularity of Web services, SOAP applications growing.
Web Service hopes to achieve the different systems can use the "software - software dialogue" means each call, broken software applications, websites and various devices fit between the state, to achieve "seamless integration of Web-based" targets.
WSDL. Web Service Description Language WSDL is a machine can read the official description of the document, which is XML-based language for describing Web Service and its functions, parameters and return values. Because it is based on XML, so the WSDL is machine readable, it is human readable.
UDDI. The purpose of UDDI is to establish standards for e-commerce; UDDI is a Web-based, distributed, and for the Web Service provided information registry of standards, but also contains a set of the enterprise can provide its own Web Service registration, to enable other companies to find the realization of the standard access protocol.
Remote Procedure Call RPC and messaging. Web Service itself is in the realization of the application's communication. We now have two application methods of communication: RPC remote procedure calls and messaging. When using RPC, the client's concept of remote procedure call server, the usual way to instantiate a remote object and call its methods and properties. RPC system attempts to reach a position of transparency: the server object exposes remote interfaces, and the client as if the local use of these objects, like the interface, thus hiding the underlying message, the client also does not need to know the object in that machine.