Web Services)

Web Service is a network-based, distributed modular component that executes specific tasks and complies with specific technical specifications. These specifications Enable Web service to interoperate with other compatible components. It can use standard Internet protocols, such as hypertext transfer protocol HTTP and XML, to embody functions on the Internet and the enterprise intranet. The Web service platform is a set of standards that define applications. Program How to implement interoperability on the web. You can use any language to write Web Services on any platform.
The Web Service Platform requires a set of protocols to create distributed applications. Any platform has its Data Representation Method and type system. To achieve interoperability, the Web service platform must provide a set of standard type systems for communication between different platforms, Programming Language And different types of systems in the component model. Currently, these protocols include:
XML and XSD
Soap
WSDL
UDDI
Remote Procedure Call RPC and message passing
From the perspective of external users, a Web Service is an object/component deployed on the Web. It has the following features:
Sound encapsulation. Since Web services are deployed on the web, they naturally have good encapsulation of objects. for users, you can only view the function list provided by this object.
Loose coupling. This feature is also derived from the object/component technology. When the implementation of a Web service changes, the caller will not feel this. For the caller, as long as the Web service call interface remains unchanged, any changes to the implementation of Web services are transparent to them, even when the implementation platform of Web Services is migrated from J2EE. net or the opposite migration process, users can have no idea about this. For loose coupling, especially for Web Services in the Internet environment, a message exchange protocol suitable for the Internet environment is required. XML/soap is currently the most suitable message exchange protocol.
The normative use of the contract. This feature comes from the object, but it is more standardized and easier to understand than the interface specifications of general objects. First, as a web service, the functions provided by the object interface should be described in a standard descriptive language (such as WSDL). Second, the service interface described by the standard descriptive language should be discoverable. Therefore, this descriptive document must be stored in a private or public registry. At the same time, the Use Agreement described in standard descriptive languages will not only be a service interface, but will be extended to Web Service aggregation, cross-web service transactions, workflows, etc, all of these require QoS Assurance. Secondly, we know the importance of security mechanisms for loosely coupled object environments. Therefore, we need to perform authorization authentication and data integrity (such as signature mechanisms) use standard methods to describe, transfer, and exchange the source authentication and the non-repudiation of transactions. Finally, the processing at all levels should be manageable, so the same mechanism should be applied to the management agreement.
The use of standard protocol specifications, as Web Services, all public agreements require the use of open standard protocols for description, transmission and exchange. These standard protocols are fully free of charge for implementation by any party. In general, the vast majority of standards will end with W3C or oasis as the publisher and maintainer of the final version.
Highly integrated. Because Web services adopt simple and easy-to-understand standard web protocols as Component Interface descriptions and collaborative description specifications, the differences between different software platforms are completely shielded, both CORBA, DCOM, and EJB can use this standard protocol for interoperability, achieving the highest possible integration in the current environment.