What is the role of webservice in C#?

1.Web service, also known as XML Web Service, is a lightweight independent communication technology that can receive requests from other systems on the Internet or Intranet. Yes: Software services provided on the Web through SOAP are described by WSDL files and registered through UDDI. \ x0d \ XML: Extensible Markup Language. Short-term temporary data processing and World Wide Web are the basis of Soap. \ x0d \ 2。 Soap: (Simple Object Access Protocol) Simple Object Access Protocol. Is the communication protocol of XML Web service. When a user finds your WSDL description document through UDDI, he can call one or more operations in the Web service you set up through SOAP. SOAP is a specification of calling methods in the form of XML documents, which can support different underlying interfaces, such as HTTP(S) or SMTP. \ x0d \ 3。 WSDL: (Web service description language) a wsdl file is an XML document that describes a set of SOAP messages and how to exchange them. In most cases, it is automatically generated and used by software. \ x0d \ UDDI (Universal Description, Discovery and Integration) is a new project, mainly for Web service providers and users. Before users can call a Web service, they must determine which business methods are included in the service, find the definition of the called interface, and compile the software on the server. UDDI is a mechanism that guides the system to find the corresponding service according to the description document. UDDI uses SOAP message mechanism (standard XML/HTTP) to publish, edit, browse and find registration information. It uses XML format to encapsulate various types of data and sends them to the registration center or the registration center to return the required data. \ x0d \ 4。 Characteristics of XML Web Service \ x0d \ The main goal of Web Service is cross-platform interoperability. In order to achieve this goal, Web services are completely based on platform-independent and software vendor-independent standards, such as XML (Extensible Markup Language) and XSD(XML Schema). It is a new platform for creating interoperable distributed applications. Therefore, there are many advantages to using Web Service: \x0d\5. Communication through the firewall \x0d\ If the application has thousands of users and is distributed all over the world, the communication between the client and the server will be a thorny issue. Because there is usually a firewall or proxy server between the client and the server. The traditional way is to choose a browser as the client, write a large number of ASP pages, and expose the middle layer of the application to the end users. Therefore, it is difficult to develop and maintain programs. If the client code is no longer so dependent on HTML forms, the programming of the client will be much simpler. If the middle-tier component is replaced by a Web service, you can call the middle-tier component directly from the user interface, thus eliminating the step of creating an ASP page. To invoke a Web service, you can directly use a SOAP client, such as Microsoft SOAP Toolkit or. Net, or you can use your own SOAP client and connect it with the application. It not only shortens the development cycle, but also reduces the code complexity and enhances the maintainability of the application. At the same time, the application no longer needs to jump to the corresponding "result page" every time it calls the middle-tier component. \x0d\6。 Application integration \x0d\ Enterprise application developers know that all kinds of programs written in different languages and running on different platforms are often integrated in enterprises, and this integration will consume a lot of development power. Applications often need to get data from programs running on the host; Or send data to a host or other platform application. Even on the same platform, various softwares produced by different software vendors often need to be integrated. Through Web services, applications can "expose" functions and data in a standard way for other applications to use. \x0d\XML Web services provides the ability to exchange messages using standard protocols (HTTP, XML, SOAP and WSDL) in a loosely coupled environment. Messages can be structured, typed or loosely defined. \ x0d \ 7。 B2B integration \x0d\B2B refers to business-to-business, such as business with other enterprises, and business-to-business e-commerce, that is, enterprises exchange products, services and information through the Internet. Generally speaking, the supply and demand sides of e-commerce transactions are merchants (or enterprises and companies), who use Internet technology or various business network platforms to complete the process of business transactions. \x0d\Web service is the key to successful B2B integration. Through Web services, companies can simply "expose" key business applications to designated suppliers and customers. Web service runs on the Internet and can be easily implemented anywhere in the world, so its running cost is relatively low. Web service is only the key part of B2B integration, and many other parts are needed to realize the integration. The biggest advantage of B2B integration with Web Service is that it can easily achieve interoperability. As long as the business logic is "exposed" and becomes a Web service, it can be called by any designated partner, no matter what platform their system runs on or what development language they use. This greatly reduces the time and cost spent on B2B integration. \x0d\8。 Software and data reuse \x0d\Web services can reuse the data behind the code, while allowing the code to be reused. With Web services, it is no longer necessary to buy and install software components from third parties before calling them from applications. Just call the remote Web service directly. Another example of software reuse is that by integrating the functions of several applications and "exposing" them through Web services, all these functions can be easily integrated into your portal website to provide users with a unified and friendly interface. You can use the functions provided by third-party Web services in your application, or you can provide your own application functions to others through Web services. In both cases, you can reuse the code and the data behind it. \x0d\ As can be seen from the above discussion, Web services are most useful when interoperating or calling remotely through the Web. However, in some cases, Web services can't bring any benefits at all. Web services have the following disadvantages: \x0d\9. Stand-alone applications \x0d\ At present, enterprises and individuals still use many desktop applications. Some of them only need to communicate with other programs on this machine. In this case, it is best not to use Web Service, but to use local API directly. COM is very suitable for working in this situation, because it is small and fast. The same is true for server software running on the same server. Of course, Web Service can also be used in these occasions, but that will not only consume too much, but also bring no benefits. \x0d\ 10。 Some LAN applications \x0d\ In many applications, all programs use COM under the Windows platform and all run on the same LAN. Among these programs, DCOM is much more effective than SOAP/HTTP. Similarly, if one. net program wants to connect to another. Net program on LAN, which should be used. Net remote processing. Actually, yes. Net remoting, you can also specify using SOAP/HTTP to make Web service calls. However, it is better to make RPC calls directly through TCP, which will be much more effective. \x0d\ 1/application of. xmlweb service \ x0d \1. The original XML Web service is usually an information source, which can be easily integrated into applications, such as stock prices, weather forecasts, sports competitions and so on. \x0d\2。 Providing existing applications in the form of XML Web services can build new and more powerful applications, and use XML Web services as building blocks. \x0d\ For example, users can develop a purchasing application to automatically obtain the price information of different suppliers, so that users can select suppliers, submit orders, and then track the transportation of goods until they receive them. In addition to providing services on the Web, suppliers' applications can also use XML Web Service to check customers' credit, collect payment and handle the freight formalities of freight companies.