What is Web Services?

Today I found a new term. When studying the structure of ado.net, Baidu has been reading n articles for a long time, but this is the most popular one.

In summary, there are several words: an interface, a function, and a call.

Original article:

Web service concept

What is Web service? On the surface, Web Service is an application that exposes an API that can be called through the Web. That is to say, you can use a programming method to call a web application to implement a function. For example, the author creates a web service to query the basic information of an employee in a company. It accepts the employee ID as a query string and returns the employee's specific information. You can directly enter an http get request in the address bar of the browser to call the ASP page listing the employee's basic information. This can be regarded as a Web service experience.

From a deeper perspective, Web Service is a new Web application branch. It is a self-contained, self-described, and modular application that can be deployed on the Network (usually Web) is described, published, searched, and called through the Web.

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 how applications implement interoperability on the web. You can use any language you like (the author uses C #) to write Web Services on any platform you like.
Technical support for Web Service

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 standard type system for communicating different types of systems in different platforms, programming languages, and component models. Currently, these protocols include:

1. xml and XSD

The extensible markup language XML is the basic format for data representation on the Web service platform. In addition to ease of creation and analysis, XML has the primary advantage of being independent from the platform and the vendor. XML was created by the World Wide Web society (W3C). xml schemaxsd developed by W3C defines a set of standard data types and provides a language to extend this data type.

The Web service platform uses XSD as the data type system. When you construct a web service in a language such as VB. NET or C #, to comply with the Web service standard, all the data types you use must be converted to the XSD type. To enable it to be transmitted across different organizations on different platforms and software, you also need something to wrap it. This is a protocol, such as soap.

2. Soap

Soap is the Simple Object Access Protocol. It is a lightweight protocol used to exchange XML encoding information. It has three main aspects: XML-envelope defines a framework for describing information content and how to handle content, encodes program objects into XML object rules, and executes Remote Procedure Calls (RPC). Soap can run on any other transmission protocol. For example, you can use SMTP, or the internet email protocol, to transmit soap messages, which is tempting. The headers in the transport layer are different, but the XML payload remains the same.

The Web Service allows different systems to call each other in the form of "software-software conversation", breaking the incompatibility between software applications, websites, and various devices, achieve the goal of "seamless web-based integration.

3. WSDL

Web Service Description Language (WSDL) is a formal description document provided by machines that can be read. It is an XML-based language used to describe Web services and their functions, parameters, and returned values. Because it is based on XML, WSDL is machine readable and human readable.

4. UDDI

The purpose of UDDI is to establish standards for e-commerce. UDDI is a set of web-based, distributed, and standard standards for implementing information registration centers for Web Services, it also contains a set of access protocols that enable enterprises to register their own web services so that other enterprises can discover.

5. Remote Procedure Call RPC and message passing

Web services are actually implementing communication between applications. Now we have two methods for Application Communication: RPC remote process call and message transmission. When RPC is used, the client calls the Remote Process on the server. Generally, a remote object is instantiated and its method and attributes are called. The RPC system tries to achieve the transparency of a location: the server exposes remote object interfaces, and the client is like the interfaces of these objects used locally, in this way, the underlying information is hidden, and the client does not need to know the machine on which the object is located.

Web service software support

The operating system is inseparable from the support of a wide range of application software. Similarly, the Web Service technology can reflect its value only through increasingly wide application. Currently, the popular implementation method is to use. net and Java, and the two implementation methods can operate on each other; now we can see Web service applications created using Web Service building tools from different vendors, such as Microsoft, IBM, sun, and Borland.

Microsoft. NET

Microsoft's. NET technology should be regarded as the most popular Web service development technology nowadays. First of all, because the company has a considerable market share in the previous products, it has made new products available. net can have a relatively stable user group; and more importantly. the net platform not only continued Microsoft's consistent programming style, but also added many key technologies that support web services. net achieves a very good combination of simplicity of operations and execution stability and efficiency.

Microsoft Visual Studio. Net is a development tool that facilitates Web Services. Microsoft's goal is to use its new programming language, C #, as the preferred language for Web Services. Although C # looks similar to Java, there are some unique features not available in Java .. The main tool used for Web service development in net technology is ASP. in terms of technology, aspasp.net provides some advantages beyond ASP versions (for example, code and HTML separation, compared with the script language, support for "true" programming languages such as C ).

IBM WebSphere

IBM is the first company in the industry to provide e-commerce infrastructure middleware that fully supports Web Services. Through years of joint efforts with W3C (the World Wide Web Consortium, all IBM software, including DB2, Lotus, Tivoli, and websphere, provides comprehensive support for open technologies and standards such as SOAP, WSDL, UDDI, Linux, XML, and J2EE. IBM Websphere is also a good infrastructure software development platform. WebSphere software platform and development tools include WebSphere Studio Application Developer wsad based on open standards such as J2EE, XML, and Web Services, and has the main advantages of IBM in reliability, scalability, and security. WebSphere is the core platform of IBM in Web services policies. It supports all open standards and technologies necessary for the development, release, and deployment of web services applications, including UDDI, soap, J2EE, WSDL, and the enhancement of XML technology integration, this special envoy is that it has many users around the world.

Borland JBuilder

In jbuilder7, Borland users can use its Borland Web Services kit for Java and Borland JBuilder mobileset 3 to develop Web Services and wireless applications more quickly. This allows developers to easily create and integrate Web Services in the same development environment. Jbuidler8 launched this year provides more convenient and efficient methods for Web service development.

In short, in Web service development ,. net and Java are both good choices. Although both of them need to be improved, they are still the best development methods and technologies. The specific development tool is also a matter of benevolence and wisdom. Basically, these two methods are not superior or inferior, but are determined based on the user's mastery of these two methods and their preference for specific languages.