Web Service is a platform-independent, low-coupling, self-contained, programmable Web-based application that uses Open XML (a subset of standard common markup languages) to describe, publish, discover, orchestrate, and configure these applications for the development of distributed, interoperable applications.  WEB service technology enables different applications running on different machines to exchange data or integrate with each other without the use of additional, specialized third-party software or hardware. Applications that are implemented according to the Web Service specification can exchange data with each other, regardless of the language, platform, or internal protocol they are using. Web service is a self-describing, self-contained, available network module that can perform specific business functions. Web service is also easy to deploy because they are based on some common industry standards and some of the technologies that are available, such as subset XML, HTTP, in standard generic markup language. Web service reduces the cost of application interfaces. WEB Service provides a common mechanism for integration of business processes across the enterprise and even across multiple organizations.
exchanging data or integration
- 1 History
- 2 Trends
- 3 Trends
- 4 Support
- ? Technical Support
- ? Software Support
- 5 Applications
Technologies used extensively in the history Web:
- TCP/IP: Universal network protocol, used by various devices
- HTML (an application under the standard Universal Markup Language): a common user interface that can display data using HTML tags
- . NET: Sharing data and data exchange among different applications
- Java: Write a common programming language that can run on any system, because Java has cross-platform features
- XML (a subset of standard common markup languages): a common data expression language, an easy way to transfer structured data over the web
They are characterized by their openness, cross-platform and openness, which is the foundation of Web services. In recent years, the rapid development of the Internet has made it a huge resource for global information transmission and sharing. More and more Web applications in the network environment have been built up, using HTML, CGI and other web technology can easily in the Internet environment to achieve e-commerce, e-government and other applications. However, these applications may be distributed in different geographic locations, using different data organization forms and operating system platforms, and inconsistent data resulting from the application, making it possible to centralize these highly distributed data and make full use of them as a problem to be solved urgently. With the development of network technology and network operation concept, a new solution of application integration using Network--web Service is proposed. Web Service is a new branch of Web application that can perform any function from simple requests to complex business processing. Once deployed, other Web service applications can discover and invoke the services it deploys. As a result, Web service is the latest technology and development trend for building distributed, modular applications, and service-oriented application integration. Trend
more dynamic Content
- Bandwidth bandwidth cheaper and easier to get
- Memory storage cheaper and easier to get
- Universal computing becomes even more important: a large number of devices, such as mobile phones, pages, computers, PCs, have become ubiquitous on the Internet, platforms become more diversified, and cross-platform technologies such as XML (a subset of standard universal markup languages) become more important
Trends above these trends mean that more intelligent processing, manipulation and aggregation of content becomes very important. Let's take a look at the four trends predicted by the Web services perspective:
- Content is more dynamic: A Web service must be able to merge content from multiple different sources, including stocks, weather, news, content in traditional environments, such as inventory levels, shopping orders or directory information, all from back-end systems;
- Bandwidth is cheaper: Web services can distribute various types of content (audio, video streaming, etc.);
- Storage is cheaper:: Web services must be able to handle large amounts of data intelligently, which means maintaining scalability with technologies such as databases, LDAP directories, buffers, and load balancing software;
- Universal computing is more important: Web services cannot require customers to use a version of the traditional browser of Windows, must support a variety of devices, platforms, browser type, various content types;
Two important technologies to achieve this goal, WEB Services uses two technologies:
- XML (a subset of standard common markup languages): XML is a great way to deliver structured data on the web, where Web services operate data in a reliable, automated way, and HTML (an application under the standard Universal Markup Language) does not meet the requirements, and XML enables the Web Services are very convenient to process data, its content and presentation of the separation is ideal;
- SOAP:SOAP uses XML messages to invoke remote methods so that Web services can interact with remote machines via the post and get methods of the HTTP protocol, and SOAP is more robust and flexible to use;
Other technologies like UDDI and WSDL are tightly coupled with XML and SOAP technologies for service discovery. Support for the Technical Support Web service platform requires a set of protocols for the creation of distributed applications. Any platform has its own data representation method and type system. To achieve interoperability, the WEB service platform must provide a standard set of type systems for communicating different types of systems in different platforms, programming languages, and component models. These agreements are:
XML and XSD
Extensible Markup Language (a subset of standard generic markup languages) is the basic format for representing data in a Web service platform. In addition to being easy to establish and easy to analyze, the main advantage of XML is that it is platform-independent and vendor-independent. XML is created by the World Wide Web Association (SCHEMAXSD), which defines a standard set of data types and provides a language to extend this set of data types. The WEB service platform uses XSD as the data type system. When you use a language such as VB. NET or C # to construct a Web service, all of the data types you use must be converted to the XSD type in order to conform to the Web service standard. If you want it to be passed between different organizations on different platforms and different software, you need to wrap it up with something. This kind of thing is a protocol, like SOAP.
Soap, a Simple Object access protocol, is a lightweight protocol for exchanging XML (a subset of the standard Universal Markup Language) encoded information (PROTOCOL). It has three main aspects: Xml-envelope defines a framework for describing information content and how to handle content, encodes program objects as rules for XML objects, and executes remote procedure call (RPC) conventions. Soap can run on any other transport protocol. For example, you can use SMTP, the Internet e-mail protocol, to pass SOAP messages, which is tempting. The headers between the transport layers are different, but the XML payload remains the same. Web Service wants to implement a "software-software dialogue" between different systems can be called each other, breaking the software application, Web site and various devices in the state of incompatibility between the realization of "web-based seamless integration" goal.
The Web Service Description Language WSDL is a formal description document provided in a machine-readable manner and is based on the language of the XML (a subset of the standard Universal Markup Language) that describes the Web service and its functions, parameters, and return values. Because it is XML-based, WSDL is both machine-readable and human-readable.
The purpose of UDDI is to establish standards for e-commerce; UDDI is a web-based, distributed, Web service-provided, information Registry Implementation Standard specification that also includes a set of Web service registrations that enable enterprises to provide themselves. To enable other enterprises to discover the implementation criteria for the Access Protocol.
calling RPC with message delivery
The WEB service itself is actually implementing communication between applications. We have two methods of application communication: RPC Remote procedure call and message delivery. When using RPC, the concept of a client is to invoke a remote procedure on the server, typically by instantiating a remote object and calling its methods and properties. The RPC system attempts to achieve a position of transparency: the server exposes the interface of the remote object, and the client is like the interface of these objects that are used locally, so that the underlying information is hidden, and the client does not need to know which machine the object is on. Software support operating system is inseparable from rich application software support. Similarly, the technology of WEB service can only realize its value through the more and more extensive application, the more popular way is to use. NET and Java two technologies, and the two implementation methods are interoperable; now we can see the use of Microsoft, Oracle, SUN, Web Service applications built by different vendors ' Web service building tools such as Borland.
Microsoft's. NET technology should be regarded as the most popular web Service development technology nowadays. First, because its company in the previous corresponding products occupy a considerable market share, so that the new launch. NET to have a relatively stable user base, and secondly, more importantly. NET platform not only extends Microsoft's consistent programming style, but also adds a number of key technologies to support Web services. NET has achieved a very good combination in the simplicity of operation and the stability of execution. Microsoft's visual Studio. NET is a convenient development tool for WEB services. Microsoft's goal is to--c# its new programming language as the preferred language for Web service. While C # looks like Java, there are some unique features that are not in Java. NET technology, the main tool for Web Service development is ASP. NET. Technically speaking, ASP. NET provides some advantages over previous versions of ASP (for example, the separation of code and HTML (an application under the standard Universal Markup Language), and the scripting language for "real" programming languages such as C # support).
IBM is the first company in the industry to offer an e-commerce infrastructure that fully supports Web services. Through years of joint efforts with the world Wide Web Consortium, all IBM software, including DB2, Lotus, Tivoli, and WebSphere, has been implemented for soap, WSDL, UDDI, Linux, XML (a subset of standard universal markup languages), Java EE, and other open technologies and standards for full support. IBM's WebSphere is also a better infrastructure software development platform. The WebSphere software platform and development tools include the WebSphere Studio application Developerwsad open standards based on Java EE, XML, and Web services, with IBM's key advantages in reliability, scalability, and security. WebSphere is the core platform of IBM's Web services strategy, supporting all the open standards and technologies necessary to develop, publish, and deploy Web services applications, including UDDI,SOAP,J2EE,WSDL, and enhancements to XML technology integration, This makes it a lot of users around the world.
Borland company in JBuilder7, users can develop Web service and wireless applications more quickly with their Borland web Services Kit for Java and Borland JBuilder Mobileset 3. This will enable developers to easily create and integrate Web Service in the same development environment. The new JBuidler8 provides a convenient and efficient way to develop Web service. In summary, both. NET and Java are good choices for Web service development, and although there are some areas that need to be perfected, they are the best development tools and techniques. The specific choice of which development tools, but also the benevolent see of the problem. Fundamentally, these two methods are not the best of the question, but based on the user's mastery of the two methods and the degree of preference for specific language to decide. What exactly is the application Web service, and under what circumstances should you use a Web service. If you look at the current application development, you will find an absolute tendency: people are beginning to prefer browser-based client applications. This is certainly not because the client is able to provide a better user interface, but because it avoids the high cost of desktop application publishing. Publishing desktop applications is expensive, in part because of problems with application installation and configuration, and the other half because of communication between the client and server. Traditional Windows client applications use DCOM to communicate with the server and invoke remote objects. Configuring DCOM to work properly in a large network is a challenging task and a nightmare for many it engineers as well. In fact, many it engineers prefer to tolerate the limitations of the browser's functionality, rather than running a DCOM on the LAN. In my opinion, the result is an application that is easy to publish, but very difficult to develop and extremely limited in user interface. In extreme terms, you spend more money and time, but you develop applications that are weaker from the user's perspective. Don't believe me? Ask your accountant what the idea of the new browser-based accounting software is: The vast majority of business program users want to use a more user-friendly Windows UI. A perfect solution to the client-server communication problem is to use the HTTP protocol to communicate. This is because any machine running a Web browser is using the HTTP protocol. At the same time, many firewalls are currently configured to allow only HTTP connections. Many commercial applications also face another problem: interoperability with other programs. If all applications are written in the COM or. NET language and run on the Windows platform, it will be all right. In fact, however, most business data remains non-relational on mainframeFile (VSAM), and is accessed by a mainframe program written in the COBOL language. Also, many commercial programs continue to be written in C + +, Java, Visual Basic, and a variety of other languages. In addition to the simplest programs, all applications need to integrate with and exchange data with applications running on other heterogeneous platforms. Such tasks are usually done by special methods such as file transfer and parsing, Message Queuing, and APIs that are only applicable in certain situations, such as IBM's Advanced Program-to-Program communication (APPC). Previously, there was no application communication standard, which was independent of the platform, the build model, and the programming language. Only through web Service, the client and the server are free to communicate with HTTP, regardless of the platform and programming language of the two programs.
what is a Web Service
We have at least two kinds of answers to this question. On the surface, a Web service is an application that exposes an API that can be called through the web. This means that you can programmatically invoke the application via the Web. We call the application calling this Web service a customer. For example, you want to create a Web service that is useful for returning the current weather conditions. Then you can create an ASP page that accepts the ZIP code as a query string, and then returns a comma-separated string containing the current temperature and weather. To invoke this ASP page, the client needs to send the following HTTP get returned data should be: This ASP page should be counted as a Web service. It exposes an API that can be called through the Web because it is based on an HTTP GET request. Of course, there is more to the WEB service. The following is a more precise explanation of Web services: A Web service is a new platform for building interoperable, distributed applications. As a Windows programmer, you may have built a component-based distributed application with COM or DCOM. COM is a very good component technology, but we can easily cite the case that COM does not meet the requirements. The Web service platform is a set of standards that defines how applications can interoperate on the web. You can write Web services on any platform you like, in any language you like, as long as we can query and access them through the Web service standard.
The Web service platform requires a set of protocols for the creation of distributed applications. The WEB service platform must provide a standard set of type systems for communicating different types of systems in different platforms, programming languages, and component models. In traditional distributed systems, the interface-based (interface) platform provides methods for describing interfaces, methods, and parameters (such as IDL languages in COM and Cobar). Similarly, the Web service platform must provide a standard for describing Web service, allowing customers to get enough information to invoke the Web service. Finally, we must also have a way to make remote calls to this Web service. This approach is actually a remote procedure call Protocol (RPC). To achieve interoperability, this RPC protocol must also be independent of the platform and programming language. The three techniques that make up the Web service platform are briefly described in the next few sections.
XML and XSD
Extensible Markup Language (a subset of standard generic markup languages) is the basic format for representing data in a Web service platform. In addition to being easy to establish and easy to analyze, the main advantage of XML is that it is platform-independent and vendor-independent. Independence is more important than technical superiority: Software vendors do not choose a technology invented by competitors. XML solves the problem of data representation, but it does not define a set of standard data types, much less how to extend this set of data types. For example, what does shaping number mean? 16-bit, 32-bit, or 64-bit? These details are important to achieving interoperability. The XML Schema (XSD) developed by the consortium is a set of standards specifically designed to address this problem. It defines a standard set of data types and gives a language to extend this set of data types. The WEB service platform uses XSD as its data type system. When you use a language (such as VB. NET or C #) to construct a Web service, all data types you use must be converted to the XSD type in order to conform to the Web service standard. The tool you used may have automatically helped you with the conversion, but you will probably have to modify the conversion process to suit your needs.
When the Web service is built, you or someone else will call it. The Simple Object Access Protocol (SOAP) provides a standard RPC method to invoke a Web service. In fact, soap is a bit of a misnomer here: it means that the following Web service is represented as an object, but that's not necessarily true: you can write your Web service as a series of C functions and still call it using SOAP. The SOAP specification defines the format of the SOAP message and how to use SOAP through the HTTP protocol. Soap is also based on XML (a subset of standard common markup languages) and XSD, and XML is the data encoding method of soap.
How would you describe to others what your Web service does, and what parameters are available for each function call? You may write a set of documents yourself, and you may even verbally tell people who need to use your Web service. These informal approaches have at least one serious problem: when programmers sit in front of a computer and want to use your Web service, their tools, such as visual Studio, can't help them because they don't know your Web service at all. The solution is to provide a formal description document in a way that the machine can read. The Web Service Description Language (WSDL) is a language based on XML (a subset of standard generic markup languages) that describes Web service and its functions, parameters, and return values. WSDL is both machine readable and human readable, which is a great benefit. Some of the latest development tools can generate WSDL documents based on your Web service, import WSDL documents, and generate code that invokes the corresponding Web service.
Universal Description, Discovery and integration a plan for accelerating Web service promotion and enhancing interoperability of Web services, based on standard service description and Discovery Specifications ( Specification). The UDDI Business Registry is operated as a Web service by multiple actors in a resource-sharing manner. The core component of the UDDI plan is the UDDI business registration, which uses XML documents to describe the enterprise and the Web Service it provides. UDDI Business Registration provides three types of information: The white page contains the address, contact method, and known enterprise identity. Yellow page contains industry categories based on the standard taxonomy. Green page contains technical information about the Web service provided by the enterprise in the form of pointers to files or URLs that serve the service discovery mechanism.
WEB Service Development Examples
scenarios for using Web service
- Using WebService for data addition
- Using WebService for Data deletion
- Using WebService to send text messages to your phone 
scenarios where Web services are not suitable for use
- Across firewalls;
- application integration;
- Business-to-business integration;
- Software Reuse
- standalone application;
- Homogeneous applications on a local area network
Web service--Baidu Encyclopedia