Several important concepts of WEB service

web| concept

Last time, before we use the Web service, we need to know a few things:
1, SOAP

SOAP is the basic Communication protocol for Web service. Because soap is conceptually similar to DCOM and CORBA, many people are asking: "How does soap activate objects?" "or" What naming service is used by soap (naming service)? ”。 This may be used in the process of executing soap, but these are not within the scope of the SOAP specification to consider. Soap simply defines the XML format of the SOAP message (XML format), and if you surround the XML document with a pair of soap tokens (soap Elements), then this is a SOAP message, isn't it easy?
The SOAP specification also defines how to use XML to describe program data, and how to perform RPC (Remote Procedure call). These optional specifications are designed to build Rpc-style applications (client SOAP messages contain the name of the function and the parameters used in the functions, while server-side SOAP messages contain the results after the function is executed). Most SOAP solutions support rpc-style applications because many programmers are familiar with DCOM or CORBA. SOAP also supports Document-style applications (SOAP messages contain only XML text information). Document-style applications have great flexibility, so many Web service that is difficult to build with RPC is built in this way.
The final SOAP specification also defines how the HTTP message transmits the SOAP message. This does not mean that SOAP can only use HTTP as a transport protocol, and MSMQ, SMTP, and TCP/IP can do SOAP transport protocols.
Many large companies have developed their own SOAP solutions based on the SOAP specification. All of these solutions are relative to a language. For example, the Microsoft SOAP toolkit2.0 converts COM functions into SOAP messages, while the Apache toolkit converts Java functions into SOAP messages. This inevitably brings some compatibility issues.
Many of the most compelling features of soap have now become reality (soap is already running on different hardware and software platforms), and there are more than 70 solutions. Soap is loved by people because soap is easier to use than other similar technologies (CORBA, DCE).
Security is important for applications. So what about the security of soap? There is no problem with the use of HTTP as a transport protocol, because the HTTP protocol already has a good security architecture. Are there any security issues with other transport protocols? No, you don't have to worry, because there's already a specification for this (http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dnglobspec/html/ws-security.asp).

2. WSDL

WSDL is an XML document that defines how SOAP messages are exchanged with those messages. IDL (Interface Description Language) is used for COM and CORBA, and the WSDL is used for soap. WSDL is an XML document, so we can read and edit it, but most of the time it is created with tools and read by programs.
For example, you would use a vendor's Web service to build your application. You can ask the vendor for an example of using a Web service, and then follow the example to build the application. There may be unexpected errors, for example, the data type of the client code you use in the program is an integer, and the data type used by the vendor is string. WSDL defines the format of the client message in detail, and what parameters are required, so that unnecessary errors can be avoided.

3. UDDI

UDDI can be likened to a telephone book, where the phone information is recorded and the UDDI Records Web service information. You can not register the Web service to UDDI. But if you want to let people around the world know about your web Service, it's best to register for UDDI.
The UDDI directory description file is also an XML document, which includes three parts. White Paper describes the company (person) information that provides the Web service, such as name, address, contact, and so on. The Yellow Pages (yellow Paper) describes the classification of UDDI directories, such as finance, services, and printing. Green Paper describes the details of the interface (provided by the Web Service). UDDI offers a variety of queries to help you find the Web Service you need. If you are looking for a financial-related web Service, UDDI provides detailed information.

Just a little bit, like looking for more information please refer to
XML Web Service Basics, Roger wolter,microsoft Corporation, December 2001
Http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dnwebsrv/html/webservbasics.asp (This article is translated in the following article)
Original: http://www.trueobject.net/board/zboard.php?id=web_service_lecture&no=2