Project 1 SOAP Extensions ---- 网页服务程序构件设计指要.doc

学习资料收集于网络，仅供参考 Project 1 SOAP Extensions - 网页服务程序构件设计指要 詹叔浩 The project requires application developers to add credit card payment feature into an existing retail sales system for a chain store. Step by step, the document highlights how to develop application of SOAP XML Web Services and SOAP Web Services. And document will issue important details if you work on a complex system which contains both Web Services and XML Web Services.KEY WORDS：Web Services, XML Web Services, SOAP, SOAP Extensions, SOA Headers Model of Client and Server SOAP Communication WITHOT SOAP Extensions Client SideServer SideReferring to the figure above, we will add feature of processing SOAP message to the below existing SOAP Web Services without SOAP Extensions. Also, the SOAP massage includes costumer credit card info such as card number. Asynchronous call to a Web method does not block other callings while this call is waiting for a result. Whenever developer creates a proxy class on client side, .NET automatically enables asynchronous calls to Web methods. Serialization processes SOAP message and converts one or more message objects to their XML representation. De-serialization processes SOAP message and converts one or more message objects to their binary representation. SOAP Request means a SOAP message sent from client to server for invoking a Web method. SOAP Response means a SOAP message sent from server to client with the results of a Web method.$ 1 Solution Model and AlgorithmReferring to the figure below, the black disks indicate where SOAP Extensions perform. The XML Web Service is named LookUpService. The service LookUpService exposes a Web method named RetrieveCardInfo. The method RetrieveCardInfo takes credit card info from SQL server database and returns it. We capture and inspect and modify SOAP message in Web method RetrieveCardInfo.Model of Client and Server SOAP Communication WITH SOAP Extensions $ 2 Three Major Coding Steps1. We create HTTP and SOAP XML web service using .NET Framework (selecting Console Application).2. We derive SOAP Extensions classes from SoapExtension base class. Thus, the classes expose and implement the following methods: * Getlnitialize (to be called one time when a soap extension is first loaded), * lnitialize (to be called each time for each calling SOAP web service); * ChainStream (for intercepting actual soap message stream), and * ProcessMessage (to be called with actual request and response).3. We intercept a SOAP message and call method EncrptMessage after serialization stage and call method DecryptMessage before deserialization stage.$ 3 Technical NotesWhy do we select SOAP Extensions rather than SOAP headers in this project?This project requires only capture and procedure of confidential SOAP messages instead of security concerns such as authentication (Ex: user name and password for log-in) and authorization (Ex: application role) and encryption (Ex. converting text to secret code). SOAP extensions are a class to be invoked during the serialization or de-serialization of SOAP message and to allow developer to insert customer-own code into SOAP request and response process loop. SOAP extensions are usually deployed in pairs with matching the extension on client and server. SOAP headers are a class to be derived from SoapHeader base class and represent the data in a particular SOAP header. SOAP headers handle authentication, encryption, and signing directly in SOAP messages.$4Whole Picture of Web Services and XML Web ServicesShowing as the Fig below, suppose an object of client application interacts with one object of another client application over internet and server of web services. Referring to the Sketch Figure on the last page, we discuss the technical terms below, （示意图） SOAP (Simple Object Access Protocol) is a standard to encapsulate messages between Web services server and Web services client when the message objects (as well as methods and properties) are transmitted as XML format through HTTP channel. Remember, message objects cannot be invoked! Disco is a Microsoft standard to discover documents of Web services on server by directory connecting to the server. UDDI (Universal Description, Discovery, and Integration) is a multi-vendor standard to discover code details (documents, classes, methods, and so on) of the Web services and other online business services by directory via the Internet. WSDL (Web Service Description Language) is a standard to describe the interface between the Web services and the Web services server. In fact, WSDL let developer to retrieve information on the classes and methods supported by a particular Web service. Disco.exe is a tool related to Disco to discover documents of Web services on server. Wsdl.exe may create Proxy Class connected to Web Reference for communicating with XML Web service. Also, a Local Proxy Class connected to Web Reference may be created for communicating with Web service. When do we select the techniques Wsdl.exe? There are both of Web service and XML Web service in the existing internet system. And a developer may add new-both services to the existing system. SOAP Proxy Tool is used to test and debug Web service without executing Web service client application. XWL wire format is the structure of actual XML file message passed between Web services server and Web services client. By using attributes, .NET allows d