Web Services Defined


A web service defines a contract between a client and the service itself. In English, this contract states something like, "If you send me data in this format, I will process it and return you the results in this other format." The format of this data and the communication parameters of these calls are all based on open standards such as XML and SOAP. Similar standards allow a client to often "discover" a web service and its contract and then work to program against it. These web service standards apply across technology boundaries and therefore make web services very attractive for exchanging data between heterogeneous environments.

Visual Studio 2005 does a lot to abstract the intricacies of these standards away from everyday programming tasks. This is no different from the manner in which the .NET Framework abstracts "plumbing" code for developers. The intent (and result) is a more productive development experience. You spend less time worrying about how to create a proper SOAP message and more time building business value.

Web Service Terms

It is important that developers understand the key concepts and standards around web services. This knowledge ensures you know what is happening in your application. It also helps when you are reading the .NET documentation and articles related to web services. Therefore, we have put together the following glossary of key terms related to web services:

  • Web Service A web service represents a cohesive set of application logic that performs actions and provides data. A web service groups web methods. It can therefore be helpful to think of a web service as a component or class.

  • Web Service Method (or Web Method) A web service method represents a method exposed by a web service. A web method can take parameters and return a response.

  • XML (Extensible Markup Language) XML is used to both represent and describe data in a platform-neutral manner. XML can be used to represent both simple and complex data elements and relationships. It is the XML standard that makes web services possible.

  • WSDL (Web Service Description Language) WSDL is used to describe the contents of a web service and its web methods. The WSDL provides the message data contracts that allow clients to work with a given service.

  • XSD (XML Schema Document) XSD contains a set of predefined types (string, decimal, and so on) and a standard language for describing your own complex types. An XML Schema Document (also referred to as an XSD) uses these types to describe (and restrict) the contents of an XML message.

  • SOAP (Simple Object Access Protocol) SOAP is an XML-based protocol for communicating between client and web service. It is helpful to think of SOAP as representing the format of the messages as they pass over the wire. SOAP wraps XML messages (in envelopes) for communication across the Web. Most SOAP messages are sent over HTTP. However, they can also be sent with transport protocols such as SMTP and FTP.

  • HTTP (Hypertext Transfer Protocol) HTTP represents the communication protocol used by web services to transfer SOAP-formatted (or encoded) messages. HTTP is also the way standard web page requests (GET and POST) communicate.

  • UDDI (Universal Description, Discovery, and Integration) UDDI is used to define a registry of web services. This capability is useful for the publication of services for developers to find and consume.

  • URI (Uniform Resource Identifier) URIs provide a means for locating items on the web. In most cases URIs are URLs (uniform resource locators) that point to a given service.

  • DISCO (Discovery Document) A DISCO file provides information that links to other key elements of a web service. This includes links to XSDs, SOAP bindings, and namespaces. A program can use a DISCO file to determine how to work with a given web service.

  • WS-* This term represents the overall standards for web services.

  • WSE (Web Service Enhancements) Microsoft's implementation of WS-* standards. Currently, WSE 3.0 is the latest version. It enables web service transactions and enhanced security. WSE is a plug-in to Visual Studio.




Microsoft Visual Studio 2005 Unleashed
Microsoft Visual Studio 2005 Unleashed
ISBN: 0672328194
EAN: 2147483647
Year: 2006
Pages: 195

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