webservice——基本概念

1. SOAP--Simple Object Access Protocal<o:p></o:p>

SOAP is a lightweight protocol intented to exchanging structured information in a decentralized, distributed environment.The two major goals for SOAP is simplicity and extensibility.<o:p></o:p>

SOAP is widely used for XML messaging as it :<o:p></o:p>

    defines thin layer on top of widely understood HTTP 
    is flexible and extensible 
    enjoys broad industry and developer community support <o:p></o:p>

Main uses of SOAP are for <o:p></o:p>

    messaging: sending XML data orders, invoices, forms 
    RPC: invoking services querying data sources, transacting<o:p></o:p>

2. WSDL--Web Service Definition Language<o:p></o:p>

As the communication protocols and message formats are standardized in the web community, it becomes increasingly possible and important to be able to describe the communication s in some structured way.WSDL addresses this need by defining an XML grammar for describing network services as collections of communication endpoints capable of exchanging messages.<o:p></o:p>

3.  UDDI-- Universal Description, Discovery, and Integration <o:p> </o:p>

UDDI protocol is a central element of the group of related standards that comprise the Web services stack. The specification defines a standard method for publishing and discovering the network-based software components of a service-oriented architecture.<o:p></o:p>

4.  the relationship between SOAP,WSDL and UDDI <o:p> </o:p>

web service client 需要定位另一个应用程序或者是网络上的某一段业务逻辑， client 通过 name 、 catagory 、 identifier 或者 specification 来从 UDDI registry 中查询服务，定位以后， client 从 UDDI registry 中得到 WSDL 文档的位置信息。在 WSDL 文档的 XML schema 中包含了如何访问 web service 和请求信息的格式， client 按照 xml schema 的格式来创建一个 soap 消息，并向 host 发送请求。