WEB Service Platform Overview

The main technologies involved in the Web service platform are soap (Simple Object access, protocal, and Description), WSDL (Web service Language, Web Serv Ice Description Language), UDDI (Universal Description and integration, unified description, Discovery, and consolidation protocol).

One, SOAP (Simple Object Access Protocol)

Soap, Simple Object access protocal, is an extensible XML message protocol that allows one application to send an XML message to another application. A SOAP message is a single message from a SOAP sender to a SOAP recipient, and any application can act as either a sender or a recipient. Soap only defines the message structure and protocol for message processing, independent of the underlying transport protocol. Therefore, the SOAP protocol can be transmitted through the HTTP,JMS or SMTP protocol.

SOAP relies on XML documents to build, a SOAP message is a specific XML document, the SOAP message contains the following three main elements:

1. Required <Envelope.../> root element, the XML document corresponding to the SOAP message takes the element as the root element.

2. Optional <Header.../> element that contains the header message for the SOAP message.

3. Required <Body.../> elements, including all calls and response messages.

In terms of the structure of the current SOAP message, the,<envelope.../> root element usually contains only two child elements, the first child element is an optional <Header.../> element, and the second element is the required <Body.../> element.

Ii. WSDL (Web Service Description Language)

The WSDL (Web service Description language,web Service Description Language) uses XML to describe the Web service, including the information necessary to access and use the Web service, defining the location of the Web service , functions, and how to communicate and other descriptive information.

In general, as long as the caller is able to obtain the WSDL corresponding to the Web service, you can learn about the services it provides and how to invoke the Web service. Because a WSDL file clearly defines three aspects of the content.

1. What part: Used to define the operation (or method) provided by the Web service, that is, what the Web service can do. Defined by the <types.../>, <message.../>, and <portType.../> elements in WSDL.

2. How section: Used to define how to access Web service, including data format details and the necessary protocols for accessing Web service operations. That is, it defines how to access the Web Service.

3. Where section: Specifies the network address, such as a URL, that is used to determine where a Web service is located, using a specific protocol. This section uses the <service.../> element definition to see the <service.../> element in the last part of the WSDL file.

A WSDL document can usually be divided into two parts:

The first section defines the service interface, which consists of <message.../> elements and <portType.../> two elements in the WSDL, where the <message.../> element defines how the operation interacts. While the <portType.../> element can contain any number of <operation.../> elements, each <operation.../> element represents an operation that allows remote invocation (that is, a method).

The second section defines the service implementation, which consists of <binding.../> elements and <service.../> two elements in the WSDL, where <binding.../> defines the use of a specific communication protocol, The data encoding model and the underlying communication protocol map the Web service interface definition to a specific implementation, while the <service.../> element contains a series of <port.../> sub-elements,<port.../> The child element will combine the binding mechanism, the Service Access protocol, and the endpoint address.

Third, UDDI (Universal Description, Description and integration, unified description, Discovery and Integration protocol) is a set of information registration specifications, it has the following characteristics:

1, web-based.

2, distributed.

UDDI includes a set of implementation standards that allow enterprises to register web Service outward to enable other enterprises to discover access. The core component of UDDI is the UDDI registry, which uses XML files to describe the enterprise and the Web Service it provides.

Allows other enterprises to invoke the enterprise registered Web service by using the Uddi,web service provider through the UDDI registry. The Web service provider adds information about the Web service it provides to the UDDI registry through the UDDI Registry's web interface. The Web service can be discovered and invoked.

Web service users also find and discover the services they need through the UDDI registry. After the Web service consumer finds the service it needs, it can bind itself to the specified Web service provider and invoke the other's service based on the WSDL document corresponding to the Web service.

WEB Service Platform Overview