Web Services Architecture and Its Specifications [Electronic resources] : Essentials for Understanding WS-* نسخه متنی

Addressing: Using Endpoint References

When the Order message is transmitted from the school's procurement system to the book-ordering system, message routing and delivery information, such as the endpoint address, must be provided. This routing and delivery information can be obtained by the sender through multiple means. One approach is through an out-of-band exchange of Endpoint References between the system administrators.

The most primitive Endpoint Reference for the order service is equivalent to the traditional URL. It is structured as follows:

Order Service Base Endpoint Reference
(01) <wsa:EndpointReference>
(02)  <wsa:Address>http://ex.mspress/microsoft.com/orders</wsa:Address>
(03) </wsa:EndpointReference>

Line 02 The URI of the ordering system is provided in the Address element.

This address information is then included in the To element of the SOAP Header of each PurchaseOrder message.

Note

A common source of confusion is that an Endpoint Reference is an XSD type and not an element name. Thus, any element of type Endpoint Reference has the appropriate information, irrespective of the name the element has. When Endpoint References are exchanged in SOAP messages, the element name will be specific to its usage.

WS-Addressing headers in SOAP messages are used to satisfy a variety of messaging requirements. Different endpoints can be defined for the To, From, Reply, and Fault locations, as shown next. The processing behavior required is defined in the Action header.

Address Blocks in a SOAP Header
(01) <env:Header>
(02)  <wsa:To:>
(03)  <wsa:Address>http://ex.mspress.microsoft.com/orders</wsa:Address>
(04)  </wsa:To>
(05)  <wsa:From>
(06)  <wsa:Address>http://fineartschool.net/orders</wsa:Address>
(07)  </wsa:From>
(08)  <wsa:ReplyTo>
(09)  <wsa:Address>http://fineartschool.net/orders</wsa:Address>
(10)  </wsa:ReplyTo>
(11)  <wsa:FaultTo>
(12)  <wsa:Address>http://fineartschool.net/status</wsa:Address>
(13)  </wsa:FaultTo>
(14)  <wsa:Action>http://ex.mspress.microsoft.com/PO</wsa:Action>
(15) </env:Header>

Lines 0204 The Address element provided in the Endpoint Reference above is used as the value of the To Endpoint Reference in the message's address block.

Lines 0513 The From, ReplyTo, and FaultTo endpoint references are populated to by the sending system to make sure that any responses are routed properly. The optional From element can be used to specify the message origin.

Line 14 The Action element conveys the intent of the message. The URI to be used as the Action element is conveyed out of band and is determined by the system's understanding of the "contract" for Purchase Order processing.