Notifications and Resources in the WS-Resource Framework

WS-ResourceLifetime also standardizes the way WS-Notification can be used to inform interested parties about the termination of a WS-Resource. There is a standardized topic (recall the topics concept we discussed in the section "Topics") in the WS-ResourceLifetime namespace ResourceTermination. Requestors can use this topic to subscribe for a notification message when a WS-Resource of interest is terminated.

In order for this facility to work, the following pieces must be in place:

• The Web service component of the WS-Resource must support the notification producer operations (for example, the subscribe operation).

• The Web service component of the WS-Resource must include the wsrl:ResourceTermination topic in its list of topics (recall the Topics resource property described in the section "Resource Properties of a Notification Producer").

SkatesTown's POPortType Web service supports generating the notification messages on the ResourceTermination topic as described earlier. The Skateboard Warehouse can issue a subscribe operation as follows to register interest in when a PurchaseOrder WS-Resource is destroyed:

<soap:Envelope
...
<soap:Header>
...
<!-- the reference property to id the PO -->
<poRP:POResourceID>43871</poRP:POResourceID>
</soap:Header>
<soap:Body>
<wsnt:Subscribe>
<wsnt:ConsumerReference>
<wsa:Address>

http://www.skateboardwarehouse.com

/services/inventoryManagement
</wsa:Address>
</wsnt:ConsumerReference>
 <wsnt:TopicExpression dialect=
"http://www.ibm.com/xmlns/stdwip/web-

services/WS-Topics/TopicExpression/
 simple">
 wsrl:ResourceTermination
 </wsnt:TopicPathExpression>
...

 </wsnt: Subscribe>
</soap:Body>
</soap:Envelope>

When the PurchaseOrder WS-Resource is terminated, a notification message will be delivered to the notification consumer indicating (among other information) the time the WS-Resource was terminated and the reason for its termination. WS-ResourceLifetime specifies that the notification message must contain an element of the following form:

<wsrl:TerminationNotification>
<wsrl:TerminationTime>xsd:dateTime</wsrl:

TerminationTime>
<wsrl:TerminationReason>xsd:any</wsrl:

TerminationReason>?
</wsrl:TerminationNotification>