Another set of interceptors installed by the policy framework is responsible for verifying that one of the alternatives in the effective policy of the underlying message is indeed supported. These interceptors are:
|
Chain |
Phase |
Interceptor |
|---|---|---|
|
Out, OutFault |
POST_STREAM |
PolicyVerificationOutInterceptor |
|
In |
PRE_INVOKE |
PolicyVerificationInInterceptor |
|
InFault |
PRE_INVOKE |
PolicyVerificationInFaultInterceptor |
Their behaviour is symmetric on client and server side. On the outbound chain the effective message policy was known by the time the policy interceptor executing in the SETUP phase had inserted the AssertionInfoMap into the message. As the map was built exclusively from the Assertion objects that are part of the chosen alternative of the effective message policy, all of them must be supported. In other words, all of the AssertionInfo objects need to be in the asserted state. If one of them is not, the interceptor throws a Fault (wrapping a PolicyException).
On the inbound paths a little bit more work is necessary: If the message is a fault, we know by now what type of fault it is and what operation it applies to. If the message is not a fault message, knowing the underlying operation we can, from the location of the interceptor (client or server side), infer the message subject (input or output message). Either way, all information is now available to obtain the effective message policy. To check if any of is alternatives is supported, the policy verification interceptors then simply check if for each of its assertions the associated AssertionInfo object in the map is in the asserted state. If no alternative is supported, the interceptor throws a Fault (wrapping a PolicyException).
One thing worth noting is that - both on outbound and inbound chains - there may be assertions that only the conduit or destination can support. Although conduit or destination could access Assertion objects and tailor their behaviour when sending or receiving the current message, it is not knoan at this point whether this "tailoring" actually succeeded for the underlying message, i.e. whether the assertions in questions could actually be supported. For this reason, the policy verification interceptors check if the conduit or destination implements the Assertor interface. It it does, they pass it the Message object so they confirn their support (or the lack thereof) for these assertions. The above described traveral of the AssertionInfo map only takes place after the conduit or destination had a chance to m ake their contribution.