260 Smart SOA Solutions with WebSphere Enterprise Service Bus Registry Edition V7.5
If no service in WSRR matches the query, the output terminal (noMatch)
propagates the original incoming message. The Match Policy settings are not
considered in this situation.
8.3.2 SLA Check mediation primitive
The SLA Check mediation primitive determines whether a service consumer has
an appropriate SLA in place to access a requested service provider. A capability
version, an SLA, and a service level definition (SLD) need to be defined in WSRR
to enable the registry to be queried. The SLA Check mediation primitive queries
WSRR for this information.
As shown in Figure 8-6, the SLA Check mediation primitive has one input
terminal, one fail terminal (rectangle shaped terminal), and two output terminals
(accept and reject). The input terminal is wired to accept a message, and the
other terminals are wired to propagate a message. If the information passed on
the incoming message is used to successfully find a matching SLA in WSRR, the
original incoming message is propagated by the accept terminal. However, if no
matching SLA is found, the reject terminal is fired and propagates the original
incoming message.
Figure 8-6 SLA Check mediation primitive
Return all matching
endpoints and set
alternate routing
targets
Callout address in the message header is updated with
the first service address from the results returned
Alternate targets list in the message header is updated
with the remaining service addresses from the results
returned
Message context is updated with service information for
all services returned by the registry
Return endpoint
matching latest
compatible version
of SCA
module-based
services
Callout address in the message header is updated with
the service address that has the highest version from
the results returned
Message context is updated with service information
related to the address in the callout address
Alternate targets list in the message header is deleted
Match Policy Effect on the outgoing result message
Chapter 8. Implementing a mediation 261
To find a matching SLA in WSRR, the SLA Check mediation primitive uses
information in the incoming message. Figure 8-7 shows the Details tab in the
Properties view where the parameters for the search can be configured.
Figure 8-7 Configuration details for SLA Check mediation primitive
The SLA is matched on the following parameters:
Endpoint This parameter can be a literal value or can be passed as
part of the incoming message. This field is mandatory. If
not set, the reject terminal is fired and the original
incoming message is propagated.
Consumer Identifier This parameter can be a literal value or can be passed as
part of the incoming message. It identifies the service
consumer of the target endpoint.
Context Identifier This parameter can be a literal value or can be passed as
part of the incoming message. It identifies the context
under which the service consumer’s invocation of the
target endpoint occurs.

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