To reduce the overall processing time of an aggregation you can call multiple services concurrently, instead of processing each service in series.
A branched aggregation block such as shown in Figure 1 will
not, by default, be processed in parallel.
Figure 1. Branched aggregation block
To enable multiple service invocations to occur before
the processing of response messages you must complete the following
steps:
- Specify the Invocation style property on each Service Invoke mediation
primitive to be Async, as shown in Figure 2. Figure 2. Service invoke mediation primitive property details
- If the mediation flow component is configured to run under a Global
Transaction, ensure that the component Reference that is associated
with the Service Invoke mediation primitive has a qualifier for Asynchronous
invocation that is set to Call, as shown in Figure 3.Figure 3. Setting the Asynchronous invocation qualifier
If a global Transaction is configured, and the Asynchronous invocation setting is Commit, then request messages are never sent, because the service request cannot be sent until the transaction commits.
- An additional step of configuration is required when the aggregation
block processes in Iterate mode. Using the Fan Out mediation primitive
you can specify the number of concurrent unprocessed requests that
can be made before the response messages are processed. By specifying
an integer value in the Check for asynchronous responses
after X messages have
been fired field, as shown in Figure 4,
the runtime completes the processing of X requests
and then processes the response messages before further iterations
are processed. This way you can restrict the number of parallel requests
being processed by back-end services, such as the Payroll and HR services.
To process all entries within the array before the handling of any
response messages, select Check for asynchronous responses
after all messages have been fired.Figure 4. Setting the number of requests that should be processed
By using the Invocation style and Asynchronous invocation settings both Payroll and HR services are called prior to either of the response messages being processed.