Setting up Universal Messaging for use by Apama
For Apama to use the Universal Messaging message bus, there are some required Universal Messaging tasks. These steps will be familiar to experienced Universal Messaging users.
Plan and implement the configuration of the
Universal Messaging cluster that Apama will use. The recommendation is to have at least three
Universal Messaging realms in a cluster because this supports
Universal Messaging quorum rules for ensuring that there is never more than one master in a cluster. However, if you can have only two
Universal Messaging realms, you can use the
isPrime flag to correctly configure a two-realm cluster. For details about configuring a
Universal Messaging cluster, see the topics in the
Universal Messaging documentation that describe the following:
Quorum
Clusters with Sites, which describes an exception to the quorum rule.
To set up Universal Messaging for use by Apama, do the following for each Universal Messaging realm to be used by Apama:
1. Install Universal Messaging.
2. Start a Universal Messaging server.
3. Use Universal Messaging's Enterprise Manager or Universal Messaging client APIs to set the access control lists of the Universal Messaging server to allow the user that the correlator is running on. See the Universal Messaging documentation for details.
4. If you will use the default channel mode, use Universal Messaging's Enterprise Manager or client APIs to add the channels that Apama will use.
When you add channels, set the channel attributes as follows. Together, these attributes provide behavior similar to that provided by using the Apama correlator tool engine_connect.
Set
Channel Capacity to
20000 or some suitable number, at least 2000 events. A number higher than 20,000 would allow larger bursts of events to be processed before applying flow control but would not affect overall throughput.
Select
Use JMS engine. See also the information on engine differences in the
Universal Messaging documentation.
Set
Honour Capacity when channel is full to
true.
These channel attributes provide automatic flow control. If a receiver is slow, then event publishers block until the receivers have consumed events.
Other channel attributes are allowed. However, it is possible to set Universal Messaging channel attributes in a way that might prevent all events from being delivered to all intended receivers, which includes correlators. For example, Universal Messaging can be configured to conflate or throttle the number of events going through a channel, which might cause some events to not be delivered. Remember that delivery of events is subject to the configuration of the Universal Messaging channel. Consult the Universal Messaging documentation for more details before you set channel attributes that are different from the recommended attributes.
5. Ensure that Apama can locate the Universal Messaging libraries.
If
Universal Messaging has been installed in the same Software AG installation directory as Apama, no further steps are required. In this case, Apama will locate the
Universal Messaging installation automatically at
${APAMA_HOME}/../UniversalMessaging and will load the
Universal Messaging libraries from the appropriate subdirectory.
If
Universal Messaging has
not been installed in the same Software AG installation directory as Apama, do the following. Before running the correlator, IAF, or an Apama deployment script, add the location of the
Universal Messaging libraries for your platform to your environment's
PATH or
LD_LIBRARY_PATH. You can do this either in the environment in which you start the Apama components in or in the system's environment. For example, on Windows you can select
Computer > Properties > Advanced System Settings > Environment Variables.
