Apama 10.3 | Apama Documentation | Developing Apama Applications | Developing Apama Applications in EPL | Making Application Data Available to Clients | Using multiple correlators
Using multiple correlators
The DataViewService is designed to primarily interact with other EPL or JMon applications that reside in the same correlator. Therefore, the DataViewService implementation does not emit any events. You can inject the following optional additional monitors, which are in the monitors directory of your Apama installation, to emit the events when that is required:
This enables Dashboard Builder clients to visualize the state of a number of applications, each of which is running in a separate correlator, and each of which may fail-over to another correlator. Since configuring all of the dashboards to know about each of these correlators might be difficult and fragile, you can designate an additional single correlator as the "view correlator", which holds the DataViewService and ScenarioService to which any client dashboard can connect.
With this architecture, the individual applications in the separate correlators need to emit DataViewService request events to a channel that has been connected to the view correlator. These applications can either emit the events directly, or with the Application Emitter injected they can route the events and the extra monitor will emit them to the channel. The DataViewService in the view correlator routes its responses (as normal), but the Service Emitter monitor will then emit those events out on the com.apama.dataview channel so that the originating correlators can receive them.
Note that these two emitters are entirely optional, and are not required for most deployments. Moreover, you normally do not inject these two monitors into the same correlator. Also, there is no bundle in Software AG Designer that provides these monitors.

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