Hi All, In Apache Stratos (incubating) 4.0.0 we are using WSO2 CEP for aggregating statistics events sent by load balancers and cartridge agents (agents in VM instances). The aggregated values are used by the Autoscaler for taking autoscaling decisions.
Here the events are sent to CEP using the default input adapter (via Thrift) and the aggregated events are sent to an AMQP based message broker using the JMS Output Adapter. Event formatters have been used for defining the formats of the output messages. *A Sample Event Formatter:* <?xml version="1.0" encoding="UTF-8"?> <eventFormatter name="AverageRequestsInflightEventFormatter" statistics="disable" trace="enable" xmlns=" http://wso2.org/carbon/eventformatter";> <from streamName="average_in_flight_requests" version="1.0.0"/> <mapping customMapping="enable" type="json"> <inline>{"average_in_flight_requests":{"cluster_id":"{{cluster_id}}","network_partition_id":"{{network_partition_id}}","value":"{{count}}"}}</inline> </mapping> <to eventAdaptorName="JMSOutputAdaptor" eventAdaptorType="jms"> <property name="transport.jms.Destination">summarized-health-stats</property> </to> </eventFormatter> The above is a sample event formatter which defines an aggregated event. Similarly there is a collection of events sent by CEP to the message broker. For each event there is an event formatter defined. *The Requirement:* Here there is a requirement to include a set of AMQP Properties [1] in the output message. These properties may include name value pairs specific for each event: *A Sample AMQP Message* Message Properties: event_class_name: org.apache.stratos.messaging.event.health.stat.AverageInFlightRequests Message Body: {"average_in_flight_requests":{"cluster_id":"{{cluster_id}}","network_partition_id":"{{network_partition_id}}","value":"{{count}}"}} *The Proposal:* As I understood this functionality is not supported by the JMS Output Adapter at the moment and I think it's logical since AMQP features should not be included in JMS Output Adapter. As a solution to this requirement I would like to implement an AMQP Output Adapter on top of the JMS Output Adapter to support this functionality [2]. I will send more implementation design details in another mail as I progress. Really appreciate your thoughts on this. [1] http://en.wikipedia.org/wiki/Advanced_Message_Queuing_Protocol#Message_format [2] http://docs.wso2.org/display/CEP300/Output+Event+Adaptors Many Thanks -- *Imesh Gunaratne* Technical Lead WSO2 Inc: http://wso2.com T: +94 11 214 5345 M: +94 77 374 2057 W: http://imesh.gunaratne.org Lean . Enterprise . Middleware
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