Thursday, February 14, 2013

Load Balancing Data Publishers and Sending Events to Multiple Receivers

WSO2 BAM/CEP has hight performance thrift based event receiving model, which basically receives the events via TCP. Even though thrift is high performance receiving protocol, load balancing the thrift events is problematic as you need tcp based load balancer rather http based load balancer. Therefore in WSO2 we have added support to have load balancing between Data bridge receivers (ie, WSO2 BAM servers, CEP servers) from the client side, by sending the events in a round robin manner to BAM servers, such that load of events will be balanced between them.

For this we have added a Wrapper class called LoadBalancingDataPublisher, which uses the AsyncDataPublisher in it. It not only load balances the events between the set of servers and also can send same events to some servers. All the capabilities of using the LoadBalancingDataPublisher is provided in BAM 2.2.0 documentation here, which explains the use cases of using the load balancing data publisher.

This provides more fail over handling also with load balancing, which can detect the node failure and stop further publishing for the dead node and it also recognozes the node startup and it starts load balancing the events from that instance.

I'll provide a more detailed description about using LoadDataPublisher to publish events to BAM/CEP in next article.

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