Sample 0107 - Load Balancing and Fail-Over Data Publisher

Introduction

This sample demonstrates how to set up an execution plan with a basic pass through query. It selects some attributes of each incoming event and gives an output event with the selected attributes. This sample uses wso2Event for both inputs and outputs, but we send events to two databridge listening servers using LoadBalancing data publisher.

The query used in this sample is as follows:

from InMediationStatsStream
select meta_host, timestamp, resource_id, direction, fault_count, count
insert into OutMediationStatsStream;

The above query,

Processes the events received through InMediationStatsStream
From each event received, selects the attributes (meta_host, timestamp, resource_id, direction, fault_count, count) specified under the select clause
Gives output events through the OutMediationStatsStream. Because this query does no processing apart from selecting a few attributes, it can be considered as a pass-through query.

Prerequisites

See Prerequisites in CEP Samples Setup page.

Building the sample

Start the WSO2 CEP server with the sample configuration numbered 0107. For instructions, see Starting sample CEP configurations. This sample configuration does the following:

Creates <CEP_HOME>/repository/conf/data-bridge/stream-definitions.xml file, which is used to create the stream definitions for the sample.
Points the default Axis2 repo to <CEP_HOME>/sample/artifacts/0107 (by default, the Axis2 repo is <CEP_HOME>/repository/deployment/server).

Executing the sample

Open a terminal, go to <CEP_HOME>/samples/consumers/wso2-event and run the command below:
```
ant -Dport=7661
```
Again, open another terminal, go to <CEP_HOME>/samples/consumers/wso2-event and run the following command:
```
ant -Dport=7662
```
Both steps build the sample wso2event consumer and execute it.

Do not close these terminals. They are required to keep the servers running and receiving events.
Open another terminal, go to <CEP_HOME>/samples/producers/mediation-stats and run ant from there.

It builds and runs the wso2event producer, which sends some mediation statistics data to the CEP server.
From the terminal opened in step 3, see the events sent.
Note

To configure host, port, username, password and No. of events use -Dhost=xxxx -Dport=xxxx -Dusername=xxxx -Dpassword=xxxx -Devents=xx.
For example : ant -Devents=5
See the output events received from the CEP via the terminals opened in step 1 and 2.

For example, given below is the console output of the consumer when sending 5 events from the producer.
Terminal 1 with port 7661 - Output

Terminal 2 with port 7662 - Output

Note that the events are published according to round-robin algorithm to both data-bridge listening servers. For more information, see Setting up Multi Receiver and Load Balancing Data Agent.