Working with Event Streams

Event Streams are another main part in CEP. All the processing happens based on streams. Here, Event streams need to be defined as WSO2Event Stream Definition. All the created streams are stored in the registry (governance) of the CEP.

Don't try to edit edit streams definitions directly which are stored in registry. Because it may leads to unpredictable situations.

Creating Stream Definitions (Streams)

Start the CEP, log in to its management console, select Event Streams and click Add Event Stream.
Enter details in the form that appears and click the Add Event Stream button at the end of the form. For example,
Here, fill the necessary fields according to the stream definition that you want to create.
Finally, Click the Add Event Stream button to add the stream definition to the registry. Then Available Event Stream page will open. To delete event stream, click the Delete button.

To create an event builder or execution plan it is mandatory to create necessary event streams before hand.

Other than the server UI, you can also define the stream definition using a config file which is in the <CEP_HOME>/repository/conf/stream-manager-config.xml. But this file used to create streams only in the server start-up (This file is not hot deploy-able). Please see the below syntax

<streamManagerConfiguration xmlns="http://wso2.org/carbon/streammanager">
    <streamDefinition name="org.wso2.sample.stock.quote.basic" version="1.0.0">
        <payloadData>
            <property name="price" type="DOUBLE"/>
            <property name="symbol" type="STRING"/>
        </payloadData>
    </streamDefinition>
    <streamDefinition name="org.wso2.sample.twitter.feed" version="1.0.0">
        <payloadData>
            <property name="company" type="STRING"/>
            <property name="wordCount" type="INT"/>
        </payloadData>
    </streamDefinition>
    <streamDefinition name="org.wso2.sample.predicted.stock.quotes" version="1.0.0">
        <payloadData>
            <property name="company" type="STRING"/>
            <property name="amount" type="DOUBLE"/>
            <property name="words" type="LONG"/>
        </payloadData>
    </streamDefinition>
    <streamDefinition name="twitterFeed" version="1.0.0">
        <payloadData>
            <property name="company" type="STRING"/>
            <property name="wordCount" type="INT"/>
        </payloadData>
    </streamDefinition>

</streamManagerConfiguration>