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WSO2Event Event Builder converts events/streams from an input adaptor that supports WSO2-Events into an event stream that is compatible with the event processor. WSO2-Event has three data types (meta, correlation and payload), which can be mapped to the CEP backend runtime event attributes by specifying the mapping in the event builder. 

You can configure through the management console as explained below or by manually adding an XML file as explained in step 5.

  1. Start the CEP, log in to its management console, select Event Builders and click Add Event Builder.
  2. Enter details in the form that appears and click the Add Event Builder button at the end of the form. For example,

    The fields in the above configuration are as follows:

    • Event Builder Name : Property to uniquely identify an event formatter configuration
    • Input Event Adaptor (marked as 1 in the screenshot) : The input event adaptor used to publish events to the CEP. This drop-down list only displays the adaptors that are already created. In this example, we select an Input WSO2Event Event Adaptor already created.
    • Input Event Adaptor properties (marked as 2 in the screenshot) : Properties required by the input event adaptor depending on the input event adaptor type selected before. For example, if you select WSO2Event, then the required properties are:
      • Stream Definition - Stream name of the incoming WSO2Event stream
      • Stream Version - Version of the incoming stream
    • Input Mapping Type (marked as 3 in the screenshot): Select WSO2Event mapping type. This property changes based on the event adaptor selected. It lists only the mapping types supported by a particular event adaptor.
    • Mapping properties (marked as 4 in the screenshot) : Map the incoming stream to the outgoing stream received by the event processor. In this case, mappings are further divided as meta data, correlation data and payload data. Provide the necessary details in the input fields:
      • Enter the attribute name of the incoming stream in Input Attribute Name
      • Enter the attribute name for the outgoing stream in Mapped To
      • Select the data type of the attribute from the To Stream Data Type drop-down
      • Click Add to add the individual attribute mapping to the event builder

        For the correct properties to show, you must selected an input event adaptor that supports WSO2Event mapping type.

    • To Stream Name/Version : Stream name/version of the outgoing stream

    If custom mapping is disabled, please give the 'To Stream' name and version should match the 'From Stream' name and version. Note that with custom mapping disabled, the stream definitions exposed will not be visible to execution plans or event formatters unless the stream definition is already available in registry.

  3. After a builder is successfully created, you can change its configuration and redeploy it. To do this, click the Edit link associated with it. You can also click the other links associated with it to delete or enable statistics and tracing.
  4. An XML based editor opens allowing you to edit the event builder configuration from the UI itself, without having to edit the file in the file system. Do your modifications and click Update.
  5. Alternatively, you can specify an event builder configuration using an XML file and save it in <PRODUCT_HOME>/repository/deployment/server/eventbuilders directory, which is the event builder deployment directory. Since hot deployment is enabled, you can simply add/remove files to deploy/undeploy from the server.

    Create the XML file with the following WSO2Event based event builder configurations. Event builder implementation must start with <eventbuilder> root element and the namespace set to  as in the example below.

    <eventBuilder name="SearchStatBuilder" xmlns="">
        <from eventAdaptorName="localEventReceiver" eventAdaptorType="wso2event">
            <property name="stream">access_Analytics</property>
            <property name="version">1.0.0</property>
        <mapping type="wso2event">
                <from dataType="meta" name="ipAdd"/>
                <to name="ipAddress" type="string"/>
                <from dataType="payload" name="username"/>
                <to name="username" type="string"/>
                <from dataType="payload" name="keywords"/>
                <to name="searchTerms" type="string"/>
        <to streamName="searchStatistics" version="1.0.0"/>

    Here if custom mapping disabled, then it is considered as a pass-through event builder which allows to send all the events without pre-configured mapping. But this feature is only implemented for wso2Event builder. (you cannot configure execution plan for pass-through event builder in UI level, you have to create it in the back-end, because CEP doesn't know about the stream definition until first event comes to CEP. Then you can configure the execution plan and event formatter in back-end and deploy it.

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