12.2. Event Declaration

To declare a fact type as an event, assign the @role meta-data tag to the fact with the event parameter. The @role meta-data tag can accept two possible values:
  • fact: Assigning the fact role declares the type is to be handled as a regular fact. Fact is the default role.
  • event: Assigning the event role declares the type is to be handled as an event.
This example declares that a stock broker application's StockTick fact type will be handled as an event:

Example 12.1. Declaring a Fact Type as an Event

import some.package.StockTick

declare StockTick
    @role( event )
end
Facts can also be declared inline. If StockTick was a fact type declared in the DRL instead of in a pre-existing class, the code would be as follows:

Example 12.2. Declaring a Fact Type and Assigning it to an Event Role

declare StockTick 
    @role( event )

    datetime : java.util.Date
    symbol : String
    price : double
end
For more information on type declarations, please refer to the Rule Language section of the JBoss Rules Reference Guide.
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