Dear All, I have been trying to figure our the best strategy to query a stream of events. Basically what I need to do is match a given event pattern based on the events injected to the working memory so far. Event pattern is a simple expressions like (EventId=001 && EventId=023 ). I need to support AND, OR, XOR relationships of two pr more events. e.g. (EventId=001 && EventId=023 ) || EventId=013 All the input events are of the same type but can be distinguished based on its Id attribute. They keep coming from a event source. The event patterns are formed dynamically. These dynamic event patterns are evaluated like a query against the events so far recorded in working memory. Im sure this is is usual requirement and there is a simple answer from Drools fusion. But so far failed to do it and now Im investigating drools template too. If anyone has done this earlier OR know a solution for this I highly appreciate if you can share it. Cheers, Malinda __________________________________________________________________________________ Yahoo!7: Catch-up on your favourite Channel 7 TV shows easily, legally, and for free at PLUS7. www.tv.yahoo.com.au/plus7