Portal eventing

Hi,

I would like to know where I can find some documents on Portal eventing.

Also I would like to know how to achieve this using Portal eventing.

1. I have an iView-1 where I have drop-down box from which I select a particular value 'A'. This drop-dwon box will have values from a BW Query-1.

2. Using this value 'A', I have set a variable in BW Query-2. I think I have define this variable as SAP exit.

3. iView-2 will have a BW Query-2.

So how can I achieve this. I know this has to be done using Portal eventing, but not able to find the correct pointers.

Thanks and regards,

Srini