Fast Esp Custom Stage Development
The FAST documentation (ESP Document Processor Integration Guide) has a pretty good example of how to write a custom document processor.  FAST does not provide the source code to any of it's software, but the AttributeFilter stage functionality should be very straightforward.
I am working on Enterprise Search and we are using Fast ESP and for now i have 4 projects but i have no information about stages and python. But i realize that i have learn custom stage development. Because we have a lot of difficulties about document processing. I want to know how can i develop custom stage and especially i wanna know about how i can find  Attributefilter stage source code. I am waiting your answers