User Defined Function

Hi Folks,

    Basically I am a PI consultant from the ABAP background. I really find it difficult when it comes to a UDF scenario or say I just don't know what to do in that case. Can somebody let me know about some good blogs where I can educate myself on UDFs. FYI I have already followed the below Blogs & wikis which I feel didn't help me much as I don't know the starting point.

http://scn.sap.com/people/william.li/blog/2008/01/02/sap-pi-71-mapping-enhancements-series-share-user-defined-functions

http://wiki.sdn.sap.com/wiki/display/XI/User+Defined+Function's+Part+1

Regards,

  Santosh