BAPI or ES? Any change in ECC needs to be reflected to subscribers(nonSAP)

Question

Here is my scenario:
WBS elements are part of PS module of SAP. As and when there is a change in WBS element - all changes must be updated to its subscriber thrid party applications(non SAP).
Ther were two ways I was thinking to design this scenario.
1. Webserivce - ES has some prepacked services.
2. Proxy ( BAPI )
ECC -
>           PI --->  non SAP Parties
  +                              +
Common Rules        Party specific rules
As the data on ECC can grow over the time - some common rules are needed  to restrict the data at ECC.
The problems I am facing is about filtering the data. Subscribed systems have some rules which have to be applied - For example Party A just want only projects with some budget and Party B wants all projects.
Q: I have not used ES so far - what is the best way to get all records + filtered records?
Q: How to make changes triggered from ECC - change pointers to trigger?
Q: If I use SOAP Adapter to get the data from ES - Can we automate the process to get triggered after change is made in ECC.
Thanks.
Edited by: sanju XI on Oct 7, 2010 6:36 PM

Answer 1

The best way to go for this is -
Use ABAP proxy to send changes to PI. Whenever there will be real-time change in ECC, the program will trigger a proxy message out to PI.
Filters - You can use filter either in the receiver determination or message mapping.
Data to 3rd party system - since it a web service, use SOAP.
So, the zest is the below flowchart :-
ECC (for any real-time changes, trigger ABAP proxy) -> PI (filter conditions) -> 3rd Party (SOAP).
This way your 3rd party system will be updated with real-time changes.