Integration scenarios from scratch -- idocs or enterprise service bundles

Question

Hello,
We are starting a SAP PI implementation for a new SAP ECC 6.0 system. The implementation is from scratch, so we don't have to consider any historical issues or decisions. One of the first business processes to be integrated with business partners is the Procure-to-Pay process. The old way of implementing this B2B scenario was with idocs (e.g. ORDERS05 and INVOIC03), but nowadays the enterprise service bundles also contain services for this scenario. Should I choose idocs or enterprise services as a technique to get the information send to SAP PI or send the information to SAP ECC? What are the advantages and disadvantages of both techniques? Does anyone have experience with the implementation of the enterprise services for Procure-to-Pay?
Thanks for your response!
Kind Regards,
Mark

Answer 1

Hi Mark,
here are my 2 cents to your very interesting disussion.
The IDOC was designed to customize EDI data distributions between SAP Systems via messagetypes and transaktioncodes (Vorgangscodes) in the partnerdetermination which itself is mapped (the "Vorgangscode") to functional modules to do "something". The complete customizing of IDOC distribution might sometimes seems to be complex (and we both know it is more than that but it is FULL CUSTOMIZABLE from a consulting point of view.
The Enterprise Service (my personal view multiplied with the last TechEds and RampUp Delta courses) have another focus. An Enterprise Service is (mostly) some entity which is consumable from the outside world such that they are implemented with Request-Response patterns. When you only want to distribute information why will one use something like Request Response Patterns? One could argue to get back any response, any confirmation or something else....but this is also possible with IDOCs and their acks.
Another argument against to use an ES for P2P outbound scenario is, if yet not seen any ES which is triggert while create a purchase order in its related transaction. Is the BADI for such Transaction triggering the ES while the save event has been processed? If you could find out this fact and if the BADI (or some new kind of user exit for transactions) is implemented and fully supported from SAP I would choose the ES in the P2P processs. Otherwise why using the ES instead of the IDOC when using a PI as Middleware which is converting the source message type (ES or IDOC) into its proparitary legacy system format. Please let me know when you found such userexit/BADI for ES.
Please don't missunderstand my point of view, I would really throw away these IDOCS and using a couple of ES instead but what is the fully supported STANDARD from a customizable and manageable point of view. When you are familiar with proxy technology you know how easy to implement, monitor and manageble theses technology is - BUT - you always have to code some (maybe not release independent) proxy method and you maybe have to invest some knowledge for error handling, rollbacks or additional commit works - all of these stuff will be handled (mostly ) by the SAP standard delivered functions.
Last but not least - if there is any standard out there to trigger an ES from a transaction without coding I would rather use the ES instead of the IDOC. If there is no such standard I would discuss the functionality with the customer (if to complex implement an inbound or outbound proxy=ES) or extend the IDOC or use a BAPI (and extend the BAPI if needed) - mostly the proxy will the be the easiest choice if the needed field count is not to much (<30).
So long, let me know about your findings and your decision.
Regards,
Dries