Hi Anu,
1. Is there no mechanism in place that takes care that these updates can be retriggered without EM in case of failure (like possible with qRFC)?
We have recently gone a live like staging table (buffering what we have in SAP EM) concept where we collect all day events and post events in the night through custom program. You may go with this approach:
a) If any of events failed then will reside the staging table and trigger email to support team. This way we don't lose data and will be addressed failed events like any preceding event not posted, data incorrect, format issue, sender code issue etc then it will reside in staging table.
2. the requirement is that EE status in EM gives visibility on the update in application system as well?
You can freely define your own custom status based on client requirement as suggested by Steffen. However, if you want later edit only status then good option would go with custom report to edit directly with reporting the events.'
3. You then need a custom rule activity that stores these event messages in a custom table.
You can define your customer rule activity to use existing SAP EM standard tables. There could be some reasons customer project gone with custom table solution as I saw few projects they had gone through storing event message data in custom tables as they couldn't fit their custom solutions.
Regards
GGOPII