Hi,
Retrieval gets the documents from messaginng provider into local IS storage and Processing performs the real work on the document and returns an ack to the messaging provider.
For the case the IS goes down and not all locally cached documents have been processed and acked to the messaging provider, these will remain available on the messaging provider.
When IS is restarted, these documents will then be retransferred from messaging provider to IS for processing.
Additionally I agree with Holm.
Regards,
Holger
#Integration-Server-and-ESB#webMethods