A. Event handling processes such as writing to a log, sending an error or recovery process, or sending an extra message, can be assumed to be handled by middleware.

B. Provide true message queueing for integration scenarios (including orchestration,process choreography, quality of service, etc.) given that a middleware solution is required.

C. Message transformation and protocol translation should be done within Salesforce.
Recommend leveraging Salesforce native protocol conversion capabilities as middle watools are NOT suited for such tasks

D. Transform a fire-and-forget mechanism to request-reply should be handled bymiddleware tools (like ETL/ESB) to improve performance.

E. Event handling in a publish/subscribe scenario, the middleware can be used to route requests or messages to active data-event subscribers from active data-event publishers.