Event vs Services to initiate a BPEL process in AS11

Since As11 supports both events and services to initiate a SOA composite ( may be having a BPEL process within it), there is always a question around when to use events and when to use service invocation to start the process.

The decision can be based on the following understanding of the events and service patterns.

Events

• Events are suitable for a decoupled integration.
  
• Events are one way messaging (no request response pattern and correlation)
  
• The publisher does not know about the subscribers (there might not be subscribers too)
• The publisher is not blocked for the execution of the subscriptions
• Events support 1:n fan out (multiple subscribers for the same event)
  

Service invocations

• Service invocation is a tight integrations with the service provider
• Service invocation supports request response patterns (sync or async)
• Synchronous service invocation is blocked till the execution of the service completes.
• Async Request response pattern is often supported via WS-adderessing and correlation