Reasons for message immutable: A received message might have

multiple subscribers (orchestration, sendports etc) means each

subscriber of a particular message references the same, single

copy of that message. So, it make sense the message is not

modified by any single service like Orchestration or

pipelines.

2. Since single copy is referenced by multiple subscribers, it

minimize storage. ( A ref counter is maintained for each

message and messages with ref count of 0 are periodically

removed.)

3. The concept of messages being immutable also allows for

detailed tracking of message state as messages flow through

the system.