Extracting a default.incoming.message.id.key

[maccac]

This allows the setting uniqueReference to be overridden, or turned off.

I think having a global default should be good enough at this stage. If we want to have different values per queue we can look at adding to the bridge configuration or adding a new type of transformation.

This should resolve #12

[rajeshgpai]

@maccac Could this be done instead using jolt, where we define a tranformation where aws message id is converted into a specific key?

[maccac]

Good question. Maybe not directly with jolt as the message Id isn't part of the 'body' of the message at this point in the code. I could be wrong, but I think we would either need a non-jolt type of transformation to do that, or to do something similar to this and create a message with more fields that we could then pass it to jolt to do extra transformations.

Options:

• Just have the default (this approach)
• Leave it hardcoded as unique reference and suggest users apply a transformation to remove it or to shift it to whatever value they prefer on each bridge (Maybe tackled by #25)
• Both. Imagine you want the majority to be globallyUniqueMessageId for most things, but have a few special snowflakes that want say a globalMessageId instead.

Do you have any thoughts?

[maccac]

Had a chat with @rajeshgpai about this offline. We decided that we should default this setting to null. Others can provide pull requests to do transformations, or push this information into the rabbit header instead of the message body if they find it useful.