Actionable transport headers

Principle

A consumer can make high-level decisions on the basis of a message’s metadata, without processing the message and inspecting its contents

Description

Regardless of the transport mechanism for messages (e.g. a queue, topic or virtual topic, smtp, etc) the consumer should be able to make high-level decisions on the basis of a message’s metadata, without processing the message and inspecting its contents.

The minimum required headers are:

• correlationId
• messageType
• schemaVersion
• sequenceNumber

Consequences

• A publisher will add the messageType header to all emitted messages
• Naming conventions will be followed for messageType headers across the software estate
• A publisher will add the required headers but may omit sequenceNumber etc. if it is not implemented yet

Example

Any message would contain headers for:

• correlationId: 97f81df5-4339-42aa-9dcb-a8d278ebeee1
• messageType: REGISTRATION_NUMBER_UPDATED_EVENT
• sequenceNumber: 98765
• schemaVersion: 1.4

References

See this reference from Oracle on built-in JMS headers.