Message Format
AMQP defines as the bare message, that part of the message that is created by the sending application. This is considered immutable as the message is transferred between one or more processes.
Ensuring the message as sent by the application is immutable allows for end-to-end message signing and/or encryption and ensures that any integrity checks (e.g. hashes or digests) remain valid. The message can be annotated by intermediaries during transit, but any such annotations are kept distinct from the immutable bare message. Annotations may be added before or after the bare message.
The header is a standard set of delivery related annotations that can be requested or indicated for a message and includes time to live, durability, priority.
The bare message itself is structured as an optional list of standard properties (message id, user id, creation time, reply to, subject, correlation id, group id etc.), an optional list of application-specific properties (i.e. extended properties) and a body (which AMQP refers to as application data).
Properties are specified in the AMQP type system, as are annotations. The application data can be of any form, and in any encoding the application chooses. One option is to use the AMQP type system to send structured, self-describing data.
Read more about this topic: Advanced Message Queuing Protocol
Famous quotes containing the word message:
“No it is better not. She would only ask me to take a message to Albert.”
—Benjamin Disraeli (1804–1881)