4.2.2. Components of an ESB Message

An ESB message is made up of the following components:
Header
The header contains such information as the destination end-point reference, the sender end-point reference, and where the reply goes. This is all general message-level functional information.
Context
This is additional information that further explains the message; for example, transaction or security data, the identity of the ultimate receiver or HTTP-cookie information.
Body
The actual contents of the message.
Fault
Any error information associated with the message.
Attachment
Any attachments (additional files) associated with the message.
Properties
Any message-specific properties.(For example, the jbossesb.message.id property specifies a unique value for each message).
Here is a code representation: 
    <xs:complexType name="Envelope">
	<xs:attribute ref="Header" use="required"/>
	<xs:attribute ref="Context" use="required"/>
	<xs:attribute ref="Body" use="required"/>
	<xs:attribute ref="Attachment" use="optional"/>
	<xs:attribute ref="Properties" use="optional"/>
	<xs:attribute ref="Fault" use="optional"/>
</xs:complexType>