The Mule message consists of a header containing metadata properties and a payload containing business data. Properties provide information about the message and have names and values, while variables are user-defined temporary metadata. Properties are immutable inbound properties generated by the message source or mutable outbound properties set during message processing. Variables have three scopes - flow, session, and record - and are more likely set by humans while properties are more likely set by systems.
3. • The Mule message is the data that passes through an application via
one or more flows. It consists of two main parts:
• the message header, which contains metadata about the message
• the message payload, which contains your business-specific data.
• A Mule message is, itself, embedded within a Mule message object
4.
5. Properties
• The metadata contained in the message header consists
of properties which provide useful information about the message.
• Properties has a name and a value.
• Inbound Properties
• Outbound Properties
6. Properties
• Want to interact with server properties
• #[server.date]
• Current Application properties
• #[app.name]
7. Inbound Properties
• Inbound properties are immutable, are automatically generated by
the message source and cannot be set or manipulated by the user
• For HTTP – http.query.string
8. Outbound Properties
• Outbound properties are mutable; they are set during the course of a
flow and can become inbound properties when the message passes
from the outbound endpoint of one flow to the inbound endpoint of
a different flow via a transport.
• They contain metadata similar to that of an inbound property, but an
outbound property is applied after the message enters the flow.
9. Outbound Properties
• Outbound properties can be set automatically by Mule or a user can
set them by manually inserting one or more transformer elements in
the flow.
• Note that if the message is passed to a new flow via a flow-ref rather
than a connector, the outbound properties remain outbound
properties rather than being converted to inbound properties
10. Variables
• Variables are user-defined metadata about a message. Variables have
three scopes:
• Flow variables apply only to the flow in which they exist.
• Session variables apply across all flows within the same application.
• Record variables apply to only to records processed as part of a batch.
11. Variables vs Properties
• Variables are temporary pieces of information about a message that
are meant to be used by the application that is processing it, rather
than passed along with the message to its destination.
• Variables are more likely to be set by humans
• Properties are more likely to be set and invoked by systems.
• Variables also have name and value
• Properties have two main scopes: inbound and outbound
