Mule Message Structure - These slides will explain about Properties and Variables

1. Mule Message Structure
Properties and Variables
By Srilatha Kante

2. Agenda
• Introduction to Mule Message
• Message Headers
• Properties
• Variables
• Flow and Flow References

3. Mule Message
• 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. Mule Message Structure

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.workDir]

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.