The document provides information on Mule ESB and its core components for handling message structure and flow. It describes how a Mule message contains a header and payload, and how properties and variables provide metadata about messages. It also explains key components like splitters that divide messages, aggregators that combine related messages, and resequencers that reorder out-of-order messages. Transformers are described that can change message types, contents, and properties during flow processing in Mule applications.

1. Mule ESB

2. Mule Message Structure
 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.

3. Mule Message Properties and Variables
 Message header consists of properties which provide
useful information about the message
 variables represent data about a message
 Properties have two main
scopes: inbound and outbound.Inbound Property

4. Mule Message 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.

6. Outbound Endpoint
Mapping message headers to transport headers

7. Mapping transport headers to message headers
Inbound Endpoint

8. Transformation Types
 3 Types of Transformers
Type transformation - involves converting the ‘type’ of the
message, for example; converting a byte stream to a string or
converting a JMS Message to a Java object.
Message transformation involves converting the message itself,
for example; converting a BookingRequest object into an
AirlineTicket object.
Property Transformations involves the properties on a message.
Each message may contain properties, usually related to the
transport used. For example, a message sent to an SMTP server would
have ‘To’, ‘From’ and ‘CC’ properties

9. SPLITTER
 A message splitter can be used to break down an outgoing message into parts
and dispatch those parts over different endpoints configured on the router.

10. SplitterExample
<flow name="SplitterExampleFlow1" doc:name="SplitterExampleFlow1">
<http:inbound-endpoint exchange-pattern="request-response"
host="localhost" port="8081" doc:name="HTTP"/>
<splitter expression="#[xpath('//actor')]" doc:name="Splitter"
enableCorrelation="IF_NOT_SET"/>
<logger message="#[message.payload]" level="INFO"
doc:name="Logger"/>
</flow>

11. <flow name="aggregateLineItems">
<jms:inbound-endpoint queue="lineitem.complete“ connector-
ref="jmsConnector"/>
<collection-aggregator timeout="60000“ failOnTimeout="true" />
<custom-transformer
class="com.prancingdonkey.transformer.LineItemsToOrderTransformer"/>
<component class="com.prancingdonkey.service.OrderProcessingService"/>
</flow>
Mule Aggregator Example

12. Resequencer
If fractions of the message are being processed in
parallel in different servers, there's a good chance that
they may take different lengths of time to be processed,
and consequently fall out of order.

13.  The Resequencer will wait for all of the messages in the
group to arrive (keeping track of MULE_CORRELATION_ID and
MULE_CORRELATION_GROUP_SIZE )
 Reorder them according to their MULE_CORRELATION_SEQUENCE
index.
 The Resequencer outputs will be in distinct messages,

14. Thank You