This document discusses Mule, an open source enterprise service bus (ESB). It describes Mule's architecture including connectors, transformers, routers and message processing capabilities. Mule aims to provide integration, flexibility, decentralized operation and scalability through separation of concerns. However, its generality results in complexity, ambiguity with standards, and limited support for runtime refactoring and conceptualization.

1. By
Achyuta Laxmi

2.  What is an ESB?
 Java Business Integration (JBI)
 Mule Architecture
 Mule in the Real World

3.  [Mul] Mule Architecture Guide.
http://mule.mulesource.org/display/MULE/Architecture+Guide
 September [mule-user archive]

4.  Integration of existing systems
 Refactorable in real time
 Flexibility to change as requirements change
 Decentralized (service-location transparency)
 Scalable (point solutions to full enterprise)
 Sharing of services across enterprise
 Ability to separate Business Services from
Service Implementations
 Leverages standards

5. Gartner Group
Giant exercise in Separation of Concerns
[Ric]

6. [Ric]

7.  Routing
 Message Transformation
 Message Enhancement
 Protocol Transformation
 Service Mapping
 Message Processing
 Process Choreography
 Service Orchestration
 Transaction Management
 Security
[Ric]

8. General case
Client calls Choreographer Client calls Mediator
vs

9.  JSR-208 Standard
 Defines service engines (SE – choreographers,
transformers, security, etc) and binding
components (BC – xml, http, etc)
 Concerned with how internal customers (not
external services) interact with service providers
COTS

10.  XSLT – message transformation
 PXE – choreography
 Groovy – scripting
[Ric]

11. Service Mix
Binding Components
Service Engines

12. [Mule]

13.  Channel – a method of connecting between two points
(not part of Mule)
 Connector – a transport provider (e.g., http, jms, soap,
smtp, etc) implementing message receive and message
dispatch
 Transformer – converts message structure/format (e.g.,
http to xml)
 Router – moves messages amongst UMOs and connectors

14. http://myapp.com pop3://user@userland.comhttp→xml xml→pop3
myUMO (xml→xml)
[Mule]

15.  AS400 DQ
 EJB
 E-mail
 File
 FTP
 HTTP
 IMAP
 JDBC
 JMS
 Multicast
 POP3
 Quartz
RMI
 Servlet
 SMTP
 SOAP
 SSL
 Stream
 TCP
 UDP
 VFS
 VM
 WSDL
 XMPP

16.  Requires a component resolver (e.g., Spring
or Pico) for
 Instantiation of UMOs
 Configuration of UMOs
 Event processing
 Asynchronous
 Synchronous
 Request-Response
[Mule]

17. Application logic
Application glue
Mule glue
[Mule]

18. [Mule]

19.  Applies one or more filters to incoming payload, then
branch based on filter
<inbound-router>
<catch-all-strategy
className="org.mule.routing.ForwardingCatchAllStrategy">
<endpoint address="jms://topic:error.topic"/>
</catch-all-strategy>
<router
className="org.mule.routing.inbound.SelectiveConsumer">
<filter expression="msg/header/resultcode = 'success'"
className="org.mule.routing.filters.xml.JXPathFilter"/>
</router>
</inbound-router>

20. <outbound-router>
<catch-all-strategy
className="org.mule.routing.ForwardingCatchAllStrategy">
<endpoint="jms://error.queue"/>
</catch-all-strategy>
<router className="org.mule.routing.outbound.FilteringOutboundRouter">
<endpoint address="smtp://ross@muleumo.org"/>
<filter expectedType="java.lang.Exception"
className="org.mule.routing.filters.PayloadTypeFilter"/>
</router>
<router className="org.mule.routing.outbound.FilteringOutboundRouter">
<endpoint address="jms://string.queue"/>
<filter className="org.mule.routing.filters.logic.AndFilter">
<left-filter expectedType="java.lang.String"
className="org.mule.routing.filters.PayloadTypeFilter"/>
<right-filter pattern="the quick brown (.*)"
className="org.mule.routing.filters.RegExFilter"/>
</filter>
</router>
</outbound-router>

21.  Allows synchronous callouts that can be intercepted and routed
<mule-descriptor name="InvokerComponent"
implementation="org.mule.foo.Invoker">
<inbound-router>
<endpoint address="jms://Invoker.in"/>
</inbound-router>
<nested-router>
<binding interface="org.mule.foo.HelloInterface">
<endpoint
address="axis:http://192.168.2.14:81/services/HelloWebComponen
t?method=helloMethod" remoteSync="true"/>
</binding>
</nested-router>
<outbound-router>
<router
className="org.mule.routing.outbound.OutboundPassThroughRouter
">
<endpoint address="jms://Invoker.out"/>
</router>
</outbound-router>

22.  September [mule-user archive]
 How to get a hold of Endpoint object from the
component? {mule}
 Failed to throw UserDefined Exception {jaxws}
 Failed to invoke lifecycle “start” using CXF in
JBOSS {cxf}
 Problem in loading xsd files {mule}
 Problems with RemoteDispatcher {mule}
 Inject MuleClient Singleton with Spring {mule}
 Mule transaction support {mule}

23.  Routing
 Message Transformation
 Message Enhancement
 Protocol Transformation
 Service Mapping
 Message Processing
 Process Choreography
 Service Orchestration
 Transaction Management
 Security
X
X
√
√
√
√
√

24.  Mule’s generality results in great flexibility, but
at the cost of great complexity for users
 Mule is the focal point of ambiguity and
difficulties with many standards-based packages
 Mule delivers (to a degree) on:
 Integration, flexibility, decentralized operation,
scalability
 Mule doesn’t deliver (so much) on:
 Runtime refactoring, conceptualization