The document discusses the Enterprise Service Bus (ESB) Mule and its core concepts. Mule is an open-source ESB that uses advanced technologies like Staged Event-Driven Architecture (SEDA) and Java New Input/Output (NIO) to route messages between applications. It decomposes applications into stages connected by queues to improve performance. Mule's universal message object (UMO) allows messages to be received and sent from anywhere. Core concepts include endpoints, transports, connectors, routers, filters and transformers that define how messages flow through the system.
4. Mule is Has Advanced
Technologies
SEDA
Staged Event-Driven Architecture
Java NIO
Java New Input/Output
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5. SEDA
SEDA decomposes a complex, event-driven software application
into a set of stages connected by queues
This design avoids the high overhead associated with thread-based
concurrency models, and decouples event and thread scheduling
from application logic
By performing admission control on each event queue, the service
can be well-conditioned to load, preventing resources from being
overcommitted when demand exceeds service capacity
SEDA employs dynamic control to automatically tune runtime
parameters (such as the scheduling parameters of each stage) as
well as to manage load, for example, by performing adaptive load
shedding
Decomposing services into a set of stages also enables modularity
and code reuse, as well as the development of debugging tools for
complex event-driven applications
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6. Java NIO
NIO is a collection of Java programming language APIs that
offer advanced features for intensive I/O operations
NIO facilitates an implementations that can directly use
the most efficient operations of the underlying platform
NIO includes:
Buffers for data of primitive types
Character set encoders and decoders
A pattern-matching facility based on Perl-style regular expressions
(in package java.util.regex)
Channels, a new primitive I/O abstraction
A file interface that supports locks and memory mapping
A multiplexed, non-blocking I/O facility for writing scalable servers
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7. Mule’s “Moves Things
Around”
Folder to folder
Queue to queue
Shared memory to shared memory
Using different types of transports
In a flexible way
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8. XML Pipeline
An XML pipeline is a series of operation that are
performed on one or more XML files
Examples include:
validate
transform
prune (remove nodes)
split (break a single XML file into many files)
merge (join two or more files together)
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9. CRV Example
Flow of XML document through approval processes
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Submit
CRV
Deed
Matched
CRV
SSN
Stripped
CRV
Income
Tax
Audit
County
Audit
County
Approval
State
Audit
State
Approval
10. Decomposition
Example of XML Operations used on CRV
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Validate Split
Remove
SSN
Element
Store
Modify
Value
Add
Element
Modify
Value
Add
Element
11. Declarative Approach
Focus on specifying "What" not "How"
Empower business analysis to write machine-readable
specifications
Hide the "How" behind services with clear interfaces
(SOA)
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13. Universal Message Object
(UMO)
A UMO is a type of Java object that can
receive events "from anywhere"
send events
UMO Components are usually your
business objects. They are components
that execute business logic on an
incoming event
UMO are standard JavaBeans (containers)
There is no Mule-specific code in your
components
Mule handles all routing and
transformation of events to and from your
objects based on the configuration of your
component
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14. Transport
A transport or "provider", is a set of objects that add
support to Mule to handle a specific kind of transport or
protocol
Examples
the "Email Provider" enables Mule to send and receive
messages via the SMTP, POP and IMAP protocols
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15. Connector
A connector is the object that sends and receives
messages on behalf of an endpoint.
Connectors are bundled as part of specific transports or
providers.
For example, the FileConnector can read and write
file system files.
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16. Router
A router is the object that do something with messages
once they have been received by a connector, or prior
to being sent out by the connector
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17. Filter
A filter optionally filters incoming or
outgoing messages that are coming
into or going out from a connector.
For example, the File Provider comes
with a FilenameWildcardFilter
that restricts which files are read by
the connector based on file name
patterns. For example only files with
the .xml extension can be routed.
Filters are used in conjunction with
Routers.
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18. Transformer
A transformer optionally changes incoming or outgoing
messages in some way
This is usually done to make the message format
useable by a downstream function
Examples:
the ByteArrayToString transformer converts byte arrays
into String objects.
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19. Mule Event Flow
The nine stages of a mule event
first 2 – inbound
middle 4 – component
last 2 – outbound
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Endpoint
(Message Receiver)
Endpoint
(Message Dispatcher)
Inbound Router
Outbound Router
Inbound Transformer
Outbound Transformer
Interceptor
Service Invocation
Interceptor
Inbound
Component
Outbound
Optional Step
20. Message Receiver Endpoint
Some event triggers a message flow
A file being written into a folder
A message arriving on a message queue
A record in a database
Data written to a socket
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Endpoint
(Message Dispatcher)
Inbound Router
Outbound Router
Inbound Transformer
Outbound Transformer
Interceptor
Service Invocation
Interceptor
Endpoint
(Message Receiver)
21. Inbound Router
The inbound router is the fist step
in a message. Functions typically
performed by an inbound router
Filtering
Remove duplicate messages
Matching messages
Aggregation (combining)
Re-sequence data
Forwarding
See also
IdempotentReceiver
CorrolationAggregator
CorrelationResequencer
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Endpoint
(Message Dispatcher)
Inbound Router
Outbound Router
Inbound Transformer
Outbound Transformer
Interceptor
Service Invocation
Interceptor
Endpoint
(Message Receiver)
22. Interceptor
Used to intercept message
flow into your service
component
Used trigger monitor/events
or interrupt the flow of the
message
Example: an authorization
interceptor could ensure that
the current request has the
correct credentials to invoke
the service.
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Endpoint
(Message Dispatcher)
Inbound Router
Outbound Router
Inbound Transformer
Outbound Transformer
Service Invocation
Interceptor
Endpoint
(Message Receiver)
Interceptor
23. Inbound Transformer
If the inbound data is not in the
correct format for the service it
must be transformed at this point
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Endpoint
(Message Receiver)
Endpoint
(Message Dispatcher)
Inbound Router
Outbound Router
Outbound Transformer
Interceptor
Service Invocation
Interceptor
Inbound Transformer
24. Service Invocation
The actual service is performed
In mule, this is generally a Java object
Service invocation can also be a "pass
through"
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Endpoint
(Message Receiver)
Endpoint
(Message Dispatcher)
Inbound Router
Outbound Router
Outbound Transformer
Interceptor
Interceptor
Inbound Transformer
Service Invocation
25. Outbound Router
Dispatching the data to all the
relevant endpoints
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Endpoint
(Message Receiver)
Endpoint
(Message Dispatcher)
Inbound Router
Outbound Transformer
Interceptor
Interceptor
Inbound Transformer
Service Invocation
Outbound Router
26. Built-in Router Classes
Inbound Outbound Response
Idempotent Receiver Filtering Outbound Router Response Aggregator
Selective Consumer Recipient List
Aggregator Multicasting Router
Resequencer Chaining Router
Forwarding Consumer Message Splitter
Filtering List Message
Splitter
Filtering Xml Message
Splitter
Exception Based Router
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27. Outbound Transformer
Any transformations that needs
to be done on the message after
a service has been performed on
the message can be executed
before it is put into the endpoint
See Also
EnvelopeInterceptor
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Endpoint
(Message Receiver)
Endpoint
(Message Dispatcher)
Inbound Router
Interceptor
Interceptor
Inbound Transformer
Service Invocation
Outbound Router
Outbound Transformer
29. Omitted From Examples
for Brevity<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE mule-configuration PUBLIC "-//MuleSource
//DTD mule-configuration XML V1.0//EN"
"http://mule.mulesource.org/dtds/mule-
configuration.dtd">
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32. Only Moving XML Files
<inbound-router>
<endpoint address="file:///c:/mule-class/in">
<filter pattern="*.xml"
className=
"org.mule.providers.file.filters.FilenameWildcardFilter"/>
</endpoint>
</inbound-router>
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Add the filter line to only move files with the extension
"*.xml". If you add a file "foobar.txt to the input folder it
will not be moved.
33. Keeping the Name The Same
<outbound-router>
<router className="org.mule.routing.outbound.OutboundPassThroughRouter">
<endpoint
address=
"file:///c:/mule-class/out?outputPattern=$[ORIGINALNAME]"
/>
</router>
</outbound-router>
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Add the outputPattern parameter to keep the output
name the same as the input.
34. Happy Path and Exceptions
By default, error free documents follow a central path
known as the "happy path"
Documents that have errors may be handled in different
ways (rejected, warnings etc.)
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Start StopStep 1 Step 2 Step 3
Stop Stop Stop
35. Exception Handling
Mule has a special way of handling non-happy path processing.
This is called an "Exception Strategy" but is it really just and
exception path and there is very little strategy involved.
There are three places you can associate an exception strategy
connector
component
model (set for all components in a model)
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37. Sample XML
<?xml version="1.0" encoding="UTF-8"?>
<Data>
<Element1>Hello World!</Element1>
<Element2>String</Element2>
<Element3>String</Element3>
<DansInvalidDataElement>This is Dans invalid data element</DansInvalidDataElement>
</Data>
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XML Schema validation will generate an error message
when it gets to the fourth invalid data element:
Given the following XML Schema file:
38. Validating against an XML
Schema<outbound-router>
<router className="org.mule.routing.outbound.FilteringXmlMessageSplitter">
<endpoint
address="file:///c:/mule-class/out?outputPattern=$[ORIGINALNAME]"/>
<properties>
<property name="validateSchema" value="true"/>
<property name="externalSchemaLocation"
value="file:///c:/mule-class/labs/07-validate/my-schema.xsd"/>
</properties>
</router>
</outbound-router>
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To validate the XML Schema, just add two properties:
1) tell it to validate the document
2) tell it what file to use and where to find it
39. Error Message
document : cvc-complex-type.2.4.d: Invalid content was found
starting with element 'DansInvalidDataElement'. No child
element is expected at this point.
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This error message is generated on the Mule console
when an invalid data element is found. But what should
we do with it? How do we redirect it to the appropriate
user?