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Spring Integration

Connecting Enterprise Applications

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Topics in this session

• Introduction to Spring Integration• Spring Integration Compared• Enterprise Integration Patterns• Examples and demos• Summary and questions

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The synchronous breakdown

• A customer orders a coffee– and waits

• The waiter walks to the barista and passes the order– and waits

• The barista walks to the coffee machine– and waits

• How about the next customer?

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What is Messaging?

How can multiple agents work together?...

...without being in each others way.

Waiter helps customer and cook to collaborate.

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Characteristics of Messaging

TransportThe waiter takes an order and moves it to the barista

AsynchronousDifferent actors do different things in parallel

Translationmenu item => number => recipe

RoutingOrders arrive back at the proper table

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Why messaging (1/4)

Loose coupling

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Why Messaging? (2/4)

Performance

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Why Messaging? (3/4)

Flexibility

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Why Messaging? (4/4)

Interception and filtering

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Spring Integration

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Hello world

<service-activator input-channel="inputChannel" default-output-channel="outputChannel" ref="helloService" method="sayHello"/>

<beans:bean id="helloService" class="...HelloService"/>

public class HelloService { public String sayHello(String name) { return "Hello " + name; }}

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Hello world

inputChannel = context.getBean("inputChannel");

outputChannel = context.getBean("outputChannel");

inputChannel.send(new StringMessage("World"));System.out.println(

outputChannel.receive().getPayload());

$ java HelloWorldDemoHello World

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Channels

<channel id="incoming"/>

<channel id="orderedNotifications"> <queue capacity="10"/></channel>

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Channels

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MessageEndpoints

SenderApplication

ReceiverApplication

Channel

MessageEndpoint

MessageEndpoints are the knots that tie applications to the integration solution.

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Missing link

SenderApplication

ReceiverApplication

Channel

Invoked by Sender Who is responsible?

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The Poller

<poller default="true"/>In Spring Integration:

you don't need to worry about it

A Message Bus enables separate applications to work together, but in a decoupled fashion such that applications can be easily added or removed without affecting the others.

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Topics in this session

• Introduction to Spring Integration• Comparing Spring Integration to others• Enterprise Integration Patterns• Examples and demos• Summary and questions

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What’s different about Spring Integration?

• Can be used from within an existing application.

• Lightweight (like any Spring application):– run from JUnit test– run within webapp

• Focussed on messaging and integration• Not an ESB

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Others in general

• Full blown ESB• It’s an application, not a framework

– You need to install it – You need to run it

• Typically a lot heavier• Focus on the deployment architecture

not the actual integration.

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Mule

• Integrates with Spring• Lots of integration options:

– REST, SOAP– JMS

• Embeddable• Distribution

– 32Mb– 2Mb jar only (for embedding)

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ServiceMix

• Based on JBI – (Mediated Message Exchange Model)

• Distribution:– 100mb

• http://servicemix.apache.org/how-to-evaluate-an-esb.html

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Camel

• Most direct competition for Spring Integration

• Less consistent with Spring• Focus on routing• Fluent interface as an alternative to xml

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Considerations

• Routing complexity– a bus can be useful for more complex

routing problems

• Comfort zone– what will the developers feel at home with

• Keep it clean– don’t scatter the routing rules

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25

Basic Integration

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26

With a bus

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Topics in this session

• Introduction to Spring Integration• Comparing Spring Integration to others• Enterprise Integration Patterns• Examples and demos• Summary and questions

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Message Router

• Takes messages from a channel and forwards them to different channels

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Competing Consumers

• Multiple consumers take messages from the channel

• First come first serve

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Competing Consumers

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Selective Consumer

• Select only relevant messages• Reduces the need for dedicated

channels

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Selective Consumer

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Splitter

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Detour

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Topics in this session

• Introduction to Spring Integration• Comparing Spring Integration to others• Enterprise Integration Patterns• Examples and demos• Summary and questions

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Demo Time

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Topics in this session

• Introduction to Spring Integration• Comparing Spring Integration to others• Enterprise Integration Patterns• Examples and demos• Summary and questions

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Summary

• Spring Integration– works from existing Spring applications– lightweight– decentralized (if you want)

• Enterprise Integration Patterns– describe ways of plumbing the enterprise

application landscape.

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Questions and Plugs

• You can ask questions now while you ignore these shameless plugs

• Thanks to Babiche Israel (cartoons)– http://babicheisrael.blogspot.com/

• Come to Java meetup May 23– http://tinyurl.com/66hfnt or– Google for ‘java meetup q2 2008’