Bruce Snyderbsnyder@apache.org

IASA DenverSeptember 2009

Using Enterprise Integration Patterns

as Your Camel Jockey

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Integrationis

everywhere!2

Just Because You Can, Doesn’t Mean You Should

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And Then There’s the Llama Car

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Options For Integration

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1 2

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Option One - DIY

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Do It Yourself

Option Two - Buy It

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Buy It

Option Three - Adopt It

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Adopt It

What Are Design Patterns?

A design pattern is a formal way of documenting a solution to a design problem in a particular field of expertise.

(Wikipedia)

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Enterprise Integration Patterns

Got EIP?

Pattern Overview

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Visualizing EIPs

::Stencils exist for Visio and OmniGraffle ::http://www.eaipatterns.com/downloads.html

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What is Apache Camel?

A framework for simplifying integration through the use of the Enterprise Integration Patterns for message mediation, processing, routing and transformation

http://camel.apache.org/

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Apache Camel is Focused on EIP

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http://camel.apache.org/

=>

http://eaipatterns.com/

History of Apache Camel

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Message Routing

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from("A").to("B");

Simple Routing

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from("file:///tmp/myFile.txt").to("jms:TEST.Q");

Slightly More Complex Routing

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from("file:///tmp/myFile.txt").to("bean:MyBean?method=handleMessage").to("jms:TEST.Q");

Multicast Routing

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from("file:///tmp/myFile.txt").choice().when(). method("MyBean", "matches"). to("Q").end().multicast("B", "C", "D");

Pipeline Routing

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from("file:///tmp/myFile.txt").choice().when(). method("MyBean", "matches"). to("Q").end().pipeline("B", "C", "D");

Camel Components

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:: 70+ components supported

Pattern Examples

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Patterns Again

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Content Based Router

RouteBuilder builder = new RouteBuilder() { public void configure() { from("activemq:NewOrders") .choice() .when(header("order-type").isEqualTo("widget")) .to("activemq:Orders.Widgets") .when(header("order-type").isEqualTo("gadget")) .to("activemq:Orders.Gadgets") .otherwise() .to("file:errors"); } };

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Java DSL

<camelContext xmlns="http://activemq.apache.org/camel/schema/spring"> <route> <from uri="activemq:NewOrders"/> <choice> <when> <xpath>/order/product = 'widget'</xpath> <to uri="activemq:Orders.Widgets"/> </when> <when> <xpath>/order/product = 'gadget'</xpath> <to uri="activemq:Orders.Gadgets"/> </when> <otherwise> <to uri="activemq:Orders.Bad"/> </otherwise> </choice> </route> </camelContext>

Content Based Router

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Spring DSL

Message Filter

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public class MyRouteBuilder extends RouteBuilder { public void configure() { from("activemq:topic:Orders) .filter().xpath("/order/product = ʻwidgetʼ") .to("ftp://bsnyder@host:2223/widgets/orders"); }}

Java DSL

Message Filter

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<camelContext xmlns="http://activemq.apache.org/camel/schema/spring"> <route> <from uri="activemq:topic:Orders"/> <filter> <xpath>/order/product = ʻwidgetʼ</xpath> <to uri="ftp://bsnyder@host:2223/widgets/orders"/> </filter> </route> </camelContext>

Spring DSL

Splitter

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public class MyRouteBuilder extends RouteBuilder { public void configure() { from("file:///orders")

.splitter(body(String.class).tokenize("\n")) .to("activemq:Order.Items"); }}

Java DSL

Splitter

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<camelContext id="camel" xmlns="http://camel.apache.org/schema/spring"> <route> <from uri="file:///orders" /> <split> <tokenize token="\n" /> <to uri="activemq:Order.Items" /> </split> </route> </camelContext>

Spring DSL

Aggregator

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public class MyRouteBuilder extends RouteBuilder { public void configure() { from("activemq:STOCKS") .aggregator(header("symbol")) .batchSize(10) .to("activemq:MY.STOCKS"); }}

Java DSL

Aggregator

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<camelContext id="camel" xmlns="http://camel.apache.org/schema/spring"> <route> <from uri="file:///orders" /> <aggregate> <correlationExpression> <simple>header.symbol</simple> </correlationExpression> <batchSize>10</batchSize> <to uri="activemq:MY.STOCKS" /> </aggregate> </route> </camelContext>

Spring DSL

Throttler

public class MyRouteBuilder extends RouteBuilder { public void configure() { from("seda:a”) .throttler(3).timePeriodMillis(30000) .to("seda:b"); }}

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Java DSL

Delayer

public class MyRouteBuilder extends RouteBuilder { public void configure() { from("seda:a”)

.delayer(header("JMSTimestamp", 3000) .to("seda:b"); }}

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Java DSL

Load Balancer

public class MyRouteBuilder extends RouteBuilder { public void configure() { from("file:/path/to/file") .loadBalance().roundRobin() .to("file:///one", "activemq:MY.Q", "http://host1:8181/fooApp"); }}

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Policy DescriptionRound Robin Balance the exchange load across the available endpoints

Random Randomly choose an endpoint to send the exchange

Sticky Sticky load balancing of exchanges using an expression

Topic Send exchange to all endpoints (JMS topic semantics)

Java DSL

Multicast

public class MyRouteBuilder extends RouteBuilder { public void configure() { from("direct:a") .multicast() .to("direct:x", "mock:y", "file:///tmp/bar?fileName=test.txt");

}}

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Java DSL

More Patterns

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Wire Tap

public class MyRouteBuilder extends RouteBuilder { public void configure() { from("direct:a") .to("log:com.mycompany.messages?level=info") .to("mock:foo");

}}

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Java DSL

Content Enricher

public class MyRouteBuilder extends RouteBuilder { public void configure() { from("activemq:My.Queue") .to("velocity:com/acme/MyResponse.vm") .to("activemq:Another.Queue");

}}

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Java DSL

More Content Enricher

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public class MyRouteBuilder extends RouteBuilder { public void configure() { from("activemq:My.Queue") .beanRef("myPojo", “methodName”) .to("activemq:Another.Queue"); }}

Java DSL

Content Filter

public class MyRouteBuilder extends RouteBuilder { public void configure() { from("direct:start").process(new Processor() { public void process(Exchange exchange) { Message in = exchange.getIn(); in.setBody(in.getBody(String.class) + " World!"); } }).to("mock:result"); }}

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Java DSL

Combine Patterns

public class MyRouteBuilder extends RouteBuilder { public void configure() { from("seda:a”). resequencer(header("JMSGroupSeq")).

delayer(3000). to("mock:x"); }}

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Java DSL

Error Handling in Camel

::Global Error Handler:

::Local Error Handler:

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RouteBuilder builder = new RouteBuilder() {    public void configure() {        errorHandler(deadLetterChannel("file:errors"));        from("bean:foo").to("seda:b");    }};

RouteBuilder builder = new RouteBuilder() {    public void configure() {      from("seda:a").        errorHandler(loggingErrorHandler("FOO.BAR")).        to("seda:b");      from("seda:b").to("seda:c");    }};

Java DSL

Exception Policies in Camel

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RouteBuilder builder = new RouteBuilder() {    public void configure() {        exception(IOException.class)          .initialRedeliveryDelay(5000L)          .maximumRedeliveries(3)          .maximumRedeliveryDelay(30000L)          .backOffMultiplier(1.0)          .useExponentialBackOff()          .setHeader(MESSAGE_INFO, constant("Damned IOException!"))          .to("activemq:errors");        from("seda:a").to("seda:b");   }}; 

Java DSL

Make Context Discover Beans

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package com.mycompany.beans;

public class MyBean {

public void someMethod(String name) { ... }}

<camelContext xmlns="http://activemq.apache.org/camel/schema/spring"> <package>com.mycompany.beans</package></camelContext>

Bean as a Message Translator

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public class MyRouteBuilder extends RouteBuilder { public void configure() {

from("activemq:Incoming”). beanRef("myBean"). to("activemq:Outgoing"); }}

Java DSL

Bean as a Message Translator

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public class MyRouteBuilder extends RouteBuilder { public void configure() { from("activemq:Incoming”). beanRef("myBean", "someMethod"). to("activemq:Outgoing"); }}

*With Method Name

Java DSL

Binding Beans to Camel Endpoints

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public class Foo {

@MessageDriven(uri=”activemq:cheese”) public void onCheese(String name) { ... }}

Java DSL

Binding Method Arguments

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public class Foo {

public void onCheese( @XPath(“/foo/bar/”) String name, @Header(“JMSCorrelationID”) String id) { ... }}

Java DSL

Injecting Endpoints Into Beans

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public class Foo { @EndpointInject(uri= “activemq:foo.bar”) ProducerTemplate producer;

public void doSomething() { if (whatever) { producer.sendBody(“<hello>world</hello>”); } }}

Java DSL

Type Convertors

public class MyRouteBuilder extends RouteBuilder { public void configure() { from("direct:start").process(new Processor() { public void process(Exchange exchange) { Message in = exchange.getIn(); in.setBody(in.getBody(String.class) + " World!"); } }).to("mock:result"); }}

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Support for the following types: • File• String• byte[] and ByteBuffer • InputStream and OutputStream • Reader and Writer • Document and Source

Type Conversion

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@Converterpublic class IOConverter {

@Converter public static InputStream toInputStream(File file) throws FileNotFoundException { return new BufferedInputStream(

new FileInputStream(file)); }}

Business Activity Monitoring (BAM)

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public class MyActivities extends ProcessBuilder {

public void configure() throws Exception {

// lets define some activities, correlating on an // XPath query of the message body ActivityBuilder purchaseOrder = activity("activemq:PurchaseOrders") .correlate(xpath("/purchaseOrder/@id").stringResult());

ActivityBuilder invoice = activity("activemq:Invoices") .correlate(xpath("/invoice/@purchaseOrderId").stringResult());

// now lets add some BAM rules invoice.starts().after(purchaseOrder.completes()) .expectWithin(seconds(1)) .errorIfOver(seconds(2)).to("activemq:FailedProcesses"); }}

The Camel Truck!

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Ride the Camel!http://camel.apache.org/

bsnyder@apache.orghttp://twitter.com/brucesnyder