Using Enterprise Integration Patterns as Your Camel Jockey

Using
Enterprise Integration Patterns
as Your Camel Jockey

Bruce Snyder
bsnyder@apache.org

IASA Denver
September 2009 1

Integration
is
everywhere!
2

Just Because You Can, Doesn’t Mean You Should

3

And Then There’s the Llama Car

4

Options For Integration

1 2

3

5

Option One - DIY

Do It Yourself
6

Option Two - Buy It

Buy It
7

Option Three - Adopt It

Adopt It
8

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)

9

Enterprise Integration Patterns

Got EIP?

Pattern Overview

11

Visualizing EIPs

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

12

What is Apache Camel?

A framework for simplifying
integration through the use of the
Enterprise Integration Patterns for
message mediation, processing,
http://camel.apache.org/
routing and transformation

13

Apache Camel is Focused on EIP

=>

http://camel.apache.org/ http://eaipatterns.com/

14

History of Apache Camel

15

Message Routing

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

16

Simple Routing

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

17

Slightly More Complex Routing

to("bean:MyBean?method=handleMessage").
to("jms:TEST.Q");

18

Multicast Routing

choice().when().
method("MyBean", "matches").
to("Q").
end().
multicast("B", "C", "D");
19

Pipeline Routing

choice().when().
method("MyBean", "matches").
to("Q").
end().
pipeline("B", "C", "D");

20

Camel Components

:: 70+ components supported

21

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");
}
}; Java DSL
24

Content Based Router

<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>
Spring DSL
25

Message Filter

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

Java DSL
26

Message Filter

<camelContext
<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
27

Splitter

from("ﬁle:///orders")
.splitter(body(String.class).tokenize("n"))
.to("activemq:Order.Items");
}
}

Java DSL
28

Splitter

<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
29

Aggregator

from("activemq:STOCKS")
.aggregator(header("symbol"))
.batchSize(10)
.to("activemq:MY.STOCKS");
}
}

Java DSL
30

Aggregator

<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
31

Throttler

from("seda:a”)
.throttler(3).timePeriodMillis(30000)
.to("seda:b");
}
}

Java DSL
32

Delayer

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

Java DSL
33

Load Balancer

from("file:/path/to/file")
.loadBalance().roundRobin()
.to("file:///one", "activemq:MY.Q", "http://host1:8181/fooApp");
}
}

Policy Description
Round 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
34

Multicast

from("direct:a")
.multicast()
.to("direct:x", "mock:y", "ﬁle:///tmp/bar?ﬁleName=test.txt");
}
}

Java DSL
35

Wire Tap

from("direct:a")
.to("log:com.mycompany.messages?level=info")
.to("mock:foo");
}
}

Java DSL
37

Content Enricher

from("activemq:My.Queue")
.to("velocity:com/acme/MyResponse.vm")
.to("activemq:Another.Queue");
}
}

Java DSL
38

More Content Enricher

from("activemq:My.Queue")
.beanRef("myPojo", “methodName”)
.to("activemq:Another.Queue");
}
}

Java DSL
39

Content Filter

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");
}
}

Java DSL
40

Combine Patterns

from("seda:a”).
resequencer(header("JMSGroupSeq")).
delayer(3000).
to("mock:x");
}
}

Java DSL
41

Error Handling in Camel

:: Global Error Handler:
errorHandler(deadLetterChannel("ﬁle:errors"));
from("bean:foo").to("seda:b");
  }
};

:: Local Error Handler:
from("seda:a").
   errorHandler(loggingErrorHandler("FOO.BAR")).
to("seda:b");
from("seda:b").to("seda:c");
  } Java DSL
}; 42

Exception Policies in Camel

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
43

Make Context Discover Beans

package com.mycompany.beans;

public class MyBean {

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

<camelContext
<package>com.mycompany.beans</package>
</camelContext>

44

Bean as a Message Translator

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

Java DSL
45

Bean as a Message Translator

*With Method Name

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

Java DSL
46

Binding Beans to Camel Endpoints

public class Foo {

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

Java DSL
47

Binding Method Arguments

public class Foo {

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

Java DSL
48

Injecting Endpoints Into Beans

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

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

Java DSL
49

Type Convertors

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");
}
}

Support for the following types:
• File
• String
• byte[] and ByteBuffer
• InputStream and OutputStream
• Reader and Writer
• Document and Source
50

Type Conversion

@Converter
public class IOConverter {

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

51

Business Activity Monitoring (BAM)

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");
}
}

52

The Camel Truck!

53

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

bsnyder@apache.org
http://twitter.com/brucesnyder 54

Using Enterprise Integration Patterns as Your Camel Jockey

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