1. Using
Enterprise Integration Patterns
as Your Camel Jockey
Bruce Snyder
bsnyder@apache.org
IASA Denver
September 2009 1

2. Integration
is
everywhere!
2

3. Just Because You Can, Doesn’t Mean You Should
3

4. And Then There’s the Llama Car
4

5. Options For Integration
1 2
3
5

6. Option One - DIY
Do It Yourself
6

7. Option Two - Buy It
Buy It
7

8. Option Three - Adopt It
Adopt It
8

9. 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

10. Enterprise Integration Patterns
Got EIP?

11. Pattern Overview
11

12. Visualizing EIPs
:: Stencils exist for Visio and OmniGraffle
:: http://www.eaipatterns.com/downloads.html
12

13. 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

14. Apache Camel is Focused on EIP
=>
http://camel.apache.org/ http://eaipatterns.com/
14

15. History of Apache Camel
15

16. Message Routing
from("A").to("B");
16

17. Simple Routing
from("file:///tmp/myFile.txt").
to("jms:TEST.Q");
17

18. Slightly More Complex Routing
from("file:///tmp/myFile.txt").
to("bean:MyBean?method=handleMessage").
to("jms:TEST.Q");
18

19. Multicast Routing
from("file:///tmp/myFile.txt").
choice().when().
method("MyBean", "matches").
to("Q").
end().
multicast("B", "C", "D");
19

20. Pipeline Routing
from("file:///tmp/myFile.txt").
choice().when().
method("MyBean", "matches").
to("Q").
end().
pipeline("B", "C", "D");
20

21. Camel Components
:: 70+ components supported
21

22. Pattern
Examples
22

23. Patterns Again
23

24. 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

25. 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

26. Message Filter
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
26

27. Message Filter
<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
27

28. Splitter
public class MyRouteBuilder extends RouteBuilder {
public void configure() {
from("file:///orders")
.splitter(body(String.class).tokenize("n"))
.to("activemq:Order.Items");
}
}
Java DSL
28

29. 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

30. Aggregator
public class MyRouteBuilder extends RouteBuilder {
public void configure() {
from("activemq:STOCKS")
.aggregator(header("symbol"))
.batchSize(10)
.to("activemq:MY.STOCKS");
}
}
Java DSL
30

31. 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

32. Throttler
public class MyRouteBuilder extends RouteBuilder {
public void configure() {
from("seda:a”)
.throttler(3).timePeriodMillis(30000)
.to("seda:b");
}
}
Java DSL
32

33. Delayer
public class MyRouteBuilder extends RouteBuilder {
public void configure() {
from("seda:a”)
.delayer(header("JMSTimestamp", 3000)
.to("seda:b");
}
}
Java DSL
33

34. 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");
}
}
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

35. Multicast
public class MyRouteBuilder extends RouteBuilder {
public void configure() {
from("direct:a")
.multicast()
.to("direct:x", "mock:y", "file:///tmp/bar?fileName=test.txt");
}
}
Java DSL
35

36. More
Patterns
36

37. Wire Tap
public class MyRouteBuilder extends RouteBuilder {
public void configure() {
from("direct:a")
.to("log:com.mycompany.messages?level=info")
.to("mock:foo");
}
}
Java DSL
37

38. Content Enricher
public class MyRouteBuilder extends RouteBuilder {
public void configure() {
from("activemq:My.Queue")
.to("velocity:com/acme/MyResponse.vm")
.to("activemq:Another.Queue");
}
}
Java DSL
38

39. More Content Enricher
public class MyRouteBuilder extends RouteBuilder {
public void configure() {
from("activemq:My.Queue")
.beanRef("myPojo", “methodName”)
.to("activemq:Another.Queue");
}
}
Java DSL
39

40. 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");
}
}
Java DSL
40

41. Combine Patterns
public class MyRouteBuilder extends RouteBuilder {
public void configure() {
from("seda:a”).
resequencer(header("JMSGroupSeq")).
delayer(3000).
to("mock:x");
}
}
Java DSL
41

42. Error Handling in Camel
:: Global Error Handler:
RouteBuilder builder = new RouteBuilder() {
public void configure() {
errorHandler(deadLetterChannel("file:errors"));
from("bean:foo").to("seda:b");
}
};
:: Local Error Handler:
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
}; 42

43. Exception Policies in Camel
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
43

44. Make Context Discover Beans
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>
44

45. Bean as a Message Translator
public class MyRouteBuilder extends RouteBuilder {
public void configure() {
from("activemq:Incoming”).
beanRef("myBean").
to("activemq:Outgoing");
}
}
Java DSL
45

46. Bean as a Message Translator
*With Method Name
public class MyRouteBuilder extends RouteBuilder {
public void configure() {
from("activemq:Incoming”).
beanRef("myBean", "someMethod").
to("activemq:Outgoing");
}
}
Java DSL
46

47. Binding Beans to Camel Endpoints
public class Foo {
@MessageDriven(uri=”activemq:cheese”)
public void onCheese(String name) {
...
}
}
Java DSL
47

48. Binding Method Arguments
public class Foo {
public void onCheese(
@XPath(“/foo/bar/”) String name,
@Header(“JMSCorrelationID”) String id) {
...
}
}
Java DSL
48

49. 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

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

51. Type Conversion
@Converter
public class IOConverter {
@Converter
public static InputStream toInputStream(File file)
throws FileNotFoundException {
return new BufferedInputStream(
new FileInputStream(file));
}
}
51

52. 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

53. The Camel Truck!
53

54. Ride the
Camel!
http://camel.apache.org/
bsnyder@apache.org
http://twitter.com/brucesnyder 54