Here is a Camel cheatsheet you can use to build your Camel routes quickly:
Processor Component
<bean id="myProcessor" class="com.mycompany.MyProcessor"/> <process ref="myProcessor"/>
package com.mycompany;
import org.apache.camel.Processor;
import org.apache.camel.Exchange;
public class MyProcessor implements Processor {
public void process(Exchange exchange) throws Exception {
String payload = exchange.getIn().getBody(String.class);
System.out.println("Payload"+payload);
payload = payload.toLowerCase();
exchange.getIn().setBody(payload);
}
}
Bean Component
<bean id="mybean" class="com.mycompany.jb421.chapter10.Validate" /> <bean ref="mybean" method="doSomething"/>
import org.apache.camel.Exchange;
public class Validate {
public void doSomething(Exchange exchange) {
exchange.getIn().setBody("Bye World");
}
}
How to use Properties in a Camel blueprint
Include in your project’s classpath a Property file (e.g. sql.properties)
<camelContext xmlns="http://camel.apache.org/schema/blueprint">
<propertyPlaceholder location="classpath:sql.properties" id="properties"/>
. . . .
<to uri="sql:{{sql.insertCustInfo}}?alwaysPopulateStatement=true"/>
</camelContext>
Using Embedded ActiveMQ
<bean id="jms" class="org.apache.activemq.camel.component.ActiveMQComponent">
<property name="connectionFactory">
<bean class="org.apache.activemq.ActiveMQConnectionFactory">
<property name="brokerURL"
value="vm://localhost?broker.persistent=false&broker.useJmx=false" />
</bean>
</property>
</bean>
<from uri="jms:queue:myqueue"/>
Using Remote ActiveMQ
<bean id="jms" class="org.apache.activemq.ActiveMQConnectionFactory">
<property name="brokerURL" value="tcp://0.0.0.0:61616" />
</bean>
<from uri="jms:queue:myqueue"/>
How to create a Java Producer
package com.sample;
import javax.jms.Connection;
import javax.jms.ConnectionFactory;
import javax.jms.DeliveryMode;
import javax.jms.Destination;
import javax.jms.MessageProducer;
import javax.jms.Session;
import javax.jms.TextMessage;
import org.apache.activemq.ActiveMQConnection;
import org.apache.activemq.ActiveMQConnectionFactory;
public class ProducerExample {
public static void main(String[] args) {
try {
// Create a ConnectionFactory
ConnectionFactory connectionFactory=new ActiveMQConnectionFactory("admin", "admin", ActiveMQConnection.DEFAULT_BROKER_URL);
// Create a Connection
Connection connection = connectionFactory.createConnection();
connection.start();
// Create a Session
Session session = connection.createSession(false, Session.AUTO_ACKNOWLEDGE);
// Create the destination
Destination destination = session.createQueue("demoMQ");
// Create a MessageProducer from the Session to the Queue
MessageProducer producer = session.createProducer(destination);
producer.setDeliveryMode(DeliveryMode.NON_PERSISTENT);
// Create a messages
TextMessage message = session.createTextMessage("Helloworld");
producer.send(message);
session.close();
connection.close();
System.out.println("Message sent");
}
catch (Exception e) {
System.out.println(e);
e.printStackTrace();
}
}
}
How to catch Exception with OnException
<camelContext xmlns="http://camel.apache.org/schema/spring" >
<propertyPlaceholder location="fabric8/route.properties"
id="properties" />
<route>
<from uri="file:/home/francesco/files/in?noop=true" />
<onException>
<exception>org.xml.sax.SAXParseException</exception>
<handled>
<constant>true</constant>
</handled>
<log message="Transformation result in error ${body}" />
<to uri="file:/home/francesco/files/" />
</onException>
<choice>
<!-- condition here -->
</choice>
</route>
</camelContext>
How to use Try Catch Finally
<doTry>
<bean ref="myProcessor"/>
<transform>
<constant>Transformed!</constant>
</transform>
<doCatch>
<exception>com.error.MyException</exception>
<to uri="mock:error"/>
<transform>
<constant>An error happened!</constant>
</transform>
</doCatch>
<doFinally>
<to uri="mock:finally"/>
</doFinally>
</doTry>
How to code a DLQ Handler
<camelContext xmlns="http://camel.apache.org/schema/spring" errorHandlerRef="DLQhandler">
<errorHandler id="DLQhandler" type="DeadLetterChannel" deadLetterUri="jms:queue:dead"
useOriginalMessage="false" />
<route>
<from uri="file:/home/francesco/files/in?noop=true"/>
<bean ref="mybean" method="doSomething"/> <!-- In case of exception the message is routes to the DLQ -->
<to uri="jms:queue:myqueue"/>
</route>
</camelContext>
How to reference a RouteBuilder from Spring passing properties
<bean id="javaRouteBuilder" class="com.sample.JavaRouteBuilder" >
<property name="queue" value="jms:queue:orders"/>
<property name="path" value="/home/francesco/cli"/>
<property name="pathOut" value="/home/francesco/cli/out"/>
</bean>
import org.apache.camel.builder.RouteBuilder;
public class JavaRouteBuilder extends RouteBuilder {
String path;
String pathOut;
String queue;
. . .
public void configure() throws Exception {
from("file:"+path +"?noop=true").to("log:com.mycompany?level=DEBUG").process(new MyProcessor()).to("file:"+pathOut);
}
}
An Hello World Camel example
public class App1 {
public static void main(String args[]) throws Exception {
// This is a Registry for Beans used in the route
SimpleRegistry registry = new SimpleRegistry();
registry.put("taxCalculator", new TaxCalculator());
CamelContext context = new DefaultCamelContext(registry);
context.addRoutes(new RouteBuilder() {
public void configure() throws Exception {
from(
"file:/home/demo/in?noop=true&include=.*.csv")
.beanRef("taxCalculator", "processTax").to(
"file:/home/demo/out");
}
});
context.start();
System.out.println("Press enter to continue...");
Scanner keyboard = new Scanner(System.in);
keyboard.nextLine();
context.stop();
}
}
How to make Content Based Routing
Example: Header based CBR
<route>
<from uri="file:/home/demo/in?noop=true" />
<choice>
<when>
<simple>${header.CamelFileName} regex '^.*xml
Example: Body based CBR
<choice>
<when>
<simple>${bodyAs(String)} contains 'expensive'</simple>
<to uri="activemq:BigSpendersQueue"/>
</when>
<otherwise>
<to uri="file:/home/demo/in/error" />
</otherwise>
</choice>
<choice>
<when>
<xpath>/person/city = 'London'</xpath> <!-- TEXT -->
<!-- <xpath>/CustInfo[@infotype="LoanCustomer"]</xpath> ATTRIBUTE -->
<log message="UK message" />
<to uri="file:target/messages/uk" />
</when>
<otherwise>
<log message="Other message" />
<to uri="file:target/messages/others" />
</otherwise>
</choice>
How to set header in Camel (various examples)
<setHeader headerName="customer">
<xpath>/Payments/Payment/customer/text()</xpath>
</setHeader>
<setHeader headerName="subject">
<constant>new incident reported</constant>
</setHeader>
<setHeader headerName="CamelFileName">
<method bean="filenameGenerator" method="generateFilename"/>
</setHeader>
<setHeader headerName="CityList">
<simple>${listCity.ListCities()}</simple>
</setHeader>
How to set Body in Camel (various examples)
<transform>
<simple>Hello ${bodyAs(String)} how are you?</simple>
</transform>
<convertBodyTo type="java.lang.String"/>
<transform>
<simple>Hello ${bodyAs(String)} how are you?</simple>
</transform>
<transform>
<simple>${body.toUpperCase()}</simple>
</transform>
How to Filter Messages
<route>
<from uri="jms:queue:inbox"/>
<filter>
<!-- Header test = false -->
<xpath>$test = 'false'</xpath>
<to uri="jms:queue:inbox"/>
</filter>
</route>
Aggregation Strategy example
<bean id="myAggregationStrategy" class="com.sample.MyAggregationStrategy" />
<camelContext xmlns="http://camel.apache.org/schema/spring"
trace="false">
<route>
<from uri="file:/home/demo/in/aggregate?noop=true" />
<log message="Sending ${body}" />
<aggregate strategyRef="myAggregationStrategy"
completionSize="2" completionTimeout="5000">
<!-- Aggregate messages based on the following Correlation Expression -->
<correlationExpression>
<xpath>/Payments/Payment/customer/text()</xpath>
</correlationExpression>
<log message="Sending out ${body}" />
<to uri="file:/home/demo/in?fileName=out.xml" />
</aggregate>
</route>
</camelContext>
public class MyAggregationStrategy implements AggregationStrategy {
public Exchange aggregate(Exchange oldExchange, Exchange newExchange) {
if (oldExchange == null) {
return newExchange;
}
String oldBody = oldExchange.getIn().getBody(String.class);
String newBody = newExchange.getIn().getBody(String.class);
String body = oldBody + newBody;
oldExchange.getIn().setBody(body);
return oldExchange;
}
}
How to create a Recipient List (Dynamic Multicast)
<bean id="calculateRecipients" class="com.mycompany.jb421.chapter3.XMLProcessor" />
<process ref="calculateRecipients" />
<recipientList>
<header>recipients</header>
</recipientList>
public class XMLProcessor implements Processor {
@Override
public void process(Exchange exchange) throws Exception {
String recipients = "jms:others";
String customer =
exchange.getIn().getHeader("customer", String.class);
// Send these messages also to another queue
if (customer.equals("JOHN DOE")) {
recipients += ",jms:john";
}
exchange.getIn().setHeader("recipients", recipients);
}
}
Multicast dispatching of Messages
<multicast strategyRef="myAggregationStrategy">
<to uri="direct:callRest1" pattern="InOut"/>
<to uri="direct:callRest2" pattern="InOut"/>
</multicast>
public class MyAggregationStrategy implements AggregationStrategy {
public Exchange aggregate(Exchange oldExchange, Exchange newExchange) {
if (oldExchange == null) {
return newExchange;
}
String oldBody = oldExchange.getIn().getBody(String.class);
String newBody = newExchange.getIn().getBody(String.class);
String body = oldBody + newBody;
oldExchange.getIn().setBody(body);
return oldExchange;
}
}
Transformation
1. From CSV to Java Object
<dataFormats>
<bindy type="Csv" id="transform-csv" classType="com.demo.csv.Order" />
</dataFormats>
<route>
<from uri="file:/home/demo/in?fileName=order.csv&noop=true"/>
<unmarshal ref="transform-csv"/>
<log message="${body}"/>
<to uri="activemq:queue:orders"/>
</route>
@CsvRecord(separator=",",crlf="UNIX")
public class Order implements Serializable{
// Getter-setters
@DataField(pos=1)
private int id;
@DataField(pos=2)
private String description;
@DataField(pos=3)
private double price;
@DataField(pos=4)
private double tax;
}
2. From XML to Object
<unmarshal>
<jaxb contextPath="com.sample.xml"/>
<!-- Class Order is in com.sample.xml package -->
</unmarshal>
@XmlRootElement
@XmlAccessorType(XmlAccessType.FIELD)
public class Order {
@XmlAttribute
public int id;
@XmlAttribute
public String description;
@XmlAttribute
public double price;
@XmlAttribute
public double tax;
// Getter-setters
}
@XmlRegistry
public class ObjectFactory {
public ObjectFactory() {
}
public Order createOrderInfo() {
return new Order();
}
}
3. From Java to XML
<marshal>
<jaxb contextPath="com.sample.chapter3.xml"/>
</marshal>
<b>3. From CSV to JSON</b>
sourceModel=com.sample.Customer
targetModel=com.sample.Account
<camelContext trace="false" xmlns="http://camel.apache.org/schema/spring">
<endpoint id="csv2json" uri="dozer:csv2json?unmarshalId=transform-csv&marshalId=transform-json&sourceModel=com.sample.Customer&targetModel=com.sample.Account&mappingFile=transformation.xml"/>
<dataFormats>
<bindy type="Csv" id="transform-csv" classType="com.sample.Customer" />
<json library="Jackson" id="transform-json"/>
</dataFormats>
<route>
<from uri="file:/home/demo/in?fileName=customers.csv&noop=true"/>
<!-- Splitting messages tokenizing by carriage return -->
<split streaming="true">
<tokenize token="\n" trim="true" />
<log message="Transform input ${body} to json" />
<to ref="csv2json" />
<to uri="file:/home/demo/out?fileName=csv-record-${date:now:yyyyMMdd}-${property.CamelSplitIndex}.txt"/>
</split>
</route>
</camelContext>
transformation.xml file with mappings:
<mappings xmlns="http://dozer.sourceforge.net" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://dozer.sourceforge.net http://dozer.sourceforge.net/schema/beanmapping.xsd">
<configuration>
<wildcard>false</wildcard>
</configuration>
<mapping>
<class-a>com.sample.Customer</class-a>
<class-b>com.sample.Account</class-b>
<!-- Map fields here from Customer to Account -->
<field>
<a>customerId</a>
<b>accountId</b>
</field>
. . .
</mapping>
</mappings>
Split and Tokenize
<split streaming="true">
<tokenize token="\n" trim="true" />
<log message="Transform input ${body} to json" />
<to uri="file:/home/demo/out?fileName=csv-record-${date:now:yyyyMMdd}-${property.CamelSplitIndex}.txt"/>
</split>
Split with Custom Thread Pool
<bean id="threadPool" class="java.util.concurrent.Executors" factory-method="newFixedThreadPool">
<constructor-arg index="0" value="20"/>
</bean>
<split executorServiceRef="threadPool">
<tokenize token="\n" trim="true" />
<log message="Transform input ${body} to json" />
<to uri="file:/home/demo/out?fileName=csv-record-${date:now:yyyyMMdd}-${property.CamelSplitIndex}.txt"/>
</split>
Split using an XPath expression
<split>
<xpath>/Payments/Payment</xpath>
<to uri="targetUri"/>
</split>
<split>
<xpath>/PurchaseOrder/@PurchaseOrderNumber</xpath>
<to uri="targetUri"/>
</split>
Velocity example
<route>
<from uri="file:/home/demo/in?fileName=order.xml&noop=true"/>
<unmarshal ref="transform-xml"/>
<to uri="velocity:etc/MailBody.vm"/>
<to uri="file:/home/demo/out"/>
</route>
file etc/MailBody.vm
#set( $order = ${body})
Order status:
- Id: ${order.id}
- Price: ${order.price}
Tax: ${order.tax}
Details:
${order.description}
JDBC example
<bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource" destroy-method="close">
<property name="driverClassName" value="org.h2.Driver"/>
<property name="url" value="jdbc:h2:file:~/h2/homeloan;AUTO_SERVER=TRUE"/>
<property name="username" value="sa"/>
<property name="password" value=""/>
</bean>
<bean id="sql" class="org.apache.camel.component.sql.SqlComponent">
<property name="dataSource" ref="dataSource"/>
</bean>
<route>
. . .
<!-- Execute a Delete and Insert -->
<to uri="sql:{{sql.deleteCustInfo}}?alwaysPopulateStatement=true" />
<to uri="sql:{{sql.insertCustInfo}}?alwaysPopulateStatement=true"/>
</route>
Sample SQL file:
sql.insertCustInfo=INSERT INTO CustInfo (nationalID, firstName, lastName, age, occupation) values (:#${body.nationalID}, :#${body.firstName}, :#${body.lastName}, :#${body.age}, :#${body.occupation})
sql.deleteCustInfo=delete from CustInfo where nationalID = :#${body.nationalID};
JPA Example: From XML file to Database
<bean id="jpa" class="org.apache.camel.component.jpa.JpaComponent">
<property name="entityManagerFactory" ref="entityManagerFactory" />
<property name="transactionManager" ref="jpaTxManager" />
</bean>
<bean id="jpaTxManager" class="org.springframework.orm.jpa.JpaTransactionManager">
<property name="entityManagerFactory" ref="entityManagerFactory" />
</bean>
<bean id="entityManagerFactory"
class="org.springframework.orm.jpa.LocalEntityManagerFactoryBean">
<property name="persistenceUnitName" value="persistenceUnit" />
</bean>
<camelContext trace="true" xmlns="http://camel.apache.org/schema/spring">
<route>
<from uri="file:/home/demo/person?noop=true" />
<!-- Unmarshal files from XML to JPA -->
<unmarshal>
<jaxb contextPath="com.demo.model" prettyPrint="true" />
</unmarshal>
<to uri="jpa:com.demo.model.Person" />
</route>
</camelContext>
@XmlRootElement
@XmlType
@Entity(name="Person")
@NamedQuery(name="Person.findAll", query="SELECT c FROM Person c")
public class Person {
private Long id;
private String name;
private String surname;
@Id
@GeneratedValue(strategy=GenerationType.AUTO)
public Long getId() {
return id;
}
// Getter-setters
}
@XmlRegistry
public class ObjectFactory {
public ObjectFactory() { }
public Person createPerson() {
return new Person();
}
}
JPA: From Database to XML
<dataFormats>
<jaxb contextPath="com.sample.model" id="jaxb-xml"/>
</dataFormats>
<route>
<from uri="jpa:com.sample.model.Person?consumeDelete=false&consumer.namedQuery=Person.findAll"/>
<marshal ref="jaxb-xml"/>
<to uri="file:/home/demo/in/person/fileout"/>
<stop/>
</route>
How to expose a CXF Web service
<cxf:cxfEndpoint id="claimEndpoint" address="/claim" serviceClass="org.demo.ClaimService" />
<bean id="claimProcessor" class="org.demo.ClaimProcessor" />
<camelContext trace="false" id="blueprintContext" xmlns="http://camel.apache.org/schema/blueprint">
<route id="cxfRoute">
<from uri="cxf:bean:claimEndpoint"/>
<log message="${header.operationName}"/>
<recipientList>
<!-- Based on the Operation request, create a recipient list to execute a Processor methos -->
<simple>direct:${header.operationName}</simple>
</recipientList>
</route>
<route id="executeRoute">
<from uri="direct:execute"/>
<bean method="process" ref="claimProcessor"/>
</route>
<route id="cancelRoute">
<from uri="direct:cancel"/>
<bean method="cancel" ref="claimProcessor"/>
</route>
</camelContext>
How to expose a CXF Rest service
<cxf:rsServer id="statusEndpoint" address="/status" serviceClass="org.demo.StatusService" />
<bean id="claimProcessor" class="org.demo.ClaimProcessor" />
<route>
<from uri="cxfrs:bean:statusEndpoint"/>
<log message="${header.operationName}"/>
<!-- Choice based on the operationName contained in the Header -->
<choice>
<when>
<simple>${header.operationName} == "status"</simple>
<bean method="status" ref="claimProcessor"/>
</when>
<when>
<simple>${header.operationName} == "restCancel"</simple>
<setHeader headerName="operationName">
<simple>cancel</simple>
</setHeader>
<bean method="prepareList" ref="claimProcessor"/>
<to uri="cxf:bean:claimEndpoint"/>
</when>
</choice>
<marshal>
<json library="Jackson" prettyPrint="true"/>
</marshal>
</route>
</camelContext>
Timer
<route>
<from uri="timer:timerName?period=60000"/>
<to uri="http://camel.apache.org"/>
<to uri="file:/home/francesco/Desktop/FUSE/in/person/fileout"/>
</route>
Jetty
<route>
<from uri="jetty:http://localhost:8080/myservice"/>
<process ref="processorBean"/> <!-- ritorna HTML -->
</route>
Mock Test example
public class TestWithMock extends CamelTestSupport {
@Override
protected CamelContext createCamelContext() throws Exception {
CamelContext context = super.createCamelContext();
context.addComponent("jms", context.getComponent("seda"));
return context;
}
@Override
protected RouteBuilder createRouteBuilder() throws Exception {
return new RouteBuilder() {
@Override
public void configure() throws Exception {
from("direct:start")
.convertBodyTo(String.class) //
.process(new Processor() {
@Override
public void process(Exchange exc) throws Exception {
String body = exc.getIn().getBody(String.class);
exc.getIn().setBody(body.toUpperCase());
}
})
.to("mock:orders");
}
};
}
@Test
public void testMock() throws Exception {
MockEndpoint mock = getMockEndpoint("mock:orders");
mock.expectedMessageCount(1);
mock.expectedBodiesReceived("JB421 COURSE");
context.createProducerTemplate().sendBody("direct:start", "jb421 Course");
mock.assertIsSatisfied();
List<Exchange> exchanges = mock.getReceivedExchanges();
String body = exchanges.get(0).getIn().getBody(String.class);
assertTrue(body.contains("JB421"));
}
}