camel routing slip EIP

Camel With Routing Slip EIP with simple steps.


In this tutorial we learn about routing slip EIP in camel.In routing slip EIP , route is defined dynamically.For example based on incoming message we can put filter and decide route in which message will undergo.

Routing slip requires a preexisting header as attached slip.Before sending message to routing slip we need to create initial slip that routing slip reads.

Example

In our example we will send a message to queue and will call a bean where based on business logic we will decide route where message will undergo..From test case we will validate our output.So let us start

  • In eclipse go to MyFirstCamelProject that we created in earlier page and right click on src/main/java to create package.New -> package



  • Give any name for example com.preparationforinterview and click on Finish



  • Right click on package and create a java class for example MyRoute.



  • Add following dependency in pom.xml file.you can use any latest version.

  •  	
    <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    	xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    	<modelVersion>4.0.0</modelVersion>
    	<groupId>MyFirstCamelProject</groupId>
    	<artifactId>MyFirstCamelProject</artifactId>
    	<version>0.0.1-SNAPSHOT</version>
    	<dependencies>
    		<dependency>
    			<groupId>org.apache.camel</groupId>
    			<artifactId>camel-test</artifactId>
    			<version>2.5.0</version>
    			<scope>test</scope>
    		</dependency>
    		<dependency>
    			<groupId>junit</groupId>
    			<artifactId>junit</artifactId>
    			<version>4.8.1</version>
    			<scope>test</scope>
    		</dependency>
    	</dependencies>
    </project>
    
  • Run mvn:install from command prompt or if you are using Eclipse right click on pom.xml and run mvn install.It will download camel jars

  • Copy below code in MyRoute.

  •  	
    package com.preparationforinterview;
    
    import org.apache.camel.builder.RouteBuilder;
    
    public class MyRoute extends RouteBuilder {
    
    	@Override
    	public void configure() throws Exception {
    		from("direct:start")
    		.log("Sending ")
    		.setHeader("myRoutingSlipHeader").method(MyRoutingSlipBean.class)
    		.routingSlip("myRoutingSlipHeader");
    
    
    	}
    
    }
    

    Explain

    To create a route in camel we need to extend RouteBuilder class and override configure method.In configure method we define our route.In above route we are accepting message from in memory route and logging it to see the content of the message.After that we are setting header using setHeader header and value is fetched from bean MyRoutingSlipBean.When we invoke routingSlip with header name then it get header values and send messages to them router got from header.

  • Right click on package and create one more java class for example MyRoutingSlipBean.



  • Copy below code in MyRoutingSlipBean.

  •  	
    package com.preparationforinterview;
    
    public class MyRoutingSlipBean {
    
    	public String routingSlip(String body) {
    		String response = "mock:first";
    		if (body.contains("World")) {
    			response += ",mock:second";
    		}
    		response += ",mock:third";
    		return response;
    	}
    
    }
    

    Explain

    In above bean we have a single method routingSlip where we have business logic to find route.Route are comma separated.

    To test above routing slip we will create one class RoutingSlipTest.java.



  • At the end we will have following structure


  • Copy below code in RoutingSlipTest.java.

  •  	
    package com.preparationforinterview;
    
    import org.apache.camel.builder.RouteBuilder;
    import org.apache.camel.test.junit4.CamelTestSupport;
    import org.junit.Test;
    
    public class RoutingSlipTest extends CamelTestSupport {
    	@Override
    	protected RouteBuilder createRouteBuilder() throws Exception {
    		return new MyRoute();
    	}
    
    	@Test
    	public void testSplitterEIP() throws Exception {
    		
    	 String output = "Hello, I am preparaing from PreparationforInterview.com";
    
    		getMockEndpoint("mock:first").expectedMessageCount(1);
    		getMockEndpoint("mock:second").expectedMessageCount(0);
    		getMockEndpoint("mock:third").expectedMessageCount(1);
    		
    		getMockEndpoint("mock:first").expectedBodiesReceived(output);
    		getMockEndpoint("mock:third").expectedBodiesReceived(output);
    
    		template.sendBody("direct:start",output
    				);
    		assertMockEndpointsSatisfied();
    
    	}
    }
    

    Explain

    To get camel test kit advantage we need to extend CamelTestSupport.CamelTestSupport class is wrapped on Junit.When we extend CamelTestSupport then we need to override one method createRouteBuilder.In that method create an object of route class.In our case we have done MyRoute.To test router we created method annotated with @Test. In that method we are getting mock endpoint and we have set expectation for example Expected expectedBodiesReceived and expectedMessageCount.After expectation has been set,we are sending message to direct:start queue.To Test execution with our result we fire assertion.template, we get from CamelTestSupport.

    To check the output right click on RoutingSlipTest.java and run it.It will pass test case and we will get following output.


    To run the program from command prompt,open command prompt and go to project location and run below command.
    mvn compile exec:java -Dexec.mainClass=com.preparationforinterview.RoutingSlipTest

Download source code

Camel With Routing Slip EIP



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