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Splitter has been edited by Claus Ibsen (Mar 10, 2009). Content:SplitterThe Splitter As of Camel 2.0, you need to specify a Splitter as split(). In earlier versions of Camel, you need to use splitter().
ExampleThe following example shows how to take a request from the queue:a endpoint the split it into pieces using an _expression_, then forward each piece to queue:b Using the Fluent Builders RouteBuilder builder = new RouteBuilder() { public void configure() { from("seda:a").split(body(String.class).tokenize("\n")).to("seda:b"); } };
Parallel execution of distinct 'parts'If you want to execute all parts in parallel you can use special notation of split() with two arguments, where the second one is a boolean flag if processing should be parallel. e.g. XPathBuilder xPathBuilder = new XPathBuilder("//foo/bar"); from("activemq:my.queue").split(xPathBuilder, true).to("activemq:my.parts"); In Camel 2.0 the boolean option has been refactored into a builder method parallelProcessing so its easier to understand what the route does when we use a method instead of true|false. XPathBuilder xPathBuilder = new XPathBuilder("//foo/bar"); from("activemq:my.queue").split(xPathBuilder).parallelProcessing().to("activemq:my.parts"); Stream basedAvailable as of Camel 1.5 You can split streams by enabling the streaming mode using the streaming builder method. from("direct:streaming").split(body().tokenize(",")).streaming().to("activemq:my.parts"); Specifying a custom aggregation strategyAvailable as of Camel 2.0 This is specified similar to the Aggregator. Specifying a custom ThreadPoolExecutorYou can customize the underlying ThreadPoolExecutor used in the parallel splitter. In the Java DSL try something like this: XPathBuilder xPathBuilder = new XPathBuilder("//foo/bar"); ThreadPoolExecutor threadPoolExecutor = new ThreadPoolExecutor(8, 16, 0L, TimeUnit.MILLISECONDS, new LinkedBlockingQueue()); from("activemq:my.queue").split(xPathBuilder, true, threadPoolExecutor).to("activemq:my.parts"); In the Spring DSL try this: Available as of Camel 1.6.0 <camelContext id="camel" xmlns="http://camel.apache.org/schema/spring"> <route> <from uri="direct:parallel-custom-pool"/> <split threadPoolExecutorRef="threadPoolExecutor"> <xpath>/invoice/lineItems</xpath> <to uri="mock:result"/> </split> </route> </camelContext> <!-- There's an easier way of specifying constructor args, just can't remember it at the moment... old Spring syntax will do for now! --> <bean id="threadPoolExecutor" class="java.util.concurrent.ThreadPoolExecutor"> <constructor-arg index="0" value="8"/> <constructor-arg index="1" value="16"/> <constructor-arg index="2" value="0"/> <constructor-arg index="3" value="MILLISECONDS"/> <constructor-arg index="4"><bean class="java.util.concurrent.LinkedBlockingQueue"/></constructor-arg> </bean> Using a Pojo to do the splittingAs the Splitter can use any _expression_ to do the actual splitting we leverage this fact and use a method _expression_ to invoke a Bean to get the splitted parts. In the route we define the _expression_ as a method call to invoke our Bean that we have registered with the id mySplitterBean in the Registry. from("direct:start") // here we use a POJO bean mySplitterBean to do the split of the payload .split().method("mySplitterBean") .to("mock:result"); And the logic for our Bean is as simple as. Notice we use Camel Bean Binding to pass in the message body as a String object. public class MySplitterBean { /** * The split method returns something that is iteratable such as a java.util.List. * * @param body the payload of the incoming message * @return a list containing each part splitted */ public List split(String body) { // since this is based on an unit test you can of couse // use different logic for splitting as Camel have out // of the box support for splitting a String based on comma // but this is for show and tell, since this is java code // you have the full power how you like to split your messages List answer = new ArrayList(); String[] parts = body.split(","); for (String part : parts) { answer.add(part); } return answer; } } Split aggregate request/reply sampleThis sample shows how you can split an Exchange, process each splitted message, aggregate and return a combined response to the original caller using request/reply. The route below illustrates this and how the split supports a aggregationStrategy to hold the in progress processed messages: // this routes starts from the direct:start endpoint // the body is then splitted based on @ separator // the splitter in Camel supports InOut as well and for that we need // to be able to aggregate what response we need to send back, so we provide our // own strategy with the class MyOrderStrategy. from("direct:start") .split(body().tokenize("@"), new MyOrderStrategy()) // each splitted message is then send to this bean where we can process it .to("bean:MyOrderService?method=handleOrder") // this is important to end the splitter route as we do not want to do more routing // on each splitted message .end() // after we have splitted and handled each message we want to send a single combined // response back to the original caller, so we let this bean build it for us // this bean will receive the result of the aggregate strategy: MyOrderStrategy .to("bean:MyOrderService?method=buildCombinedResponse") And the OrderService bean is as follows: public static class MyOrderService { private static int counter; /** * We just handle the order by returning a id line for the order */ public String handleOrder(String line) { return "(id=" + ++counter + ",item=" + line + ")"; } /** * We use the same bean for building the combined response to send * back to the original caller */ public String buildCombinedResponse(String line) { return "Response[" + line + "]"; } } And our custom aggregationStrategy that is responsible for holding the in progress aggregated message that after the splitter is ended will be sent to the buildCombinedResponse method for final processing before the combined response can be returned to the waiting caller. /** * This is our own order aggregation strategy where we can control * how each splitted message should be combined. As we do not want to * loos any message we copy from the new to the old to preserve the * order lines as long we process them */ public static class MyOrderStrategy implements AggregationStrategy { public Exchange aggregate(Exchange oldExchange, Exchange newExchange) { // put order together in old exchange by adding the order from new exchange // copy from OUT as we use InOut pattern String orders = oldExchange.getOut().getBody(String.class); String newLine = newExchange.getOut().getBody(String.class); // put orders together separating by semi colon orders = orders + ";" + newLine; // put combined order back on old to preserve it oldExchange.getOut().setBody(orders); // return old as this is the one that has all the orders gathered until now return oldExchange; } } So lets run the sample and see how it works. HandleOrder: A HandleOrder: B Aggregate old orders: (id=1,item=A) Aggregate new order: (id=2,item=B) HandleOrder: C Aggregate old orders: (id=1,item=A);(id=2,item=B) Aggregate new order: (id=3,item=C) BuildCombinedResponse: (id=1,item=A);(id=2,item=B);(id=3,item=C) Response to caller: Response[(id=1,item=A);(id=2,item=B);(id=3,item=C)] Using This PatternIf you would like to use this EIP Pattern then please read the Getting Started, you may also find the Architecture useful particularly the description of Endpoint and URIs. Then you could try out some of the Examples first before trying this pattern out. |
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