Added Java-DSL docs to Gitbook
Project: http://git-wip-us.apache.org/repos/asf/camel/repo Commit: http://git-wip-us.apache.org/repos/asf/camel/commit/d67a95ea Tree: http://git-wip-us.apache.org/repos/asf/camel/tree/d67a95ea Diff: http://git-wip-us.apache.org/repos/asf/camel/diff/d67a95ea Branch: refs/heads/master Commit: d67a95ea21127efdbd89bc0fde33e15ddff776e3 Parents: 70d6968 Author: Andrea Cosentino <anco...@gmail.com> Authored: Tue Jul 19 10:57:42 2016 +0200 Committer: Andrea Cosentino <anco...@gmail.com> Committed: Tue Jul 19 10:57:42 2016 +0200 ---------------------------------------------------------------------- docs/user-manual/en/SUMMARY.md | 1 + docs/user-manual/en/java-dsl.adoc | 200 +++++++++++++++++++++++++++++++++ 2 files changed, 201 insertions(+) ---------------------------------------------------------------------- http://git-wip-us.apache.org/repos/asf/camel/blob/d67a95ea/docs/user-manual/en/SUMMARY.md ---------------------------------------------------------------------- diff --git a/docs/user-manual/en/SUMMARY.md b/docs/user-manual/en/SUMMARY.md index 448836f..bb215ef 100644 --- a/docs/user-manual/en/SUMMARY.md +++ b/docs/user-manual/en/SUMMARY.md @@ -18,6 +18,7 @@ * [Dependency Injection](dependency-injection.adoc) * [Dozer Type Conversion](dozer-type-conversion.adoc) * [DSL](dsl.adoc) + * [Java DSL](java-dsl.adoc) * [Groovy DSL](groovy-dsl.adoc) * [Endpoint](endpoint.adoc) * [Exchange](exchange.adoc) http://git-wip-us.apache.org/repos/asf/camel/blob/d67a95ea/docs/user-manual/en/java-dsl.adoc ---------------------------------------------------------------------- diff --git a/docs/user-manual/en/java-dsl.adoc b/docs/user-manual/en/java-dsl.adoc new file mode 100644 index 0000000..60a6681 --- /dev/null +++ b/docs/user-manual/en/java-dsl.adoc @@ -0,0 +1,200 @@ +[[JavaDSL-JavaDSL]] +Java DSL +~~~~~~~~ + +Apache Camel offers a Java based DSL using the fluent builder style. The +Java DSL is available by extending the +link:routebuilder.html[RouteBuilder] class, and implement the +`configure` method. + +This is best illustrate by an example. In the code below we create a new +class called `MyRouteBuilder` that extends the +`org.apache.camel.builder.RouteBuilder` from Camel. + + In the `configure` method the Java DSL is at our disposal. + +[source,java] +------------------------------------------------------------------------- +import org.apache.camel.builder.RouteBuilder; + +/** + * A Camel Java DSL Router + */ +public class MyRouteBuilder extends RouteBuilder { + + /** + * Let's configure the Camel routing rules using Java code... + */ + public void configure() { + + // here is a sample which processes the input files + // (leaving them in place - see the 'noop' flag) + // then performs content based routing on the message using XPath + from("file:src/data?noop=true") + .choice() + .when(xpath("/person/city = 'London'")) + .to("file:target/messages/uk") + .otherwise() + .to("file:target/messages/others"); + } + +} +------------------------------------------------------------------------- + +In the `configure` method we can define Camel link:routes.html[Routes]. +In the example above we have a single route, which pickup +https://cwiki.apache.org/confluence/pages/createpage.action?spaceKey=CAMEL&title=File&linkCreation=true&fromPageId=30747520[File]s, +(eg the from). + +[source,java] +--------------------------------------- + from("file:src/data?noop=true") +--------------------------------------- + +Then we use the link:content-based-router.html[Content Based Router] (eg +the choice) to route the message depending if the person is from London +or not. + +[source,java] +------------------------------------------------------- + .choice() + .when(xpath("/person/city = 'London'")) + .to("file:target/messages/uk") + .otherwise() + .to("file:target/messages/others"); +------------------------------------------------------- + +[[JavaDSL-Routes]] +Routes +~~~~~~ + +Camel supports the definition of routing rules using a Java +link:dsl.html[DSL] (domain specific language) which avoids the need for +cumbersome XML using a link:routebuilder.html[RouteBuilder]. + +For example a simple route can be created as follows. + +[source,java] +------------------------------------------------------- +RouteBuilder builder = new RouteBuilder() { + public void configure() { + errorHandler(deadLetterChannel("mock:error")); + + from("direct:a").to("direct:b"); + } +}; +------------------------------------------------------- + +As you can see from the above Camel uses link:uris.html[URIs] to wire +endpoints together. + +[[JavaDSL-URIStringformatting]] +URI String formatting +^^^^^^^^^^^^^^^^^^^^^ + +*Available as of Camel 2.0* + +If you have endpoint URIs that accept options and you want to be able to +substitute the value, e.g. build the URI by concat the strings together, +then you can use the `java.lang.String.format` method. But in Camel 2.0 +we have added two convenient methods in the Java DSL so you can do +`fromF` and `toF` that uses String formatting to build the URI. + +[source,java] +------------------------------------------------------- +from("direct:start").toF("file://%s?fileName=%s", path, name); + +fromF("file://%s?include=%s", path, pattern).toF("mock:%s", result); +------------------------------------------------------- + +[[JavaDSL-Filters]] +Filters +^^^^^^^ + +You can combine simple routes with filters which can be arbitrary +link:predicate.html[Predicate] implementations. + +[source,java] +------------------------------------------------------- +RouteBuilder builder = new RouteBuilder() { + public void configure() { + errorHandler(deadLetterChannel("mock:error")); + + from("direct:a") + .filter(header("foo").isEqualTo("bar")) + .to("direct:b"); + } +}; +------------------------------------------------------- + +[[JavaDSL-Choices]] +Choices +^^^^^^^ + +With a choice you provide a list of predicates and outcomes along with +an optional default otherwise clause which is invoked if none of the +conditions are met. + +[source,java] +------------------------------------------------------- +RouteBuilder builder = new RouteBuilder() { + public void configure() { + errorHandler(deadLetterChannel("mock:error")); + + from("direct:a") + .choice() + .when(header("foo").isEqualTo("bar")) + .to("direct:b") + .when(header("foo").isEqualTo("cheese")) + .to("direct:c") + .otherwise() + .to("direct:d"); + } +}; +------------------------------------------------------- + +[[JavaDSL-Usingacustomprocessor]] +Using a custom processor +++++++++++++++++++++++++ + +Here is an example of using a custom link:processor.html[Processor] + +[source,java] +------------------------------------------------------- +myProcessor = new Processor() { + public void process(Exchange exchange) { + log.debug("Called with exchange: " + exchange); + } +}; + +RouteBuilder builder = new RouteBuilder() { + public void configure() { + errorHandler(deadLetterChannel("mock:error")); + + from("direct:a") + .process(myProcessor); + } +}; +------------------------------------------------------- + +You can mix and match custom processors with filters and choices. + +[source,java] +------------------------------------------------------- +RouteBuilder builder = new RouteBuilder() { + public void configure() { + errorHandler(deadLetterChannel("mock:error")); + + from("direct:a") + .filter(header("foo").isEqualTo("bar")) + .process(myProcessor); + } +}; +------------------------------------------------------- + +[[JavaDSL-SeeAlso]] +See Also +^^^^^^^^ + +* link:dsl.html[DSL] +* link:examples.html[Examples] +
