Merge pull request akka#2014 from trobert/master

Add the ability to use an external camel context

akka-camel/src/main/resources/reference.conf

@@ -7,6 +7,11 @@
 
 akka {
   camel {
+    # FQCN of the ContextProvider to be used to create or locate a CamelContext
+    # it must implement akka.camel.ContextProvider and have a no-arg constructor
+    # the built-in default create a fresh DefaultCamelContext
+    context-provider = akka.camel.DefaultContextProvider
+
     # Whether JMX should be enabled or disabled for the Camel Context
     jmx = off
     # enable/disable streaming cache on the Camel Context

akka-camel/src/main/scala/akka/camel/Camel.scala

@@ -11,8 +11,8 @@ import org.apache.camel.ProducerTemplate
 import org.apache.camel.impl.DefaultCamelContext
 import org.apache.camel.model.RouteDefinition
 import com.typesafe.config.Config
-import scala.concurrent.duration.{ Duration, FiniteDuration }
-import java.util.concurrent.TimeUnit._
+import scala.concurrent.duration.FiniteDuration
+import scala.collection.immutable
 
 /**
  * Camel trait encapsulates the underlying camel machinery.
@@ -105,8 +105,17 @@ class CamelSettings private[camel] (config: Config, dynamicAccess: DynamicAccess
 
     (s: String, r: RouteDefinition) ⇒ conversions.get(s).fold(r)(r.convertBodyTo)
   }
-
+  /**
+   * Configured setting, determine the class used to load/retrive the instance of the Camel Context
+   */
+  final val ContextProvider: ContextProvider = {
+    val fqcn = config.getString("akka.camel.context-provider")
+    dynamicAccess.createInstanceFor[ContextProvider](fqcn, immutable.Seq.empty).recover {
+      case e ⇒ throw new ConfigurationException("Could not find/load Context Provider class [" + fqcn + "]", e)
+    }.get
+  }
 }
+
 /**
  * This class can be used to get hold of an instance of the Camel class bound to the actor system.
  * <p>For example:

akka-camel/src/main/scala/akka/camel/ContextProvider.scala

@@ -0,0 +1,27 @@
+/**
+ * Copyright (C) 2009-2014 Typesafe Inc. <http://www.typesafe.com>
+ */
+package akka.camel
+
+import akka.actor.ExtendedActorSystem
+import org.apache.camel.impl.DefaultCamelContext
+
+/**
+ * Implement this interface in order to inject a specific CamelContext in a system
+ * An instance of this class must be instantiable using a no-arg constructor.
+ */
+trait ContextProvider {
+  /**
+   * Retrieve or create a Camel Context for the given actor system
+   * Called once per actor system
+   */
+  def getContext(system: ExtendedActorSystem): DefaultCamelContext
+}
+
+/**
+ * Default implementation of [[akka.camel.ContextProvider]]
+ * Provides a new DefaultCamelContext per actor system
+ */
+final class DefaultContextProvider extends ContextProvider {
+  override def getContext(system: ExtendedActorSystem) = new DefaultCamelContext
+}

akka-camel/src/main/scala/akka/camel/internal/DefaultCamel.scala

@@ -15,9 +15,7 @@ import org.apache.camel.ProducerTemplate
 import scala.concurrent.{ Future, ExecutionContext }
 import akka.util.Timeout
 import akka.pattern.ask
-import java.io.InputStream
-import org.apache.camel.model.RouteDefinition
-import akka.actor.{ ExtendedActorSystem, ActorRef, Props, ActorSystem }
+import akka.actor.{ ExtendedActorSystem, ActorRef, Props }
 
 /**
  * INTERNAL API
@@ -33,7 +31,7 @@ private[camel] class DefaultCamel(val system: ExtendedActorSystem) extends Camel
   private[camel] implicit val log = Logging(system, "Camel")
 
   lazy val context: DefaultCamelContext = {
-    val ctx = new DefaultCamelContext
+    val ctx = settings.ContextProvider.getContext(system)
     if (!settings.JmxStatistics) ctx.disableJMX()
     ctx.setName(system.name)
     ctx.setStreamCaching(settings.StreamingCache)

akka-camel/src/test/scala/akka/camel/CamelConfigSpec.scala

@@ -46,6 +46,10 @@ class CamelConfigSpec extends WordSpec with Matchers {
       conversions.getString("file") should be("java.io.InputStream")
       conversions.entrySet.size should be(1)
     }
+
+    "have correct Context Provider" in {
+      settings.ContextProvider.isInstanceOf[DefaultContextProvider] should be(true)
+    }
   }
 }
 

akka-docs/rst/java/camel.rst

@@ -89,6 +89,12 @@ Below you can see how you can get access to these Apache Camel objects.
 
 One ``CamelExtension`` is only loaded once for every one ``ActorSystem``, which makes it safe to call the ``CamelExtension`` at any point in your code to get to the
 Apache Camel objects associated with it. There is one `CamelContext`_ and one `ProducerTemplate`_ for every one ``ActorSystem`` that uses a ``CamelExtension``.
+By Default, a new `CamelContext`_ is created when the ``CamelExtension`` starts. If you want to inject your own context instead,
+you can implement the `ContextProvider`_ interface and add the FQCN of your implementation in the config, as the value of the "akka.camel.context-provider".
+This interface define a single method ``getContext()`` used to load the `CamelContext`_.
+
+.. _ContextProvider: @github@/akka-camel/src/main/scala/akka/camel/ContextProvider.scala
+
 Below an example on how to add the ActiveMQ component to the `CamelContext`_, which is required when you would like to use the ActiveMQ component.
 
 .. includecode:: code/docs/camel/CamelExtensionTest.java#CamelExtensionAddComponent

akka-docs/rst/scala/camel.rst

@@ -88,6 +88,12 @@ Below you can see how you can get access to these Apache Camel objects.
 
 One ``CamelExtension`` is only loaded once for every one ``ActorSystem``, which makes it safe to call the ``CamelExtension`` at any point in your code to get to the
 Apache Camel objects associated with it. There is one `CamelContext`_ and one `ProducerTemplate`_ for every one ``ActorSystem`` that uses a ``CamelExtension``.
+By Default, a new `CamelContext`_ is created when the ``CamelExtension`` starts. If you want to inject your own context instead,
+you can extend the `ContextProvider`_ trait and add the FQCN of your implementation in the config, as the value of the "akka.camel.context-provider".
+This interface define a single method ``getContext`` used to load the `CamelContext`_.
+
+.. _ContextProvider: @github@/akka-camel/src/main/scala/akka/camel/ContextProvider.scala
+
 Below an example on how to add the ActiveMQ component to the `CamelContext`_, which is required when you would like to use the ActiveMQ component.
 
 .. includecode:: code/docs/camel/Introduction.scala#CamelExtensionAddComponent