pjagwani / camel-dynamic-routing

An example of Camel's dynamic routing capabilities in routing to newly deployed OSGi bundles

Camel and JBoss Fuse Dynamic Routing Example

If you want to deploy ths example using fabric, please follow the instructions described in the Managing a Deployment using Fuse Fabric guide.

Overview

This example shows how to use Apache Camel, and its OSGi integration to dynamically route messages to new or updated OSGi bundles within JBoss Fuse. This allows you to route to newly deployed services at runtime without impacting running services.

This example combines use of the Camel Recipient List, which allows you to at runtime specify the Camel Endpoint to route to, and use of the Camel VM Component, which provides a SEDA queue that can be accessed from different OSGi bundles running in the same Java virtual machine.

Note: Extra steps, like use of Camel VM Component, need to be taken when accessing Camel Routes in different Camel Contexts, and in different OSGi bundles, as you are dealing with classes in different ClassLoaders...

The example further is explained by the following EIP diagram:

Alternative Approaches

Instead of using Camel VM Component, use of ActiveMQ Camel Component would also work. You'd need to configure a single ActiveMQ broker instance that all Camel routes can reference. To optimize performance, if the ActiveMQ broker runs embedded within JBoss Fuse, then you can use ActiveMQ's VM Transport, which is conceptually similar to Camel's VM Component in that it effectively uses direct method calls to enhance message transfer to and from the ActiveMQ Broker within a single Java Virtual Machine. This approach may be slightly less efficient than using the Camel VM approach, but use of ActiveMQ would allow to easily horizontally scale out multiple Fuse instances.

You could also use the Camel NMR Component, which leverages JBoss Fuse / Apache [ServiceMix NMR][] component. This provides a way to reference named endpoints across OSGi bundles. The issue with this approach is that the NMR within JBoss Fuse / ServiceMix is loosing favor within the Apache ServiceMix community, and may be deprecated in the not to distant future.

At the end of this ReadMe is a section describing how to management a deployment of this example using Fuse Fabric and Management Console.

---

Requirements:

• JBoss Fuse 6.1.0 or later (https://access.redhat.com/jbossnetwork - registration required)
• Maven 2.2.1 or 3.0 (http://maven.apache.org/)
• Java SE 6 or Java SE 7

Notes:

• if you see linkage errors related to javax.activation.DataHandler, you may need to edit JBoss Fuse's etc/jre.properties file, and add javax.activation to the list of packages exported by the base bundle by uncommenting (remote the leading '#') the javax.activation line.

  jre-1.6=
  javax.accessibility,
  javax.activation;version="1.1",
  javax.activity,
  ....

• In JBoss Fuse, make sure that you've added a smx/smx userid and password to <JBoss Fuse Home>/etc/users.properties, or update the included Camel route to the userid and password you have defined for the JBoss Fuse embedded ActiveMQ.

---

Building and Running

To build this project use Apache Maven in the base directory of this project

mvn install

This example will be deploying into JBoss Fuse. Follow the instructions to download, and install your own copy.

Below are a sequence of steps that highlight the core concepts:

1. Install Base Service
2. Test Base Service
3. Deploy Newservice Service
4. Test Base Service now able to route to both existing and new

1. Install Base Service

Within the Base Camel route there are 3 routes:

• an HTTP listener that routes to other endpoints based on the contents of the request
• a “simple” route that responds with a “Simple Response: {body of message}”
• a “other” route that responds with a “Other Response: {body of message}”

Start JBoss Fuse, by running the included start script

<JBoss Fuse Home>/bin/fuse

In the JBoss Fuse console, do the following

features:addurl mvn:org.fusesource.example.dynamic/features/0.0.1-SNAPSHOT/xml/features
features:install dynamic-routing-base

2. Testing Base Service

Then in a different Command Prompt, change to the client sub-project, and run

mvn -Psimple

You should see log entries in both JBoss Fuse console, and the Command Prompt that messages are flowing to the Simple Route

18:37:45,126 | INFO  | qtp317981251-233 | Base                             | 139 - org.apache.camel.camel-core - 2.10.0.redhat-60024 | Processing: direct:simple
18:37:45,127 | INFO  | qtp317981251-233 | Simple                           | 139 - org.apache.camel.camel-core - 2.10.0.redhat-60024 | Processing: direct:simple
18:37:46,043 | INFO  | qtp317981251-232 | Base                             | 139 - org.apache.camel.camel-core - 2.10.0.redhat-60024 | Processing: direct:simple
18:37:46,043 | INFO  | qtp317981251-232 | Simple                           | 139 - org.apache.camel.camel-core - 2.10.0.redhat-60024 | Processing: direct:simple

You can also try the Other route to see that the recipient list is working correctly within the Base service

mvn -Pother

with the following log output

18:39:59,483 | INFO  | qtp317981251-232 | Base                             | 139 - org.apache.camel.camel-core - 2.10.0.redhat-60024 | Processing: direct:other
18:39:59,484 | INFO  | qtp317981251-232 | Other                            | 139 - org.apache.camel.camel-core - 2.10.0.redhat-60024 | Processing: direct:other
18:40:00,399 | INFO  | qtp317981251-235 | Base                             | 139 - org.apache.camel.camel-core - 2.10.0.redhat-60024 | Processing: direct:other
18:40:00,400 | INFO  | qtp317981251-235 | Other                            | 139 - org.apache.camel.camel-core - 2.10.0.redhat-60024 | Processing: direct:other

3. Deploying Newservice Service

In the JBoss Fuse console, do the following

features:install dynamic-routing-newservice

4. Testing Newservice Service

Then in a different Command Prompt, change to the client sub-project, and run

mvn -Pnewservice

You should see log entries in both JBoss Fuse console, and the Command Prompt that messages are flowing to the New Service Route

18:41:51,479 | INFO  | qtp317981251-233 | Base                             | 139 - org.apache.camel.camel-core - 2.10.0.redhat-60024 | Processing: vm:newservice
18:41:51,480 | INFO  |  vm://newservice | newservice-route                 | 139 - org.apache.camel.camel-core - 2.10.0.redhat-60024 | Message: vm:newservice
18:41:51,489 | INFO  | umer[newservice] | newservice-consumer              | 139 - org.apache.camel.camel-core - 2.10.0.redhat-60024 | Consumer: vm:newservice
18:41:52,394 | INFO  | qtp317981251-232 | Base                             | 139 - org.apache.camel.camel-core - 2.10.0.redhat-60024 | Processing: vm:newservice
18:41:52,396 | INFO  |  vm://newservice | newservice-route                 | 139 - org.apache.camel.camel-core - 2.10.0.redhat-60024 | Message: vm:newservice
18:41:52,399 | INFO  | umer[newservice] | newservice-consumer              | 139 - org.apache.camel.camel-core - 2.10.0.redhat-60024 | Consumer: vm:newservice

Notice that the original Base service did not reload or restart to start forwarding messages to the newly loaded routes. You can re-run the original tests against mvn -Psimple and mvn -Pother to see that those still work correctly.

Newservice grabs the messages from the Camel VM component, and puts them onto (and off of) an ActiveMQ Queue. This shows how to route to new endpoints and integration routes at runtime -- it does not have to be ActiveMQ, it could easily be WS, REST, other JMS (Tibco, WMQ), etc.