Introduction

This document discusses how to package and deploy a lightweight component to the ServiceMix lightweight container (servicemix-lwcontainer). The ServiceMix lightweight container is a service engine JBI component whose purpose is to allow lightweight components (POJOs) to be deployed at runtime rather than only deploying them statically via the servicemix.xml file. Please see What is a lightweight component for a good explanation of the different types of JBI components.

As explained in What is a Lightweight Component there are two main use cases for ServiceMix:
1. As a full JBI container - using ServiceMix as a full JBI container in which you can deploy Service Assemblies and standard JBI components. And you may also deploy lightweight components in this mode - they must be deployed to the servicemix-lwcontainer.

2. Embedded - this is a static configuration used mainly for testing or perhaps for encapsulating ServiceMix into a web application. This uses the servicemix.xml file to configure components thare are only deployed when ServiceMix is started, not at runtime. You cannot deploy service units to this type of ServiceMix configuration at runtime. You would have to shutdown, reconfigure and then restart.

Just a brief background: A JBI component is either a service engine (SE) or a binding component (BC). These terms are defined in Introduction to ESB and/or the Glossary. A BC/SE is installed on ServiceMix by copying it into the install directory which resides under the ServiceMix home directory. So what gets deployed? JBI components can act as containers themselves. Artifacts can be deployed to an existing BC or SE to add more functionality to that component. Adding artifacts to installed components is called deployment. To deploy artifacts to a component the artifacts can be placed in the deploy directory under the ServiceMix home directory. A term that is important to know is service assembly. A service assembly is a collection of deployment artifacts and metadata. A service unit is a single deployment artifact which is deployed on a single component. For deployment to happen, the artifacts must be in a very specific format, which is specified in the JSR 208 specification. Please see chapter 6 of the JSR 208 specification for more details.

Manually Creating a Service Unit and Service Assembly

We are going to use the existing ServiceMix Loan Broker example, which can be found Loan Broker Demo for ServiceMix, as the basis for this discussion.

There are several things to note about this example. First of all it is meant to be run stand-alone. Specifically, when running this example, ServiceMix will be started for you, then the loan broker is deployed and run. Therefore, there is a servicemix.xml file in the loan-broker directory. This servicemix.xml file is used for configuring the ServiceMix JBI container upon ServiceMix starting up. This is not to be confused with the servicemix.xml located in the loan-broker\src\su directory. The SU servicemix.xml file is used to configure the servicemix-lwcontainer. Every service unit must contain some kind of configuration file. For example, if we were creating a service unit for the BPEL service engine there would also be a configuration file, but it would not be a servicemix.xml file, such as the one used for configuring the lightweight container.

NOTE: There are two major phases to creating a lightweight component that is ready for deployment: one, is the development phase of the component, which includes coding and compiling and building the code, the second phase is creating the packaging necessary for the component to be installed onto the JBI container. This document will focus on the second part. Any steps relating to compilation are simply performed here to get us to the point that we can assemble the component into a JBI service assembly or service unit.

In general, there are three steps to creating the SA and deploying it to the ServiceMix container.

1. Create the service units.
2. Create the service assemblies.
3. Deploy the service assemblies to their respective components in the JBI container.

The following provides details on each step above using the loan-broker example to illustrate.

Although we are not covering the component development phase, in this case we do need to perform a compile. We will use Apache Ant to compile the loan-broker demo components:

cd [servicemix_dir]\examples\loan-broker
ant build-components

This will compile the Java code and put the Java class files into the [servicemix_dir]\examples\loan-broker\build\loanbroker\components directory.

Now we are ready to assemble the lightweight components together. The loan broker demo supplies us with a build.xml file (which was used in the compile step above). The build.xml contains targets for creating service units and service assemblies. If you run "ant setup" a service unit and service assembly will automatically be created. Ultimately, this is what you will want to do, however, the following procedure gives the manual steps for creating a service unit and service assembly, to facilitate in understanding the contents of a SUs and SAs.

1. First create the service unit. The service unit is a ZIP file that will contain your application's Java class files and the servicemix.xml configuration file. The service unit can also contain a jbi.xml which provides information about services statically provided and consumed. In ServiceMix it is optional to include this file. In the case of our example, we have not included it.
   
   
   1. Use a ZIP compression tool, such as Winzip or gzip to create a zip file containing the classes in [servicemix_dir]\examples\loan-broker\build\loanbroker\components and the servicemix.xml file which can be found in [servicemix_dir]\src\su. The zip file name is arbitrary, but it is used in the Service Assembly's jbi.xml file, so to match the example call it loanbroker-su.zip.
      
   2. Put the loanbroker-su.zip file in the [servicemix_dir]\examples\loan-broker\build directory for later use. Note: you may store the zip file anywhere.
      
      The above two steps can be done automatically using the ant script: "ant build-su". If you look in the build.xml file you will see the build-su target does exactly what we just did manually.
      
      
2. Create the Service Assembly. A service assembly is a zip file containing one or more service units and a jbi.xml file. The jbi.xml file must be in the META-INF directory. you may also include other files in the META-INF directory. The ZIP file directory structure for our example looks like this:

   loanbroker-su.zip
   META-INF\
        jbi.xml
        LICENSE.txt
        DISCLAIMER.txt
   

   
   
   The jbi.xml looks like this:

   <?xml version="1.0" encoding="UTF-8"?>
   <jbi xmlns="http://java.sun.com/xml/ns/jbi" version="1.0">
   
      <service-assembly>
        <identification>
          <name>loanbroker</name>
          <description>LoanBroker Service Assembly</description>
        </identification>
        <service-unit>
          <identification>
            <name>loanbroker</name>
            <description>LoanBroker Service Unit</description>
          </identification>
          <target>
            <artifacts-zip>loanbroker-su.zip</artifacts-zip>
            <component-name>servicemix-lwcontainer</component-name>
          </target>
        </service-unit>
       </service-assembly>
   
   </jbi>
   

   
   
   The interesting thing to note is that the jbi.xml file tells the JBI container what service units are in the service assembly and where to deploy them. There is only one service unit in our example, which is "loanbroker" (see the artifacts-name tag) and the component to which it will be deployed is servicemix-lwcontainer (see the <component-name> tag). There could be multiple service units in a service assembly and they would each be included in the jbi.xml file with the same type of information for each.
   Create the service assembly ZIP file and include the loanbroker-su.zip file and the META-INF\jbi.xml directory and file in it. To remain consistent with our example, call the zip file loanbroker-sa.zip.
   Put the loanbroker-sa.zip file in the [servicemix_dir]\examples\loan-broker\build directory for later use. Note: in a real world application you may store the zip file anywhere.
   

3. The final step is to deploy the service assembly to the JBI container. To do this copy the loanbroker-sa.zip file to the [servicemix_dir]\deploy directory. If ServiceMix is already running it will detect the file is there and start it. If ServiceMix is not running, start it to see the example start running:

   ..\..\bin\servicemix servicemix.xml
   

Related Documentation

The JBI spec describes in detail how to create a valid JBI deployment unit. Please see JSR 208.

Spring Related information

Inside the servicemix.xml file, the ability to import the common beans using the following:

<import resource="classpath:otherBeans.xml" />

The resource is a SpringResource so the following also works:

<import resource="file:path/to/file/jmx.xml" />

if you run ServiceMix (or JBoss) with a param:

JAVA_OPTS="-DMYHOME=somepath/"
JAVA_OPTS=-DMYHOME=somepath/ # windows

then in the servicemix.xml and xbean.xml you can reference MYHOME.

eg:

<import resource="file:${MYHOME}/path/to/file/jmx.xml" />

Then you can also import a properties file from this same path to pull in other config you may need. (that you want outside an SU/SA bundle).

<bean id="propertyConfigurer"
  class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
  <property name="locations">
    <list>
      <value>${MYHOME}/conf/config.properties"</value>
    </list>
  </property>
</bean>