5.2 Creating the DataSource project

This section describes how to use the bundle project creation wizard to create a new Bundle Project. The project’s Spring bean definition files will also be created using the Spring bean configuration file creation wizard.

Creating a new Bundle Project

Create a new project by right-clicking in the Package Explorer view and selecting NewProject…. In the resulting dialog select SpringSource dm ServerBundle Project and press Next:

In the New Bundle Project dialog, name the project greenpages.db. Choose the create the project from an existing source location and specify a location that will place the new greenpages.db alongside the project skeletons that were imported into the workspace earlier. If the start directory of the GreenPages sample is being used this will be $GREENPAGES_HOME/start/greenpages.db. Click Next.

In this page of the wizard, many of the Bundle Properties are already populated. The Bundle-SymbolicName is the name of the project. The Bundle-Name is derived from the Bundle-SymbolicName. The Bundle-Version is set, and there is no Bundle-Description.

Change the Bundle-Name to “GreenPages DataSource” to more accurately describe the bundle’s purpose. An option to select a ‘Bundle Classpath Container’ is already selected. It should be de-selected, as a Maven Classpath container will be configured later. Lastly, check the target runtime JVM version is appropriately configured; it should specify a JVM version of 1.6 or later. Click Finish.

The greenpages.db project appears in the Package Explorer view.

Configuring the project’s classpath container

Before a Maven Classpath Container can be added to the project, a pom.xml file must be created. Create a new file in the root of the greenpages.db project named pom.xml and add the following contents to it:

<?xml version="1.0" encoding="UTF-8"?>
	xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">





Save the file.

A Maven Classpath Container can now be added to the project. Right-click the greenpages.db project in the Package Explorer and select Maven 2Enable dependency management. Eclipse will perform some workspace building, and the greenpages.db project will now be marked as a Maven project. (If the error Cannot find artifact for parent POM occurs check that the version is correct. It may differ from the one given here.)

Configuring the source folders

The last part of the setup of the project is to configure its source folders. Return to the Properties dialog of the greenpages.db project (from the Package Explorer view). Select Java Build Path on the left-hand side and the Source tab on the right-hand side. Remove any pre-configured source folders by selecting them and clicking Remove.

Now click Add folder and then Create new folder…. Specify src/main/resources as the folder name and click Finish, then OK and OK again.

The final change to be made is to drag the META-INF folder from src to src/main/resources. Once these changes have been made the project will appear similar to the following in the Package Explorer view:

Configuring the DataSource

The DataSource bundle’s main rôle is to configure and create a DataSource object and to publish this to the OSGi service registry. This will be done by creating a handful of Spring beans.

By default, Spring DM looks for application context files in a bundle’s META-INF/spring directory. Create a new folder named spring in the greenpages.db project’s META-INF folder. Having created the new folder, right-click it in the Package Explorer and select New Spring Bean Configuration File. This will open the wizard for creating Spring bean configuration files.

In the wizard enter a File name of module-context.xml and click Next:

Add the p - http://www.springframework.org/schema/p namespace declaration to the pre-selected beans declaration and then click Finish.

Update the newly-created file (which is opened by Eclipse) to declare a bean that defines the DataSource object that will be used to access the GreenPages database. Do this by adding the following bean declaration:

	<bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource" 
	p:driverClassName="org.h2.Driver" p:url="jdbc:h2:~/greenpages-db/greenpages"
	p:username="greenpages" p:password="pass"
	init-method="createDataSource" destroy-method="close" />

The new bean has introduced a dependency on Commons DBCP, which will cause an error to be reported by Eclipse.

This dependency must be recorded in the project’s pom file. Open the pom file for greenpages.db and add the following dependency between the <dependencies> tags:


Save the updated pom and then switch back to the editor for module-context.xml. Save the updated file and observe that the previously reported problem is now resolved as Commons DBCP is available on the classpath.

Now that the DataSource bean is available, it can be published into the OSGi service registry.

Right-click the spring folder and select New Spring Bean Configuration File again. This time specify a name of osgi-context.xml, click Next, and add the osgi namespace declaration. Click Finish and then add the following to the new file to publish the DataSource as a service:

        export the dataSource bean to the OSGi service registry under the
        DataSource interface
    <osgi:service ref="dataSource" interface="javax.sql.DataSource" />

Configuring Bundlor’s manifest template

Bundlor uses a manifest template to control the contents of the generated manifest. Create a new file named template.mf in the root of the greenpages.db project. Open the existing MANIFEST.MF and switch to the MANIFEST.MF tab to view its source. Copy the contents. Switch to the editor for template.mf, switch to the template.mf tab and paste the contents from MANIFEST.MF. These entries will tell Bundlor what the resulting manifest’s bundle symbolic name, bundle version, etc. should be. Save the updated template.

Still in the template.mf editor switch to the Overview tab and click Update MANIFEST.MF which is under the “Bundle Actions” section.

At this point Bundlor will scan the project to determine its dependencies. It will scan both module-context.xml and osgi-context.xml looking for references to classes. For each class to which it finds a reference, an import for the class’s package will be added to the resulting manifest.

In this case, Bundlor will generate imports for both javax.sql and org.apache.commons.dbcp. These imports may not be resolved. The greenpages.db project needs to be associated with a dm Server instance which has the Commons DBCP bundle in its repository to resolve them. In any event the next step adds the greenpages.db project to the GreenPages PAR and will result in it inheriting the PAR project’s targetted runtime configuration.

Double-click the MANIFEST.MF file in the greenpages project in the Package Explorer view. Switch to the Dependencies tab and click Add…. Select greenpages.db and click OK. Save the updated file. A problem concerning the org.apache.commons.dbcp dependency should now be resolved (along with any other resolution errors) and (if the server is running) the GreenPages application will be redeployed due to the addition of the greenpages.db module. Start the server if it is not already running and observe that this deployment fails.

The deployment will fail because the org.h2.Driver class that is referenced in the DataSource bean’s definition in module-context.xml is not available to the bundle. (Check for the exception org.springframework.beans.factory.BeanCreationException with text something like:

Error creating bean with name 'dataSource'
	defined in URL [bundleentry://68.fwk504117357/META-INF/spring/ module-context.xml]: 
	Invocation of init method failed; 
	nested exception is org.apache.commons.dbcp.SQLNestedException: Cannot load JDBC driver class 'org.h2.Driver'

though the numbers might be different.)

There are a few cases where Bundlor will not identify a dependency on a class and, at the moment, this is one of them, although this is an area of Bundlor that is being improved all the time. Thankfully, it is easy to add the required import by making a simple update to the template.

Open the editor for the template.mf file in the greenpages.db project and add the following Import-Package header and save the updated manifest:

Import-Package: org.h2;version="[1.0.71,1.0.71]"

Saving the manifest will trigger a redeployment (or click on Update MANIFEST.MF as before) which will fail if the H2 database is not available. (Refer to the section the section called “Starting and configuring the database” in Chapter 3, Installing and exploring GreenPages to run and configure the database.)

If the database is running the GreenPages application should correctly deploy. Although the application web front-end will run, the database contents is not visible, of course, because we are still running with the stub version of the search method on the controller. The implementation of the Directory service needs to be changed to exploit the database.