Hi,
On 16.07.2009, at 10:53, Benoît Thiébault wrote:
Hi list !
I'm new to OSGI and iPOJO and I'm trying to create my first
application using these tools with Maven. The purpose of this
application is to test a messaging system accross components
(basically an observer pattern).
The application is composed of 4 bundles :
1) The CoreServices bundle defines service interfaces in two
packages : one for the execution service and one for the messaging
service. The execution package defines just one ExecutionService
interface, while the messaging service defines the MessagingService
and the Message interfaces (plus an Enum Class).
There is no metada.xml file defined for this bundle and the pom.xml
file declares the two packages in the <Export-Package> tag
2) The ExecutionService bundle implements the ExecutionService
interface. The metada.xml file declares the component that
<provides /> the services and creates an instance. The pom file
declares the compilation dependency with the first bundle and
declares the impl package as <Private-Package>
3) The MessagingService bundle implements the MessagingService and
the Message interfaces. The MessageImpl class uses an
executionService field. The metadata.xml file is provided below. The
pom.xml file declares the compilation dependency with the first
bundle and declares the impl package as <Private-Package>
<iPOJO xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance";
xsi:schemaLocation="org.apache.felix.ipojo http://felix.apache.org/ipojo/schemas/CURRENT/core.xsd
"
xmlns="org.apache.felix.ipojo">
<component classname="myapp.messaging.impl.MessagingServiceImpl"
name="MessagingServiceImpl" public="false">
<provides />
</component>
<component classname="myapp.messaging.impl.MessageImpl"
name="MessageImpl">
<requires field="executionService"/>
</component>
<instance component="MessagingServiceImpl"/>
</iPOJO>
There is no instances of MessageImpl declared there. How are they
created ? If you call "new" on the class, it will not be managed by
iPOJO.
4) The Test bundle implements two classes : a GUI that allows the
user to send messages and a Logger that subscribes the message and
prints "Hello World" when received.
I manage to build and launch the application without any problem.
The arch command confirms that all my instances are valid. However,
when I click the "send message" button, I have a null pointer
exception on the executionService field in the MessageImpl class.
What did I do wrong ? Do I need to split the CoreServices bundle
into two bundles (one declaring the execution service and the other
one the messaging service ?)
I also tryed to launch all bundles except the ExecutionService
bundle, and even though the MessagingService bundle requires it,
arch tells me its instance is valid and the application is correctly
launched.
Can you send the architecture of the MessagingServiceImpl instance and
of the MessageImpl instance ? (arch -instance instance_name).
Regards,
Clement
Thanks for your help,
Benoît
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