OSGi Access
Overview
OSGi Access is an API defined to manage remotely an OSGi framework independently of the technology used in the agent.
The
purpose
is to assure that the applications doesn’t depends on the
Management Agent that
runs in the framework. If the Management agent changes we only must to
implement the OSGi Access API for the new agent. The main reason to
create this API is the lack of a specification of remote management in
the OSGi fraework.
The
API
includes:
- Connection interface.
- ConnectionFactory class.
- ConnectionPool class.
- Several interfaces for manage the framework and
some standard services:
FrameWorkAccess, BundleAccess, ServiceAccess, StartLevelAccess,
etc… This
interfaces are implemented by the managed components that are
registered in the connection object.
- Specific exception to be thrown instead of the captured exceptions of the implementations.
Other characteristics that will be included soon:
- Notification of OSGi events.
- JUnit tests
to validate API implementations (and/or the framework).
Implementing the API
There
are two implementations of this API for two management agents:
JMood and TID-JMA4O.
Usage
To use the API, you need the osgi-access.jar library and one implementation. What is needed for each implementation depends on the own implementation, but there are some share requisites. Of course, one management agent must be running on an OSGi Framework (JMood and TID-JMA4O runs in OSCAR and Knopflerfish frameworks).
Common requisites for JMood and TID-JMAO4:
The .jar files distributed have been compiled with j2sdk1.4.2, but have been succesfully tested in j2sdk1.5 too. If you use j2sdk1.4.2 you will need some libraries of the MX4J project (mx4j.jar, mx4j-remote.jar and mx4j-tools.jar).
Requisites for JMood:
The distribution includes a /jmood-impl directory with JMood.properties (example of properties needed to create a conection), osgi-access_jmood_impl.jar (implementation of OSGi Access for JMood) and jmood-lib.jar (some classes of the JMood agente needed to compile and run this impl).
Requisites for TID-JMA4O:
The distribution includes a /tid-jma4o-impl directory with tid-jma4o.properties (example of properties needed to create a conection), osgi-access_tid-jma4o_impl.jar (implementation of OSGi Access for TID-JMA4O impl.).
An example of how the API can be used.
Create a connection:
Connection conn = ConnectionFactory.newOSGiConnection(props,null);
The connection factory needs a java.util.Properties object and a classloader (if you want to specify one). In this properties file must exists the property “osgi.connection.class” that specify what class must be instantiated with this properties as argument. The distribution includes a default properties file for each implemented agent.
All
the
other properties are no relevant for the API. The properties are the
needed by
the implementations (and can be completely different in case of
different
implementations).
When
you
have a connection object, you can get Managed Components (that has been
loaded
by the connection when created) through the interfaces. For example:
FrameworkAccess framAcc =
(FrameworkAccess)
conn.getManagedComponent(AccessConstants.FRAMEWORK);
BundleAccess bundleAcc = framAcc.getBundleById(new
Long(bundleId));
Its
important to denote that the
“AccessConstants.FRAMEWORK” string is used to
recover and expected managed component. We recover the managed
components with
this strings, and the implementations of Connection interface must
register the
managed components with the associated string defined in
“AccessConstants”.
Project Status
This API is under development and the actual version can't be consider as stable version. Many improvements and changes should be done for the first version, but what it's done works and you can see and example of an application based on OSGi Access in the OSGi Manager project.
License
OSGi Access is distributed under the GNU Lesser General Public License, LGPL, for detailed information visit LGPL
The two availables implementations are distributed under GPL license too.
Team
OSGi Access has been developed in the context of the participation of the Departamento de Ingeniería Telemática (DIT) and of the Universidad Politécnica de Madrid (UPM) in the ITEA-OSMOSE project. OSGi Access programs and documentation have been created by Miguel García, Manuel Santillan, Jose Luis Ruiz and Juan C. Dueñas.
OSGi Access R4 is the updated version for OSGi Release 4 frameworks and its maintained and developed by Telefonica I+D in the context of the ITEA-OSIRIS project.