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Re: [equinox-dev] Creating and Starting a BundleActivator when the framework launches


So my choices are:

- Call the Bundle object's start() method, or
- Update a configuration file in the local filesystem.

Hmmm, neither of these seem to be what I'm looking for: Calling the Bundle's start() method assumes that I can get the Bundle object for my bundle, which I usually do through the BundleContext, which is not created until the BundleActivator's start has been called.  The configuration file is not really feasible since I'm talking about building a bundle that is available for installation from an update site.  I would imagine that updating the config.ini is something you need to do by hand before Eclipse is started.

Here's my scenario, in a nutshell:

"I wish to write a bundle that can be installed into Eclipse from a update site.  The bundle is "pure model" (no UI) and has a BundleActivator that simply creates an instance of the model class and registers it as a service with the OSGi framework.  To do this I shall be using the traditional BundleContext APIs, and NOT declarative services.  Other bundles will acquire the imported service from the OSGi framework and therefore will never touch any of the bundle's classes directly.  Even the service interface used to implement the service might be defined by another bundle, for which import/export package dependencies will exist."

So far I'm stumped.  Surely this simple scenario should be supported by the Eclipse platform.  Here are some possible ways that Eclipse could be enhanced to help:

1.  Add a manifest header that informs the platform that this bundle should be started as soon as it is installed.  Even broadening the legal values for Eclipse-LazyStart might suffice.

2.  Add an extension point to the platform (not UI) that causes the bundle to be started as soon as it is installed.

3.  Enhance the platform so that when a bundle with a BundleActivator and an Export-Service header is installed it is automatically started.  This is probably my least favorite of the 3, since an Export-Service header is purely informational and therefore optional.


I'm happy to file a feature request in bugzilla for this. Comments? Suggestions?

Thanks

Simon




BJ Hargrave/Austin/IBM@IBMUS
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04/08/2006 08:09 AM

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Re: [equinox-dev] Creating and Starting a BundleActivator when the        framework launches





If you start the bundle with Bundle.start(), then the framework will
persistently mark it started and will restart each time the framework is
started.

If you launch the framework with -console, you can follow that with
"install some://bundle/url start" to install and start a bundle.

You can also mark it to be started in the configuration/config.ini file.
See the osgi.bundles key:

# The comma-separated list of bundles which are automatically installed
and optionally started
# once the system is up and running.  Each entry if of the form
#     <URL | simple bundle location>[@ [<startlevel>] [":start"]]
# If the startlevel is omitted then the framework will use the default
start level for the bundle.
# If the "start" tag is added then the bundle will be marked as started
after being installed.
# Simple bundle locations are interepreted as relative to the framework's
parent directory.
# The startlevel indicates the OSGi start level at which the bundle should
run.
# If this value is not set, the system computes an appropriate default.
osgi.bundles=org.eclipse.equinox.common@2:start,
org.eclipse.update.configurator@3:start, org.eclipse.core.runtime@start

BJ Hargrave
Senior Technical Staff Member, IBM
OSGi Fellow and CTO of the OSGi Alliance
hargrave@xxxxxxxxxx
Office: +1 407 849 9117 Mobile: +1 386 848 3788



Simon J Archer/Raleigh/IBM@IBMUS
Sent by: equinox-dev-bounces@xxxxxxxxxxx
2006-04-08 07:24 AM
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[equinox-dev] Creating and Starting a BundleActivator when the  framework
launches







It is my understanding that simply having a BundleActivator class and a
Bundle-Activator header in the MANIFEST.MF is not enough to force the
bundle's activator to be created and started by Equinox when the framework
is launched.

I have learned that adding Eclipse-LazyStart: true to the MANIFEST.MF is
the way ensure that the bundle's activator is started when one of its
classes is first touched by another bundle.

But how am I to create a bundle that has a BundleActivator that is created
and started when the OSGi framework is launched?  I am aware of the
org.eclipse.ui.startup extension point and accompanying IStartup class,
but I do not want to use that when my bundle is "pure model", since they
reside in an Eclipse UI plug-in.  I don't want to couple my model to
anything UI related.

I'm building plugins that will run in the Eclipse IDE rather than pure
OSGi bundles, so I'm using an "Eclipse Application" launch configuration.
It is curious that only the "Equinox OSGi Framework" launch configurations
allow you to specify the default start level for a bundle and whether it
will start automatically when the framework launches.

While I understand that the early creation and starting of a bundle
activator is considered a bad thing by many Eclipse developers, it should
still be possible and should not be this hard.

Thanks

Simon
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