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

[Simon J Archer <sarcher@xxxxxxxxxx>]

Hi Neil

Thanks for the response.  I am
very familiar with all the tricks available via the BundleContext, but
until my bundle is started, and a BundleContext provided to me, none are
possible.  The point of my posting is exactly this: My model-based
bundle that registers a service is never started.  I hope now that
you understand my dilemma.

Regarding IStartup, that is in a UI
plugin, and sadly the extension point requires the BundleActivator to implement
an interface in a UI plugin.  I do not want to create an unholy dependency
upon any UI plugin, since my bundle is purely headless.  Requiring
the Eclipse UI would be madness.  All I want is to build a bundle
on the Eclipse platform that starts as soon as it is installed; it's really
as simple as that.

Your point regarding IPlatformRunnable
is of interest to me.  If my bundle is not yet started, how am I to
make use of IPlatformRunnable?  Remember, I'm asking for a solution
to the problem of providing one (or more) model-based bundles that simply
register OSGi services.  OSGi services are not widely used yet in
the Eclipse community, so I'm likey one of the few that is running into
this problem.

Thanks

Simon

"Neil Bartlett" <neil@xxxxxxxxxxxxxx>
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04/09/2006 05:33 PM

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

Simon,

Maybe I misunderstood your problem, but there are a number of easy solutions
and I don't really see why you've dismissed all of them.

Firstly, why can't you get the Bundle object? You seem to be under the
impression that the Bundle object is only available within the bundle that
it describes. Actually any bundle can get the Bundle object for any other
bundle just by calling getBundle(id) or getBundles() on its own BundleContext.
You could even write a bundle that uses a BundleListener to listen for
Bundle Installed events, checks the value of some header you define eg
"Bundle-EarlyActivation", and immediately starts those bundles.

If that's no good, what's wrong with IStartup? That works in any Eclipse
application that uses the Workbench. Is your application entirely headless?

Finally, if your application is headless (or if it isn't), you can get
the Bundle and start it from the IPlatformRunnable.

Regards,
Neil



On 4/9/06, Simon J Archer <sarcher@xxxxxxxxxx>
wrote:

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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Subject	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 
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2006-04-08 07:24 AM
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Subject
[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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-- 
Neil Bartlett
Senior Technical Consultant, Integility Ltd
Tel: +44 (0) 20 7043 8328
Fax: +44 (0) 20 7043 8329

LinkedIn Profile: https://www.linkedin.com/in/neilbartlett
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