The bundle activation policy (specified by the Bundle-ActivationPolicy header) indicates to the framework how the bundle should be activated when Bundle#start(Bundle.START_ACTIVATION_POLICY) is called. When the policy is "lazy" then the BundleActivator#start(BundleContext) method is delayed until the first "trigger" class is loaded from the bundle. When no policy is specified then the default policy is "eager" which means that when Bundle#start(Bundle.START_ACTIVATION_POLICY) is called then the BundleActivator is loaded and start(BundleContext) is called immediately (as long as the bundle start-level is adequate).
In Eclipse the management agent (old update manager and p2) only calls
Bundle#start(Bundle.START_ACTIVATION_POLICY) by default on bundles that
have the "lazy" bundle activation policy. We have had many debates on what
should happen for bundles that have no activation policy. Some folks want
all these bundles to be activated "eagerly" each and every launch, others
want to have the bundles be activated only if they are really needed,
others want to be able to control which set of bundles are eagerly
activated for their configuration.
In old Eclipse Update, none of the "eager" bundles are activated by
default. You must use some other means of getting the bundles you want
eagerly activated to be started. In p2 there is an option to install an IU
(installable unit) that configures bundles to be eagerly started. The
point is many folks will want different things when it comes to eagerly
activating bundles installed into the framework. We should not bake into
the install agent a policy to eagerly activate all bundles. Instead we
should have an agent that is flexible and can be provisioned to do exactly
what we want. This is one of the goals of p2.
Tom
From: Amol Mathur <[EMAIL PROTECTED]>
To: [email protected]
Date: 05/30/2008 03:04 PM
Subject: [equinox-dev] Bundle Activation
Hi all,
I had a doubt about bundle activation. I have been reading the sections
about lazy activation policy in osgi spec and i am a little confused.
1) What is the difference between Bundle Activation and calling
BundleActivator.start() method.
2) Does bundle activation mean loading of all classes that are there in the
bundle?
3) I was assuming that is BundleActivation policy is not set to lazy the,
on deployment the BundleActivator.start() method will be called
automatically by the framework, but it doesnt happen that way.
Sorry if you feel its a dumb question but i have managed to confuse my self
royally.
Thanks in advance.
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