On 4/22/10 10:41, Stijn de Witt wrote:
I just wanted to let you know that I now have implemented the suggested
solution using startlevels and it seems to be working like a charm. Some
more testing is still needed to verify all the different scenarios, but
I have a good feeling about it. Incidentally this change actually made
our code smaller and simpler, always a good sign I think!
Great.
We are no longer installing File Install manually, but are requesting
Felix to install it using configuration property:
felix.auto.start.2=<url_to_File_Install_jar>
and making sure the framework initially starts up to startlevel 1 by
specifying:
felix.startlevel.framework=1
If you are using Felix 2.0.x, then you should use
"org.osgi.framework.startlevel.beginning" which is the standard name for
this property starting with OSGi R4.2.
Then, when we have entered NORMAL mode, we lookup the StartLevel service
and set startlevel to 2 manually:
ServiceReference serviceRef =
this.context.getServiceReference(StartLevel.class.getName());
StartLevel startLevelService = (StartLevel)
this.context.getService(serviceRef);
startLevelService.setStartLevel(2);
I still have one question though:
I read in various places that you should never use startlevels to manage
dependencies between services (not applicable for us I think) and that
there is a compatibility option in OSGi that will force all startlevels
of all bundles to 1....
Not precisely sure to what you are referring, but perhaps if the
framework doesn't offer a start level service, then it would treat them
all as being start level 1. You could just have your application fail if
there is no start level service, but typically this should not be the case.
It's that last part that is worrying me... Our code would fail in that
compatibility mode I think?
Any thoughts about that? Should I be worried? It's not completely clear
to me whether this is just for backward compatibility with older
bundles/frameworks or if this is some 'compliancy check' feature that we
should be able to deal with. We have control over the used Felix version
and OSGi spec. version so backward compatibility is not an issue for us.
I don't think you need to worry about it.
-> richard
Thanks for your great help!
-Stijn
-----Original Message-----
From: Stijn de Witt [mailto:stijn.dew...@planon.nl]
Sent: donderdag 22 april 2010 11:42
To: users@felix.apache.org
Subject: RE: Prevent specific cached bundle from starting
Ok thanks Karl, going to read up on that right away!
-Stijn
-----Original Message-----
From: Karl Pauls [mailto:karlpa...@gmail.com]
Sent: donderdag 22 april 2010 11:39
To: users@felix.apache.org
Subject: Re: Prevent specific cached bundle from starting
Just have a look at the startlevel service. It can do what you want. I
guess the idea would be something like: start the framework with
startlevel one. All bundles in startlevel one get started. When the
bundle in question is done with its work, it uses the startlevel
service to go to startlevel two. File install will be started in
startlevel two.
regards,
Karl
On Thu, Apr 22, 2010 at 11:33 AM, Stijn de Witt<stijn.dew...@planon.nl>
wrote:
Ok that sounds interesting. I will definitely look into these start
levels, thanks!
One question though. If we have some time consuming work to do after
Felix has started, but before we enter NORMAL mode, wouldn't the File
Install bundle still start during that time consuming work? It is
important to us that it never starts before we enter NORMAL mode, even
if it might take ten seconds after the last system bundle was
installed
in INITIALIZE mode before we finally enter NORMAL mode.
I am currently looking into uninstalling the File Install bundle when
we
shutdown, so it will be removed from the cache once we startup again,
but the problem I have with that is that I fear it may not be as
robust.
if the server would stop without going through the shutdown code in
the
intended manner (crash, power outage etc) the File Install bundle
would
still be lingering in the cache and cause problems on the next
startup.
A possible solution would be to set some flag after the shutdown code
has finished and check that flag again on startup, clearing the bundle
cache if the shutdown code was not completed correctly. But this all
adds to complexity of course.
Maybe I could combine both approaches.
Is there some way to set a startlevel manually? Something like this:
Server.enterNormalMode();
Felix.setStartLevel(3);
Or perhaps by using the ServiceTracker we could signal the File
Install
bundle when it's good to go?
-Stijn
-----Original Message-----
From: Karl Pauls [mailto:karlpa...@gmail.com]
Sent: donderdag 22 april 2010 11:05
To: users@felix.apache.org
Subject: Re: Prevent specific cached bundle from starting
It sounds to me like what you want to do is to look into startlevels.
Basically, all your bundles from your INITIALZE mode should be in one
startlevel and the file install bundle in a higher level. That way,
all your bundles will be started before the file install bundle gets
started (and that will be the case for the startup with an exisiting
cache as well).
regards,
Karl
On Thu, Apr 22, 2010 at 10:49 AM, Stijn de Witt
<stijn.dew...@planon.nl>
wrote:
Hi all,
I was wondering if it is possible to prevent a specific cached bundle
from starting when Felix starts?
We have started using OSGi and Felix in our existing product a while
ago
but still are coming to grips with it. One thing that we had some
trouble with (and had implemented badly) is the use of the Felix
bundle
cache.
We initially always cleared the bundle cache before starting Felix
and
then had Felix install some system bundles by setting the property
"felix.auto.start.1" to a list of bundles to be started. We then did
some application specific startup logic and only when that was done
would we install the Felix File Install bundle 'manually' with a call
to
BundleContext#installBundle.
Unfortunately this degraded our startup performance. An OSGi expert
pointed out to us that this is not very efficient and that the bundle
cache is meant to (be able to) survive between shutdown and startup,
so
we are now refactoring our code to use this feature. It is here that
we
run into the problem.
Basically startup of our server consists of two phases: INITIALIZE
mode
and NORMAL mode. During initialize mode the system bundles should be
installed and started and any 'user' bundles that were already
installed
and running before the server was stopped should resume. Then, when
we
enter NORMAL mode, the File Install bundle should be installed and
started and monitor the bundle deploy folder for new, changed or
removed
user bundles. However, when we start Felix with the File Install
bundle
in the cache, that starts right away and immediately begins
installing
'user' bundles when we are still in INITIALIZE mode, causing havoc.
So what I want is, just before calling Felix.start, remove the File
Install bundle from the cache so we can install it manually after we
entered the NORMAL mode.
Is that possible? Or even the right way to go about it? Or is there
some
smarter approach we could take?
Any advice would be greatly appreciated.
Thanks for a great open source project!
-Stijn
--
Karl Pauls
karlpa...@gmail.com
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