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Posted to users@tomcat.apache.org by Juha Laiho <Ju...@iki.fi> on 2007/07/01 11:21:14 UTC
How to inject a webapp listener?
Hello,
I would like to have the Tomcat container to inject a specific
ServletContextListener to each loaded webapp on my server - without
touching the individual web.xml files, and am looking for advise on
how to achieve this.
In other words, I'd like to have the container act as if there was
<listener>
<listener-class>MyListenerClass</listener-class>
</listener>
section in the web.xml file for each application?
Currently, I have added a ContainerListener on my Host, which
is listening on ADD_CHILD messages to discover newly added
StandardContext instances, and performs the following on each
new StandardContext (where ctx is a reference to the added context):
Object[] listeners = ctx.getApplicationLifecycleListeners();
Object[] newListeners = new Object[listeners.length+1];
System.arraycopy(listeners,0,newListeners,0,listeners.length);
newListeners[newListeners.length-1]=ctxListener;
ctx.setApplicationLifecycleListeners(newListeners);
With this, my listener is already able to capture the contextDestroyed
events from the webapp - but not the contextInitialized. It looks like the
Context is added to the host only after it has been already initialized.
What I'm looking for is a way to be able to inject the webapp listener
in an earlier phase, so that I can also capture the contextInitialized
messages. Any ideas? Also, if there's an overall better way to inject
the webapp listener, please let me know -- the above way feels rather
crude.
Thanks,
--
..Juha
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RE: How to inject a webapp listener?
Posted by "Caldarale, Charles R" <Ch...@unisys.com>.
> From: Juha Laiho [mailto:Juha.Laiho@iki.fi]
> Subject: How to inject a webapp listener?
>
> I would like to have the Tomcat container to inject a specific
> ServletContextListener to each loaded webapp on my server - without
> touching the individual web.xml files, and am looking for advise on
> how to achieve this.
Add it to the existing $CATALINA_HOME/conf/web.xml file. This file
becomes part of every webapp's configuration, unless overridden by a
particular WEB-INF/web.xml's settings. Note that this will also affect
the various webapps supplied with Tomcat.
- Chuck
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Re: How to inject a webapp listener?
Posted by Juha Laiho <Ju...@iki.fi>.
Thanks,
the reason why I believe I need to do this from the context level
is that the code running in the listener needs to access the context
classloader of the individual webapps - and they seem to me at least
be most straightforward to access from the webapp listener.
Of course, a way to access the individual webapp context classloaders
from ADD_CHILD/REMOVE_CHILD events of the container would be a good
alternative (definitely more clean approach than my current idea of
injecting the listener).
--
..Juha
David Delbecq wrote:
> Am not sure, but, whatever job your injected contextlistener is supposed
> to do, it could perhaps be done in the container listener without
> ressorting to context listener, isn't it? (using ADD_CHILD for the
> 'context initialized' and REMOVE_CHILD for contect destroyed)?
> As for calling init on your injected listern, is suppose you will have
> to do it yourself.
>
> Juha Laiho a écrit :
>> Hello,
>>
>> I would like to have the Tomcat container to inject a specific
>> ServletContextListener to each loaded webapp on my server - without
>> touching the individual web.xml files, and am looking for advise on
>> how to achieve this.
>>
>> In other words, I'd like to have the container act as if there was
>> <listener>
>> <listener-class>MyListenerClass</listener-class>
>> </listener>
>> section in the web.xml file for each application?
>>
>> Currently, I have added a ContainerListener on my Host, which
>> is listening on ADD_CHILD messages to discover newly added
>> StandardContext instances, and performs the following on each
>> new StandardContext (where ctx is a reference to the added context):
>>
>> Object[] listeners = ctx.getApplicationLifecycleListeners();
>> Object[] newListeners = new Object[listeners.length+1];
>> System.arraycopy(listeners,0,newListeners,0,listeners.length);
>> newListeners[newListeners.length-1]=ctxListener;
>> ctx.setApplicationLifecycleListeners(newListeners);
>>
>> With this, my listener is already able to capture the contextDestroyed
>> events from the webapp - but not the contextInitialized. It looks like
>> the
>> Context is added to the host only after it has been already initialized.
>>
>> What I'm looking for is a way to be able to inject the webapp listener
>> in an earlier phase, so that I can also capture the contextInitialized
>> messages. Any ideas? Also, if there's an overall better way to inject
>> the webapp listener, please let me know -- the above way feels rather
>> crude.
>>
>> Thanks,
>
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Re: How to inject a webapp listener?
Posted by David Delbecq <de...@oma.be>.
Am not sure, but, whatever job your injected contextlistener is supposed
to do, it could perhaps be done in the container listener without
ressorting to context listener, isn't it? (using ADD_CHILD for the
'context initialized' and REMOVE_CHILD for contect destroyed)?
As for calling init on your injected listern, is suppose you will have
to do it yourself.
Juha Laiho a écrit :
> Hello,
>
> I would like to have the Tomcat container to inject a specific
> ServletContextListener to each loaded webapp on my server - without
> touching the individual web.xml files, and am looking for advise on
> how to achieve this.
>
> In other words, I'd like to have the container act as if there was
> <listener>
> <listener-class>MyListenerClass</listener-class>
> </listener>
> section in the web.xml file for each application?
>
> Currently, I have added a ContainerListener on my Host, which
> is listening on ADD_CHILD messages to discover newly added
> StandardContext instances, and performs the following on each
> new StandardContext (where ctx is a reference to the added context):
>
> Object[] listeners = ctx.getApplicationLifecycleListeners();
> Object[] newListeners = new Object[listeners.length+1];
> System.arraycopy(listeners,0,newListeners,0,listeners.length);
> newListeners[newListeners.length-1]=ctxListener;
> ctx.setApplicationLifecycleListeners(newListeners);
>
> With this, my listener is already able to capture the contextDestroyed
> events from the webapp - but not the contextInitialized. It looks like
> the
> Context is added to the host only after it has been already initialized.
>
> What I'm looking for is a way to be able to inject the webapp listener
> in an earlier phase, so that I can also capture the contextInitialized
> messages. Any ideas? Also, if there's an overall better way to inject
> the webapp listener, please let me know -- the above way feels rather
> crude.
>
> Thanks,
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Re: How to inject a webapp listener?
Posted by Martin Gainty <mg...@hotmail.com>.
I would suggest spring ..but springs injected entities are *usually*
classical pojos such as DBDrivers
Here is a project which shows great promise of injecting whole listeners
which may be of help for your effort
http://oranjestad.sourceforge.net/spring-oranjestad.html
hyva?
Martin-
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----- Original Message -----
From: "Juha Laiho" <Ju...@iki.fi>
To: <us...@tomcat.apache.org>
Sent: Sunday, July 01, 2007 5:21 AM
Subject: How to inject a webapp listener?
> Hello,
>
> I would like to have the Tomcat container to inject a specific
> ServletContextListener to each loaded webapp on my server - without
> touching the individual web.xml files, and am looking for advise on
> how to achieve this.
>
> In other words, I'd like to have the container act as if there was
> <listener>
> <listener-class>MyListenerClass</listener-class>
> </listener>
> section in the web.xml file for each application?
>
> Currently, I have added a ContainerListener on my Host, which
> is listening on ADD_CHILD messages to discover newly added
> StandardContext instances, and performs the following on each
> new StandardContext (where ctx is a reference to the added context):
>
> Object[] listeners = ctx.getApplicationLifecycleListeners();
> Object[] newListeners = new Object[listeners.length+1];
> System.arraycopy(listeners,0,newListeners,0,listeners.length);
> newListeners[newListeners.length-1]=ctxListener;
> ctx.setApplicationLifecycleListeners(newListeners);
>
> With this, my listener is already able to capture the contextDestroyed
> events from the webapp - but not the contextInitialized. It looks like the
> Context is added to the host only after it has been already initialized.
>
> What I'm looking for is a way to be able to inject the webapp listener
> in an earlier phase, so that I can also capture the contextInitialized
> messages. Any ideas? Also, if there's an overall better way to inject
> the webapp listener, please let me know -- the above way feels rather
> crude.
>
> Thanks,
> --
> ..Juha
>
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> To unsubscribe, e-mail: users-unsubscribe@tomcat.apache.org
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>
>
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