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From Mark Eggers <its_toas...@yahoo.com>
Subject Re: Tomcat 6.0 CLASSPATH query
Date Sat, 08 Dec 2012 20:39:07 GMT
See at the end for a truly spectacularly bad potential solution. Note 
that I have not tried this, so your mileage may vary.

On 12/8/2012 11:51 AM, vicky wrote:
> Thanks Mark for your valuable suggestions.
>
> But in my project i have a requirement to share one
> "resource/properties file " across 10 applications deployed on single
> tomcat instance
>
> We cannot afford to add the same properties file to all archives as
> its contents keep changing.
>
> Another restriction which i have is that i cannot place any file
> under "$CATALINA_HOME" directories , these are read only for us.
>
> Based on afore said concerns, do you have any better way out ..please
> suggest.
>
> Appreciated all of your help
>
> Thanks for ur time Vicky
>
>
> ________________________________ From: Mark Eggers
> <its_toasted@yahoo.com> To: Tomcat Users List
> <users@tomcat.apache.org> Sent: Sunday, 9 December 2012 12:23 AM
> Subject: Re: Tomcat 6.0 CLASSPATH query
>
> Comments inline below (a bit fuzzy from the move yet).
>
> On 12/8/2012 9:58 AM, vicky wrote:
>>
>> I have read the Tomcat 6.0 classloader documentation(below link),
>> from this what i understood is that the
>> "classes/jar/resource/properties file" get loaded  from the
>> following locations
>>
>> 1.Bootstrap classes of your JVM  ($JAVA_HOME/jre/lib/ext).
>> 2.System class loader classes  ( Add bootstrap.jar &
>> tomcat-juli.jar to CLASSPATH variable) 3.Common class loader
>> classes ( refers $CATALINA_BASE/lib  & $CATALINA_HOME/lib ) & uses
>> $CATALINA_BASE/conf/catalina.properties 4. /WEB-INF/classes of
>> your web application 5. /WEB-INF/lib/*.jar of your web application
>>
>> The thing which is still puzzling me is that how my
>> "resource/properties files" get loaded to Tomcat CLASSPATH when i
>> add them to "$CATALINA_BASE/bin" directory & When i move the same
>> files to $CATALINA_BASE/conf directory then it doesn't get added to
>> Tomcat CLASSPATH.
>>
>> My deployed applications need"properties/resource files ", Can
>> someone please help me in understand the optimal way of adding
>> these files to Tomcat CLASSPATH. Does placing the files under
>> <CATALINA_BASE>/bin is the right approach.Please suggest
>>
>
> Why in the world are you adding these resource files to Tomcat's
> CLASSPATH? If the resources are application - specific, you don't
> need to do this at all.
>
> Just add the files to your local application. In Maven, there's a
> special directory for that:
>
> src/main/resources
>
> In NetBeans, I normally create a separate package for all of my
> configuration files.
>
> I think in Eclipse you'll have to make a subdirectory under
> WEB-INF/classes and copy the files there. That's unpleasant. Eclipse
> will include that in the build of the WAR file when you do an
> "export".
>
> Then, just do the following in your code to reference the resource.
>
> InputStream in =
> this.getClass().getClassLoader().getResourceAsStream(configfile);
>
> Where configfile is the complete classpath to your resource.
>
> This is nice. It works in exploded WARs, it works in WAR files, it
> works in JARs.
>
> No mucking about with CLASSPATH. No polluting other applications or
> Tomcat with spurious application - specific resources. This enables
> you to run several copies of the same web application in the same
> container, all with different configurations.
>
> Just search for getResourceAsStream() for more explanation.
>
>> In my organisation i cannot add anything to "$CATALINA_HOME/lib or
>> bin" location ,these are read only directories
>>
>> http://tomcat.apache.org/tomcat-6.0-doc/class-loader-howto.html
>> Thanks for your help Vicky
>
> Not needed.
>
>>
>>
>> ________________________________ From: Pid * <pid@pidster.com> To:
>> Tomcat Users List <users@tomcat.apache.org> Sent: Saturday, 8
>> December 2012 10:34 PM Subject: Re: Tomcat 6.0 CLASSPATH query
>>
>> On 8 Dec 2012, at 03:29, "vicky007aggarwal@yahoo.co.in"
>> <vicky007aggarwal@yahoo.co.in> wrote:
>>
>>> Application is deployed under tomcat webapps directory . It
>>> tries to refer to application specific properties file from
>>> tomcat classpath, for that we copied it under tomcat bin
>>> directory.
>>>
>>> My query is that does this is the right way to add properties
>>> file to tomcat classpath?
>>
>> Did you try putting it in tomcat/lib?
>>
>>
>> p
>
>>
>>
>>
>>>
>>> Thanks for ur help, Vicky
>>>
>>>
>>>
>>> On Dec 8, 2012, at 2:11 AM, Christopher Schultz
>>> <chris@christopherschultz.net> wrote:
>>>
>>>> -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA256
>>>>
>>>> Vicky,
>>>>
>>>> On 12/7/12 11:48 AM, vicky wrote:
>>>>> I have a requirement in which i need to add couple of
>>>>> properties files to tomcat CLASSPATH as these are needed for
>>>>> my application deployed in Tomcat 6.0.
>>>>>
>>>>> One strange thing is that, i need to add the all my
>>>>> properties files to "<CATALINA_BASE>/bin" directory else
>>>>> these all wont get added to Tomcat classpath.
>>>>
>>>> Where does the code live that attempts to load those
>>>> properties files?
>>>>
>>>> - -chris
>
> . . . just my (I hate moving) 2 cents /mde/

Vicky,

So let me now understand your requirements.

1. Properties files to be read by web applications
2. 10 web applications on one Tomcat instance
3. All 10 web applications read identical files
4. Property files change frequently
5. $CATALINA_HOME and $CATALINA_BASE are read-only
6. $CATALINA_BASE/lib and $CATALINA_BASE/bin are read-only

In the future it would be a good idea to list all of your requirements 
and restrictions at once, rather than having the list extract it by 
recommending solutions which fail one or more requirements.

The approach (placing resource files on the CLASSPATH) is probably not a 
good one given the requirements as you've stated them.

If you're wedded to reading resources from a CLASSPATH, the only 
reasonable way to live with the above requirements is to use files in 
WEB-INF/classes. Then the application will have to be changed each time 
you update the resource files. This all can be scripted so that 
operations won't have too big of a burden.

Placing the resources in a JAR somewhere on Tomcat's CLASSPATH poses 
several problems.

1. You cannot modify the directories where Tomcat reads JARs
2. A change to the resource will require a Tomcat restart

One of the only ways I can see around this is as follows.

1. create a setenv.sh in $CATALINA_BASE/bin (or setenv.bat)

I realize you do not have write access to this, but maybe operations can 
create that file.

2. In that setenv.sh, add the following:

CLASSPATH=/place/where/your/jar/is.jar
EXPORT CLASSPATH

3. Make the /place/where/your/jar/is.jar readable

This JAR file must be readable by the user running Tomcat

4. In is.jar add all your configuration files

This is a pretty spectacularly bad solution for several reasons.

1. You're reading a file outside of Tomcat's directory structure
2. Eunning under the security manager would be challenging
3. Tomcat restart for changing the JAR with the properties files

At this point, I would seriously look at scripting the 10 web 
application updates, or loading the properties files in a database and 
access them via JNDI.

. . . . just my two cents.
/mde/

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