geronimo-dev mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Matt Hogstrom <m...@hogstrom.org>
Subject Re: replacing tomcat classes
Date Thu, 11 May 2006 16:44:42 GMT


David Jencks wrote:
> 
> On May 11, 2006, at 8:29 AM, Joe Bohn wrote:
> 
>>
>> Thanks for the quick response Jeff.
>>
>> I like the idea of a "system patch" location in the classpath where we 
>> can pick up patches for anything we might include in a geronimo  
>> assembly.
> 
> I think this "system patch" idea will only work in environments with 
> only one classloader, i.e. not geronimo.  The problem is that the 
> patched classes need to get into the correct classloader, "before" the 
> normal versions.   We'd need a patch directory for each module.  I also 
> think any solution that relies on the order of stuff in a classpath is 
> inherently unstable and unreliable.

I agree that it would be very unwieldy.  For some folks providing support for Geronimo it
might be 
nice for the classloaders to look in an aside dir (./patches) for a jar with the artifact
name with 
a -pyyyymmddss suffix so patches can be applied.  The ss allows for the sequencing to be addressed.

  This would make it easier to provide one hit patches that can get rolled up into the released
jar 
you describe below and the user would not have to wait for a release to come out which could
be a 
few months.

> Basically I think this is a terrible idea and we should avoid it at all 
> costs.  I think instead we should use our new version independence and 
> replace jars with patched jars with slightly higher version numbers.  
> IIUC this is what you propose doing below.  This should not require 
> removing the standard tomcat jars: the hight version number should be 
> enough to get the correct version picked up.
> 
> thanks
> david jencks
> 
>>
>> I too was confused by the tomcat recommendation but it does seem that 
>> they have a strategy for addressing necessary changes with minimal 
>> interference in tomcat.  I have also noticed some things that make me 
>> wonder if my local tomcat build of 5.5.15 really does match the 
>> official 5.5.15 build.  For example, the only source for 5.5.15 that I 
>> could find was a zip file rather than a svn branch or tag.  I am not 
>> able to build from the unpacked zip without making a change to move 
>> the contents of jasper/jasper2 into the jasper directory itself.  And 
>> the version that is displayed when I hit tomcat with my rebuilt image 
>> is 5.5 rather than 5.5.15 as with the official image.
>>
>> Until we figure out the correct approach for Geronimo I'm thinking of 
>> using a compromise solution.   The changes I need in tomcat result in 
>> 4 of the 13 tomcat jars getting rebuilt.   Rather than replacing all 
>> of the tomcat jars with my local build I have verified that replacing 
>> just the 4 changed jars appears to work fine.  I'm hoping this hybrid 
>> solution keeps most of the official tomcat image and our local 
>> changes.   I haven't noticed any problems.   Assuming the source is 
>> mostly identical (apart from our changes) does anybody know of a 
>> reason that I should definitely not take this approach?
>>
>> Joe
>>
>>
>> Jeff Genender wrote:
>>> Ultimately, we probably would need to somehow build a "patch" directory
>>> or lib directory where we can ensure the URLClassLoader picks that up
>>> before all other classes.  I think this is probably a good idea to have
>>> as well, so that we could release "service paks" or patches.  I would be
>>> interested in others' thoughts on this, but I think this would be a nice
>>> feature to have.
>>> Right now I think your only choices are to either hard set a classpath
>>> to be sure the patches get picked up first or build a hacked Tomcat
>>> version, or rebuild Tomcat.  Dain or David Jencks may be able to verify
>>> if the classpath solution would work or not as I have not dug into the
>>> new G classloaders to know if this would even be possible.
>>> The best solution right now may be to just build TC. I am a little
>>> confused as to why the TC guys say not to build the Tomcat from source
>>> (after its hacked).  It seems like just an ant build script, so I don't
>>> understand why this is being discouraged.  This way you can replace the
>>> Tomcat jars in the repo and you are good to go.
>>> Jeff
>>> Joe Bohn wrote:
>>>> Jeff,
>>>>
>>>> I am working with a user that is moving some applications from 
>>>> tomcat to
>>>> geronimo.   Due to some problems they have had to modify tomcat source.
>>>> I was chatting with jasonb on the tomcat irc channel and he recommended
>>>> that we only build the classes rather than rebuilding all of 
>>>> tomcat.  He
>>>> discouraged rebuilding all of tomcat because there are many 
>>>> permutations
>>>> that can result in different build images and we should run with as 
>>>> much
>>>> of the official tomcat build as possible to avoid problems.  He also
>>>> indicated that Tomcat's directory structure provides a place to put
>>>> these "patch classes" in CATALINA_HOME/server/classes .
>>>>
>>>> Is there a similar place that we can put classes when tomcat is running
>>>> under geronimo to have them picked up?  Adding the tomcat classes to 
>>>> our
>>>> new sharedlib doesn't seem to be the right place because it would
>>>> require a dependency from the tomcat config on sharelib.  The net 
>>>> result
>>>> would be that all tomcat apps would potentially pick up user classes
>>>> added in sharedlib even if the user only intended these classes for 
>>>> some
>>>> subset of the apps.
>>>>
>>>> Joe
>>>>
>>
>> --Joe Bohn
>> joe.bohn at earthlink.net
>>
>> "He is no fool who gives what he cannot keep, to gain what he cannot 
>> lose."   -- Jim Elliot
> 
> 
> 
> 

Mime
View raw message