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Posted to users@tomcat.apache.org by Vinay Binny <c_...@yahoo.com> on 2008/10/16 13:00:14 UTC
Controlling the order of classloading.
Hi all,
I have a situation where I need to control the order in which the webapp jar files(in lib folder) are loaded by Tomcat. Is there anyway to acheive this?
To give you a background of the problem, I am using struts2 and Oracle's XSU in one of our webapps. XSU has a tight dependency on its own XML parser xmlparserv2.jar, when I drop this into the web-inf lib folder, struts2 picks the classes in this jar to do its xml parsing chore instead of picking its own xml parser, and fails. If I could lazy load or load xmlparserv2.jar after all struts2 specific jars have been loaded I should be devoid of problems. Any suggestions?
Thanks a lot,
Vinay.
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Re: Controlling the order of classloading.
Posted by supareno <re...@free.fr>.
hi,
i did some research and i found this
http://mail-archives.apache.org/mod_mbox/struts-user/200606.mbox/%3C44A1BB70.5010402@rochester.rr.com%3E
and this
http://java.sun.com/j2se/1.5.0/docs/api/javax/xml/parsers/SAXParserFactory.html
i don't know if it could help you but i learn something new: we can
configure the SAXParserFactory in java :-)
bye
>> From: André Warnier [mailto:aw@ice-sa.com]
>> Subject: Re: Controlling the order of classloading.
>>
>> But is there not a <load-at-startup> tag or something like it in a
>> web.xml file, with a numeric value for that purpose ?
>>
>
> It specifies that the designated servlet be loaded during startup, but does not have anything to do with the search order for jars that contain conflicting classes.
>
> One thing to do is to prune the jars so there's only one copy of the class in question (don't know if that's really feasible here).
>
> - Chuck
>
>
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RE: Controlling the order of classloading.
Posted by "Caldarale, Charles R" <Ch...@unisys.com>.
> From: André Warnier [mailto:aw@ice-sa.com]
> Subject: Re: Controlling the order of classloading.
>
> But is there not a <load-at-startup> tag or something like it in a
> web.xml file, with a numeric value for that purpose ?
It specifies that the designated servlet be loaded during startup, but does not have anything to do with the search order for jars that contain conflicting classes.
One thing to do is to prune the jars so there's only one copy of the class in question (don't know if that's really feasible here).
- Chuck
THIS COMMUNICATION MAY CONTAIN CONFIDENTIAL AND/OR OTHERWISE PROPRIETARY MATERIAL and is thus for use only by the intended recipient. If you received this in error, please contact the sender and delete the e-mail and its attachments from all computers.
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Re: Controlling the order of classloading.
Posted by André Warnier <aw...@ice-sa.com>.
Mark Thomas wrote:
> Vinay Binny wrote:
>> Hi all,
>>
>> I have a situation where I need to control the order in which the webapp jar files(in lib folder) are loaded by Tomcat. Is there anyway to acheive this?
> Sorry, no. You simply don't have that much control over the classloader in
> a servlet container.
>
Consider this a question, since I would not dream of even thinking of
contradicting Mark.
But is there not a <load-at-startup> tag or something like it in a
web.xml file, with a numeric value for that purpose ?
Or does that mean something else ?
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Re: Controlling the order of classloading.
Posted by Mark Thomas <ma...@apache.org>.
Vinay Binny wrote:
> Hi all,
>
> I have a situation where I need to control the order in which the webapp jar files(in lib folder) are loaded by Tomcat. Is there anyway to acheive this?
Sorry, no. You simply don't have that much control over the classloader in
a servlet container.
> To give you a background of the problem, I am using struts2 and Oracle's XSU in one of our webapps. XSU has a tight dependency on its own XML parser xmlparserv2.jar, when I drop this into the web-inf lib folder, struts2 picks the classes in this jar to do its xml parsing chore instead of picking its own xml parser, and fails. If I could lazy load or load xmlparserv2.jar after all struts2 specific jars have been loaded I should be devoid of problems. Any suggestions?
You might be able to do this with an OSGI compliant application server.
Mark
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Re: Controlling the order of classloading.
Posted by Christopher Schultz <ch...@christopherschultz.net>.
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Vinay,
Vinay Binny wrote:
> I am using struts2 and
> Oracle's XSU in one of our webapps. XSU has a tight dependency on its
> own XML parser xmlparserv2.jar, when I drop this into the web-inf lib
> folder, struts2 picks the classes in this jar to do its xml parsing
> chore instead of picking its own xml parser, and fails.
I don't believe S2 ships with an XML parser; it should just use whatever
XML parser is available from the system. Is it possible that
xmlparserv2.jar supplies an implementation that is not recent enough to
work with S2 (which I think just uses commons-digester)?
You might want to ask on the struts user list if there's a way to force
S2 (or the digester) to use a particular implementation instead of the
currently-loaded default XML parser implementation.
- -chris
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