Re: Porting app from Tomcat 5.0.28 to 6.0.26

[Jeff Hubbs]

Also, this wiki says " Hibernate ships with the CP30 connection pooling 
classes, so as long as the Hibernate jars are in WEB-INF/lib directory 
(which they should be), they should be available. "  Was that also true 
as of Hibernate 2.1b6?

On 5/14/10 9:48 AM, Jeff Hubbs wrote:
Thanks, Mark - this is useful but it also raises more questions for me...
This page specifically mentions " Tomcat's database connection pool" - 
distinct from Hibernate's and I assume distinct from c3p0.  Did Tomcat 
sprout this ability during the years between 5.0.28 and 6.0.26, and if 
so, should I abandon c3p0 entirely?

Another question:  this app has Hibernate 2.1b6 packaged in with 
it...should I fly in a newer one as long as the usage won't have 
changed?  I'm not really in a position to rework the app to handle 
usage changes.

Thanks,

Jeff

On 5/13/10 5:28 PM, Mark Eggers wrote:
Here's a link from the Tomcat Wiki.

http://wiki.apache.org/tomcat/TomcatHibernate

The bottom portion of the document explains how to use Hibernate to 
manage database pooling instead of Tomcat.

I hope it gives you some leads.

. . . . just my two cents

/mde

--- On Thu, 5/13/10, Jeff Hubbs<jhubbsl...@att.net>  wrote:

From: Jeff Hubbs<jhubbsl...@att.net>
Subject: Porting app from Tomcat 5.0.28 to 6.0.26
To: "Tomcat Users List"<users@tomcat.apache.org>
Date: Thursday, May 13, 2010, 12:55 PM
Hello -

I have a DB2-backed legacy app on a legacy platform that
I'm trying to modernize.  My objective is to modernize
the platform underneath the app (Gentoo Linux for now,
Tomcat 6.0.26, Sun JDK 1.6.0.20) and do so in a way that a
longtime Java/Tomcat integrator would readily recognize (I'm
not one).  App uses Hibernate and c3p0; Hibernate is
packaged in the app's war but c3p0 is not; I've installed
c3p0 through Gentoo's usual package management system. I've also 
brought in the jar for the proper version of IBM
DB2 JDBC driver and its corresponding "license jar" to match
the DB2 instance version (versioning between DB2 and JDBC
driver are tightly coupled).

On the legacy Tomcat 5.0 / JDK 1.5 platform, the database
connection configuration info is handled in a seemingly
customized way - something to do with virtual hosts. At the top of 
the Tomcat-instance-wide server.xml file is
this structure:

<!DOCTYPE web-app[
<!ENTITY vhosts SYSTEM "vhosts.xml">
      ]>

But for now, I'm not interested in dealing with any kind of
virtual host arrangement.  The impetus behind that was
so that users can run two independent sessions of the app in
two separate browser tabs or windows .

In the vhosts.xml file is info that looks like it ought to
belong in the app's context.xml file.  I understand
that how context sections are written have changed since 5.0
and I *think* I've got that worked out.

The app's original MANIFEST.MF file has this in it:

      Classpath:
WEB-INF/classes/mycapp/resource
WEB-INF/classes/myapp/resource
       /tld
WEB-INF/classes/elms/resource/hbm/MYAPP

So:  given a working platform and after deploying the
app war that I've been given (let's call it "myapp.war"),
here are the post-deploy steps I've worked out so far:

* Create a symlink for
$CATALINA_BASE/webapps/myapp/WEB-INF/lib/c3p0.jar to where
the package manager has put c3p0.jar

* Create symlinks for db2jcc.jar and db2jcc_license_cu.jar
in $CATALINA_BASE/webapps/myapp/WEB-INF/lib to where I've
put them under /usr/src

* Generate a new
$CATALINA_BASE/webapps/myapp/META-INF/context.xml (see
below) and symlink
$CATALINA_BASE/conf/Catalina/localhost/myapp.xml to it

* Add the following to
$CATALINA_BASE/webapps/myapp/WEB-INF/web.xml, before the
closing "</web-app>":

<resource-ref>
<description>DB connection pool for
MYAPP</description>
<res-ref-name>jdbc/myappqa</res-ref-name>
<res-type>com.mchange.v2.c3p0.ComboPooledDataSource</res-type>
<res-auth>Container</res-auth>
</resource-ref>

I've created a context.xml that looks like:

<Context
docBase="${catalina.home}/webapps/myapp" path=""
    reloadable="false">
<Resource name="jdbc/myappqa"
             description =
"MYAPP connection pool"
             auth="Container"
            type="com.mchange.v2.c3p0.ComboPooledDataSource"
            username="myappuser"
            password="myapppassword"
            driverClass="com.ibm.db2.jcc.DB2Driver"
            url="jdbc:db2://mydb2server:50000/TESTDATA"
            factory="org.apache.naming.factory.BeanFactory"
             minPoolSize="15"
             .
             .<scissors of
brevity applied - more parameters set>
             .
             />
</Context>


I've been able to browse to the app and get a login page,
but things explode at login attempt, i.e., first attempt to
access the data source.

Question 1:  For this to work, do I need to add
"WEB-INF/lib" to the "Classpath:" list?  There are
about 80 jar files (including log4j, ftpbean, Hibernate) in
there aside from the symlinks I've added for the c3p0, JDBC
driver, and license jar files.

Question 2:  In my context.xml, is that one parameter
supposed to be "driverClass" or "driverClassName"? I've seen both 
used seemingly for the same purpose.

Question 3:  Some customization has been done
involving hibernate.properties which I don't think is
necessarily causing a problem (its "meat" has been replaced
by a reference to another file much like server.xml), but in
there I've noticed this:

<property
name="hibernate.connection.pool_size">15</property>

As I understand it, setting this parameter activates
Hibernate's own connection pooler and further that
Hibernate's own connection pooler is not supposed to be used
in any capacity other than learning and testing.  Does
having this setting be in here mean that this app was built
(intentionally or not - likely not) to use Hibernate's
connection pooler and c3p0 end-to-end?

Thanks in advance for your opinions/assistance.






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