FULL PRODUCT VERSION :
java version "1.6.0"
Java(TM) SE Runtime Environment (build 1.6.0-b105)
Java HotSpot(TM) Client VM (build 1.6.0-b105, mixed mode, sharing)

ADDITIONAL OS VERSION INFORMATION :
windows 2000 sp4
windows XP sp2

EXTRA RELEVANT SYSTEM CONFIGURATION :
Internet Explorer 6
Internet Explorer 7
Firefox 2

A DESCRIPTION OF THE PROBLEM :
With multiple applets running on the same web page you used to be able to make them use the same classloader by ensuring the cache_archive and cache_version parameters were the same (i.e. same codebase). Using the same classloader allowed the applets to share information.

In 1.5 (1.5.0_10) the applets always use the same classloader if the cache_archive and cache_version tags match in the OBJECT and EMBED sections

In 1.6 the applets use different classloaders when you use the cache_archive parameter, they share a classloader if you don't use the cache_archive parameter

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :

1) Complie the java source below and package app1.class into app1.jar and app2.class into app2.jar

2) Create a directory called test15versioned copy the JARs into it
3) Create a directory called test16versioned copy the JARs into it

4) Create the html and js files from the source provided
   test15versioned will have the following:

Main.html
app1.15.v.html
app2.15.v.html
app1.15.v.js
app2.15.v.js
app1.jar
app2.jar

5) Create the html and js files from the source provided
   test16versioned will have the following:

Main.html
app1.16.v.html
app2.16.v.html
app1.16.v.js
app2.16.v.js
app1.jar
app2.jar

6) Install JRE 1.5.0_10 and JRE 1.6.0

7) Open test15versioned/Main15.html in internet explorer
8) Open the java console
9) ensure the text app1 started and app2 started is showing
10) Press l to dump classloader list
11) Note ONE classloader

12) Open test16versioned/Main16.html in internet explorer
13) Open the java console
14) ensure the text app1 started and app2 started is showing
15) Press l to dump classloader list
16) Note TWO classloaders

17) As a final test remove the cache_archive parameter from app1.16.v.js and
app2.16.v.js.

18) Repeat steps 12-15
19) Note ONE classloader

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
One classloader should be used when the applets have the same cache_archive, cache_version and codebase

ACTUAL -
Multiple classloaders are used if the cache_version parameter is used

REPRODUCIBILITY :
This bug can be reproduced always.

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Attached Seperatly
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CUSTOMER SUBMITTED WORKAROUND :
Do not use cache_version