Actual situation: We have several huge forms-applications running with JINItiator 184.108.40.206. No problem.
Now we have one new forms-application developed, which runs on Forms 10g Rel. 2 with JInitiator 220.127.116.11. Some PC's now need the 18.104.22.168-installation parallel to their 22.214.171.124 installation.
In our test-environment the guys found out, that the JInitiator-Installation will change registry-keys for HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\App Paths\javaw.Exe and some other keys.
They fear, that installing 126.96.36.199 on a PC where 188.8.131.52 is running changes permanently the destination for "javaw.exe". That may be no problem, but the test-guys say: "You have to test the whole big old application on 184.108.40.206, before we install 220.127.116.11"
What should we do? We have to use 18.104.22.168 for our little application and we have no time to check, if the old application with 22.214.171.124 is running as before...
We have versions 9,13 and 18 running. They definitely run seperate versions of Jiniator.
There are issues with using multiple versions however. If the browser session has already started a JVM it won't start another. If the jiniator version ipreviously started is too high the application won't start. This is counter inuitive. If you start the new app first the old app won't start from the same browser session. It will start from a new browser instance.
You can run as many Jinits on the same machine as your hard drive can hold as long as they are versions 126.96.36.199 or newer. Only the one which is called in the CLSID or mime type (of the html) will be used.
Also, javaw is not called when running applets.
You can prove all of this with SysInternals FileMon:
I have 2 applications running on many terminals, each having an instance of 188.8.131.52 for an old application and 184.108.40.206 for a new application. For over a year, there haven't been any problems reported, but I'd certainly like to know if people have faced any - for precautionary measures.