Finally.... Video captured from applet in Vista!!

Question

Hello!
Hurray!! finally I can see myself smiling and waving back in browser in Vista.
I mentioned in another thread just a day earlier that I will post a new topic if I succeed in capturing from applets in Vista, so thats what I am doing.... This thread is all about how achieved it.
I have seen many posts mentioning problems in capturing from applets in vista. I was also one of the sufferer. And most people including me blamed that on restricted sandbox of Vista. But surprisingly it was all about classpath.
I think I mentioned in some earlier thread that the 'Java console' shows the classpath to be *"{JREHOME}/classes"* instead of the classpath specified in CLASSPATH environment variable. You can check that by pressing 's' which *'dumps system and deployment properties'* in the Java Console. You can check the classpath by noting the value of *"java.class.path"* field which for my case was"C:\\PROGRA~1\\Java\\jre6\\classes". This turned out to be the main problem. The applet was not accessing any classes from the real CLASSPATH instead it was considering the classpath to be jrehome/classes. So, now I had enough hint what to do next. I simply created a folder 'classes' in {JREHOME} and copied the jmf registry files to that folder. By registry files I mean *'jmf.properties'* and *'jmf.properties.orig'* files in *'{JMF Install}/lib'* folder (actually i don't which among them has got some thing to do with the registry but I copied them both). So, after doing this, all my capture applets, whether signed or unsigned started running. Earlier they all were throwing *"java.lang.RuntimeException: No permission to capture from applets"* exception even after I have allowed capture from applets in JMF registry. That was perhaps not taking affect because of classpath issues. So, thats the story.... if someone faces the same problem he can use this workaround or you can say hack ;-)
Some questions which can be asked from me would be:
1- Did you set your CLASSPATH environment variable correctly?
ans: Yes, infact all my jmf applications were running correctly, the problem was only with the applets.
2- What classpath other systems (e.g. XP) mention in the Java console ?
ans: surprisingly, the same classpath that Vista mentions i.e. {JREHOME}/classes. I tested on XP-SP3, but it supposedly had access to the real CLASSPATH also.
3- Is this problem really Vista specific?
ans: Can't say... but it can be. It maybe the case that Vista does not allow access to real CLASSPATH, but this problem can easily be my system specific, it would be called a general vista problem if this happens on all Vista systems, I need volunteers for this test. captfoss, can you please test this on your system? :)
4- Is this problem JMF specific?
ans: Chances are low. I am going to test this by making my own test library and adding it to classpath and then try to access it via applet. If this fails then this problem is not JMF specific.
Drawbacks of this work around:
1- This can be a pain for ordinary users , copying registry files from JMF/lib to JRE/classes.
2- Whatever you change in JMF registry would not be effective to the applets. As the old registry files are to be replaced with new registry files every time JMF registry is changed for changes to take effect in applets.
The real big question:
How can we force Vista to look in the real CLASSPATH? this is the real question, if this can be done just by changing some settings then all this workaround is useless :) I am looking forward to the answer of this question.....
captfoss, I would highly appreciate your comments.
Thanks for reading this rather long post.... :)
Thanks!

Answer 1

A couple of comments here...the answer is, in fact, no, you didn't set your classpath correctly. One, you're probably using a JAR file to run your applet from (I'm not an applet programmer but I do believe that a JAR is required) which do not use the environment's classpath, they use their manifest classpath. No, the applet was not jared.
Second, I believe that the browser itself specifies its own classpath, which you cannot modify. I believe this would be considered a security feature...Both IE7 and firefox3 fail.
"You have little control over the CLASSPATH used by a browser for an Applet"
[http://mindprod.com/jgloss/classpath.html]
Ok this maybe the reason, I will go through the link....
2- What classpath other systems (e.g. XP) mention in the Java console ?
ans: surprisingly, the same classpath that Vista mentions i.e. {JREHOME}/classes. I tested on XP-SP3, but it supposedly had access to the real CLASSPATH also. There isn't a "real" CLASSPATH, there is just the classpath stored as an environmental variable. It's no more or less real than the one in the browser.Thats what I thought.... but I think {JREHOME}/classes is the default class path used by the jre whether we set any CLASSPATH variable or not it would be there, something of that sort.....
Lots of possibilities, but my best guess is that Vista doesn't let code running in the browser read environmental variables.Yes, I fully agree with this. I think I should file a bug report.
4- Is this problem JMF specific?
ans: Chances are low. I am going to test this by making my own test library and adding it to classpath and then try to access it via applet. If this fails then this problem is not JMF specific. Definately not. It would apply to any code that wants to access something on the classpath. You are right... as I said I would test it, I tested by making a small library, added it to classpath, made an application and an applet. As expected, the aplication worked while the applet failed.
Any application with a custom classpath would be affected.I don't understand what you mean here, do you mean 'Class-path' header in jar manifest?
I like the "installation requirement" part. I'd suggest looking into that. Alternately, there may be something in the security settings to allow access to environmental variables.I will try to look into both.
I just tried this statement in applet:
System.out.println( System.getProperty( "java.class.path" ) );It threw this exception:
Exception: java.security.AccessControlException: access denied (java.util.PropertyPermission java.class.path read)
I don't know what conclusion should I draw from this... this does mean applet has no right to know what the classpath is.... but this doesn't mean even jre plugin responsible for running applet does not know what the classpath is :)
Finally, I want to say that due to some problems I could not post earlier, and I may not post for few more days. But I appreciate your comments and would appreciate more of them.
Thanks!