Problem with Sun's Bootstraping Example

[Zak Nixon]

Here is my problem:
I am trying to recreate the example located here :
Bootstraping Example

I have set up everything to the tutorials specifications, yet I still
get this error :

C:\Davidson_Projects\RMI_HTTP\ClientBootstraper>java -Djava.rmi.server.codebase=
"http://192.168.1.95:2002" RMIClientLoader
<a href="http://192.168.1.95:2002" target="_blank" rel="nofollow">http://192.168.1.95:2002</a>
Asking for: <a href="http://192.168.1.95:2002" target="_blank" rel="nofollow">http://192.168.1.95:2002</a> and RMIClient
RMIClientLoader, class not found: java.lang.ClassNotFoundException: access to class loader denied

To resolve this problem, I have followed a topic on JGuru that seemed to encounter the same issue, but we can not fix it using their advice.
Bootstrap Topic

Please help in any way you can. If you have that example up and running,
please reply.

Running out of options,

Zak ( ) and Morgan ( )

[Nathan Pruett]

I was able to get the code to run by using either the "good" "use a policy file" approach or the "bad" "override checkPermission in RMIClientBootstrapSecurityManager" approach... which approach did you use?

[Zak Nixon]

Well, both ways. Can you somehow post all your code and batch files, so I can
try to run them on this side? We are really frustrated, and cannot get this to work.

Thanks

Zak

[Zak Nixon]

What version of Java are using to run this example ?

[Zak Nixon]

Current status: Still no solution.

We have tried to get the example working in 1.4 and 1.5, but the error is the same. (i.e. Access denied to the classloader).

This is our file structure:

C:\RMI_HTTP
|- server (contains ClassFileServer and ClassServer, also the batch file to run the http server)
|- serve (contains all of the server + client code. Hello,Hello_Impl,MessageObject,RMIClient,RMIServer, and the batch file)
|- client (contains the RMIClientLoadernRMIClientBootstrapSecurityManager)

Also here are my batch files:

Batch for the HTTP Server:

rem     This file will run a simple HTTP Server that only functions as a 
rem     source for Java class files.
rem
rem     The first parameter is the TCP/IP port number on which this server
rem     listens.
rem
rem     The second parameter is the local directory that contains the
rem     Java class files to be served.
 
java ClassFileServer 100 "C:\\RMI_HTTP\\serve\\"

Batch for the RMI Server :

java -Djava.rmi.server.codebase="http://192.168.1.99:100/" -Djava.security.policy="C:\\java.policy" RMIServer
pause

And finally the client bootstrap program:

java -Djava.rmi.server.codebase="http://192.168.1.99:100/" -Djava.rmi.policy="C:\\java.policy" RMIClientLoader
pause

Now, for my policy files:

C:\\java.policy (basically just modified the JDK's policy file)

// Standard extensions get all permissions by default
 
grant codebase "file:C:/RMI_HTTP/serve/-"{
permission java.security.AllPermission;
};
 
grant codebase "http://192.168.1.99"{
permission java.security.AllPermission;
};
 

// default permissions granted to all domains
 
grant { 
// Allows any thread to stop itself using the java.lang.Thread.stop()
// method that takes no argument.
// Note that this permission is granted by default only to remain
// backwards compatible.
// It is strongly recommended that you either remove this permission
// from this policy file or further restrict it to code sources
// that you specify, because Thread.stop() is potentially unsafe.
// See "http://java.sun.com/notes" for more information.
permission java.lang.RuntimePermission "stopThread";
 
// allows anyone to listen on un-privileged ports
permission java.net.SocketPermission "localhost:1024-", "listen";
 
// "standard" properies that can be read by anyone
 
permission java.util.PropertyPermission "java.version", "read";
permission java.util.PropertyPermission "java.vendor", "read";
permission java.util.PropertyPermission "java.vendor.url", "read";
permission java.util.PropertyPermission "java.class.version", "read";
permission java.util.PropertyPermission "os.name", "read";
permission java.util.PropertyPermission "os.version", "read";
permission java.util.PropertyPermission "os.arch", "read";
permission java.util.PropertyPermission "file.separator", "read";
permission java.util.PropertyPermission "path.separator", "read";
permission java.util.PropertyPermission "line.separator", "read";
 
permission java.util.PropertyPermission "java.specification.version", "read";
permission java.util.PropertyPermission "java.specification.vendor", "read";
permission java.util.PropertyPermission "java.specification.name", "read";
 
permission java.util.PropertyPermission "java.vm.specification.version", "read";
permission java.util.PropertyPermission "java.vm.specification.vendor", "read";
permission java.util.PropertyPermission "java.vm.specification.name", "read";
permission java.util.PropertyPermission "java.vm.version", "read";
permission java.util.PropertyPermission "java.vm.vendor", "read";
permission java.util.PropertyPermission "java.vm.name", "read";
};
 

We have just about tried everything we can think of. Can anyone help us?

Thanks

Zak

[Nathan Pruett]

I'm using JDK 1.4 on the machine I got the example to work on.

OK, I'll go through the steps I did to get it to work...

Downloaded all the files into these directories -

C:\
 | - source\
      |
      | - RMI_Client\
      |    | - RMIClientBootstrapSecurityManager.java
      |    | - RMIClientLoader.java
      |    | - runclient.bat
      |
      | - RMI_HTTP
      |    | - ClassFileServer.java
      |    | - ClassServer.java
      |    | - runhttp.bat
      |
      | - RMI_Server
           | - Hello.java
           | - HelloImpl.java
           | - MessageObject.java
           | - RMIClient.java
           | - RMIServer.java
           | - runserver.java

Next, edited the RMI_HTTP/runhttp.bat file to point to the RMI_Server directory -

java ClassFileServer 2002 C:\source\RMI_Server\

Compiled all code in the RMI_HTTP directory -

javac *.java

Started runhttp.bat in a new terminal window. See -

ClassFileServer started...

and the ClassFileServer keeps running.

Now to get the RMI_Server part working.
First, I had to edit the following line into the RMIServerSecurityManager inside the RMIServer.java source file -

class RMIServerSecurityManager
    extends RMISecurityManager
    {
    ...
    public synchronized void checkAccept(String host, int port)
    {
        System.out.println( "checkAccept()" );
    }
    ...
    }

Otherwise, when the server runs it throws an AccessException (I'm sure that this could be done using a .policy file, but if we're going to use a SecurityManager with an overridden checkConnect() method, I don't see why an overridden checkAccept() is going to hurt anything.)

OK, now compile the RMI_Server classes and run rmic on the remote interface -

javac *.java
rmic HelloImpl

Finished with that, start runserver.bat in a new terminal window, see some log output, and it keeps running...

Now, on to the RMI_Client code.

First, the *bad* way - overridding checkPermission() so there are no security checks.
Edit runclient.bat to use your hostname -

java -Djava.rmi.server.codebase=http://localhost:2002/ RMIClientLoader

Edit the RMIClientBootstrapSecurityManager.java source to override checkPermission() -

public class RMIClientBootstrapSecurityManager
    extends RMISecurityManager {
...
 public synchronized void checkPermission(java.security.Permission p)
 {
 }
...
}

Compile (javac *.java), run (runclient.bat), and voila! everything runs (with no security). You'll see some output in the client terminal and it will complete. The RMI_HTTP and RMI_Server terminals will also display some new log messages.

Now, how to make it work with a policy file -

Remove the changes to the RMIClientBootstrapSecurityManager.java file (if you've made them).

I created a policy file (called "policy" in the RMI_Client directory, with the contents -

//////   client file:  policy   //////
 
grant codebase "file:///C:/source/RMI_Client" {
  permission java.net.SocketPermission "localhost", "connect";
};

Then, I edited the runclient.bat to contain (Note: the following is on multiple lines due to formatting, in reality this is all on one line) -

java -Djava.security.policy=C:\source\RMI_Client\policy 
-Djava.rmi.server.codebase=http://localhost:2002/ RMIClientLoader

Again, compile (javac *.java) and run (runclient.bat) and, again it runs (this time with a *teensy, tiny* bit more security).

[ February 08, 2006: Message edited by: Nathan Pruett ]
[ February 09, 2006: Message edited by: Nathan Pruett ]

[Zak Nixon]

Wow, Nate, great job. We followed your tutorial, and it worked beautifully.

Some changes we saw in your examples need to be made for clarity though.

1. When compiling the RMI_Server classes the command is :

   
javac *.java
rmic HelloImpl
 

There was a typo stating compiling *.jave files, which is not the case.

2. In the client .bat file (runclient.bat), the policy file flag should be the following :

-Djava.security.policy=C:\source\RMI_Client\policy.policy 

The trailing .policy was missing.

Other than that, everything seems 100% correct.
Thanks again Nate for your help. It is worth 1 trillion dollars.

Until the next RMI question,

Zak and Morgan

[Nathan Pruett]

Glad that you got it to work!

I went back and fixed the "jave" typo, but the policy file I used was just called "policy" - you can call it whatever you want "Client.policy", "policy", ".policy", "poly.see", "ZAK_ROCKS", "no.name" - as long as it follows your OS file naming conventions. You just have to be sure to use the same name when specifying it in the java.security.policy property.

[Tamilselvan Guru]

Excellent Work... This tutorial saved lot of my time...

Thanks Nate