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POspecial things to do when using rmi + plugins
 

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    <p>I have an application <code>FooApplication</code> (code in <code>foo.jar</code>) with a plugin <code>BarPlugin</code> (code in <code>foo-bar-plugin.jar</code>). The application instantiates an instance of the plugin dynamically. It works great. </p> <p>FooApplication has some functionality accessible via an RMI interface <code>FooRemote</code>. That also works great, except for one thing. <code>FooRemote</code> has a method to access <code>Remote</code> objects exported by plugins, and I get an java.rmi.UnmarshalException when I try to hand out one of those plugins to an RMI client.</p> <pre><code>public interface FooRemote extends Remote { /* other methods */ public RemoteControl getPluginRemoteControl(int i) throws RemoteException; } /** just a named Remote object for debugging purposes */ public interface RemoteControl extends Remote { public String getName() throws RemoteException; } </code></pre> <p>What I am doing in my FooRemoteImpl is the following:</p> <pre><code>/* just a test object */ private static class RC0 extends UnicastRemoteObject implements RemoteControl { public RC0() throws RemoteException { super(); } @Override public String getName() throws RemoteException { return "RC0"; } } @Override public RemoteControl getPluginRemoteControl(int i) throws RemoteException { int j = i; if (j &lt;= 0) return new RC0(); Collection&lt;RemoteControl&gt; rclist = this.model.getApplicationPluginRemotes(); for (RemoteControl rc : rclist) { if (--j == 0) return rc; } return null; } </code></pre> <p>When I call <code>FooRemote.getPluginRemoteControl(0)</code>, it hands out an instance of my dummy class <code>RC0</code>, and works fine from a client. When I call <code>FooRemote.getPluginRemoteControl(1)</code>, it tries to hand out one of the real plugin remotes, and it fails:</p> <pre><code>??? Java exception occurred: java.rmi.UnmarshalException: error unmarshalling return; nested exception is: java.lang.ClassNotFoundException: com.example.plugin.BarPluginRemoteControl (no security manager: RMI class loader disabled) at sun.rmi.server.UnicastRef.invoke(Unknown Source) at java.rmi.server.RemoteObjectInvocationHandler.invokeRemoteMethod(Unknown Source) at java.rmi.server.RemoteObjectInvocationHandler.invoke(Unknown Source) at $Proxy5.getPluginRemoteControl(Unknown Source) Caused by: java.lang.ClassNotFoundException: com.example.plugin.BarPluginRemoteControl (no security manager: RMI class loader disabled) [ more stuff deleted ] </code></pre> <p>What gives?</p>
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