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Remote Server Mode


Remote server mode lets you access a BeanShell Interpreter inside of a remote VM. With remote server mode activated you can literally telnet into the running application and type commands at the BeanShell shell prompt. Or, even better, you can use any web browser to bring up a remote GUI console.

Warning:
When activated remote server mode can provide unrestricted access to all parts of your application and the host server. This mode should not be used in production environments or anywhere that server security is an issue.

To enable remote access simply issue the BeanShell server() command, specifying a base port number: 

server(1234);
// Httpd started on port: 1234
// Sessiond started on port: 1235

At this point BeanShell will run two services: a tiny HTTP server on the port you specified and the BeanShell telnet session server on the next port (the port you specified + 1).

Web Browser Access

After starting the server you can connect your web browser to the port you specified. BeanShell will respond by sending an HTML page offering you a choice of the Swing based JConsole or the older AWTConsole. You may choose whichever is appropriate for your web browser.

You can skip this decision page by hitting one of the following URLs directly:
http://<yourserver>:<port>/remote/jconsole.html Swing based JConsole page
http://<yourserver>:<port>/remote/awtconsole.html Minmal (old) AWT based Console page
The httpd server then serves the remote console applet. When it starts you will have a BeanShell session that looks like the regular console, but is connected to the remote BeanShell VM.

You can open as many sessions into that VM as you like in this way, but note that unlike the BeanShell desktop environment - All remote sessions share the same global scope. You are effectively working in the same interpreter instance for all connections. This is intended as a feature, as the primary usefulness of this mode is for debugging. You can set variables and access components across many sessions.

Example

Let's look at a quick example of how you might start a remote session from within your application: 

// Java code
import bsh.Interpreter;
i = new Interpreter();

i.set( "myapp", this );  // Provide a reference to your app
i.set( "portnum", 1234 );  
i.eval("setAccessibility(true)"); // turn off access restrictions

i.eval("server(portnum)");

Here we have set up the interpreter instance just as we would to do any other kind of scripting - passing in Java objects using set(). In this case we passed a general reference to our application using 'this', as well. We have turned on accessibility so that we can access private and protected members of our classes (useful for debugging). Finally we start the server on the desired port.

Telnet Access

We mentioned earlier that BeanShell starts its telnet session server on the port next to the HTTP port. You can use any telnet client to access a BeanShell command line directly, in text only-mode, without the use of a web browser. 

telnet <myhost> <port+1>

Note that this command line is not very friendly. In particular it does not respond to gratuitous newlines with a new prompt (as the text only Interpreter command line does).

At the time of this writing there is no explicit way to close a session. BeanShell will simply detect the end of streams.

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