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SafeServer.javaAPI DocExample13156Mon Sep 22 13:30:32 BST 1997None

SafeServer

public class SafeServer extends Object
This class is a program that uses the Server class defined in Chapter 9. Server would load arbitrary "Service" classes to provide services. This class is an alternative program to start up a Server in a similar way. The difference is that this one uses a SecurityManager and a ClassLoader to prevent the Service classes from doing anything damaging or malicious on the local system. This allows us to safely run Service classes that come from untrusted sources.

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Constructors Summary
Methods Summary
public static voidmain(java.lang.String[] args)

    try {
      // Install the Security manager
      System.setSecurityManager(new ServiceSecurityManager());

      // Create the ClassLoader that we'll use to load Service classes.
      // The classes should be stored in (or beneath) the directory specified
      // as the first command-line argument
      LocalClassLoader loader = new LocalClassLoader(args[0]);

      // Create a Server object that does no logging and
      // has a limit of five concurrent connections at once.
      Server server = new Server(null, 5);

      // Parse the argument list, which should contain Service name/port pairs.
      // For each pair, load the named Service using the class loader, then
      // instantiate it with newInstance(), then tell the server to start
      // running it.
      int i = 1;
      while(i < args.length) {
        Class serviceClass = loader.loadClass(args[i++]);      // dynamic load
        Service service = (Service)serviceClass.newInstance(); // instantiate
        int port = Integer.parseInt(args[i++]);                // get port
        server.addService(service, port);                      // run service
      }
    }
    catch (Exception e) { // Display a message if anything goes wrong
      System.err.println(e);
      System.err.println("Usage: java SafeServer "  +
                         "<servicedir> <servicename> <port>\n" +
                         "\t\t[<servicename> <port> ... ]");
      System.exit(1);
    }