The RMISecurityManager Class

The RMISecurityManager is a subclass of the java.lang.SecurityManager class. It is used to set the security policies that govern the behavior of stub and skeleton classes. If a security manager is not set, an application will not be able to export objects over the network. By default, JVM does not allow an application to load classes dynamically, unless the application has set up its own security manager. The security manager throws an AccessException to indicate that the caller does not have permission to perform the action requested by the method call.

To use the RMISecurityManager in your application , add the following statement to your code:

 System.setSecurityManager(new RMISecurityManager());

Constructor

• public RMISecurityManager() - The security manager is set by using the System.setSecurityManager() method.

The RMIClassLoader Class

A class loader is necessary for loading classes. This includes loading classes, locally or remotely. The RMIClassLoader provides static methods for loading classes from a network location. It first attempts to locate classes locally. If the classes are not found locally, it loads them from a network location.

Methods

• public static ClassLoader getClassLoader(String codebase) - This method returns a class loader that loads classes from the given codebase URL path.

• public static Class loadClass(String codebase, String name) - It loads a class from a codebase URL path

RMI heavily depends on the Object serialization mechanism to transmit data from one JVM to another JVM. One of the central and unique features of RMI is its ability to download the code of an object(s) class if the class is not defined in the receiver(s) virtual machine. For dynamic class loading:

• A security manager must be installed.
• The java.rmi.server.codebase property must be specified, so that the stub class can be dynamically downloaded to the registry and then to the client.