State capture and resource control for java: The design and implementation of the aroma virtual machine

Although Java is currently riding a rising wave of popularity, current versions fail to address many of the unique challenges posed by the new generation of distributed applications. In particular the advent of peer-to-peer computing models and the proliferation of software agents motivates various requirements that go beyond the capabilities of current Java Virtual Machines: • Full state capture. To support checkpointing and load balancing, the Virtual Machine (VM) must be able to capture its complete state including all threads, objects, and classes in the heap. To support requirements for strong "anytime"mobility and forced migration (such as when a host is about to go offline), the VM must be able to support asynchronous requests to capture execution state for a thread or thread group. • Dynamic access and resource control. The security model in Java 2 [4] provides a fairly comprehensive model for access control but does not allow for dynamic permission revocation. Once permission is granted to a process, that permission is in effect for the lifetime of that process. Furthermore, there is no way of specifying the amount of a resource that is granted, assuring a specific quality of service for each process. For example, one would like to be able to limit the quantity of hard disk, network, or CPU usage that is available to a given process or to determine the rate at which the resource may be used. Denial-of-service conditions on a host or network resulting from code that is poorly programmed, malicious, or has been tampered with are impossible to detect and interrupt without dynamic monitoring and control mechanisms for individual processes. • Resource accounting. Tracking of resource use, based on resource control mechanisms, enables accounting and billing mechanisms that hosts can use to calculate charges for resident programs. The same mechanisms can be used to detect patterns of resource abuse.