Free jail virtual machines software for linux

Joeq is a virtual machine and compiler infrastructure designed to facilitate research in virtual machine technologies such as Just-In-Time and Ahead-Of-Time compilation, advanced garbage collection techniques, distributed computation, sophisticated scheduling algorithms, and advanced run time techniques.
Joeq is entirely implemented in Java, leading to reliability, portability, maintainability, and efficiency. It is also language-independent, so code from any supported language can be seamlessly compiled, linked, and executed -- all dynamically.
Each component of the virtual machine is written to be independent with a general but well-defined interface, making it easy to experiment with new ideas.
Joeq is released as open source software, and is being used as a framework by researchers on five continents on topics ranging from automatic distributed virtual machines to whole-program pointer analysis.
Joeq is a virtual machine and compiler infrastructure designed to be a platform for research in compilation and virtual machine technologies. We had three main goals in designing the system. First and foremost, we wanted the system to be flexible. We are interested in a variety of compiler and virtual machine research topics, and we wanted a system that would not be specific to researching a particular area.
For example, we have interest in both static and dynamic compilation techniques, and in both type-safe and unsafe languages. We wanted a system that would be as open and general as possible, without sacrificing usability or performance.
Second, we wanted the system to be easy to experiment with. As its primary focus is research, it should be straightforward to prototype new ideas in the framework. With this in mind, we tried to make the system as modular as possible, so that each component is easily replaceable. Learning from our experience with Jalapeno, another virtual machine written in Java, we decided to implement the entire system in Java.
This makes it easy to quickly implement and prototype new ideas, and features like garbage collection and exception tracebacks ease debugging and improve productivity. Java, being a dynamic language, is also a good consumer for many of our dynamic compilation techniques; the fact that our dynamic compiler can compile the code of the virtual machine itself means that it can dynamically optimize the virtual machine code with respect to the application that is running on it. Javas object-oriented nature also facilitates modularity of the design and implementation.
Third, we wanted the system to be useful to a wide audience. The fact that the system is written in Java means that much of the system can be used on any platform that has an implementation of a Java virtual machine. The fact that Joeq supports popular input languages like Java, C, C++, Fortran, and even x86 binary code increases the scope of input programs. We released the system on the SourceForge web site as open source under the Library GNU Public License.
It has been picked up by researchers on five continents for various purposes, among them: automatic extraction of component interfaces, static whole-program pointer analysis, context-sensitive call graph construction, automatic distributed computation, versioned type systems for operating systems, sophisticated profiling of applications, advanced dynamic compilation techniques, system checkpointing, anomaly detection, secure execution platforms and autonomous systems. In addition, Joeq is now used as the basis of the Advanced Compilation Techniques class taught at Stanford University.
Joeq supports two modes of operation: native execution and hosted execution. In native execution, the Joeq code runs directly on the hardware. It uses its own run-time routines, thread package, garbage collector, etc. In hosted execution, the Joeq code runs on top of another virtual machine. Operations to access objects are translated into calls into the reflection library of the host virtual machine.
The user code that executes is identical, and only a small amount of functionality involving unsafe operations is not available when running in hosted execution mode. Hosted execution is useful for debugging purposes and when the underlying machine architecture is not yet directly supported by Joeq. We also use hosted execution mode to bootstrap the system and perform checkpointing, a technique for optimizing application startup times.
Joeq system consists of seven major parts:
- Front-end: Handles the loading and parsing of input files, such as Java class files, SUIF files, and binary object files.
- Compiler: A framework for performing analyses and optimizations on code. This includes the intermediate representation (IR) of our compiler.
- Back-end: Converts the compilers intermediate representation into native, executable code. This code can be output to an object file or written into memory to be executed. In addition, it generates metadata about the generated code, such as garbage collection maps and exception handling information.
- Interpreter: Directly interprets the various forms of compiler intermediate representations.
- Memory Manager: Organizes and manages memory. Joeq supports both explicitly-managed and garbage-collected memory.
- Dynamic: Provides profile data to the code analysis and optimization component, makes compilation policy decisions, and drives the dynamic compiler.
- Run-time Support: Provides runtime support for introspection, thread scheduling, synchronization, exception handling, interfacing to external code, and language-specific features such as dynamic type checking.

Java::SJ::VirtualMachine Perl module is a Java virtual machine.

This module is used by Java::SJ::Config when generating virtual machine representations.

This module allows you to very easily run Java services that rely on complex configuration at the VM and library level. It also provides an easy way of specifying a sensible default configuration that can be overridden by specific applications should they need to.

The system is configured on a machine and application level. The system looks for configuration files in a set of well-known locations, currently these are:

* /etc/sj.conf
* .sj.conf in users HOME directory
* .sj.conf in current working directory

Every application is defined in terms of a similar configuration file. The configuration system has been designed so that it is easy to write a simple and minimal configuration file for a program.

Provided the system has a fairly complete configuration associated with it then an application configuration file need only have the class name to be executed.

Virtual Machine Manager (virt-manager for short package name) is a desktop application for managing virtual machines. It presents a summary view of running domains and their live performance & resource utilization statistics.

A detailed view presents graphs showing performance & utilization over time. Ultimately it will allow creation of new domains, and configuration & adjustment of a domains resource allocation & virtual hardware. Finally an embedded VNC client viewer presents a full graphical console to the guest domain.

The application logic is written in Python, while the UI is constructed with Glade and GTK+, based on mockups provided by UI interaction designers. The libvirt Python bindings are used to interacting with the underlying hypervisor.

This enables the application to be written independant of any particular hypervisor technology, although Xen is the current primary platform. When libvirt is ported to additional hypervisors minimal effort will be required to update the management UI.

Virtual Cron is a PHP library that can check whether it is time to run a periodical task. The class can be used to check whether it is time to run a task that must run from time to time.

It creates a control file to keep track the last time the task was scheduled.

The class can check the control file last modification time to determined whether it passed a given period of time since the last time the task was run.

If the given interval time has passed since the last run, the class recreates the control file and returns true to inform the application that is time to run the task again.

Virtual Tomcat project is a set of scripts designed to ease administration tasks involved with hosting multiple JVM instances and domains using Apache Tomcat and HTTPd.

The system (which uses jsvc to spawn instances) allows users to deploy their own applets from within their home directories, as well as allowing full access to /manager and /admin applets.

The Linux Virtual Server is a highly scalable and highly available server built on a cluster of real servers, with the load balancer running on the Linux operating system.

The architecture of the server cluster is fully transparent to end users, and the users interact as if it were a single high-performance virtual server.

The basic goal of the Linux Virtual Server Project is to:
- Build a high-performance and highly available server for Linux using clustering technology, which provides good scalability, reliability and serviceability.