Quick Transit is a product from Transitive Corporation that recently won the 2007 European ICT Grand Prize for Innovation. The product stems from research work at Manchester University, UK, going back more than ten years under Alasdair Rawsthorne, now CTO.
Quick Transit is a technology for virtualizing an OS by translating one set of Operating System (OS) calls to another. This means that you can run an application or service designed for one OS on hardware that does not run that OS. How does that help?
In summary, it gives vendors a way to help you migrate legacy applications or services to new hardware running a different OS. You could take your clunky old UNIX application and put it on your new standard hardware running Linux or a Linux virtual machine.
VMWare is probably the best-known platform for virtualization. VMWare allows you to run multiple instances of an OS on one server. You can run a Windows, Linux or Netware guest OS on a Windows or VMWare host OS. This means you can consolidate your current servers onto fewer larger servers. You can preserve application isolation by running Windows or Linux applications in a dedicated OS but on shared hardware. You can run Linux applications on a Windows server. You can bring virtual servers into play when you need them and store them when you don’t. As a vendor you can distribute your software in a virtual appliance complete with OS, ready to run on a VMWare host.
VMWare works by virtualizing the hardware device drivers. So instead of interacting with the real network card, for example, the guest OS interacts with a standard virtual card that then interacts with the real physical card through the host OS. So you achieve all sorts of versatility, but all on x86 hardware and OS. What you can’t do is run a non-x86 OS on VMWare, because they don’t use hardware the same way. So, for example:
- you can’t run a PowerPC, SPARC, MIPS or PA-RISC OS on VMWare, and
- you can’t run VMWare on PowerPC, SPARC, MIPS or PA-RISC hardware.
This rules out whole sectors of consolidation. For example, if you have a legacy application that runs on a Sun Solaris SPARC OS, you can’t run it on your VMWare infrastructure. You either have to port the application to another OS; or migrate away from the application; or continue to use SPARC hardware.
Quick Transit is the product that could solve this problem. It works by translating OS calls from one to another. This means that you could run your legacy application on Quick Transit, running on a Linux virtual machine. Transitive claim little reduction in performance in the translation, through the use of caching and optimization. The technology is explained here. Does it work?
- Apple have implemented Quick Transit, called "Rosetta", as the technology in their new Mac OS X to enable older Mac PowerPC applications to run on their newer Intel x86 hardware.
- Intel have co-developed a version to enable applications designed for Solaris SPARC to run on their x86, x64 and Itanium processors running Linux. For Intel, it provides a way to move customers to their platforms, and in particular to develop the new Itanium platform, which so far lacks applications developed for it.
- IBM have announced that they will use Quick Transit to enable x86 Linux applications to run on their System p systems.
- Sun have recently announced a version to enable applications designed for Solaris SPARC to run on Solaris x86.
So the technology evidently works and is being adopted. What are the limitations?
- There are no implementations of Quick Transit running on Windows, or Windows applications on Quick Transit. All translations at the moment are on Unix/Linux variations.
- You have the OS working in memory as well as the QuickTransit cache, so you would want a lot of memory. If you want to use it in multiple virtual machines in practice it seems best suited for the newer Itanium platform addressing more memory more effectively.
So in summary:
- VMWare is for consolidating Windows and Linux applications onto fewer servers
- Quick is Transit for migrating legacy applications onto any flavour of Linux on any hardware.