Software streaming revamps desktop

The long-elusive Holy Grail of desktop computing has been the ability to provide IT management with the centralized control it needs to improve security and drive down technology costs without compromising speed, functionality or dependability. Efforts to date – notably thin-client approaches – have fallen short.

Software streaming capitalizes on network advances to dramatically improve software distribution and desktop management. By centralizing control of operating systems and applications, software streaming slashes management and support costs while providing users with systems that are fast, flexible and dependable.

From a conceptual standpoint, software streaming is similar to audio streaming. With audio streaming, songs are maintained on a central server and streamed on-demand to a client PC. Software streaming behaves similarly but, remarkably, applications and necessary elements of operating system software are streamed to a desktop from a central server when a PC is booted up and when any applications or libraries are loaded. While the size of an operating system image might exceed 1G byte, only a fraction of that (less than 100M bytes) is in a desktop computer’s memory at any given time. With software streaming all programs run locally on a desktop PC, enabling much greater productivity than what can be achieved with a thin client.

As with audio streaming, a desktop PC can choose from a variety of “golden images,” which contain different versions of the operating system or are configured with different software. Any image can be streamed on-demand, and all that is required is a simple reboot to so do.

This breakthrough can be achieved only if desktops can boot from the network and do not need their operating systems stored on a locally attached bootable media – that is, no hard drive or compact flash are required to boot the computer. With software streaming, a desktop utilizes preboot execution environment (PXE) firmware, which is standard as part of the BIOS or the option ROM on the network interface card.

Software streaming provides a diskless, software-only solution that is transparent to clients. Windows applications and Windows device drivers run unaltered on desktop PCs. There are no hardware requirements beyond those required by Windows and a PXE-enabled network adapter.

Because software streaming is often misunderstood, it is important to reiterate that an operating system is not downloaded to each desktop, but rather the software-streaming service sends only the files necessary for each desktop to start using the operating system and desired application.

The key benefits of software streaming include:

• It lets IT ensure that all data and applications are controlled centrally to provide the best business continuity and security.

• It helps end users eliminate viruses, spyware and adware simply by rebooting.

• It lets end users run programs locally, achieving the best possible performance.

There are four critical elements required to support a streaming scenario: a communication mechanism, logon services, I/O services and administration.

The communication mechanism with client desktops includes PXE, which uses the DHCP and Trivial FTP standards to deliver an IP address and bootstrap from network servers to a client. Afterwards, PXE executes the bootstrap.

The bootstrap has been configured with the IP address of a logon service, which authenticates a desktop media access control address and establishes a handle to an I/O service. The bootstrap also emulates a hard drive by redirecting Interrupt 13 interrupts – necessary for hard disk reads and writes – over a network to the I/O service rather than to a local hard drive. (Interrupt 13 is the software interrupt for disk I/O used by Microsoft.)

The I/O service plays the role of a network drive and handles caching on a client or server. This doesn’t create significant network traffic and latency because the cache is not large and because software streaming pre-fetches and uses other cache techniques.

The PC functions and executes as if the drive were local and is not aware that the necessary operating system files are being streamed on-demand by using a block-oriented protocol.

Hibbard is vice president of marketing for Ardence. He can be reached at jhibbard@ardence.com.