OptiView dedicates 400 MB to 500 MB of RAM to the cache, with an additional 1-GB RAM maintaining a list of handles to Web objects stored on disk. The device is intended to be controlled via a Web-based interface with only initial configuration allowed via the CLI (command-line interface).

The TurboCache network comprises two "mother" caches--one on the East Coast and another on the West--that help the local TurboCache build and maintain a fast, reliable proxy caching network. The locally deployed unit is automatically upgraded with new features and a regularly updated database of compressed, cached content from the mother caches.

Client configuration can be completed via PAC (Proxy Automatic Configuration) files on most systems or by manually configuring the proxy settings in browsers, such as Opera on Linux and Microsoft Internet Explorer (IE) on Windows CE 3.0, that do not support PAC files. I tested the product with IE 5.0 and 5.5 on Microsoft Windows as well as with Netscape Navigator 4.78 and Galeon 0.12.1 on Linux.

End users (read: those stuck in dial-up hell or broadband users who desire even speedier downloads) can subscribe to a service offered by OptiView based on the TurboCache for a relatively low price--$5 to $10 per month. Network administrators can lease a TurboCache unit for deployment within the corporate infrastructure. Don't forget: OptiView's service is proxying only so you still need your own ISP. The corporate-deployed TurboCache is available internally or externally (for mobile employees), depending on configuration.

A Cache for All Devices

I configured an early beta version of TurboCache at our Real-World Labs® in Green Bay, Wis. This version comprised all the core functions of the end product but lacked a Web-based GUI, which is intended to be the only method of configuration (except initial network configuration, of course). Planned for the final release but not available in the beta version I tested are the ability to control access by user and network, configurable ports for proxy services, and access to reporting and usage statistics. The browser is configured on OptiView's Web site by specifying a PAC file set up specifically for each customer.

Three sets of proxy services run on the device: one intended for normal browsing (browsers running on full operating systems like Linux or Windows, for example) and two services for handheld devices. One of these handheld configurations serves pages and images optimized for a black and white Palm16 device; the other is for Windows CE-based devices that serve optimized color images. Although the services are configured for specific devices, you can access them via any handheld or via your browser. I tested both services using a Handspring Visor and a WinCE-based device and found the resulting images acceptable but grainy.

The TurboCache performs compression on text-based content as well as images. The TurboCache optimizes both GIF and JPEG images with little quality degradation. For handheld devices the images also are resized to appear correctly on smaller displays.

Text compression is performed using standard gzip algorithms, but the compression used by the TurboCache device is a "heavier" version than is generally offered by Web servers and content-acceleration devices. The TurboCache method achieves an average 70 percent compression ratio for text, affording dial-up users a much quicker download.

Using SST's TracePlus Web Detective, I loaded graphics-intensive pages from www.cnn.com and www.usatoday.com. First I loaded the pages without TurboCache; then, after clearing the browser cache, I loaded them again using TurboCache. The results were impressive: The www.usatoday.com home page began at 32,081 bytes and was reduced to a mere 9,482 bytes. One of the larger JPEG images served from usatoday.com with a size of 16,027 bytes was squeezed down to 5,611 bytes.

Vendor Information TurboCache, $15,000. Available: March 1. OptiView Technologies, (703) 450-8809; fax (703) 450-8870. www.optiview.com

The question that arises with image compression is quality. Was there degradation, and if so, how discernable was it? To determine this, I loaded the front pages of www.cnn.com and www.usatoday.com again in a Netscape 4.7 browser without using the TurboCache, then loaded the same two pages using Internet Explorer 5.0 with the TurboCache. Once the pages loaded I compared the images side by side and found no difference, though the download size of the images differed considerably.

Scaling Up

Once I'd determined that the core functionality of the TurboCache worked as advertised, I looked to the scalability and reliability of the device. The only concern is that to be fully reliable, TurboCache needs a PAC file, because the PAC file lets you specify how a browser should respond if the proxy is unavailable. With the PAC file, the browser was instructed first to attempt to use the local TurboCache and, if the local unit did not respond, one of the mother caches. If no proxy can be contacted, the browser is instructed to use a direct route.

Because the TurboCache was configured in our labs to let only machines on one internal network use the proxy service, I set up a browser on a machine on another network in the lab. I pointed the browser at the same PAC file used to set up the original browsers, then attempted to load cnn.com. Because the browser was not allowed to access the local TurboCache, the browser attempted to contact one of the mother caches. I was able to load the page via the mother cache in Virginia.

TurboCache has no other method of failover, so take advantage of the PAC file method of configuration to ensure that access is available--even if it may be slow. Scalability testing with RadView Software WebLoad 4.51 showed that a single TurboCache can serve 800 7-KB files per second from its cache while using other processes in the system to refresh and validate content.

For the small or medium enterprise or end user who needs faster HTTP or FTP sessions, TurboCache is a great little caching engine.