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At the heart of the XA35 is its proprietary XG3 technology, which performs the processing of XSL in hardware. With 2 GB of RAM and no moving parts, the XA35 uses only flash storage. Its VRRP (Virtual Router Redundancy Protocol)-based failover provides redundancy for mission-critical applications. Built for reliability and speed, the XA35 can be deployed in co-processor (side-arm) mode, in-line in proxy mode, or both modes simultaneously.

Configuration is accomplished via telnet or SSH, but both are disabled by default for security reasons. A separate 10/100-Mbps management port can be used to provide management access. Initial configuration via the console is straightforward, but you must use the command-line interface. The company says it has plans to expose some of the configuration and the performance statistics gathered by the XA35 in a graphical interface. The XA35 gathers statistics on throughput and number of transactions processed by the unit in several intervals--5 minutes, 30 minutes and the past 24 hours.

Although the $54,995 price tag of a single XA35 may sound expensive, when you add up the purchase and maintenance costs of servers the XA35 lets you decommission or simply not purchase, the product is well worth its price if XSLT is a part of your mission-critical infrastructure.

Transformations

Much like any other Layer 7 device in proxy mode, the XA35 accepts requests from clients and processes them by communicating with configured back-end servers. When the XA35 receives a request, it gets the XML from the back-end server, then determines the XSL to be applied. If the XSL has been previously processed and compiled down to machine code by the XA35, it will be found in the cache on the device, applied to the XML and returned to the client. If the XSL is not in cache, it will be retrieved from the back-end server, compiled and cached.

In co-processor mode, the XA35 is invoked by the calling application. The XA35 works with Altova's XML Spy, which lets developers test and deploy their XSL via the XA35 right from the IDE, much in the same manner that other IDEs provide deployment of code from the desktop to the server. Because the XA35 can perform in both modes at the same time, it can provide proxy services for multiple applications. The XA35 also offers URL rewriting and basic Layer 7 routing functionality based on any HTTP header, including SOAP (Simple Object Access Protocol) headers.

By using the XA35 as the XSLT engine of choice for an enterprise, XSLT can be standardized across applications without fear of introducing quirky behavior as the result of XSL transformations performed in disparate engines.

Benchmark Tests

I used ApacheBench and combined an Apache Web server, a Tomcat servlet engine, the commonly used Xalan XSLT engine and an IBM JVM to create benchmarks. I processed 400 KB of XML and associated 400 KB of XSL (real-life examples from a com-pany utilizing XML and XSLT). The results were abysmal--it took 132 seconds for the Xalan to process 25 transactions; it took the XA35 a mere 1.8 seconds to do the same.

SSL (Secure Sockets Layer) support, both client-to-XA35 and XA35-to-back-end devices, is available for an additional $10,000. SSL acceleration is provided via the latest Broadcom chipset, and the company claims the chipset can handle 4,000 transactions per second.

Lori MacVittie is a technology editor for Network Computing. Write to her at lmacvittie@nwc.com.