Deciding if and when to buy

The first step in deciding if you need Extensible Markup Language acceleration is determining if users have noticed that network performance has degraded. "I use the grumpy test," said Tom Rhinelander, an analyst at New Rowley Group Inc. "If users are irritated with latency, it's time to consider doing something about it."

If there is a problem that can be traced to XML processing, there are two options. You can add one or more general-purpose servers or you can buy an XML appliance.

Dedicated appliances tend to be much better at handling XML processing. However, even with new applications that use XML, not all of a workload increase is fully attributable to it. Rhinelander said most agencies get heavier XML traffic because they have extended an application to external users. For that reason, there will also be a corresponding increase in non-XML application and database server overhead. The benefit of a general-purpose server is that it can handle both XML and non-XML activity.

"The only way to really know if an XML appliance will make a cost-effective solution is to get it in-house and test it," Rhinelander said.

Starting at about $30,000, an XML accelerator is about the price of a midrange general-purpose server. However, there are hidden costs that are avoided with an XML-dedicated appliance, according to Mark Nagaitis, vice president of marketing with Conformative Systems Inc., which sells XML appliances.

These costs include:

Additional memory and disk capacity and more network and storage connections.

Software licenses for applications, databases, backup software and antivirus software.

More power and floor space consumption in the data center.

But Girish Juneja, senior vice president of product development at appliance maker Sarvega Inc., said that sometimes, you don't even have to consider hidden costs. He said he has seen cases in which appliances provide a positive return on investment when only direct cost of ownership is considered.

In one case, for example, an agency was having performance issues because of XML hits against a back-end application. Company officials determined that XML accounted for 60 percent of the hits against the applications. The applications ran on servers from Sun Microsystems Inc. and were valued at close to $1 million. Just to handle the XML traffic, the organization would have had to purchase at least one more server. Instead, officials were able to handle the XML processing using a number of appliances for a total of $400,000.