Sneak Preview: Gomez Performance Network 5.1's All-In-One Monitoring

Like other Web site monitoring systems, such as those from BMC Software and Keynote Systems, GPN places computers at various PoPs (points of presence) on the Internet. Each computer executes scripts that browse Web pages, capturing performance metrics. To conduct last-mile monitoring, GPN generates scripts from workstations placed in key customer locations worldwide.

Pricing is determined primarily by how many URLs (page sequences and single Web pages) are being monitored, the number of locations selected and how frequently the service is required to test a given Web site. The more locations you choose, the better you can gauge overall performance. Then again, if you're getting no Internet traffic from, say, Mexico, it's a waste of money to have your site monitored from there.

It's All in the Script

Script creation is vital to GPN's monitoring capability. When your Web site is browsed, GPN converts the visitor's clicks and keystrokes to a script that lets the service collect performance data. During testing, we downloaded GPN's script recorder, then waited for it to create a script file using the clicks and keystrokes we had entered while browsing the NETWORK COMPUTING Web site. Next, we saved the file locally and pushed it to the GPN server.

Executing the script was a matter of choosing the transaction and setting parameters. We indicated how frequently and from where the script should run, and defined the thresholds and alerts for each test.Real Numbers

Within minutes, data started pouring in. However, the monitoring service must take measurements over a period of days, even weeks, before it can show meaningful averages and trends.

There are three ways to examine the collected data. One is by testing a URL in real time from a specific location. We found this useful when measurements taken at a particular locale deviated from a set threshold. A second way is through an ad hoc report writer. This tool produces reports that display averages, minimums and maximums, counts, and standard deviations for one or more tests, arranged by geographical location, page and/or error type.

A third way to study the data is through e-mailed reports generated at predetermined intervals. These are available in text or HTML format.

GPN's reporting becomes more granular as you drill down. For example, a report might begin with a graph showing average page-download times plotted over the course of a month. If you select one point on the line, a new report will appear, showing all download times for each location analyzed. You can then zero in on a specific location to reveal the time it took for a computer situated there to retrieve every object on the Web page.

No doubt, GPN's reports provide important details. However, we would have preferred to see overlays showing, for example, the 10 slowest objects. The data is there, and reports containing this sort of root-cause information can be custom-made, but such reports aren't yet available in canned form.Bruce Boardman, executive editor of NETWORK COMPUTING, tests and writes about network management and systems. Write to him at [email protected].