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Resonate Commander offers round-the-clock, unattended event monitoring and automated responses that correct problems immediately. Even when you're in the office, you'll appreciate its benefits--it reboots servers, modifies your site's configuration and adds servers to handle increased site load as necessary. Commander is designed to work with Central Dispatch, but it also works with the non-Resonate components of your network.

Network Computing conducted an exclusive beta test of Commander 2.3 in our Real-World Labs® at the University of Wisconsin. Overall, I admired its ability to react to network events promptly and efficiently.

A Central Dispatch site consists of various IP services--FTP, HTTP and SMTP--that are load-balanced according to server and usage criteria, including load and content. My test site housed two NT Server 4.0 nodes and a separate NT Server for Commander. (Central Dispatch also supports IBM Corp.'s AIX and Sun Microsystems' Solaris.) Working in conjunction with Central Dispatch is Commander, which consists of three components: a monitor that displays the results of user-defined tests; a controller that creates and configures events via a GUI, a list of predefined values and thresholds, and associated automated responses; and a reporter that gathers and archives Central Dispatch site statistics.

I created a Central Dispatch site consisting of two Windows NT 4.0 server nodes. I then installed the management program, Central Dispatch Manager, on a third NT Workstation for remote management over our network. Using Central Dispatch Manager, I accessed the Commander portion of Central Dispatch.

The Commander Reporting node and SendEvent components must be installed on each node in your Central Dispatch site. In addition, Commander's controller must be installed on a host that's not part of the Central Dispatch site. After I installed the controller on a third machine, I was able to access the Commander options from within the Dispatch Manager GUI.

Playing by the Rules To test Commander's prowess, I created some events intended to trigger the product's rules. Although the Central Dispatch Scheduler component already routes incoming requests around a downed node, Commander acts on a network event to remedy it. During testing, I configured my ping test to remove a server from the Central Dispatch site completely. After removing the network cable, Commander removed the server. Other preconfigured actions include add server/VIP (Virtual IP Address), disable/enable/remove server, and start/stop site and set server weight.

Commander lets you customize an event to invoke actions. Spawning the SendEvent program sends all relevant information about the event to Commander. Once an event occurs, Commander can act on it using any of the preconfigured actions mentioned above.

Commander also uses a Custom Actions feature--executable files or scripts--to react to events. As with a regular action, you select a Custom Action for a given rule within Resonate Commander. When that rule passes, the product contacts the action, and the event name and object name are transferred. I was glad to find that Resonate Commander includes a preconfigured timeout with this feature, so it will not indefinitely block a Custom Action that fails to execute completely.

I used Commander's reporter component to gather statistics for my Central Dispatch site. It offers a trim interval capability, so you can limit the length of time that statistics are stored. Using Central Dispatch Manager, I configured the reporter to gather statistics every two minutes and ran Web Metric traffic-generating software from five client machines for 24 hours. After two separate runs, I used the Reporter Statistics Viewer to export each data file to a comma-delimited text file (.cvs) for import into Microsoft Excel. The viewer displays only one file at a time, but with Excel I could view both test runs simultaneously for convenient comparisons. Upon viewing latency and the number of server failures, I verified that my site was performing within set tolerances.

Send your comments on this article to Gregory Yerxa at gyerxa@nwc.com.