Application-mapping tools can work either as agent-based or agentless software. Increasingly, products offer both options. Agentless products do not install anything on other servers and clients and instead rely on polling or network traffic sniffing to locate application components. They may collect data via ODBC, Telnet, Secure Shell, Windows Management Instrumentation, SNMP or FTP.

Agent-based discovery tools, on the other hand, install agents on each server to gather information and send updates to the mapping application. That can be problematic in large organizations if one unit doesn't want another unit's IT department to install the agents on its servers. But agents are capable of gathering more detailed data on an application and can send updates whenever there is a change -- not just when polled by the server.

Investment banking firm JPMorgan Chase & Co. is using Symantec 's Relicore product with agents specifically for its real-time capabilities. "The agentless ones we've seen all do polling at designated times. We need to know right away if there is a change," says Kurt Hansel, assistant vice president for quality assurance infrastructure at JPMorgan.

Gartner analyst Ronni Colville explains, "Some people are afraid of security issues with agents. And data center folks are afraid of overutilization. But at the end of the day, if you want to understand in-depth changes with an application or on a server, you need an agent."

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