3.3.2 Specific Versus Generic

Another design choice is whether you need a specific manager or a generic management solution. The two examples above are applications designed for a specific task. Their inputs are known, their agents are listed in address tables, and they are programmed to provide a specific output for given inputs.

A generic management solution is much more complex. It takes advantage of all dynamic features in the JMX architecture. Agents and their resources are not known ahead of time, data formats are unknowable and the output is at best a set of guidelines. Generic managers do not implement a task, they implement a system for integrating new tasks.

Let us extend our printer management system to perform some generic management. First, we set a guideline of only managing printers whose agents contain discovery responders. That way, we can detect when printers are plugged in, we can connect to their agents, and we can add them to the management console automatically. Then we make a space in our user interface for a custom printer interface. If the printer's agent has a resource called HTMLserver, we will load the data from this server into the screen frame reserved for this printer.

Users of this management system can now install a server-enabled printer, and it will be managed automatically when it is plugged into the network. Of course, this system is only viable if you advertise the ways in which it is generic, so that printer manufacturers are encouraged to add Java dynamic management agents to their products.

Generic management systems are complex and perhaps difficult to design, but they are definitely in the range of possibilities offered through the JMX architecture and the Java Dynamic Management Kit.