on components and pro- vides object persistence by interacting with the object persistence modules in platform components. It can also perform correlation functions on the data based on predefined rules. These rules can be changed dynamically using APIs. What Is NMS? 7. Performance query and threshold component: This component makes per- formance data queries to the database based on parameters in performance records. The threshold functionality permits setting, modifying, and deleting threshold alarm generation rules based on performance data. That is, a thresh- old alarm is generated when a performance parameter crosses a predefined rule value. Both time-based and multidata-based threshold rule setting is possible. Open source applications like "OpenNMS" provide all these functions and can be used as a framework for making specialized NMS for a particular network. Open source applications that offer just one specific management functionality is also available, like "Mandrax" or "Drools" for rule-based fault correlation. 11.7 GUI Components The GUI components are standard applications that convert the formatted data generated from management functional components to user-friendly graphical rep- resentations. For example performance records like link utilization data for a day monitored at regular intervals, would be easier to track and compare when plotted as in a graph. In similar lines the fault data will have a set of predefined fields, SO when the logs have to be presented to the user, it is best to format the logs and show the log contents under a set of header in an MS Excel format based GUI. The flow of data from NE to user through GUI components is shown in Figure 11.4. Some of the sample blocks in GUI components are: 1. Chassis viewers: The network elements usually in a COTS (commercial off- the-shelf) setup based on ATCA (advanced telecom computing architecture) specifications are usually placed in a chassis and connected using a physical medium to initiate interaction. The chassis will have a front en