2.2.3 User/System Interface
The user/system interface illustrated in figure 2.6 has two basic functions. The first is to process data previously collected and stored on the database to provide desired output. The second is to schedule satellites to make new observations, process data obtained by system routines or user-written procedures, and to notify users when information is available for delivery in an appropriate format.
Individuals communicate with IESIS through a generally accessible information net. After valid identity is established, the user indicates via a natural language interface whether data retrieval or satellite scheduling is desired. If this choice is not already known, the system may be interrogated regarding relative costs in time or money of using the most recent file data or the next expected observations. Users requiring data retrieval may interact with IESIS to determine the type of information needed and to develop a carefully tailored retrieval and processing scheme. The user then ends the session or enters additional requests. Upon termination, system files and customer billing records are updated.
If a user desires satellite scheduling, the optimum method for obtaining required information including decisions about appropriate sets of sensors, observation frequencies, sites, and so on, is developed interactively. Customers are provided initial estimates as to the probable time of completion and expected costs for data collection, and may revise or cancel a request on the basis of these preliminary appraisals. Each such interaction updates the request schedule so that observing satellites can perform appropriate observations and deliver derived data to the correct user after processing. Individuals may access the system to cancel or modify a previous request at any time up to the actual taking of data. Further, IESIS can accept requests for time- or event-oriented measurements such as photography of a particular area every month, or for observations contingent on specific events or conditions recognizable by the system such as volcanic eruptions or forest fires.
DETERMINE FEASIBILITY; OPTIMUM SENSORS, PROCESS, COST AND TIME ESTIMATE
? MODIFY
V REQUEST
/ DISPLAY \
( TO
(USER CONNECTS TO SYSTEM VIA ^NETWORK
IESIS REQUEST SCHEDULE AND/ PROCESSING REQUIREMENTS\ FILE UPDATE REQUEST/ SCHEDULE AND/ PROCESSING I REQUIREMENTS^ FILE N.
Figure 2.6. User/system interface.
