Abstract: A method of monitoring objects in a database system. A client program requests monitoring of an attribute of an object in the database according to a criterion which is any of four tuning parameters. The parameters include a change value parameter, a delay time parameter, a synchronous initiation parameter, and a nervousness parameter. When an update is committed, a tracking application of a client which has requested monitoring of an attribute is invoked if the monitoring criterion specified by that client has been satisfied. The first three parameters have the effect of reducing the reactivity of the monitor. The change value parameter is satisfied if the value of the monitored attribute has changed by an amount not less than the specified change value. The delay time parameter is satisfied if at least the specified delay time has elapsed since the occurrence of a specified previous event.

Abstract: A method of monitoring objects in an interactive object-oriented database system. Any of a plurality of client programs can request monitoring of attributes of objects in the database. A record is kept of update transactions initiated by a client. When the client commits the changes, any client which has requested monitoring is notified of any change in the value of an attribute being monitored at the request of that client. The notification interrupts the client and invokes a predesignated client procedure. Overhead is minimized by creating partial view materialization paths and defining monitors ahead of time and by localizing the monitoring.

Abstract: An expert system shell efficiently computes functions of variables in response to numeric or symbolic data values input by a user. The system comprises a Knowledge Base in the form of a network of functions, an Inference Engine for efficiently updating values in the knowledge base in response to changes in entered data, and a Forms System that manages interaction with the user. A knowledge engineer creates the network of functions, and defines the user screens and the connection between screen objects and variables in the function network. The system allows many different types of variables, including numeric and symbolic types. The system associates a probability distribution with every variable, and computes the probability distributions for the dependent variables from the probability distributions for the independent variables. A variable can store multiple values as tables of probability distributions keyed by one or more key variables.