Synchronous parallel system for emulation and discrete event simulation

A method of performing object-oriented simulation in a system of interconnected processor nodes operating in parallel, said object-oriented simulation being performed at each one of said nodes and comprising:

• simulating mutual interactions of a set of discrete simulation objects distributed among said nodes as a sequence of discrete events changing state variables of respective simulation objects so as to generate new event-defining messages addressed to respective ones of said nodes;
• responding to messages received at one node by generating corresponding event objects having individual time stamps and corresponding to respective events affecting one of said simulation objects of said one node and producing therefrom changes to said state variables of said one object corresponding to a next one of said event objects and producing corresponding messages specifying events resulting therefrom;
• determining whether said changes to said state variables are superseded by another event object affecting said simulation object while refraining from effecting corresponding changes to the state variables of said one object and from transmitting said corresponding messages to others of said nodes;
• transmitting said corresponding messages and effecting said changes to said state variables of said simulation object while storing the unchanged state variables thereof in the corresponding event object if said changes to said state corresponds to the local event horizon of that node.

A method of performing object-oriented simulation in a system of interconnected processor nodes operating in parallel, said object-oriented simulation being performed at each one of said nodes and comprising:

• simulating mutual interactions of a set of discrete simulation objects distributed among said nodes as a sequence of discrete events changing state variables of respective simulation objects so as to generate new event-defining messages addressed to respective ones of said nodes;
• assigning simulation objects to each one of said nodes;
• responding to a message received at one node by generating a corresponding event object having a time-stamp corresponding to the time of receipt of said message and corresponding to an event affecting one of said simulation objects of said one node, said responding and generating steps being repeated until the end of a current repetitive cycle;
• at each node listing each event object generated for any simulation object in said node in a secondary list in the order in which it was generated;
• at the conclusion of the current cycle in said node, sorting said secondary list in accordance with the time stamps of said event objects and merging said secondary list into a primary list listing all of the event objects to be performed in said node in chronological order;
• during the next cycle, implementing changes to simulation object state variables in accordance with event objects in the order of said primary list.

A method of performing object-oriented simulation in a system of interconnected processor nodes operating in parallel, said object-oriented simulation being performed at each one of said nodes and comprising:

• simulating mutual interactions of a set of discrete simulation objects distributed among said nodes as a sequence of discrete events changing state variables of respective simulation objects so as to generate new event-defining messages addressed to respective ones of said nodes;
• assigning simulation objects to each one of said nodes;
• responding to a message received at one node by generating a corresponding event object having a time-stamp corresponding to the time of receipt of said message and corresponding to an event affecting one of said simulation objects of said one node;
• performing host processing between said system and plural external human interaction means, whereby to communicate between each external human interaction means and a respective one of said nodes.

A method of performing object-oriented simulation in a system of interconnected processor nodes operating in parallel, said object-oriented simulation being performed at each one of said nodes and comprising:

• simulating mutual interactions of a set of discrete simulation objects distributed among said nodes as a sequence of discrete events changing state variables of respective simulation objects so as to generate new event-defining messages addressed to respective ones of said nodes;
• responding to each message received at one node by generating a corresponding event having a time-stamp and affecting one of said simulation objects of said one node and producing therefrom corresponding changes to said state variables of said one simulation object and corresponding messages specifying other events resulting therefrom;
• at each node sensing the time stamp of each new event object generated by said generating step during each one of said succession of cycles and determining which said new event has the earliest time stamp and defining the value of said earliest time stamp as the local event horizon of the corresponding node;
• determining the earliest local event horizon from among all of said nodes and defining the value thereof as the global event horizon of said one cycle for said system;
• transmitting said corresponding messages and effecting said changes to said state variables of said simulation object only for those events whose time stamps are within said global event horizon.

A method of performing object-oriented simulation in a system of interconnected processor nodes operating in parallel, said object-oriented simulation being performed at each one of said nodes and comprising:

• simulating mutual interactions of a set of discrete simulation objects distributed among said nodes as a sequence of discrete events changing state variables of respective simulation objects so as to generate new event-defining messages addressed to respective ones of said nodes;
• responding to messages received at one node by generating corresponding event objects having individual time stamps and corresponding to respective events affecting one of said simulation objects of said one node and producing therefrom changes to said state variables of said one simulation object corresponding to a next one of said event objects and producing corresponding messages specifying events resulting therefrom;
• effecting corresponding changes to the state variables of said one simulation object;
• determining whether said changes to said state variables are superseded by another event object affecting said simulation object, and, if superseded, undoing the superseded changes in said one simulation object;
• at each node sensing the time stamp of each new event object generated by said generating step during each one of said succession of cycles and determining which said new event object has the earliest time stamp and defining the value of said earliest time stamp as the local event horizon of the corresponding node;
• determining the earliest local event horizon from among all of said nodes and defining the value thereof as the global event horizon of said one cycle for said system;
• performing a time warp phase comprising transmitting a first set of not more than N1 of said corresponding messages having time stamps beyond said global event horizon to others of said nodes and not more than N2 of said corresponding messages having time stamps beyond said global event horizon from all of said nodes and transmitting antimessages to cancel messages corresponding to superseded ones of said changes;
• and
• thereafter performing a time bucket phase comprising transmitting other corresponding messages not included in said first set of messages and effecting changes to said state variables of said one simulation object corresponding to said other messages only if said changes to said state variables corresponding to said other messages are not superseded.

A method of performing object-oriented simulation in a system of interconnected processor nodes operating in parallel, said object-oriented simulation being performed at each one of said nodes and comprising:

• simulating mutual interactions of a set of discrete simulation objects distributed among said nodes as a sequence of discrete events changing state variables of respective simulation objects so as to generate new event-defining messages addressed to respective ones of said nodes;
• responding to messages received at one node by generating corresponding event objects having individual time stamps and corresponding to respective events affecting one of said simulation objects of said one node and producing therefrom changes to said state variables of said one simulation object corresponding to a next one of said event objects and producing corresponding messages specifying events resulting therefrom;
• effecting corresponding changes to the state variables of said one simulation object;
• determining whether said changes to said state variables are superseded by another event object affecting said simulation object, and, if superseded, undoing the superseded changes in said one simulation object;
• determining an event horizon from the events specified by said messages;
• performing a time warp phase comprising transmitting a first set of not more than N1 of said corresponding messages having time stamps beyond said global event horizon to others of said nodes and transmitting antimessages to cancel messages corresponding to superseded ones of said changes.

A system of interconnected processor nodes operating in parallel comprising:

• a set of discrete simulation objects distributed among said nodes;
• a computer program operating on said system for simulating mutual interactions of a set of discrete simulation objects as a sequence of discrete events changing state variables of respective simulation objects so as to generate new event-defining messages addressed to respective ones of said nodes;
• wherein said computer program performs object-oriented simulation at each one of said nodes and comprises,
• self-contained simulation objects assigned to each one of said nodes, and
• corresponding active event objects generated in response to messages received at one node, said active event objects having user-defined inherent capabilities and individual time stamps and corresponding to respective events affecting one of said self-contained simulation objects of said one node, wherein said active event objects request information and change variables within a self-contained simulation object and produce corresponding messages specifying events resulting therefrom;
• wherein said respective self-contained simulation objects are restricted to only providing and receiving information from said respective active event objects;
• and
• wherein a generic object event queue is defined for said one simulation object, said generic object event queue being indicative of the order of the event objects produced by said generating step affecting said one simulation object, whereby said next event object is specified by said generic object event queue.