Shared Tools:  Reference Manual
    Release Level 5.4 Release Date 2008 10 Revision Level 1.0
Document was last modified on:   Monday, 20-Jul-09 14:05 CEST

RTXPS on-line Manual: one page summary

RTXPS is a forward-chaining expert system operating in real-time (time aware): the forward chaining loop is executed continuously, and several function obtain, compare and use cariables based on Absolute (systems) and Elapsed Time, including user defined TIMERS.

This makes it possible to execute sequences of conditional and scheduled tasks with complex interdependencies, including the execution and interpretation of dynamic simulation (forecasting or operational control) models, or ACTIONS based on the values of remote (real-time( sensors.

RTXPS can be run in two distinct modes:

  1. automatic, autonomous, continuously; here the forward chaining loops runs continuously, and is controlled only bythe RULES and ACTIONS executed;

  2. interactively, which include functions that trigger display, interactive editors, and user dialof in general. Here, the forward chaining loop can be controlled by the user with interactive input: whenever input from the user is requested, the system will wait for that input, unless a TIMEOUT is defined for the dialog with a default continuation without interactive user input.

A special case or application of RTXPS is CourseWare, an interactive web-based distance learning tool. On the basis of available rules, RTXPS decides which action is to be conducted next. Actions consist of up to 3 function out of which one should create a html page which is sent to the client. Pages can contain in-text functions - tools to display or edit descriptors or graphical elements which are created dynamically.

Files and data bases

The basic files for RTXPS are located in the (default) directory:
    /var/www/RTXPS
RTXPS contains the rtxps.cgi executanle, and the following sub-directories,
    KB  knowledge base
    bin  script and functions as part of ACTIONS
    defaults  configuration files
    logs  dynamic log files
RTXPS uses for its operation:
  • the RTXPS executable, rtxps.cgi located in the base directory /var/www/RTXPS; the RTXPS executable is started manually, but can be included in the rc.* scripts for automatic start-up at boot time; please note that RTXPS needs to be retsarted whenever the knowledge base changes.
  • A dynamic Knowledge-Base that stores the current state of the system in the data base;
  • The Knowledge Base configuration files in /var/www/RTXPS/KB: these include:
    • KBconfig: a knowledge base configuration fil, the sets the maximum dimensions, and enumerates the different files to be use, multiple entries will be concatenated in the sequence of their listing;
        MaxNr-Of-Descriptors:100
        MaxNr-Of-Rules:		100
        MaxNr-Of-RTRules:   100
        MaxNr-Of-Actions:   100
                                                                                                                                    
        DESCRIPTOR-FILES
        Descriptors
        END-DESCRIPTOR-FILES
                                                                                                                                    
        RTRULE-FILES
        Rules
        END-RTRULE-FILES
                                                                                                                                    
        ACTION-FILES
        Actions
        END-ACTION-FILES
        
    • Descriptors: DESCRIPTORS or variables: the initial set of DESCRIPTORS for RTXPS are defined in a plain ascii file, using the same format and structure as the DESCRIPTORS used in the backward-chaining expert system XPS. A special case of DESCRIPTORS are TIMERS that deal with absolute and elapsed time;
        DESCRIPTOR
        descriptor_name
        T S
        V None / B1 / B2 / B3 / B4 /
        Qquestion to be asked 
        ENDDESCRIPTOR
        

    • Rules:  RULES (the forward chaining rules).
        RULE 01000
        IF   TRUE
        THEN ACTION(main) => ready
        ENDRULE
                                                                                                                                    
        RULE 01100
        IF   ACTION(main) == done
        THEN ACTION(wait)    => ready
        ENDRULE
        

    • Actions: (the consequence part of RTXPS RULES)   ACTIONS (built-in library functions and user defined ACTIONS).
        ACTION
        main
        T Auto
        V ready / pending / ignored / failed / done /
        FUNCTION
        update_log(Running main)
        ENDFUNCTION
        FUNCTION
        run_executable(send_message)
        ENDFUNCTION
        ENDACTION
        
  • Scripts and external executable used by RTXPS, located in /var/www/RTXPS/bin

  • Dynamic LOG files, located in /var/www/RTXPS/logs:
    • XPSlog: logs the start-up sequence of reading the configuration and KLB files, reports any syntactiv error found;
    • xps: chroonological time-stamped log of the ACTION sequence:
        12:57:47 Starting: main
        12:57:47 Completed: main
        12:57:47 Starting: wait
        13:02:47 Completed: wait
        13:02:47 Starting next RTXPSd Run
        13:02:47 Starting: main
        13:02:47 Completed: main
        13:02:47 Starting: wait
        13:07:47 Completed: wait
        13:07:47 Starting next RTXPSd Run
        
    • xpsYYYYMMDD: detailed record of the logical (Rules and inference) sequence:
        rt_condition(): checking rule 1100
         Firing Rule: 1100 ACTION(wait) => ready
        Action wait set to ready
         => Action: wait
             AutoStarting Function: update_log(Waiting)
        Calling library function: update_log(Waiting)
        Calling local function: update_log(Waiting)
        Calling library function: wait(300)
        Calling local function: wait(300)
        


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