Release Level	5.4
Release Date	2008 10
Revision Level	1.0

RTXPS on-line Manual: one page summary

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

/var/www/RTXPS

KB	knowledge base
bin	script and functions as part of ACTIONS
defaults	configuration files
logs	dynamic log files

• 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)