XTRAN Example — Mine Code for Business Rule Conditions

Scenario — you want to find the Business Rules (BRs) in your code, perhaps to move them into a Business Rules Management System (BRMS).  A key to such BRs is the conditions that determine when they are executed and what they do when executed.  However, you know that not all "if" statements are part of BRs.  Additionally, you want to find out whether such conditions (and therefore the BRs they are in) are scattered throughout your code or centralized in subroutines.

What would really help would be a tally of how many times each condition occurs in your code.  Such a tally should ignore the left side of a conditional operator in such a condition, because the BR is much more likely to be reflected in the condition itself, not a specific variable to which it is applied.  And, if a condition is not a conditional operator expression (e.g. a condition name), then the tally should be of the entire condition.

XTRAN to the rescue!

The following example uses an XTRAN rules file comprising 110 non-comment lines of XTRAN's rules language ("meta-code") to mine COBOL code for control flow conditions and tally their occurrences as described above.  The rules took one hour to create and debug.  (That's right, only one hour)!

The rules output the condition tallies in the following format, one condition per line:

<cond>,<value>,<tally>

where:

      <cond>   is the condition
      <value>   is the condition's value, or (none) if none
      <tally>   is the condition's number of occurrences

That format is suitable for input to a data base, spreadsheet, or repository.  It can also can be interactively queried using existing XTRAN rules. 

The XTRAN rules used for this example are not specific to COBOL; they can be used unchanged to mine any 3GL language for BR conditions.

Here is an English paraphrase of the XTRAN rules:

    Open output file named by an environment variable; create or
      append depending on another environment variable
    For each code statement
        If it isn't an "if" statement
            Ignore it
        If its condition is an operator expression
            Grab operator as condition, plus its right hand (or only)
              term as condition's value
        Else (not operator expression)
            Use entire expression as condition, with "(none)"
              as condition's value
        Add condition to list of those we've seen
        Increment condition/value's tally (direct data base update)
    For each condition we saw
        For each value seen on this condition
            Output condition, value, and tally (direct data base fetch)
    Close output file

How can such powerful and generalized code mining be automated in only one hour and only 110 code lines of XTRAN rules?  Because there is so much capability already available as part of XTRAN's rules language.  These rules take advantage of the following functionality:

The input to and output from XTRAN are untouched.


Process Flowchart

Here is a flowchart for this process, in which the elements are color coded:

data flowchart

Input to XTRAN:

       IDENTIFICATION DIVISION.
       PROGRAM-ID. PROG.
       ENVIRONMENT DIVISION.                                                    
       INPUT-OUTPUT SECTION.                                                    
       FILE-CONTROL.                                                            
           SELECT  OUTPUT-FILE ASSIGN TO OPFILE.
       DATA DIVISION.                                                           
       FILE SECTION.                                                            
       FD  OUTPUT-FILE                                                          
           LABEL RECORDS ARE STANDARD
           RECORDING F.                                                         
       01  REPORT-REC              PIC X(132).
       WORKING-STORAGE SECTION.                                                 
       01  VAR1                    PIC X(08)  VALUE 'VAR1'.                   
       01  VAR2                    PIC 9(4).                                    
       01  CTR1                    PIC S9(09) COMP VALUE ZERO.                  
           88 CTR1-0 VALUE 0.
       01  CTR2                    PIC S9(09) COMP VALUE ZERO.                  
       01  CTR3                    PIC S9(09) COMP VALUE ZERO.                  
       01  MAX                     PIC 9(03)  COMP VALUE  100.                  
       01  TBL                     PIC X(08)  VALUE 'TABLE'.
       PROCEDURE DIVISION.
           IF CTR1 > MAX THEN
              STOP RUN
              END-IF.
           IF CTR1 = ZERO THEN
              MOVE 1 TO CTR2
              END-IF.
           MOVE 500 TO CTR3.
           IF CTR2 >= 500 THEN
               STOP RUN.
           IF CTR3 = ZERO THEN
               IF CTR2 <= 5 THEN
                   MOVE 6 TO CTR2
                   IF CTR1 <= 5 THEN
                       MOVE 6 TO CTR1
                       END-IF
                   IF CTR1-0 THEN
                       ADD 2 TO CTR1
                       END-IF
                   END-IF
               IF CTR2 > MAX THEN
                   SUBTRACT 1 FROM CTR2
                   END-IF
               END-IF.
           STOP RUN.

Output from XTRAN:

<=,5,2
=,ZERO,2
>,MAX,2
>=,500,1
CTR1-0,(none),1