Original post is here: eklausmeier.goip.de
1. Problem statement. Generate JSON from COBOL WORKING-STORAGE section memory area. GnuCOBOL can generate and parse JSON strings. Example.
1 IDENTIFICATION DIVISION.
2 PROGRAM-ID. json.
3 AUTHOR. Elmar Klausmeier.
4 DATE-WRITTEN. 12-Aug-2021.
5
6 DATA DIVISION.
7 WORKING-STORAGE SECTION.
8 77 j usage binary-long value 3.
9 77 jsono pic x(256) value spaces.
10
11 01 a1.
12 02 b.
13 03 c.
14 04 d pic x value 'd'.
15 02 e pic x value 'e'.
16
17 01 rec.
18 03 a PIC X(3) VALUE 'A'.
19 03 b PIC X(3) VALUE ALL 'B'.
20 03 c.
21 05 d PIC X(3) VALUE SPACES.
22
23 PROCEDURE DIVISION.
24 DISPLAY "Converting from COBOL to JSON".
25
26 DISPLAY "a1 = " a1.
27 JSON GENERATE jsono FROM a1 ON EXCEPTION
28 display 'cannot generate json from a1'.
29 DISPLAY "jsono = " function trim(jsono).
30
31 DISPLAY "rec = " rec.
32 JSON GENERATE jsono FROM rec ON EXCEPTION
33 display 'cannot generate json from rec'.
34 DISPLAY "jsono = " function trim(jsono).
35
36
37 STOP RUN.
This will print:
1a1 = de
2jsono = {"a1":{"b":{"c":{"d":"d"}},"e":"e"}}
3rec = A BBB
4jsono = {"rec":{"a":"A","b":"BBB","c":{"d":" "}}}
GnuCOBOL does not support occurs-items in JSON GENERATE. For example, below code will not compile:
1 01 a1.
2 02 b.
3 03 c occurs 0 to 2 depending j.
4 04 d pic x value 'd'.
5 02 e pic x value 'e'.
Error message:
1$ cobc -x json.cbl
2json.cbl:17: error: 'c' cannot have OCCURS DEPENDING because of 'e'
3json.cbl:39: warning: OCCURS items in JSON/XML GENERATE is not implemented [-Wpending]
Initially, Arch Linux GnuCOBOL was not able to properly handle JSON GENERATE. That there was something wrong with JSON GENERATE in GnuCOBOL was hinted in the NEWS file. The NEWS file of GnuCOBOL contains the following relevant information:
1** JSON GENERATE statement
2 (note: runtime support needs additional library cJSON or JSON-C)
GnuCOBOL also does not support JSON PARSE.
2. Installation. The Arch Linux gnucobol package unfortunately has a bug regarding JSON GENERATE. Therefore you have to build the compiler yourself, or install open-cobol instead.
Configure.
1$ time ./configure
2...
3configure: COB_MODULE_EXT so
4configure: COB_EXE_EXT
5configure: COB_SHARED_OPT -shared
6configure: COB_PIC_FLAGS -fPIC -DPIC
7configure: COB_EXPORT_DYN -Wl,--export-dynamic
8configure: COB_STRIP_CMD strip --strip-unneeded
9configure: Dynamic loading: System
10configure: Use gettext for international messages: yes
11configure: Use fcntl for file locking: yes
12configure: Use math multiple precision library: gmp
13configure: Use curses library for screen I/O: ncurses
14configure: Use Berkeley DB for INDEXED I/O: yes
15configure: Used for XML I/O: libxml2
16configure: Used for JSON I/O: json-c
17 real 11.63s
18 user 8.25s
19 sys 0
20 swapped 0
21 total space 0
Now compile the compiler.
1$ time make
2 real 46.61s
3 user 45.22s
4 sys 0
5 swapped 0
6 total space 0
Switch to root user, then install.
1# make install
I uninstalled the previously installed COBOL compiler via pacman -R gnucobol. Unfortunately, the Arch Linux package does not react to bug
I adopted previously orphaned package open-cobol and corrected above bug.
Added 18-Apr-2024: IBM COBOL for Linux currently does not support neither JSON GENERATE nor JSON PARSE.
From Language elements:
JSON GENERATE and JSON PARSE statements: JSON is not currently supported in COBOL for Linux on x86.
I.e., GnuCOBOL is, so to say, better than IBM's own COBOL. Apparently IBM isn't putting too much effort into COBOL, see Memory Limitations with IBM Enterprise COBOL Compiler.