Creating typed buffers

Typed buffers are defined by data structures in header files (in C) or COPY elements (in COBOL), which must be used in the participating programs.

Data is exchanged between the programs on the basis of these data structures, which must therefore be known to both the client and the server. All data types described in the table on "Typed buffers" are permitted.

The header files or COBOL COPY files in which the typed buffers are described serve as input for the configuration program xatmigen, see section “The xatmigen tool”. The following rules apply to these files:

• C and COBOL data structures must be contained in separate files. A file that contains both C includes and COBOL COPY elements is not permitted as input.

• The files can only comprise definitions of data structures, blank lines, and comment statements. Macro statements, i.e. statements beginning with ‘#’, are permitted in C.

• The data structure definitions must be specified in full. In particular, COBOL data records must begin with the level number “01”.

• The data structures must not be nested.

• Only absolute values are permitted as field lengths, macro constants are not accepted.

• Only the data types listed in the table on "Typed buffers" are permitted. In particular, no pointer types are permitted in C.

The user may have to use the configuration tool xatmigen to map the character arrays to
ASN.1 string types because neither C nor COBOL recognizes these data types; see section“The xatmigen tool”.

XATMI calls for memory allocation are available for C (tpalloc ...).

Two simple examples are provided below for C and COBOL respectively.

Example

C include for typed buffer

typedef struct {
        char   name[20];    /* person’s name */
        int    age;         /* age */
        char   sex;
        long   shoesize;
} t_person;
struct t_city {
        char  name[32];             /* name of city */
        char  country;
        long  inhabitants;
        short churches[20];
        long  founded;
}

COBOL COPY for typed record

***** Personal record
 01 PERSON-REC.
    05 NAME     PIC     X(20).
    05 AGE      PICTURE S9(9) COMP-5.
    05 SEX      PIC     X.
    05 SHOESIZE PIC     S9(9) COMP-5.
***** City record
 01 CITY-REC.
    05 NAME        PIC   X(32).
    05 COUNTRY     PIC   X.
    05 INHABITANTS PIC  S9(9) COMP-5.
    05 CHURCHES    PIC   S9(4) COMP-5 OCCURS 20 TIMES.
    05 FOUNDED     PIC   S9(9) COMP-5.

Further examples can be found in the X/Open Specification on XATMI.