Compatible Types Example in .NET COBOL Interoperation

In the InterfacingWithStdCOBOL.sln solution, the first pair of projects, StdCbl01.*, shows a COBOL program using types that are compatible with C# types. Although this works, it is a somewhat fictitious example, as COBOL modules usually use other data types and more complex structures that don't correspond to .NET types.

The StdCbl01 projects include the following programs:

• StdCbl01.cbl. This program uses types that are directly compatible with C# types. This means that you can invoke the COBOL from the C# client, without changing the COBOL. For example:

  Lines 21-31

  LINKAGE SECTION.							
  ...
  01  F-SBYTE-COMP5 PIC S9(02) COMP-5. *>   map to C# sbyte
  01  F-SHORT-COMP5 PIC S9(04) COMP-5. *>   map to C# short
  01  F-INT-COMP5   PIC S9(09) COMP-5. *>   map to C# int
  01  F-LONG-COMP5  PIC S9(18) COMP-5. *>   map to C# long
  01  F-COMP1                  COMP-1. *>   map to C# float
  01  F-COMP2                  COMP-2. *>   map to C# double
  

  This program is procedural COBOL. When you compile it to managed code, you create a class and an instance method is implicitly exposed. The Class and method names are derived from the PROGRAM-ID, StdCbl01. In this way, the program is exposed as a method so that any managed code can use it directly. For example:

  Line 12:

  PROGRAM-ID. StdCbl01. *> PROGRAM-ID is used both as class name
                        *> and as the only INSTANCE method available

  By default, the COBOL language translates all names and identifiers to upper case. If you want to maintain and expose a name in its original case, you must use the keyword AS. For example the following would expose the class and method as StdCbl01 in a C# program.

  PROGRAM-ID. StdCbl01 AS “StdCbl01”

• StdCbl01Client.cs. This is the C# client, which passes data to the COBOL, and receives data back. This C# code invokes the COBOL program by fetching the COBOL program instance and then invoking the method in the same way that it would invoke any other managed code method, as follows:

  Line 37:

  STDCBL01 stdCbl01 = (STDCBL01)Interop.CobLoad("StdCbl01");
  COBOLrc = stdcbl01.STDCBL01(ref CSsbyte, ref CSshort,
                                   ref CSint, ref CSlong,
                                   ref CSfloat, ref CSdouble);