Net.Data Language Environment Reference

System Language Environment

The System language environment is a Net.Data-defined environment that supports calls to external programs identified in an EXEC statement in the FUNCTION block.

The System language environment interprets the EXEC statement by passing the program name and parameters to the operating system for processing using the C language system() function call. This method does not allow the external program to directly pass variables to and from Net.Data, as the REXX language environment does, so Net.Data processes the variables in the following method:

• Net.Data passes input parameters to the external program as environment variables and the external program retrieves them:

  • A UNIX CSHELL script refers to environment variables by preceding the environment variable name with a dollar sign ($), such as $x.

  • A Perl language script refers to them by referring to the associative array ENV, such as %ENV{'x'}.

  • A DOS batch file refers to the variable name enclosed in percent signs (%), such as %x%.

• Most operating systems pass output parameters back to the language environment by writing to a named pipe whose name Net.Data passes in the environment variable, DTWPIPE. (Net.Data for OS/400 passes parameters back to the language environment using environment variables.) Use the DEFINE statement syntax to write the data to the named pipe:

  name = value
  

  For multiple data items, separate each item by a new-line or blank character.

  If a variable name matches an output parameter, the new value replaces the current value. Net.Data ignores variable names that do not match any output parameters.

A system language environment program accesses the values of a table parameter by the Net.Data name. The column headings for table T are T_N_i, and the field values are T_V_i_j. The number of rows and columns in table T are T_ROWS and T_COLS.

Authorization Tip: Ensure that the user ID under which Net.Data executes has access rights to any external executable files invoked from the System language environment. See the section on specifying Web server access rights to Net.Data files in the configuration chapter of Net.Data Administration and Programming Guide for more information.