[DLL] Dynamic Link Library

Format

OPEN (chan,[fileopt])"[DLL:lib_name;fnc_name]params"

Where:

[DLL ..]	File tag clause to inform PxPlus that it will be opening a Dynamic Link Library (DLL).
chan	Channel or logical file number to open.
fileopt	File options.
fnc_name	Case-sensitive name of the function. It acts as the entry point into the library. String expression.
lib_name	Path and/or name of the freestanding Dynamic Link Library that contains the external function you want to invoke. String expression.
params	DLL-specific parameters. Semi-colon separated arguments and/or variables to receive returned values, etc.

Description

Note:
DLL is supported for use in WindX or Windows only.

The [DLL] tag is used as a prefix in an OPEN statement to denote that PxPlus is to route all file I/O requests to an external (user defined) DLL. The [DLL] tag is built into the PxPlus programming language, which recognizes the tag and deals with it internally at run time. A DLL is a freestanding Dynamic Link Library of 'C'-style functions (external to PxPlus) that is used in Windows environments. For library names, the .DLL extension is not mandatory (other extensions, such as .EXE, are also used). Case-sensitive function names serve as entry points into the DLL.

Warning!
You can use third party DLLs; however, make sure you have good documentation on what you are passing and getting back. Sage Software can provide assistance on how to call a DLL but does not provide support for third party DLLs. There is no validation on what you pass. Bad pointers can cause memory corruption.

GPFs are not uncommon.

Example

process server "Inventory" on "[DLL]c:\app\server.dll;Entry"
open (1)"[dll:dbase2.dll;entry]cust.db"

See Also

DLL( ) / DLX( ) Call External Function
OPEN Open a File for Processing