cPLI External Program Interface Component

Introduction

cPLI (Programmable Language Interface) is an external program call interface component used to call external executables (such as Python, Node.js scripts) from VB6 applications and exchange data through standard input/output.

How It Works

┌─────────────────┐      ┌─────────────────┐      ┌─────────────────┐
│   VB6 App       │ ──▶ │  cPLI Component │ ──▶ │  External (PLI) │
│                 │      │                 │      │                 │
│  PLI.Request()  │      │  Base64 encode  │      │  VBMAN.PLI     │
│                 │      │  Execute cmd    │      │  (Python/Exe)  │
│  Get result     │ ◀──  │  Return result  │ ◀──  │  Process data   │
└─────────────────┘      └─────────────────┘      └─────────────────┘

File Description

File	Description
VBMAN.PLI	External executable (main program)
VBMAN.PSC	Script/config file
VBMAN.DAT	Data exchange file (for large return values)

Features

• Parameter Passing: Uses Base64 + UTF-8 encoding to pass parameters
• Timeout Control: Can set command execution timeout
• Large Return Values: Supports returning large data via file
• Auto Search: Auto searches multiple paths for PLI program

Quick Start

Basic Call

Dim PLI As New cPLI
Dim result As String

' Call external program
result = PLI.Request("param1", "param2", "param3")

Debug.Print "Return result: " & result

Set Timeout

Dim PLI As New cPLI

' Set 60 second timeout (default 30 seconds)
PLI.TimeOut = 60 * 1000

Dim result As String
result = PLI.Request("data")

Process JSON Data

Dim PLI As New cPLI

' Send JSON data
Dim json As String
json = "{\"name\":\"John\",\"age\":25}"

Dim result As String
result = PLI.Request(json)

' Parse returned JSON
Dim response As New cJson
response.Decode result
Debug.Print response.GetItem("status")

File Path Search Order

Component searches for VBMAN.PLI in the following order:

1. App.Path\VBMAN.PLI
2. App.Path\bin\VBMAN.PLI
3. App.Path\..\bin\VBMAN.PLI

If not found, throws 404 error.

Typical Use Cases

Scenario	Description
Python Scripts	Call Python for data processing, AI inference
Node.js Programs	Call JavaScript tools
Command Line Tools	Call system command line programs
Data Processing	Complex calculations, format conversion, etc.

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Last Updated: 2026-05-17