LMES Process Engine

1. Overview

The LMES Process Engine is the core component responsible for scheduling and executing production processes. It manages the entire lifecycle of a product from raw material input to finished product output, based on the defined process route (Route).

2. Core Concepts

• Route: Defines the sequence of processes a product must go through.
• Process: A specific production step (e.g., Assembly, Welding, Testing).
• Step: Finer-grained operations within a process.
• Transition: Logic for moving from one process to another (e.g., if Pass -> Next, if Fail -> Repair).

3. Engine Architecture

3.1 State Machine

The engine uses a finite state machine (FSM) to manage product states.

• Created -> InProduction
• InProduction -> WaitingForStation -> Processing -> Completed
• Processing -> Paused / Exception

3.2 Execution Context

ProcessContext contains all information required for the current execution:

• Product Information
• Current Route Node
• Collection Data
• Variable Table

4. Extension Mechanisms

The engine supports extension via Action Hooks:

• OnProcessStart: Triggered before a process starts (e.g., check machine status).
• OnProcessEnd: Triggered after a process ends (e.g., upload data).
• OnRouteComplete: Triggered when the entire route is finished.

5. Database Design

• T_PE_Route: Route definitions.
• T_PE_RouteNode: Nodes in a route.
• T_PE_Instance: Running process instances.
• T_PE_Token: Current position tokens for instances.

6. Usage Example

// Start a new process instance
var instance = await _processEngine.StartAsync(routeId, productId);

// Move to next step
await _processEngine.SignalAsync(instanceId, "CompleteStep", data);