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Communication Protocols: Microtec POS ​

Microtec POS uses a multi-layered communication strategy to balance high-speed local network performance with reliable cloud synchronization.

1. REST API (Cloud Sync) ​

The primary channel for master data synchronization and order persistence to the cloud.

Implementation: Dio ​

  • Library: Uses the Dio HTTP client with custom interceptors for authentication and logging.
  • Data Transfer: Uses JSON format for all payloads.
  • Sync Logic:
    • GET: Pulls updates for Products, Customers, Discounts, and Settings.
    • POST/PUT: Pushes Orders, Sessions, and Customer profile updates.
  • Persistence: All REST data is mapped into local ObjectBox DTOs in the lib/infra layer.

2. gRPC & Protobuf (Local Real-Time) ​

For high-speed, real-time communication between local devices (KDS/CDS/POS), the app uses gRPC.

Use Cases: ​

  • KDS (Kitchen Display System): When a POS sends an order to the kitchen, the KDS receives a gRPC message instantly, avoiding the latency and dependency of a cloud round-trip.
  • CDS (Customer Display System): Real-time item updates and totals are pushed to customer-facing tablets on the same local network.

Advantages: ​

  • Efficiency: Protobuf's binary format is significantly smaller and faster to parse than JSON.
  • Bidirectional Streaming: Enables real-time, low-latency updates without continuous polling.
  • Type Safety: Generated Dart code from .proto files ensures strict data contracts between devices.

3. TCP Sockets (Printers) ​

Direct socket communication for ESC/POS printer control.

Implementation: ​

  • Standard: Connects to port 9100 for network-based thermal printers.
  • Workflow: The POS generates the ESC/POS binary command stream (via pos_printer_manager) and sends it directly to the printer's IP address.
  • Error Handling: Retries are handled at the socket level to manage transient network drops.

4. Multi-Window IPC (Windows Desktop) ​

For dual-monitor Windows setups, the app uses Inter-Process Communication (IPC) between the main sales window and the customer display window.

Implementation: desktop_multi_window ​

  • Mechanism: The main window sends JSON-formatted messages to the secondary window's handle.
  • Sync: Both windows share the same application memory space but run distinct UI isolates, ensuring that the sales UI remains responsive even during complex rendering on the customer display.

For development standards and project architecture, see DEVELOPER_GUIDE.md.

Internal Documentation — Microtec