JAremko/ctl-api-example

Table of Contents

• Thermal Camera API Example
  • Introduction
  • Repository Structure
  • Protobuf Definitions (thermalcamera.proto)
  • Usage
    • Building and Running the Application
      • Using Docker Compose (Default)
      • Using Host for C Server (Alternative)
    • Interaction with the Thermal Camera
    • Synchronized Views
  • Additional Information
  • Stopping the Application

Thermal Camera API Example

Introduction

This repository contains a client-server application demonstrating the use of Protobufs and WebSockets to control a thermal camera. The server part consists of two separate components: a Go server and a C server, communicating via named pipes. The client is a JavaScript-based frontend that includes synchronization between clients.

Repository Structure

• /server: Contains the Go server and C server code.
• /client: Contains the frontend JavaScript code (client.js) and HTML (ctl.html and index.html).
• thermalcamera.proto: The Protobuf schema defining messages.
• Dockerfile.client, Dockerfile.go-server, Dockerfile.c-server: Dockerfiles used to build the client, Go server, and C server containers respectively.
• docker-compose.yml and docker-compose-host.yml: Docker Compose files to orchestrate the client and server containers.

Protobuf Definitions (thermalcamera.proto)

The thermalcamera.proto file defines the messages and services for controlling a thermal camera. The definitions include:

• Payload: A wrapper message that includes one of the following payload types:
  • SetZoomLevel: To set the zoom level of the camera.
  • SetColorScheme: To set the color scheme of the camera.
  • AccChargeLevel: To get the accumulated charge level of the camera, represented as a percentage (constantly streamed from the C side).
• ColorScheme: An enumeration of available color schemes, including UNKNOWN, SEPIA, BLACK_HOT, and WHITE_HOT.

These definitions are used to serialize the data sent between the client and server, ensuring a consistent and robust communication protocol.

Usage

Building and Running the Application

Using Docker Compose (Default)

1. Build the Docker images using Docker Compose:

   docker-compose build

2. Run the application:

   docker-compose up

Using Host for C Server (Alternative)

1. Build the C server on the host:

   gcc -o c_server server/main.c -lpthread
   chmod +x c_server

2. Create named pipes on the host:

   mkfifo /tmp/toC
   mkfifo /tmp/fromC

3. Run the C server on the host:

   ./c_server

4. Build the Docker images using Docker Compose with the alternative file:

   docker-compose -f docker-compose-host.yml build

5. Run the application:

   docker-compose -f docker-compose-host.yml up

The Go server will be accessible on port 8085, and the client can be accessed by opening your web browser and navigating to localhost:8086.

Interaction with the Thermal Camera

The Go server code will upgrade the HTTP connection to a WebSocket connection and listen for incoming commands defined in the thermalcamera.proto file. It will also handle commands to adjust the thermal camera's settings, such as zoom level and color scheme.

Synchronized Views

index.html includes two iframes that load ctl.html, demonstrating synchronized control of the thermal camera. Adjustments made in one view will reflect across all others.

Additional Information

The server code in Go communicates with the C server using named pipes, defined in cinterface.go. This allows for inter-process communication and control over a simulated thermal camera. The named pipes /tmp/toC and /tmp/fromC are shared between the Go and C server containers through a shared volume.

Stopping the Application

To stop the application, use the following command:

docker-compose down -v

Or, if using the host configuration:

docker-compose -f docker-compose-host.yml down -v