How to use C# to connect to Ouster Gemini TCP output

C# Implementation of the TCP Client

The following C# code creates a TCP connection to the server, reads frames of data, decodes them as JSON, and processes them with a callback function.

using System;
using System.Net.Sockets;
using System.Text;
using System.Security.Authentication;
using System.Net.Security;
using System.IO;
using Newtonsoft.Json.Linq;


class TCPClient
{
   private const string HOST = "localhost";
   private const int PORT = 3302;
   private const int FRAME_SIZE_B = 4;
   private const string ENDIAN_TYPE = "big";  // Not used in C#, assuming big-endian
  
   static void Main(string[] args)
   {
       try
       {
           // Create the SSL/TLS context
           SslStream sslStream = CreateSslStream(HOST, PORT);
          
           // Start reading frames from the server
           ReadFrames(sslStream, ProcessData);


           // Close the SSL stream and TCP connection
           sslStream.Close();
       }
       catch (Exception ex)
       {
           Console.WriteLine("Error: " + ex.Message);
       }
   }


   private static SslStream CreateSslStream(string host, int port)
   {
       TcpClient tcpClient = new TcpClient(host, port);
       SslStream sslStream = new SslStream(tcpClient.GetStream(), false, new RemoteCertificateValidationCallback((sender, certificate, chain, sslPolicyErrors) => true));


       sslStream.AuthenticateAsClient(host, null, SslProtocols.Tls12, false);


       return sslStream;
   }


   private static void ReadFrames(SslStream sslStream, Action<JObject> callbackFunction)
   {
       while (true)
       {
           // Get the size of the frame
           byte[] frameSizeBuffer = new byte[FRAME_SIZE_B];
           int bytesRead = sslStream.Read(frameSizeBuffer, 0, FRAME_SIZE_B);


           if (bytesRead == 0)
           {
               return;
           }


           // Convert the byte data to an integer, representing the number of bytes
           int frameSize = BitConverter.ToInt32(frameSizeBuffer, 0);
           if (BitConverter.IsLittleEndian)
           {
               frameSize = System.Net.IPAddress.NetworkToHostOrder(frameSize);
           }


           // Read the data frame
           byte[] dataBuffer = new byte[frameSize];
           bytesRead = sslStream.Read(dataBuffer, 0, frameSize);


           if (bytesRead == 0)
           {
               return;
           }


           // Convert the byte array to a JSON string and process it
           string jsonString = Encoding.UTF8.GetString(dataBuffer, 0, bytesRead);
           JObject data = JObject.Parse(jsonString);


           // If the message is a heartbeat, continue to the next message
           if (data.ContainsKey("heartbeat"))
           {
               continue;
           }


           // Call the callback function with the JSON data
           callbackFunction(data);
       }
   }


   private static void ProcessData(JObject data)
   {
       // Example callback function to print the data
       Console.WriteLine(data.ToString());
   }
}

Explanation of the Code

CreateSslStream Method:
- This method establishes an SSL/TLS connection to the server using TcpClient and SslStream.
ReadFrames Method:
- Continuously reads data from the stream.
- First, it reads the frame size (4 bytes).
- Then, it reads the frame of that size and processes it as JSON.
ProcessData Method:
- This is an example callback function that simply prints the JSON data. Customer can replace it with their custom logic.

Setting Up and Running the Code on Ubuntu 22.04

Step 1: Install .NET SDK

sudo apt update
sudo apt install dotnet-sdk-8.0

Step 2: Create a New C# Project

Create a new directory for your project:

mkdir -p ~/tcp_client
cd ~/tcp_client

Initialize a new C# console project:

dotnet new console -n TCPClient
cd TCPClient

Step 3: Add Newtonsoft.Json Library

Install the Newtonsoft.Json library via NuGet:

dotnet add package Newtonsoft.Json

Step 4: Replace the Default Code

Open the Program.cs file:

nano Program.cs

Replace the contents with the C# code provided above.

Save and close the file (CTRL + S, then Enter, and CTRL + X to exit).

Step 5: Build and Run the Application

Build the project:

dotnet build

Run the application:

dotnet run

You will see the output similar like this: