Advanced Techniques in Go Programming/

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Solution 4: Working with TCP/IP and WebSocket

Solution 4: Working with TCP/IP and WebSocket

Let’s solve the challenge set in the previous lesson.

We'll cover the following...

Solution

In this lesson, we will write a UNIX domain socket server (socketServer.go) that generates random numbers and socketClient.go code.

To run the client side for the socketServer.go server, open a new terminal window and copy and paste the below commands into it:

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# Set the environment variables for the Go programming language:
export GOROOT=/usr/local/go; export GOPATH=$HOME/go; export PATH=$GOPATH/bin:$GOROOT/bin:$PATH; 
# Change directory to usercode:
cd usercode
# Command to run the client:
go run socketClient.go /tmp/packt.socket

Execute the server and client sides in the following playground:

package main

import (
	"bufio"
	"fmt"
	"net"
	"os"
	"strings"
	"time"
)

func main() {
	// Read socket path
	if len(os.Args) == 1 {
		fmt.Println("Need socket path")
		return
	}
	socketPath := os.Args[1]

	c, err := net.Dial("unix", socketPath)
	if err != nil {
		fmt.Println(err)
		return
	}
	defer c.Close()

	for {
		fmt.Print(">> ")
		reader := bufio.NewReader(os.Stdin)
		text, _ := reader.ReadString('\n')

		_, err = c.Write([]byte(text))
		if err != nil {
			fmt.Println("Write:", err)
			break
		}

		buf := make([]byte, 256)

		n, err := c.Read(buf[:])
		if err != nil {
			fmt.Println(err, n)
			return
		}
		fmt.Print("\n Random numbers generated are: ", string(buf[0:n]))

		fmt.Print("\n")
		if strings.TrimSpace(string(text)) == "STOP" {
			fmt.Println("\n Exiting UNIX domain socket client!")
			return
		}

		time.Sleep(5 * time.Second)
	}
}
socketServer.go & socketClient.go

Code explanation

Here is the code explanation for socketServer.go:

  • Line 11: We define a function called echo that takes a single c argument of type net.Conn. This function will be called for each client that connects to the server.

  • Line 13: This line seeds the random number generator with the current time so that the sequence of random numbers generated will be different every time the program is run.

  • Line 14: ...