Scala equivalent of python echo server/client example?


Question

All the "server" example in scala use actors, reactors etc...

Can someone show me how to write a dead simple echo server and client, just like the following python example of Server and Client:

# A simple echo server 
import socket 

host = '' 
port = 50000 
backlog = 5 
size = 1024 
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM) 
s.bind((host,port)) 
s.listen(backlog) 
while 1: 
    client, address = s.accept() 
    data = client.recv(size) 
    if data: 
        client.send(data) 
    client.close()

# A simple echo client 
import socket 

host = 'localhost' 
port = 50000 
size = 1024 
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM) 
s.connect((host,port)) 
s.send('Hello, world') 
data = s.recv(size) 
s.close() 
print 'Received:', data
1
19
3/21/2014 8:22:01 AM

Accepted Answer

You can do following within standard library:

// Simple server
import java.net._
import java.io._
import scala.io._

val server = new ServerSocket(9999)
while (true) {
    val s = server.accept()
    val in = new BufferedSource(s.getInputStream()).getLines()
    val out = new PrintStream(s.getOutputStream())

    out.println(in.next())
    out.flush()
    s.close()
}

// Simple client
import java.net._
import java.io._
import scala.io._

val s = new Socket(InetAddress.getByName("localhost"), 9999)
lazy val in = new BufferedSource(s.getInputStream()).getLines()
val out = new PrintStream(s.getOutputStream())

out.println("Hello, world")
out.flush()
println("Received: " + in.next())

s.close()

If you don't mind using extra libraries, you might like Finagle.

31
2/13/2017 6:19:06 PM

I just wrote a blog post about using Akka IO and Iteratees to create a simple command based socket server.

Maybe it could be of interest.

http://leon.radley.se/2012/08/akka-command-based-socket-server/


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