Network Examples

• Echo via Socket

  Below example starts a server and waits client to send a string and echo back to client.

  Server

  callback function must have three parameters: socket handle, address, and port.

  proc callback {sock addr port} {
  	fconfigure $sock -translation lf -buffering line
  	fileevent $sock readable [list echo $sock]
  }
  

  echo fuction reads from socket and puts the line back.

  proc echo {sock} {
  	global var
  	if {[eof $sock] || [catch {gets $sock line}]} {
  		close $sock; set var done
  	} else {
  		puts $sock "$line"; puts "show echo: $line"
  	}
  }
  

  init socket and wait done.

  set port 2800
  set sh [socket -server callback $port]
  puts "socket is ready"
  vwait var; close $sh
  

  Client

  open a client socket in localhost.

  set host localhost; set port 2800
  set s [socket $host $port]
  fconfigure $s -buffering line; puts $s $host