Distributed program
From Rosetta Code
Programming Task
This is a programming task. It lays out a problem which Rosetta Code users are encouraged to solve, using languages they know.
Given two computers on a network, send messages between them. The protocol used may be language-specific or not, and should be suitable for general distributed programming.
Contents |
[edit] D
[edit] Socket
Works with: Tango
[edit] Server
module distributedserver ; import tango.net.ServerSocket, tango.text.convert.Integer, tango.text.Util, tango.io.Stdout ; void main() { auto Ip = new InternetAddress("localhost", 12345) ; auto server = new ServerSocket(Ip) ; auto socket = server.accept ; auto buffer = new char[socket.bufferSize] ; bool quit = false ; while(!quit) { bool error = false ; try { auto len = socket.input.read(buffer) ; auto cmd = (len > 0) ? delimit(buffer[0..len], " ") : [""] ; Stdout(cmd).newline.flush ; switch (cmd[0]) { case "square": socket.output.write(toString(toInt(cmd[1]) * toInt(cmd[1]))) ; break ; case"add": socket.output.write(toString(toInt(cmd[1]) + toInt(cmd[2]))) ; break ; case "quit": socket.output.write("Server Shut down") ; quit = true ; break ; default: error = true ; } } catch (Exception e) error = true ; if(error) socket.output.write("<Error>") ; if(socket) socket.close ; if(!quit) socket = server.accept ; } if(socket) socket.close ; }
[edit] Client
module distributedclient ; import tango.net.SocketConduit, tango.net.InternetAddress, tango.text.Util, tango.io.Stdout ; void main(char[][] args) { if(args.length> 1) { try { auto Ip = new InternetAddress("localhost", 12345) ; auto socket = new SocketConduit ; socket.connect(Ip) ; auto buffer = new char[socket.bufferSize] ; socket.output.write(join(args[1..$]," ")) ; auto len = socket.input.read(buffer) ; if(len > 0) Stdout(buffer[0..len]).newline ; if(socket) socket.close ; } catch(Exception e) Stdout(e.msg).newline ; } else Stdout("usage: supply argument as,\n\tquit\n" "\tsquare <number>\n\tadd <number> <number>").newline ; }
[edit] E
Protocol: Pluribus
This service cannot be used except by clients which know the URL designating it, messages are encrypted, and the client authenticates the server. However, it is vulnerable to denial-of-service by any client knowing the URL.
[edit] Server
(The protocol is symmetric; this program is the server only in that it is the one which is started first and exports an object.)
def storage := [].diverge()
def logService {
to log(line :String) {
storage.push([timer.now(), line])
}
to search(substring :String) {
var matches := []
for [time, line] ? (line.startOf(substring) != -1) in storage {
matches with= [time, line]
}
return matches
}
}
introducer.onTheAir()
def sturdyRef := makeSturdyRef.temp(logService)
println(<captp>.sturdyToURI(sturdyRef))
interp.blockAtTop()
This will print the URL of the service and run it until aborted.
[edit] Client
The URL provided by the server is given as the argument to this program.
def [uri] := interp.getArgs()
introducer.onTheAir()
def sturdyRef := <captp>.sturdyFromURI(uri)
def logService := sturdyRef.getRcvr()
logService <- log("foot")
logService <- log("shoe")
println("Searching...")
when (def result := logService <- search("foo")) -> {
for [time, line] in result {
println(`At $time: $line`)
}
}
[edit] Erlang
The protocol is erlang's own
[edit] Server
srv.erl
-module(srv).
-export([start/0, wait/0]).
start() ->
net_kernel:start([srv,shortnames]),
erlang:set_cookie(node(), rosetta),
Pid = spawn(srv,wait,[]),
register(srv,Pid),
io:fwrite("~p ready~n",[node(Pid)]),
ok.
wait() ->
receive
{echo, Pid, Any} ->
io:fwrite("-> ~p from ~p~n", [Any, node(Pid)]),
Pid ! {hello, Any},
wait();
Any -> io:fwrite("Error ~p~n", [Any])
end.
[edit] Client
client.erl
-module(client).
-export([start/0, wait/0]).
start() ->
net_kernel:start([client,shortnames]),
erlang:set_cookie(node(), rosetta),
{ok,Srv} = init:get_argument(server),
io:fwrite("conencting to ~p~n", [Srv]),
{srv, list_to_atom(Srv)} ! {echo,self(), hi},
wait(),
ok.
wait() ->
receive
{hello, Any} -> io:fwrite("Received ~p~n", [Any]);
Any -> io:fwrite("Error ~p~n", [Any])
end.
running it (*comes later)
|erlc srv.erl |erl -run srv start -noshell srv@agneyam ready *-> hi from client@agneyam
|erlc client.erl |erl -run client start -run init stop -noshell -server srv@agneyam conencting to "srv@agneyam" Received hi
[edit] OCaml
Works with: JoCaml
Minimalistic distributed logger with synchronous channels using the join calculus on top of OCaml.
[edit] Server
open Printf
let create_logger () =
def log(text) & logs(l) =
printf "Logged: %s\n%!" text;
logs((text, Unix.gettimeofday ())::l) & reply to log
or search(text) & logs(l) =
logs(l) & reply List.filter (fun (line, _) -> line = text) l to search
in
spawn logs([]);
(log, search)
def wait() & finished() = reply to wait
let register name service = Join.Ns.register Join.Ns.here name service
let () =
let log, search = create_logger () in
register "log" log;
register "search" search;
Join.Site.listen (Unix.ADDR_INET (Join.Site.get_local_addr(), 12345));
wait ()
[edit] Client
open Printf
let ns_there = Join.Ns.there (Unix.ADDR_INET (Join.Site.get_local_addr(), 12345))
let lookup name = Join.Ns.lookup ns_there name
let log : string -> unit = lookup "log"
let search : string -> (string * float) list = lookup "search"
let find txt =
printf "Looking for %s...\n" txt;
List.iter (fun (line, time) ->
printf "Found: '%s' at t = %f\n%!" (String.escaped line) time)
(search txt)
let () =
log "bar";
find "foo";
log "foo";
log "shoe";
find "foo"
[edit] Python
Works with: Python version 2.4 and 2.6
[edit] XML-RPC
Protocol: XML-RPC
[edit] Server
#!/usr/bin/env python
# -*- coding: utf-8 -*-
import SimpleXMLRPCServer
class MyHandlerInstance:
def echo(self, data):
'''Method for returning data got from client'''
return 'Server responded: %s' % data
def div(self, num1, num2):
'''Method for divide 2 numbers'''
return num1/num2
def foo_function():
'''A function (not an instance method)'''
return True
HOST = "localhost"
PORT = 8000
server = SimpleXMLRPCServer.SimpleXMLRPCServer((HOST, PORT))
# register built-in system.* functions.
server.register_introspection_functions()
# register our instance
server.register_instance(MyHandlerInstance())
# register our function as well
server.register_function(foo_function)
try:
# serve forever
server.serve_forever()
except KeyboardInterrupt:
print 'Exiting...'
server.server_close()
[edit] Client
#!/usr/bin/env python
# -*- coding: utf-8 -*-
import xmlrpclib
HOST = "localhost"
PORT = 8000
rpc = xmlrpclib.ServerProxy("http://%s:%d" % (HOST, PORT))
# print what functions does server support
print 'Server supports these functions:',
print ' '.join(rpc.system.listMethods())
# echo something
rpc.echo("We sent this data to server")
# div numbers
print 'Server says: 8 / 4 is: %d' % rpc.div(8, 4)
# control if foo_function returns True
if rpc.foo_function():
print 'Server says: foo_function returned True'
[edit] HTTP
Protocol: HTTP
[edit] Server
#!/usr/bin/python
# -*- coding: utf-8 -*-
import BaseHTTPServer
HOST = "localhost"
PORT = 8000
# we just want to write own class, we replace do_GET method. This could be extended, I just added basics
# see; http://docs.python.org/lib/module-BaseHTTPServer.html
class MyHTTPHandler(BaseHTTPServer.BaseHTTPRequestHandler):
def do_GET(self):
# send 200 (OK) message
self.send_response(200)
# send header
self.send_header("Content-type", "text/html")
self.end_headers()
# send context
self.wfile.write("<html><head><title>Our Web Title</title></head>")
self.wfile.write("<body><p>This is our body. You wanted to visit <b>%s</b> page</p></body>" % self.path)
self.wfile.write("</html>")
if __name__ == '__main__':
server = BaseHTTPServer.HTTPServer((HOST, PORT), MyHTTPHandler)
try:
server.serve_forever()
except KeyboardInterrupt:
print 'Exiting...'
server.server_close()
[edit] Client
#!/usr/bin/python
# -*- coding: utf-8 -*-
import httplib
HOST = "localhost"
PORT = 8000
conn = httplib.HTTPConnection(HOST, PORT)
conn.request("GET", "/somefile")
response = conn.getresponse()
print 'Server Status: %d' % response.status
print 'Server Message: %s' % response.read()
[edit] Socket, Plain Text
Protocol: Plain Text
[edit] Server
#!/usr/bin/python
# -*- coding: utf-8 -*-
import SocketServer
HOST = "localhost"
PORT = 8000
# our instance that will upper whatever it gets and send back to client
class UpperCaseHandler(SocketServer.StreamRequestHandler):
def handle(self):
print '%s connected' % self.client_address[0]
# get what client sends
get = self.rfile.readline()
# write back to client
self.wfile.write(get.upper())
if __name__ == '__main__':
tcpserver = SocketServer.TCPServer((HOST, PORT), UpperCaseHandler)
try:
tcpserver.serve_forever()
except KeyboardInterrupt:
print 'Exiting...'
tcpserver.server_close()
[edit] Client
#!/usr/bin/python
# -*- coding: utf-8 -*-
import socket
HOST = "localhost"
PORT = 8000
DATA = "my name is eren"
# connect to server and send data
sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
sock.connect((HOST, PORT))
sock.send("%s\n" % DATA)
# get
response = sock.recv(256)
sock.close()
print "We sent: %s" % DATA
print 'Server responded: %s' % response
[edit] Pyro
Note: You should install Pyro (http://pyro.sourceforge.net) first and run pyro-ns binary to run code below.
[edit] Server
#!/usr/bin/python
# -*- coding: utf-8 -*-
import Pyro.core
import Pyro.naming
# create instance that will return upper case
class StringInstance(Pyro.core.ObjBase):
def makeUpper(self, data):
return data.upper()
class MathInstance(Pyro.core.ObjBase):
def div(self, num1, num2):
return num1/num2
if __name__ == '__main__':
server = Pyro.core.Daemon()
name_server = Pyro.naming.NameServerLocator().getNS()
server.useNameServer(name_server)
server.connect(StringInstance(), 'string')
server.connect(MathInstance(), 'math')
try:
server.requestLoop()
except KeyboardInterrupt:
print 'Exiting...'
server.shutdown()
[edit] Client
#!/usr/bin/python
# -*- coding: utf-8 -*-
import Pyro.core
DATA = "my name is eren"
NUM1 = 10
NUM2 = 5
string = Pyro.core.getProxyForURI("PYRONAME://string")
math = Pyro.core.getProxyForURI("PYRONAME://math")
print 'We sent: %s' % DATA
print 'Server responded: %s\n' % string.makeUpper(DATA)
print 'We sent two numbers to divide: %d and %d' % (NUM1, NUM2)
print 'Server responded the result: %s' % math.div(NUM1, NUM2)
[edit] Spread
Note: You should install Spread (http://www.spread.org) and its python bindings (http://www.python.org/other/spread/)
[edit] Server
You don't need any code for server. You should start "spread" daemon by typing "spread -c /etc/spread.conf -n localhost". If you want more configuration, look at /etc/spread.conf.
After starting daemon, if you want to make sure that it is running, enter spuser -s 4803 command where 4803 is your port set in spread.conf, you will see prompt, type j user, you should see something like this message: Received REGULAR membership for group test with 3 members, where I am member 2
[edit] Client (Listener)
#!/usr/bin/python
# -*- coding: utf-8 -*-
import spread
PORT = '4803'
# connect spread daemon
conn = spread.connect(PORT)
# join the room
conn.join('test')
print 'Waiting for messages... If you want to stop this script, please stop spread daemon'
while True:
recv = conn.receive()
if hasattr(recv, 'sender') and hasattr(recv, 'message'):
print 'Sender: %s' % recv.sender
print 'Message: %s' % recv.message
[edit] Client (Sender)
#!/usr/bin/python
# -*- coding: utf-8 -*-
import spread
PORT = '4803'
conn = spread.connect(PORT)
conn.join('test')
conn.multicast(spread.RELIABLE_MESS, 'test', 'hello, this is message sent from python')
conn.disconnect()
[edit] UnixPipes
Uses netcat
server
(echo 1; echo 2; echo 3) | nc -l 1024
client
nc 192.168.0.1 1024 | wc -l
Categories: Programming Tasks | Solutions by Programming Task | D | E | Erlang | OCaml | Python | UnixPipes
