Distributed programming: Difference between revisions
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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. |
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. |
Revision as of 11:26, 1 June 2009
You are encouraged to solve this task according to the task description, using any language you may 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.
D
Socket
Server
<lang d>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 ;
}</lang>
Client
<lang d>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 ;
}</lang>
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.
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.)
<lang e> 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()</lang>
This will print the URL of the service and run it until aborted.
Client
The URL provided by the server is given as the argument to this program.
<lang e> 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`) } }</lang>
Erlang
The protocol is erlang's own
Server
srv.erl
<lang erlang> -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.</lang>
Client
client.erl
<lang erlang> -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.</lang>
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
Objective-C
Distributed Objects are natural to Objective-C, and OpenStep and derivated framework offers an easy way of using remote objects as if it were local. The client must only know the protocol the remote object support. For the rest, calling a remote object's method or local object's method is transparent.
Server
The server vending the object with the name DistributedAction
ActionObjectProtocol.h <lang objc>#import <Foundation/Foundation.h> // our protocol allows "sending" "strings", but we can implement // everything we could for a "local" object @protocol ActionObjectProtocol - (NSString *)sendMessage: (NSString *)msg; @end</lang>
ActionObject.h <lang objc>#import <Foundation/Foundation.h>
- import "ActionObjectProtocol.h"
@interface ActionObject : NSObject <ActionObjectProtocol>
// we do not have much for this example!
@end</lang>
ActionObject.m <lang objc>#import <Foundation/Foundation.h>
- import "ActionObject.h"
@implementation ActionObject -(NSString *)sendMessage: (NSString *)msg {
NSLog(@"client sending message %@", msg); return @"server answers ...";
} @end</lang>
server.m <lang objc>#import <Foundation/Foundation.h>
- import "ActionObject.h"
int main (void) {
NSAutoreleasePool *pool; ActionObject *action; NSConnection *connect; NSSocketPort *port; pool = [[NSAutoreleasePool alloc] init]; action = [[ActionObject alloc] init];
port = (NSSocketPort *)[NSSocketPort port]; // initWithTCPPort: 1234 and other methods are not supported yet // by GNUstep connect = [NSConnection
connectionWithReceivePort: port sendPort: port]; // or sendPort: nil
[connect setRootObject: action];
/* "vend" the object ActionObject as DistributedAction; on GNUstep the Name Server that allows the resolution of the registered name is bound to port 538 */ if ([connect registerName:@"DistributedAction"
withNameServer: [NSSocketPortNameServer sharedInstance] ] == NO)
{ NSLog(@"can't register the server DistributedAction"); exit(EXIT_FAILURE); } NSLog(@"waiting for messages...");
[[NSRunLoop currentRunLoop] run];
[pool release]; return 0;
}</lang>
Client
client.m <lang objc>#import <Foundation/Foundation.h>
- import "ActionObjectProtocol.h"
int main(void) {
NSAutoreleasePool *pool; NSArray *args; id <ActionObjectProtocol> action; NSString *msg, *backmsg;
pool = [[NSAutoreleasePool alloc] init];
action = (id <ActionObjectProtocol>) [NSConnection rootProxyForConnectionWithRegisteredName: @"DistributedAction" host: @"localhost" usingNameServer: [NSSocketPortNameServer sharedInstance] ];
if (action == nil) { NSLog(@"can't connect to the server"); exit(EXIT_FAILURE); } args = [[NSProcessInfo processInfo] arguments];
if ([args count] == 1) { NSLog(@"specify a message"); exit(EXIT_FAILURE); } msg = [args objectAtIndex: 1];
// "send" (call the selector "sendMessage:" of the (remote) object // action) the first argument's text as msg, store the message "sent // back" and then show it in the log backmsg = [action sendMessage: msg]; NSLog(backmsg);
[pool release]; return 0;
}</lang>
OCaml
Minimalistic distributed logger with synchronous channels using the join calculus on top of OCaml.
Server
<lang ocaml> 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 ()</lang>
Client
<lang ocaml> 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"</lang>
Python
XML-RPC
Protocol: XML-RPC
Server
<lang python>
- !/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()
</lang>
Client
<lang python>
- !/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'
</lang>
HTTP
Protocol: HTTP
Server
<lang python>
- !/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>
This is our body. You wanted to visit %s page
</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()
</lang>
Client
<lang python>
- !/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() </lang>
Socket, Plain Text
Protocol: Plain Text
Server
<lang python>
- !/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()
</lang>
Client
<lang python>
- !/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 </lang>
Pyro
Note: You should install Pyro (http://pyro.sourceforge.net) first and run pyro-ns binary to run code below.
Server
<lang python>
- !/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()
</lang>
Client
<lang python>
- !/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) </lang>
Spread
Note: You should install Spread (http://www.spread.org) and its python bindings (http://www.python.org/other/spread/)
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
Client (Listener)
<lang python>
- !/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
</lang>
Client (Sender)
<lang python>
- !/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() </lang>
Tcl
A rudimentary IRC Server <lang tcl>proc main {} {
global connections set connections [dict create] socket -server handleConnection 12345 vwait dummyVar ;# enter the event loop
}
proc handleConnection {channel clientaddr clientport} {
global connections dict set connections $channel address "$clientaddr:$clientport" fconfigure $channel -buffering line fileevent $channel readable [list handleMessage $channel]
}
proc handleMessage {channel} {
global connections if {[gets $channel line] == -1} { disconnect $channel } else { if {[string index [string trimleft $line] 0] eq "/"} { set words [lassign [split [string trim $line]] command] handleCommand $command $words $channel } else { echo $line $channel } }
}
proc disconnect {channel} {
global connections dict unset connections $channel fileevent $channel readable "" close $channel
}
proc handleCommand {command words channel} {
global connections switch -exact -- [string tolower $command] { /nick { dict set connections $channel nick [lindex $words 0] } /quit { echo bye $channel disconnect $channel } default { puts $channel "\"$command\" not implemented" } }
}
proc echo {message senderchannel} {
global connections foreach channel [dict keys $connections] { if {$channel ne $senderchannel} { set time [clock format [clock seconds] -format "%T"] set nick [dict get $connections $channel nick] puts $channel [format "\[%s\] %s: %s" $time $nick $message] } }
}
main</lang> Client <lang tcl>proc main {} {
global argv argc if {$argc != 2} { error "usage: [info script] serveraddress serverport" } connect {*}$argv vwait dummyVar
}
proc connect {addr port} {
global sock set sock [socket $addr $port] fconfigure $sock -buffering line fileevent $sock readable getFromServer fileevent stdin readable sendToServer
}
proc getFromServer {} {
global sock if {[gets $sock line] == -1} { puts "disconnected..." exit } else { puts $line }
}
proc sendToServer {} {
global sock set msg [string trim [gets stdin]] if {[string length $msg] > 0} { puts $sock $msg }
}
main</lang>
UnixPipes
Uses netcat
server
(echo 1; echo 2; echo 3) | nc -l 1024
client
nc 192.168.0.1 1024 | wc -l