PROGRAMMAZIONE AVANZATA JAVA E C

Transcription

1 PROGRAMMAZIONE AVANZATA JAVA E C Massimiliano Redolfi Lezione 12: networks with Java TCP vs UDP

2 TCP vs UDP TCP (Transmission Control Protocol) permette di instaurare una connessione client-server con comunicazione affidabile dei dati Servizi tipicamente di trasmissione informazioni complesse: FTP, HTTP, POP, SMTP TCP vs UDP UDP (User Datagram Protocol) permette di trasmettere pacchetti indipendenti di informazioni (datagram) senza garanzie di ricezione. A differenza del TCP non è basato su una connessione client-server Servizi tipicamente di trasmissione informazioni semplici: ping, orario,

3 URL Uniform Resource Locator URL URL aurl = new URL(" name=networking#downloading"); System.out.println("protocol = " + aurl.getprotocol()); System.out.println("authority = " + aurl.getauthority()); System.out.println("host = " + aurl.gethost()); System.out.println("port = " + aurl.getport()); System.out.println("path = " + aurl.getpath()); System.out.println("query = " + aurl.getquery()); System.out.println("filename = " + aurl.getfile()); System.out.println("ref = " + aurl.getref());

4 URL URL site = new URL(" BufferedReader in = new BufferedReader( new InputStreamReader(site.openStream())); String line; while((line = in.readline())!= null) System.out.println(line); in.close(); un modo facile e veloce per scaricare pagine di un sito web ma non solo basi di comunicazione applicativa

5 connection request data exchange Server client server : server side int port = args.length == 1? Integer.parseInt(args[0]) : 1234; System.out.println("\nStarting server on port: " + port); System.out.println("Waiting remote connection..."); try ( Server server = new Server(port); client = server.accept(); PrintWriter out = new PrintWriter(client.getOutputStream(), true); BufferedReader in = new BufferedReader(new InputStreamReader(client.getInputStream())); ) { System.out.println("Server info: " + server.getinetaddress() + ":" + server.getlocalport()); System.out.println("Connected to client: " + client.getinetaddress() + ":" + client.getport()); String request; while((request = in.readline())!= null) { System.out.println("Processing request: " + request); out.println(request.touppercase()); if("quit".equals(request.touppercase())) break; catch(ioexception e) { System.err.println("Errore durante la comunicazione! " + e); System.out.println("Server stopped!");

6 : server side int port = args.length == 1? Integer.parseInt(args[0]) : 1234; System.out.println("\nStarting server on port: " + port); System.out.println("Waiting remote connection..."); try ( Server server = new Server(port); client = server.accept(); PrintWriter out = new PrintWriter(client.getOutputStream(), true); BufferedReader in = new BufferedReader(new InputStreamReader(client.getInputStream())); ) { System.out.println("Server info: " + server.getinetaddress() + ":" + server.getlocalport()); System.out.println("Connected to client: " + client.getinetaddress() + ":" + client.getport()); String request; while((request = in.readline())!= null) { System.out.println("Processing request: " + request); out.println(request.touppercase()); if("quit".equals(request.touppercase())) break; catch(ioexception e) { System.err.println("Errore durante la comunicazione! " + e); try-with-resource System.out.println("Server stopped!"); : client side String hostname = args.length == 2? args[0] : "localhost"; int port = args.length == 2? Integer.parseInt(args[1]) : 1234; try ( // try-with-resource... client = new (hostname, port); PrintWriter out = new PrintWriter(client.getOutputStream(), true); BufferedReader in = new BufferedReader(new InputStreamReader(client.getInputStream())); ) { BufferedReader stdin = new BufferedReader(new InputStreamReader(System.in)); String request, response; while((request = stdin.readline())!= null) { System.out.println("Request : " + request); out.println(request); response = in.readline(); System.out.println("Response: " + response); if("quit".equals(response)) break; catch(ioexception e) { System.err.println("Errore durante la comunicazione! " + e); System.out.println("Connection closed!");

7 : multiple clients connection request data exchange Server client server modifico il server od il client??