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Sockets

3

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Sockets

( ) (.. UDP/TCP)

/ sockets /

application layerapplication layer

OS network

stack

Client Process Server ProcessSocket

OS network

stack

Socket

transport layer (TCP/UDP)

network layer (IP)

link layer (e.g. ethernet)

physical layer

transport layer (TCP/UDP)

network layer (IP)

link layer (e.g. ethernet)

physical layer

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: (, -, -,-, -)

(.. UDP, TCP)

- -, IP /,

- -, ( 16-bit , (port number) )

socket (endpoint)

. (, , )

H sockets socket socket

3

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CP/IP

Connection socket pair(195.251.177.9:23405, 150.140.28.20:80)

Server(port 80)

Client

Client socket address

195.251.177.9:23405Server socket address

150.140.28.20:80

Client host address195.251.177.9

Server host address150.140.28.20

IP address

Port number

To (IP address , Port number) socket-address

H 23405

80

Web servers

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Sockets Java

interfaces java.net

TCP :

Socket: client-side & server-side ServerSocket: server-side

UDP :

DatagramSocket DatagramPacket

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Socket ( ) Socket(InetAddress address, int port)

TCP stream socket port

Socket(String host, int port)

TCP stream socket port host,

InputStream getInputStream()

stream socket

OutputStream getOutputStream()

stream socket

InetAddress getLocalAddress()

socket

int getLocalPort()

socket

InetAddress getInetAddress()

/ socket

int getPort()

socket socket

void close()

socket ( socket description) 6

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ServerSocket ( ) ServerSocket(int port)

server socket . 0, ( )

ServerSocket(int port, int backlog)

server socket , ,

, Socket accept()

server . socket

void close()

server socket

InetAddress getInetAddress()

server socket

int getLocalPort()

server socket

7

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I/O Stream

Stream= /

Input Stream =

Output Stream: 8

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Java Streams

stream interfaces java.io

abstract

:

InputStream

OutputStream

9

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Stream Byte Array Streams

ByteArrayInputStream &

ByteArrayOutputStream

File Access Streams FileInputStream & FileOutputStream

Filter Streams (wrappers Streams): FilterInputStream & FilterOutputStream

BufferedInputStream

BufferedOutputStream DataInputStream

DataOutputStream

output stream 10

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CP client

11

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CP server

12

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13

client-side server-side

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(Serialization)

/ (integer, long, char, boolean, byte, float, double) DataInputStream/DataOutputStream

(..writeInt()/readInt()) strings

writeUTF()/readUTF()

,

Serializable interface ObjectInputStream/ObjectOutputStream

writeObject()

readObject() 14

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client/server Sockets

( ) C, Java ...

UNIX, Linux, MS Windows ...

:

TCP UDP

(request/replyprotocol)

To statefull stateless

, , API

(..,

) 15