كيف اعالج فشل احد السيرفرات

السلام عليكم

اخواني الافاضل

برنامجي هو عبارة عن كلاينت يقوم بالاتصال مع اثنين من السيرفرات وهو يعمل بشكل صحيح ..لكن ما احاول عمله الان هو معالجة حالة فشل احد السيرفرين..والمشكلة تحديدا هي عندما لا يجد السيرفر الاول يتوقف الكلاينت عن العمل ولا يرسل الى السيرفر الثاني ..فلا اعلم هل يوجد طريقة معينة استطيع من خلالها تجاوز هذه المشكلة وكيف يعرف الكلاينت ان السيرفر غير موجود .

ولكم خالص الشكر

client one

import java.net.*;

import java.util.Scanner;

import java.io.*;

//import java.util.Scanner;

public class client {

public static void main(String args[]) throws IOException {

String st=null;

//choose replicas

System.out.println(" If you want replica1 enter 1 \n " +

"If you want replica2 enter 2 \n" +

);

Scanner scan1 = new Scanner(System.in);

int replica =scan1. nextInt();

Scanner scan2 = new Scanner(System.in);

int usrInput1 =scan2. nextInt();

try {

Socket clientsocket1 = new Socket("localhost",11111);

// Get an input and Output

InputStream s1In1 = clientsocket1 .getInputStream();

DataInputStream dis1 = new DataInputStream(s1In1);

OutputStream s1out1 = clientsocket1 .getOutputStream();

DataOutputStream dos1 = new DataOutputStream (s1out1);

dos1.writeInt(replica);

dos1.writeInt(usrInput1);

Socket clientsocket2 = new Socket("localhost",20222);

// Get an input and Output

InputStream s1In2 = clientsocket2 .getInputStream();

DataInputStream dis2 = new DataInputStream(s1In2);

OutputStream s1out2 = clientsocket2 .getOutputStream();

DataOutputStream dos2 = new DataOutputStream (s1out2);

dos2.writeInt(replica);

dos2.writeInt(usrInput1);

if(replica==1){

dos1.writeUTF(st);

//Received the result of search

st = new String (dis1.readUTF());

while(st!=" ")

{System.out.println(st);

st = new String (dis1.readUTF());}

}//end if R1

if(replica==2){

dos2.writeUTF(st);

//Received the result of search

st = new String (dis2.readUTF());

while(st!=" ")

{System.out.println(st);

st = new String (dis2.readUTF());}

}//end if R2

// When done, just close the connection and exit

dis1.close();

s1In1.close();

dos1.close();

s1out1.close();

clientsocket1.close();

dis2.close();

s1In2.close();

dos2.close();

s1out2.close();

clientsocket2.close();

}catch (Exception e){}

}

}

server one

import java.io.*;

import java.net.*;

//import java.util.Scanner;

import java.text.SimpleDateFormat;

import java.util.Date;

public class server1 implements Runnable {

Socket csocket;

server1(Socket csocket) {

this.csocket = csocket;

}

public static void main(String args[]) throws Exception {

ServerSocket ssock = new ServerSocket(11111);

System.out.println("Listening1");

while (true) {

Socket csocket = ssock.accept();

System.out.println("Connected1");

new Thread(new server1(csocket)).start();

}

}

public void run()

{

try{

//Get a communication stream associated with the socket

OutputStream s1out = csocket.getOutputStream();

DataOutputStream dos = new DataOutputStream (s1out);

InputStream s1In = csocket.getInputStream();

DataInputStream dis = new DataInputStream(s1In);

int r =dis.readInt();

int numInput =dis.readInt();

if (r==1){

//receive a string

String BookName =dis.readUTF();

System.out.println("server1 received " + BookName + " from client");

dos.writeUTF("server1 received " + BookName + " from client and send ok from server1");

/*----------------Get a communication with server2-------------*/

Socket s2= new Socket("localhost",12222);

// Get an input and Output

InputStream s1In2 = s2.getInputStream();

DataInputStream dis2 = new DataInputStream(s1In2);

OutputStream s1out2 = s2.getOutputStream();

DataOutputStream dos2 = new DataOutputStream (s1out2);

//send information to server2

dos2.writeInt(numInput);

dos2.writeUTF(BookName);

// massage received from server2

System.out.println(dis2.readUTF());

s1out2.close();

s1In2.close();

dos2.close();

dis2.close();

s2.close();

}

if(r==2){

//Get a communication stream associated with the socket2

ServerSocket ssock = new ServerSocket(21111);

Socket csocket2;

while (true) {

csocket2 = ssock.accept();

new Thread(new server1(csocket)).start();

InputStream s1In2 = csocket2.getInputStream();

DataInputStream dis2 = new DataInputStream(s1In2);

OutputStream s1out2 = csocket2.getOutputStream();

DataOutputStream dos2 = new DataOutputStream (s1out2);

int num= dis2.readInt();

String BookName=dis2.readUTF();

// massage received from server2

System.out.println("server1 received " + BookName + " from server2");

//send information to server2

dos2.writeUTF("server1 received " + BookName + " from server2 and send ok12 from server1");

s1out2.close();

s1In2.close();

dos2.close();

dis2.close();

csocket2.close();

}

}

s1out.close();

s1In.close();

dos.close();

dis.close();

csocket.close();

}

catch (IOException e) {

System.out.println();

}

// When done, just close the connection and exit

}

}

server2

import java.io.*;

import java.net.*;

//import java.util.Scanner;

import java.text.SimpleDateFormat;

import java.util.Date;

public class server2 implements Runnable {

Socket csocket2;

server2(Socket csocket) {

this.csocket2 = csocket;

}

public static void main(String args[]) throws Exception {

ServerSocket ssock = new ServerSocket(20222);

System.out.println("Listening2");

while (true) {

Socket csocket2 = ssock.accept();

System.out.println("Connected2");

new Thread(new server2(csocket2)).start();

}

}

public void run()

{

try{

//Get a communication stream associated with the socket

OutputStream s1out2 = csocket2.getOutputStream();

DataOutputStream dos2 = new DataOutputStream (s1out2);

InputStream s1In2 = csocket2.getInputStream();

DataInputStream dis2 = new DataInputStream(s1In2);

int r =dis2.readInt();

int numInput =dis2.readInt();

if(r==1)

{

/*-------Get a communication with server1----------*/

ServerSocket ssock = new ServerSocket(12222);

Socket csocket1 ;

while (true) {

csocket1 = ssock.accept();

new Thread(new server1(csocket2)).start();

// Get an input and Output

InputStream s1In1 = csocket1.getInputStream();

DataInputStream dis1 = new DataInputStream(s1In1);

OutputStream s1out1 = csocket1.getOutputStream();

DataOutputStream dos1 = new DataOutputStream (s1out1);

// massage received from server2

int num =dis1.readInt();

String BookName=dis1.readUTF();

System.out.println("server2 received " + BookName + " from server1" );

//send information to server2

dos1.writeUTF("server2 received " + BookName + " from server1 and send ok21 from server2");

s1out1.close();

s1In1.close();

dos1.close();

dis1.close();

csocket1.close();

}

}

if(r==2)

{

//receive a string

String BookName =dis2.readUTF();

System.out.println("server2 received " + BookName + " from client");

dos2.writeUTF("server2 received " + BookName + " from client and send ok2 from server2");

/*----------------Get a communication with server1-------------*/

Socket s1= new Socket("localhost",21111);

// Get an input and Output

InputStream s1In1 = s1.getInputStream();

DataInputStream dis1 = new DataInputStream(s1In1);

OutputStream s1out1 = s1.getOutputStream();

DataOutputStream dos1 = new DataOutputStream (s1out1);

//send information to server2

dos1.writeInt(numInput);

dos1.writeUTF(BookName);

// massage received from server2

System.out.println(dis1.readUTF());

s1out1.close();

s1In1.close();

dos1.close();

dis1.close();

s1.close();

}

s1out2.close();

s1In2.close();

dos2.close();

dis2.close();

csocket2.close();

}

catch (IOException e) {

System.out.println("");

}

// When done, just close the connection and exit

}

}