synchronization of database
My assessment is to write a Client - Server application that use SQL database. A copy of database should be on both Client and Server side. While there are many Clients there is only one Server. Clients database entries change many times a day and every Client is about to synchronize with the database on the server. Synchronization is in the following form: 2 tables (with orders and orders details) are sent from Client do Server. 5 tables (with informations about products, prices, clients etc.) are sent from Server to Client.
I have already created the whole local side of the program (Client Side) but as I am new to Sockets I have a great problem with synchronization.
I implemented synchronization in the following way:
Client Size:
[code]
SocketConnection soc = (SocketConnection) Connector.open("socket://127.0.0.1:9988");
OutputStream osZ = soc.openOutputStream();
Vector worekZ = dbm.serializeZamowienia();
//serialized whole table from database
for(int i = 0; i < worekZ.size(); i++){
osZ.write((byte[]) worekZ.elementAt(i));
osZ.write(128);//rows separator
}
osZ.close();
soc = (SocketConnection) Connector.open("socket://127.0.0.1:9988");
OutputStream osZS = soc.openOutputStream();
Vector worekZS = dbm.serializeZamSzczegoly();
for(int i = 0; i < worekZS.size(); i++){
osZS.write((byte[]) worekZS.elementAt(i));
osZS.write(128);
}
osZS.close();
//so on with other tables that are about to send...
soc.close();
/////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
SocketConnection soc = (SocketConnection) Connector.open("socket://127.0.0.1:9988");
InputStream isC = soc.openInputStream();
int ch = 0;
int i = 0;
byte[] temp = new byte[1000];
Vector worek = new Vector();
while(true){
ch = isC.read();
if(ch == -1){
// -1 end of table (and also end of InputStream as each table is in separate IS)
break;
}
if(ch == 128){ // separator detected - go to next row
worek.addElement(temp);
String str = new String();
}
temp = (byte) ch;
i++;
}
dbm.deserializeCennik(worek); worek.removeAllElements();
isC.close();
soc.close();
soc = (SocketConnection) Connector.open("socket://127.0.0.1:9988");
InputStream isCK = soc.openInputStream();
while(true){
ch = isCK.read();
if(ch == -1){
break;
}
if(ch == 128){
worek.addElement(temp);
}
temp = (byte) ch;
i++;
}
dbm.deserializeCennikKlienci(worek);worek.removeAllElements();
isCK.close();
soc.close();
//and so on with other tables that are about to be received from server
[2912 byte] By [
staneqa] at [2007-11-26 17:48:10]
# 1
On the server side there is something like this. Note that number of send and received (serialized / deserialized) tables matches.
My problem is - please help me correct it to make it running.
Is the idea ok? Code compiles but it does not synchronize the database. It does nothing - difficult to diagnose.
public class ServerMobile {
private static Vector worek = new Vector();
private static SManager sm = new SManager();
private Socket clientSocket;
public static void main(String[] args) throws IOException {
ServerSocket serverSocket = null;
try {
serverSocket = new ServerSocket(9988);
} catch (IOException e) {
e.printStackTrace();
e.getMessage();
System.exit(1);
}
Socket clientSocket = null;
try {
clientSocket = serverSocket.accept();
} catch (IOException e) {
e.printStackTrace();
e.getMessage();
System.exit(1);
}
int ch = 0;
int i = 0;
byte[] temp = new byte[5000];
InputStream isZ = clientSocket.getInputStream();
while(true){
ch = isZ.read();
if(ch == -1){ // -1 koniec tabeli (Vectora)
break;
}
if(ch == 128){
worek.addElement(temp);
}
temp[i] = (byte) ch;
i++;
}
sm.deserializeZamowienia(worek);
worek.removeAllElements();
isZ.close();
clientSocket = serverSocket.accept();
ch = 0;
i = 0;
InputStream isZS = clientSocket.getInputStream();
while(true){
ch = isZS.read();
if(ch == -1){
break;
}
if(ch == 128){
worek.addElement(temp);
}
temp[i] = (byte) ch;
i++;
}
sm.deserializeZamSzczegoly(worek);
worek.removeAllElements();
isZS.close();
////////////////////////// EXPORT //////////////////////////////////
clientSocket = serverSocket.accept();
OutputStream osC = clientSocket.getOutputStream();
worek = sm.serializeCennik();
for(i = 0; i < worek.size(); i++){
osC.write((byte[]) worek.elementAt(i));
osC.write(128);
}
worek.removeAllElements();
osC.close();
clientSocket = serverSocket.accept();
OutputStream osCK = clientSocket.getOutputStream();
worek = sm.serializeCennikKlienci();
for(i = 0; i < worek.size(); i++){
osCK.write((byte[]) worek.elementAt(i));
osCK.write(128);
}
worek.removeAllElements();
osCK.close();
clientSocket = serverSocket.accept();
OutputStream osK = clientSocket.getOutputStream();
worek = sm.serializeKlienci();
for(i = 0; i < worek.size(); i++){
osK.write((byte[]) worek.elementAt(i));
osK.write(128);
}
worek.removeAllElements();
osK.close();
clientSocket = serverSocket.accept();
OutputStream osT = clientSocket.getOutputStream();
worek = sm.serializeTowary();
for(i = 0; i < worek.size(); i++){
osT.write((byte[]) worek.elementAt(i));
osT.write(128);
}
worek.removeAllElements();
osT.close();
clientSocket = serverSocket.accept();
OutputStream osU = clientSocket.getOutputStream();
worek = sm.serializeUsers();
for(i = 0; i < worek.size(); i++){
osU.write((byte[]) worek.elementAt(i));
osU.write(128);
}
worek.removeAllElements();
osU.close();
clientSocket.close();
serverSocket.close();
