problem with establish connection

[NickKovach]

hello

strange problem: i wrote for PC a simple TCP server which accepts TCP connections on port 6168.

From mobile (5500sport) i can connect this server from browser if i enter URL 80.68.5.132:6168

Of cause my simple server on PC is not a web server but it detects fact of connection from mobile for sure.

But when i write my java MIdlet for mobile which makes same URL open then i do not see connection.

public boolean Open(String server_name)
{
try {
sc = (SocketConnection) Connector.open("socket://80.68.1.132:6168");
sc.setSocketOption(SocketConnection.DELAY, 0);

is = sc.openInputStream();
//os = sc.openOutputStream();

return true;
}
catch (ConnectionNotFoundException cnfe)
{
return false;
}
catch(IOException ioe)
{
return false;
}
}

I do not know why my JAVA application cannot connect.
What i do incorrect?

nick

[peterblazejewicz]

hi,

any exception thrown in midlet or it just does not see to go through data carrier gateways?

regards,
Peter

[NickKovach]

hi,

any exception thrown in midlet or it just does not see to go through data carrier gateways?

regards,
Peter

---------------------------
hm..
i do not know..
probably exception raised but catched - You see from code that i trying to catch 2 types of exceptions - ConnectionNotFoundException and IOException.

Which exception happens i do not know yet - i should check.

Anyway it looks so: when starting connection my App hangs for long time - maybe 1-2 minutes and only after that it says cannot connect when Open() function returns false.

Besides that same midlet works fine from emulator.

Other interesting point: i got example of nokia from
MIDP_2_0_Introduction_to_Using_Sockets_and_Datagrams_v1_0_1.zip

Called TCPMidlet - it behaves exactly as my own application - when connecting long nothing and then says error.

I feel that probably matter is not a midlet java source itself but maybe mobile phone configuration? But how to configure phone? Phone browser works fine with internet so mobile looks configured OK.

Maybe i should sign midlet or similar? I am new in mobile programming and maybe i do not know some tips?

Please help me

[Summerman]

Hi NickKovach and Peter!

After fighting several weeks with TCP/UDP connections, in a real test I noticed that my MIDlet didn't connect to a ServerSocket that was running in a Servlet in a remote PC. The URL was perfect: "socket://hostort" and the "host" and "port" values were correctly too.

My problem was that the implementation noticed that the phone didn't have a real connection established at the same time that the socket was open! Finally, the code threw an Exception because the socket connection wasn't really open. If the Exception is thrown, no more attempts to open the socket are made!
I used a WLAN connection and it took one minute or two until getting the connection!

To sum up: You need to use a "loop" where you try to connect to your particular server socket (with the correct URL) and repeat this operation until you get it! If an Exception occurs, close the connections. Don't forget to close the connections previously to reopen them!
One of these attempts will work your socket connection!

I hope this explanation would be useful for you!

Summerman. --

[chinlin]

Hi NickKovach and Peter!

After fighting several weeks with TCP/UDP connections, in a real test I noticed that my MIDlet didn't connect to a ServerSocket that was running in a Servlet in a remote PC. The URL was perfect: "socket://hostort" and the "host" and "port" values were correctly too.

My problem was that the implementation noticed that the phone didn't have a real connection established at the same time that the socket was open! Finally, the code threw an Exception because the socket connection wasn't really open. If the Exception is thrown, no more attempts to open the socket are made!
I used a WLAN connection and it took one minute or two until getting the connection!

To sum up: You need to use a "loop" where you try to connect to your particular server socket (with the correct URL) and repeat this operation until you get it! If an Exception occurs, close the connections. Don't forget to close the connections previously to reopen them!
One of these attempts will work your socket connection!

I hope this explanation would be useful for you!

Summerman. --

Hi Summerman,
Do you mean that you have madethe socket class successfuly worked?
or not worked at all?

Thanks,
Chinlin

[Summerman]

Hi Chinlin,
I tested some different J2ME communication classes work! Excuse me, for not expecify what classes are.

Concretely, they are:

1) The "UDPDatagramConnection" class.

2) The "SocketConnection" class.

3) The "ServerSocketConnection" class.

In your case, you are interesting in the "SocketConnection" class. Here, I include a snippet of my code:

	
        private void openCommUntilIsConnectedToServer(){
		
		do{
			
			reOpenComm(1000);
			
		}while(!connectedToNetwork);		
	}


	private void reOpenComm(int pause){		
		try {
			closeComm();//closeComm() manages its Exceptions!
			
			Thread.sleep(pause);
			
			openComm();//openComm() manages its Exceptions!
			
		}catch (InterruptedException ie) {
			//Ignored
		} 
	}
	
        private void openComm() {

		try{
			
			// Create an outbound socket for the corresponding url. 
			sc = (SocketConnection)Connector.open(url);
			
			//Set the socket options
			setSocketOptions(DELAY_VALUE, LINGER_VALUE, KEEPALIVE_VALUE, RCVBUF_SIZE, SNDBUF_SIZE);
			
			//Open the DataOutputStream and the DataInputStream objects.
			dos=sc.openDataOutputStream();
			dis=sc.openDataInputStream();
			connectedToNetwork=true;

		}catch (Exception e){
                    //Ignored
		}

I expect this snippet code will help you!

Best regards.

Summerman.

[chinlin]

Hi,
Many thanks to you