How do I know if a socket is client disconnected?

If you called Socket. BeginReceive() on the server program and then the client closed the connection “gracefully”, your receive callback will be called and EndReceive() will return 0 bytes. These 0 bytes mean that the client “may” have disconnected.

How do you check if a socket is connected disconnected in Java?

isConnected() tells you whether you have connected this socket. You have, so it returns true. isClosed() tells you whether you have closed this socket. Until you have, it returns false.

How do you know if a socket is closed?

You could check if the socket is still connected by trying to write to the file descriptor for each socket. Then if the return value of the write is -1 or if errno = EPIPE, you know that socket has been closed.

How do I know if my TCP connection is broken?

TCP does have acknowledgments for data, so when one side sends data to the other side, it will receive an acknowledgment if the connection is stil active (or an error if it is not). Thus, broken connections can be detected by sending out data.

How does Java handle lost connection?

In order to notice that a connection is lost, you have to send some data on the application level. (*) You can try this out by unplugging the phone cable from your ADSL modem. All connections in your PC should stay up, unless the applications have some kind of application level keepalive mechanism.

How TCP terminates a connection?

The common way of terminating a TCP connection is by using the TCP header’s FIN flag. This mechanism allows each host to release its own side of the connection individually. Suppose that the client application decides it wants to close the connection. (Note that the server could also choose to close the connection).

How do I check my socket status?

There is an easy way to check socket connection state via poll call. First, you need to poll socket, whether it has POLLIN event. If socket is not closed and there is data to read then read will return more than zero. If socket is closed then POLLIN flag will be set to one and read will return 0.

When the server closes a socket what happens when the client try to use the closed socket?

The client program closes the socket using shutdown() or close() . When this happens, TCP will send a FIN packet to your server. This will show up as a closed socket in your server when you try to read beyond the last byte of data sent by the client. The next read() will probably throw an exception or error condition.

What happens when the client try to use the closed socket?

How do you keep a socket connection alive?

The SO_KEEPALIVE option for a socket is disabled (set to FALSE) by default. When this socket option is enabled, the TCP stack sends keep-alive packets when no data or acknowledgement packets have been received for the connection within an interval.

How does connection keep alive work?

Connection: Keep-Alive When the client sends another request, it reuses the same connection. The connection will continue to be reused until either the client or the server decides that the conversation is over, and one of them drops the connection.

How do I know if a socket is alive?

Just use the KeepAlive like @toster-cx says and then use the Socket Connected status to check if the Socket is still connected.