On Mon, May 31, 2010 at 13:36, Qoo Goo <qoo...@gmail.com> wrote:
> 2010/5/31 Derrell Lipman <derrell.lip...@unwireduniverse.com>:
>
> Yes, I agree. It's not the same calling a Response.End() than calling
> Response.Close(), for sure (I must admit that I haven't never used
> this method, I have to catch up who was!!). In fact, quoting VS
> built-in methods' descriptions, the first
>
> "Sends all currently buffered output to the client, stops execution of
> the page, and raises the System.Web.HttpApplication.EndRequest event"
>
> while Response.Close() simply
>
> "Closes the socket connection to a client."
>
Ok, so that's telling you what the problem is. The latter does not send all
currently buffered output to the client, so the client just gets a
connection closed notification without receiving the data it expects to
receive.
>
> Anyway, I think this is a Chrome's bug because if you flushes
> explicitly the contents before closing the connection, every bit of
> data should arrive at client side before the connection is closed and
> in this situation I think the browser should definitely process data
> before considering that the connection is finished (because it was not
> closed when content was sent).
Ah, but if the data is never flushed before closing the connection, it will
never arrive, right? :-)
Here is the relevant section from RFC793 (TCP) pertaining to what happens on
the server and client sides of a close:
3.5. Closing a Connection
CLOSE is an operation meaning "I have no more data to send." The
notion of closing a full-duplex connection is subject to ambiguous
interpretation, of course, since it may not be obvious how to treat
the receiving side of the connection. We have chosen to treat CLOSE
in a simplex fashion. The user who CLOSEs may continue to RECEIVE
until he is told that the other side has CLOSED also. Thus, a program
could initiate several SENDs followed by a CLOSE, and then continue to
RECEIVE until signaled that a RECEIVE failed because the other side
has CLOSED. We assume that the TCP will signal a user, even if no
RECEIVEs are outstanding, that the other side has closed, so the user
can terminate his side gracefully. A TCP will reliably deliver all
buffers SENT before the connection was CLOSED so a user who expects no
data in return need only wait to hear the connection was CLOSED
successfully to know that all his data was received at the destination
TCP. Users must keep reading connections they close for sending until
the TCP says no more data.
There are essentially three cases:
1) The user initiates by telling the TCP to CLOSE the connection
2) The remote TCP initiates by sending a FIN control signal
3) Both users CLOSE simultaneously
Case 1: Local user initiates the close
In this case, a FIN segment can be constructed and placed on the
outgoing segment queue. No further SENDs from the user will be
accepted by the TCP, and it enters the FIN-WAIT-1 state. RECEIVEs
are allowed in this state. All segments preceding and including FIN
will be retransmitted until acknowledged. When the other TCP has
both acknowledged the FIN and sent a FIN of its own, the first TCP
can ACK this FIN. Note that a TCP receiving a FIN will ACK but not
send its own FIN until its user has CLOSED the connection also.
Case 2: TCP receives a FIN from the network
If an unsolicited FIN arrives from the network, the receiving TCP
can ACK it and tell the user that the connection is closing. The
user will respond with a CLOSE, upon which the TCP can send a FIN to
the other TCP after sending any remaining data. The TCP then waits
until its own FIN is acknowledged whereupon it deletes the
connection. If an ACK is not forthcoming, after the user timeout
the connection is aborted and the user is told.
Case 3: both users close simultaneously
A simultaneous CLOSE by users at both ends of a connection causes
FIN segments to be exchanged. When all segments preceding the FINs
have been processed and acknowledged, each TCP can ACK the FIN it
has received. Both will, upon receiving these ACKs, delete the
connection.
TCP A TCP B
1. ESTABLISHED ESTABLISHED
2. (Close)
FIN-WAIT-1 --> <SEQ=100><ACK=300><CTL=FIN,ACK> --> CLOSE-WAIT
3. FIN-WAIT-2 <-- <SEQ=300><ACK=101><CTL=ACK> <-- CLOSE-WAIT
4. (Close)
TIME-WAIT <-- <SEQ=300><ACK=101><CTL=FIN,ACK> <-- LAST-ACK
5. TIME-WAIT --> <SEQ=101><ACK=301><CTL=ACK> --> CLOSED
6. (2 MSL)
CLOSED
Normal Close Sequence
Figure 13.
TCP A TCP B
1. ESTABLISHED ESTABLISHED
2. (Close) (Close)
FIN-WAIT-1 --> <SEQ=100><ACK=300><CTL=FIN,ACK> ... FIN-WAIT-1
<-- <SEQ=300><ACK=100><CTL=FIN,ACK> <--
... <SEQ=100><ACK=300><CTL=FIN,ACK> -->
3. CLOSING --> <SEQ=101><ACK=301><CTL=ACK> ... CLOSING
<-- <SEQ=301><ACK=101><CTL=ACK> <--
... <SEQ=101><ACK=301><CTL=ACK> -->
4. TIME-WAIT TIME-WAIT
(2 MSL) (2 MSL)
CLOSED CLOSED
Simultaneous Close Sequence
Figure 14.
Read more:
http://www.faqs.org/rfcs/rfc793.html<http://www.faqs.org/rfcs/rfc793.html#ixzz0pWvnOeaG>
Derrell
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