Req #24797 [Com]: feature request: way to close connection with client?

From: Date: Tue, 30 Jul 2013 09:04:32 +0000
Subject: Req #24797 [Com]: feature request: way to close connection with client?
References: 1  Groups: php.bugs 
Request: Send a blank email to php-bugs+get-180560@lists.php.net to get a copy of this message
Edit report at https://bugs.php.net/bug.php?id=24797&edit=1

 ID:                 24797
 Comment by:         sushantahirrao at gmail dot com
 Reported by:        spagmoid at yahoo dot com
 Summary:            feature request: way to close connection with
                     client?
 Status:             Not a bug
 Type:               Feature/Change Request
 Package:            Feature/Change Request
 Operating System:   WinXP
 PHP Version:        4.3.2
 Block user comment: N
 Private report:     N

 New Comment:

Hello,
I am facing the same issue.
Following is the scenario,
1. User opens edit profile page
2. User puts an image file for uploading
3. User cancels request before any response from the server
4. Image file keeps being uploaded in the background even if the connection is 
closed


Expected Result:
Image file should not be uploaded if client closes the connection


Actual Result:
User is still able to see newly uploaded pic even if he had closed connection 
with the server.


Previous Comments:
------------------------------------------------------------------------
[2011-10-22 11:49:48] lucb1e at hotmail dot com

I would like to see this feature too, currently you'd need a very cumbersome way to do this (as
far as I know at least). This example is about an uploading script, which also synchronises with
other servers immediately (so no cronjob which would otherwise do the job).

The user opens the uploading page, and gets an upload form together with an invisible iframe. This
iframe is a php script that opens a listening socket and saves in a database table which port it is
on (together with the client's IP or, if available, session ID). This iframe-script also sets
ignore_user_abort.
When the user uploads a file, the processing script will do the following:
- Put the file somewhere and generate a download link;
- Echo the downloadlink to the user;
- ob_flush in the hope that the browser is smart enough to display the page already;
- Lookup the listening socket for this client in the database;
- Put the filename through to the iframe-script-which-has-listening-socket;
- die().

The 'iframe-script' then knows where the file is located which was just uploaded, and
without the user waiting for it, it can synchronise it with other servers - or do whatever it would
like to do.


This technique would theoratically work allright, but has a number of problems:
- Many webhosts do not support sockets at all;
- Listening sockets have even worse support as normal (client) sockets;
- Not all hosts allow you to set a custom maximum_execution_time, which is needed to prevent the
iframe-script from killing itself;
- I don't expect all hosts to support ignore_user_abort, though I didn't look into that
yet;
- It is unnessesarily complex compared to how easy it could be done with a kill_client_connection()
function.

------------------------------------------------------------------------
[2004-06-07 15:18:13] john_ramsden at sagitta-ps dot com

> Closing the connection itself from PHP is of course
> impossible, but if the remote client decides to close
> the connection then you can allow PHP to continue
> executing.

I have the same requirement as Spagmoid's, albeit for a different reason:

In my case it's a PHP script called by an SQL trigger - The script has to read the updated
records (to replicate them in another database); but the updated records aren't available until
the trigger completes, and the trigger can't complete until the PHP script disconnects! DUH!

Like Spagmoid's, my script obviously wouldn't try to send data after the disconnect, as
this doesn't make sense.

I must say, the PHP developers seem a bit dogmatic about this issue. Why should closing the
connection from PHP be "of course impossible"? What is to stop PHP having some interface
to tell Apache to do that without terminating the script itself?

I realize there's a simple workaround: the script can spawn an autonomous background process to
do "post processing". But I'm not aware of a portable PHP call to do this; so for a
platform-independent app, it would be lot cleaner if "early disconnects", followed by
post-processing, could be done in a single PHP script.

------------------------------------------------------------------------
[2004-03-25 14:18:50] php at digdug dot cx

I am looking for the same feature.

Here is the scenario: A user submits a form into script.php. The script needs to do two things:

1) Tell the user that the submission has been accepted. (It always is.)
2) Do some background processing on the submission and flag it if necessary. This takes up to half a
minute, so I don't want to make the user wait for it to finish.

So here is what I am trying to do:
<? insert_submission_into_database($submission); ?>
<html><body>
<? echo("submission accepted"); ?>
</html></body>
<?
   close_connection_to_browser(); // currently not possible
   if (submission_bad()) flag_submission();
   // no further info is sent to the browser
?>

------------------------------------------------------------------------
[2003-07-26 19:24:35] rasmus@php.net

Sara already answered your request by pointing you at the connection handling chapter in the manual.
 You are asking for a way to keep executing your script after the connection has been closed. 
Closing the connection itself from PHP is of course impossible, but if the remote client decides to
close the connection then you can allow PHP to continue executing.

Please stop re-opening this.  

------------------------------------------------------------------------
[2003-07-26 18:42:42] spagmoid at yahoo dot com

I DO NOT WANT TO SEND DATA TO THE CLIENT AFTER THE CONNECTION IS CLOSED.  NOWHERE DID I SAY THAT. 
That is what you people keep trying to tell me to do.  I don't want to do that.  I never wanted
to do that.  I will never want to do that.  That is ridiculous.

"The only time PHP can continue executing after the data stream has closed is when the browser
closes the connection itself."

I would be more inclined to believe this if you had understood any of the question.

"The only signal PHP can send to the webserver is "I'm done executing." It sends
this "signal" by terminating."

There may be another way to send this signal, but I doubt if either of you are in a position to tell
me.

"explaining your question in detail and making an attempt at civility by not attacking those
who take the time to respond."

It was in detail.  "A way to close the connection with the client, while keeping the script
running?"  That's it, period.  It's not a complicated issue.

Sending a form letter that doesn't even match the question is not "taking the time to
respond".

------------------------------------------------------------------------


The remainder of the comments for this report are too long. To view
the rest of the comments, please view the bug report online at

    https://bugs.php.net/bug.php?id=24797


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