Explorer waiting indefinitely for IIS response

[PullWood]

Strange and curious problem I'm experiencing.

I implemeted a web site asp solution IIS 5.0.
The site performe long calculations.
What's happening is the following:
if I connect through a ADSL connection I don't have problems, the browser
(IE 6.0) wait also for 20/30 minutes and then receive correctly the response
from the IIS server. If I connect through a dial-up connection, if the
calculations duration is more that 10/15 minutes, than the browser wait
undefinitely, without any signal, and doesn't receive the response from the
server, although the calculations ended correcly. The browser didn't freeze
or crash, simply wait forever!
I've tried everything:

I checked the "current connections" counter of performance monitor on the
server host running IIS.
But it seems that the connection isn't lost.
I checked with a sniffer TCP/IP packets, and I noticed nothing strange,
apart that the response was not being sent/received.

Anyone experiencing a similar problem?
Any suggestion, or idea to solve the problem?

Thank's a lot for your help.

Andrea Tirabosco

 

[Bob Barrows [MVP]]

Strange and curious problem I'm experiencing.

I implemeted a web site asp solution IIS 5.0.
The site performe long calculations.
What's happening is the following:
if I connect through a ADSL connection I don't have problems, the
browser (IE 6.0) wait also for 20/30 minutes and then receive
correctly the response from the IIS server. If I connect through a
dial-up connection, if the calculations duration is more that 10/15
minutes, than the browser wait undefinitely, without any signal, and
doesn't receive the response from the server, although the
calculations ended correcly. The browser didn't freeze or crash,
simply wait forever!
I've tried everything:

For such a long-running calculation, I would not even try fixing this
symptom. Instead, I would do the calculation asynchronously. This is not the
type of operation that is suited for web-based applications. I would create
a page that kicked off the calculation process (perhaps via a COM object)
and then informed the user to come back later on to see the result, or use
an email notification when the result was ready. The asynchronous process
would perform the calculation and store the result somewhere along with some
sort of identification to allow the user to retrieve the result when he
returned.

 

[Anthony Jones]

Strange and curious problem I'm experiencing.

I implemeted a web site asp solution IIS 5.0.
The site performe long calculations.
What's happening is the following:
if I connect through a ADSL connection I don't have problems, the browser
(IE 6.0) wait also for 20/30 minutes and then receive correctly the response
from the IIS server. If I connect through a dial-up connection, if the
calculations duration is more that 10/15 minutes, than the browser wait
undefinitely, without any signal, and doesn't receive the response from the
server, although the calculations ended correcly. The browser didn't freeze
or crash, simply wait forever!
I've tried everything:

I checked the "current connections" counter of performance monitor on the
server host running IIS.
But it seems that the connection isn't lost.
I checked with a sniffer TCP/IP packets, and I noticed nothing strange,
apart that the response was not being sent/received.

Anyone experiencing a similar problem?
Any suggestion, or idea to solve the problem?

Thank's a lot for your help.

Andrea Tirabosco

Are you sure that the dialup isn't disconnecting during that time?
Still the answer to that question is immaterial, I agree with Bob leaving
browser in an apparently hung state for this amount of time is not a good
design. In fact expecting a ASP request to process for that amount of time
isn't some way from ideal also.

If you are not yet familar with the use of the XMLHTTPRequest or the
Microsoft.XMLHTTP object then it's worth researching.

On possible model would be this:-

Client builds parameters needed for calculation into XML then posts the XML
to an upload ASP page.

The upload page on the server allocates a unique ID for the job, delivers
the XML to a known input folder using the ID as a filename and responds to
the client with ID.

Server has a scheduled task to run some VBS which polls the input folder
looking for XML files. On finding one it loads the XML, extracts the
calculation parameters and proceeds with the calculation. On completion it
can write the results to an known output folder using the same ID filename
as the input.

Meanwhile the client polls the output folder for a filename using the
allocated ID. When it exists the client can navigate to an ASP page putting
the ID in the querystring. This ASP page can retrieve and remove the file
from the output folder and use it's contents to render the results page.


Anthony.

 

[Patrice]

You could even close the browser. The server has no way to know the browser
was closed and will continue computing the results (I believe you could use
IsClientConnected to test for this). You perhaps also hit some limits (you
have likely changed the ScriptTimeOut but my guess would be that there is
also a timeout client side that perhaps depend on the thorughtput ?).

(and yes like other posters I would do this asynchronously anyway...)

 

[PullWood]

Thank a lot for your answer.
This confirm what I was thinking about as the only solution to avoit it.

Regards,

Andrea Tirabosco