Handling requests that have a long response time

[SJ]

I have a request to the server that could take upto 10 mins to come back
and display the results.
I want to either
a) Redirect to a new "Please wait" page till the processing is done, then
redirect back to the results page , or
b) Display a "Please wait" message on the same page that sends the request
to the server and refresh the page to display the results.
I know websites like orbitz and travelocity do this.

Any idea how I would accomplish this?

Thanks,
-SJ.

 

[Rob Meade]

...

I have a request to the server that could take upto 10 mins to come back
and display the results.
I want to either
a) Redirect to a new "Please wait" page till the processing is done, then
redirect back to the results page , or
b) Display a "Please wait" message on the same page that sends the request
to the server and refresh the page to display the results.
I know websites like orbitz and travelocity do this.

Any idea how I would accomplish this?

Hi SJ,

I'm not sure if this is the "best" approach - but it is certain "an"
approach )

Presumably whatever you are 'triggering' is database driven? Hencing the
processing time? My thought was that perhaps if you were able to ascertain
an ID of sorts, you could keep redirecting to the same page every 10 seconds
or something sending the ID in the form or querystring, and, if this page
receives an ID then it checks the current "state" of the processing, until
it comes back and says "I'm done" it keeps refreshing every 10 seconds.

The page could easily have an animated .gif or something on it to indicate
that something is still happening.

As I said, probably not the best approach, but an approach none the less.

I've fired things off using threading before to ensure they complete, but
I've never (yet) had the need to wait around to see what the outcome was on
the same request.

I don't feel I've been much help - sorry..

Rob

 

[Matt Sollars]

Rob,

Don't sell your idea short. I think it's a valid one. I only see a
couple of things I would recommend in addition.

The "I'm done" state could certainly be represented by some Status
field. I would refresh the current page at a larger interval than 10
seconds if the operation could take 10 minutes. Set the refresh to occur
5-10 seconds before the script timeout (i.e. Timeout = 90 seconds,
refresh the page every 80 seconds).

Perhaps, use a postback instead of a refresh with a querystring
variable. I only say this to make things harder for tampering users or
hackers. You could emit the JavaScript with a postback reference similar
to the following:


//-------------------------------------------------------

private int TaskID {
get {
object Value = ViewState["TaskID"];
if (Value == null)
return 0;
else
return (int)Value;
}
set {
ViewState["TaskID"] = value;
}
}

private void Page_Load(object sender, System.EventArgs e) {
if (Page.IsPostBack) {
string JSFunction = GetPostBackEventReference(this);
RegisterStartupScript("Refresh", "<script
language=\"JavaScript\">window.setTimeout(\"" + JSFunction + "\", " +
((Server.ScriptTimeout - 10) * 1000).ToString() + "</script>");
}
}

private void Button1_Click(object sender, System.EventArgs e) {
// Retrieve some sort of task ID just before beginning the task.
this.TaskID = GetNewTaskID();

// Begin the very long procedure here.
...
}

//-------------------------------------------------------

I really like the idea of an animated GIF image as well.


Regards,

Matt

 

[Guest]

I have a request to the server that could take upto 10 mins to come back
and display the results.

What is processing the request?

Database? Query? Service?

If it's extreme long running, you may want to look at Message Queues...
which will let you monitor the status of a pending request without tying up
too many resources.