In a page I have multiple update panels that have timers associated with them to refresh the grids. My issue is that when asynchronous request (update panel) is in progress page does not respond. If user try to click some other link to move to some other page he even can not do that until asynchronous request is completed.
Is it not possible that user may able to cl...
Browser runs in a single-threaded mode, you can’t run any background task. If any task is running all other event gets queued up and user will get a impact that browser is hanged or not responding, so for situation like this you need to handle this by yourself.
1- Keep the partial post back light and fast.
2- If possible do it in small steps.
3- Show the progress bar, so that client will not get irritated.
Only one UpdatePanel can postback at a time. If your timer is kicking off multiple requests, the last one will win and cancel the rest.
Workaround:
Simultanious Async Requests Using Multiple Update Panel
Related
I am using asp.net and Ajax functionalities to make requests to server via web services for a search functionality. On click of search button, I am making the screen inactive by displaying a loading image over it. The issue is some searches takes longer time, and the user is forced to wait till the results are fetched. Is there any way the search can be cancelled manually, like a button click while the search is being performed by the server.
Any help or alternates will be appreciated.
One thing you can try is to set timeout on your ajax call, take a look here:asp-net-page-webmethod-ajax-call-request-timed-out
Another thing is to use javascript setTimeOut to display the user a message after a few seconds saying "its taking too long. wait for results or Abort?" where the "Abort" is a link that refreshes the page.
In our web application, a user can make a change that requires a lot of database tables to update. The load time for all that can be up to 30 seconds. I don't want the user to wait for that to complete before navigating to another page.
I've put the long-running code on its own page (say, "updateinfo.aspx") and tried a few solutions, including jQuery AJAX calls to "updateinfo.aspx" or loading an image file that calls "updateinfo.aspx". In all cases, I cannot navigate from the original HTML page that kicked off the AJAX call to another HTML page while "updateinfo.aspx" is executing. Chrome says that the request to "updateinfo.aspx" is pending. When I click on a link to navigate away from original HTML page, we're "Waiting for example.org..." until the AJAX page is finished, then the request to navigate to the next HTML page follows through and the new page loads.
So, this defeats the purpose of putting the long-running code into an AJAX page. The user's page renders quickly, but they cannot continue about their day by navigating to another page until the AJAX page is finished. I don't care about the output of the AJAX page.
Any thoughts?
You shouldn't really execute a long-running process in a web page context; the HTTP Request/Response model is not favourable to that concept when the client application is a web browser. This is a scenario I have had to address a number of times; you could: -
use MSMQ; submit a message to a queue containing details of the operation to be performed, or
write the details of the operation to be performed to a "Jobs" table
You can then create a Windows Service to read messages from the queue/pull un-processed items one at a time from the table, and perform the long-running operation.
In the most recent project I had to do this, from memory, I created a usercontrol that sat in the header (i.e. in the masterpage) which polled the database table via jQuery Ajax once every 15 seconds to detect when the job was completed, and show a popup to the user indicating the job was finished.
I can try and dig out some examples somewhere but those are the main moving parts, does that help at all ?
This is probably a really simple thing. Basically, the user clicks a button and a potentially long running task happens. I'd like to do a few things like toggle the button's enabled state, show a spinner, etc. In VB.NET Winforms I'd just do Application.DoEvents() and the updates would happen and the code can continue. How can I do this in ASP.NET? (preferable serverside or minimal javascript)
There are a few ways to approach this in ASP.Net depending on exactly what your requirement is. Getting the process started is fairly easy, but monitoring it for completion from the client side will require more work in both the server and the client.
The basic outline of the solution is:
1) Perform some action on the client that initiates the action. For example, you could post the entire page back on a button click, initiate an ajax request, or have a partial page postback depending on how much information you need from the page.
2) On the server side, initiate the task using a BackgroundWorker, make an entry in a workflow queue, or store a request in a database table that is monitored by a service that is responsible for performing the action.
3) Back on the client side, use javascript start a window.timeout loop that, when it times out, issues an ajax request to the web server to check on the completion. Using a timeout loop like this will ensure that the UI remains responsive and that any animations being displayed will display correctly. How you check on the completion will depend on how your server-side implementation is designed, but will almost certainly require a database.
We use the following general approach for initiating reports from the web client, which can be long running:
When the user initiates the report, open a new window to the report generation page on the client using javascript, passing the page enough parameters to get it started. Opening a separate window allows the user to continue working, but still see that there is something happening.
The user interface for the report page basically contains an animated GIF so that the user knows that something is going on.
When the report page is initially loaded on the server, it generates a unique id for monitoring the status of the report and embeds this in javascript for use in monitoring the status. It then stores this unique identifier in a database table that contains the unique id and a status column, initializing the status to requested.
Once the database entry has been made, the page fires off a BackgroundWorker to initiate the action and then returns the page to the user.
When the page is displayed, javascript starts a window.timeout loop that periodically fires off an ajax request to the web server, which then checks the database for the status of the report using the unique identifier created earlier.
When the backgroundworker finishes the report, either successfully or in failure, it updates the database table with the status, location of the report or error messages and terminates.
When the javascript loop finds that the report generation has completed, it either displays the error message or the report to the user.
Hopefully, this gives you some ideas for solving your issue.
The issue with this could be that once the page is posting you can't update other sections of the page.
you can use multiple asp:updatepanel and communicate to other update panel's causing the state to change in the panel.
take a look at this link:
http://www.ajaxtutorials.com/ajax-tutorials/tutorials-using-multiple-updatepanels-in-net-3-5-and-vb/
it will show you how to accomplish this.
I'm having a bit of trouble cancelling an asynch postback. I have an update panel with an update progress which contains a cancel button so that the user can cancel the postback. When the user clicks a button to generate a report the update progress is shown. The report can take a bit of time as it has to loop through a thousand or so times creating an excel spreadsheet. If the user decides to cancel running the report for any reason then they can click the cancel button which I then call abortPostBack() in javascript which stops the update progress and the page is shown again. However, the user can't do anything else like navigate to another page as the server is still processing the loop. How would I stop the loop on the server processing when the user has clicked the cancel button? Any help appreciated!
Are you saying that a simple HTTP link is not accessible on the client side until the async postback is complete? If so, that sounds like a conundrum, since you either have to optimize your server side process, or set a smaller server-side request timeout. Either that or redesign your user-interaction to make the server side Excel generation process an asynchronous one, rather than synchronous, so that the user doesn't have to wait until the Excel generation is complete. You could fancy this up on the client side to then set a JavaScript timer to periodically query the server to see if the file was ready, and if so, indicate that to the user with and give them a download file link option, or something.
Otherwise, if you could invoke another AJAX request while waiting on that to return (which you may not to from the sound of it), you could simply perform a new HTTP request that "cancels" the long running process. But that seems like it would not work since the server is still handling the long running HTTP request. So I'd opt to investigate the options in my first paragraph.
If cancelling did allow an async HTTP request to be performed on the client side, then you could set a session state value to indicate that cancel was requested. Personally I wouldn't approach it this way. But if you did, then your long-running server-side process could periodically look for the existence of a session value. Say:
if (Session["cancel-me"] != null)
{
Session["cancel-me"] = null;
abortThisLongProcess();
}
Yep, even if you navigate away from the page using the browser back button, as soon as you click anything else that needs to post back to the server the page hangs until the long process has completed. Looks like there's no way of canceling so I will have to look at redesigning the Excel generation.
I haven't found a way to cancel the request that's running, but there's no real reason that you can't start a new one.
By default ASP.Net tries (it can't always) to apply an exclusive lock on the session object - as soon as one page reads it every other page request that passes the same session ID (by cookie or on the URL) has to wait for the first page to release the session.
It doesn't matter that the client has cancelled the request - the server will continue to lock the session until the original page finishes executing.
I think the solution is to do away with the ASP session entirely. Then when the user requests another page it begins immediately, even though the server is still processing the old request on another thread.
I have a query page with a huge form that is filled out by the user. A button is clicked, and then the user waits for the process on the next page to finish running, and then is redirected to the new page. This is typical behavior if a long running process is running on the next page.
I want to run some sort of UpdateProgress in some manner to let the user know that there is a process running on the next page.
I tried doing some delay loading, but I'm not exactly sure why it isn't working. It's a simple ASPX page with a table, FormView to show data, all within an update panel. Anybody have any suggestions?
The only reliable way I got this to work for me was to create a worker thread that performed the unit of work. I then used the polling page to request an update on the threads progress and keep it redirecting to itself until the work was done.
It worked for me but I don't have any snippets to hand to help (sorry). I would point out, though, that you have to be pretty careful about how you setup your threads should you try out this approach. For a start, if memory serves me correctly you shouldn't use the backgroundworker as that will starve the asp.net thread pool (potentially).
In my code I created my own thread and handled all the polling, joining (etc) myself.
If need be, I can update this answer with some extra data unless other folk have better answers or snippets :).
HTH!