I have a asynchronous task in RQ-worker to download files from the internet, i want to monitor the progress in a webpage, i searched over internet and can not find any methods to synchronously display the progress or task states.
there's a way that is, i save the RQ-worker states in mysql, every time when my job-queue changed state,update row in mysql, in html webpage, set a timer, request the api every one or two seconds, and then refresh the status div.
I just want to know is there any other methods more elegant to solve this problem?
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I currently have a very labor intensive function called "RestoreEmail" so I've put it into a thread on the webpage like this:
Task.Factory.StartNew(() => RestoreEmail());
However, I'm finding that if the person using the webpage doesn't sit and wait for it to process (they close the browser window or move to a different page) it doesn't restore the email and all is lost. I had this problem once a while back on a different project and I called an external page that then would process the function. Would this work better for my current situation? If I was to do this how exactly would I call the external page? I don't want the page to wait for the data to download because I presume it will yet again wait for the RestoreEmail to process.
I have a table of records that has a column processed. In my web page i'm using sessions.. because every user that opens the page should see different data from the table.. so i initially have processed=0 and when i'm selecting my data i'm updating the column where processed=0 and then i'm updating the column to processed=2 so that way if another opens the page he gets other data... but the problem is that if the user closes the page without changing anything about the page i need to put my column back to 0 processed=0 but i can't handle an event on the close button of the page... and also not on the log out because they may close the page without logging out... so does anyone has any idea how can i manage this?
note that i'm using asp.net with vb.net
for what you need, don't rely on some browser action, i.e. browser close button (what if internet goes down for one of the users :) ).
The simple way to achieve this is to perform somekind of polling at both levels, i.e. in the db(since your flag is stored in the db) and at the code. Polling implies, constantly making request for certain operation after a fixed interval of time. Obviously, polling is taxing, but it is one of the solution.
Another way to do is to as soon as your user Logs in, you create a Http Long lived request, which neither of the parties(client and server) break and as soon as it ends, you set the flag to 0 again, but having a parallel long lasting request along with all those others is not simple. It is termed as Comet
So I would recommend, to constantly make an ajax request say every 2minutes, to update a certain field, say LastActive in user accounts table. This would constitute your Code side Polling
and Then create a sql server job, which constantly monitors this LastActive field and say, if the difference between it and current DateTime is more than 2.10 minutes, it sets the processed=0 for that user.
You can also look into SessionExpire fields(or whatever it is called), if you are using Forms Authentication of ASP.NET through Session
I have a table in SQL Server which contains more than 12000 rows. When I load all the rows into an asp.net web page it takes 10 to 15 minutes to load all the rows.
Please help me loading data in seconds..
Which part of the process is taking the most time? There are many distinct stages to this action:
Query execution time in SQL Server.
Transfer time from SQL Server to your data reader (ADO.NET? across a network?)
Binding the data to the grid in ASP.NET.
Transferring the rendered HTML to the client.
Only when you know exactly what is slow, can you properly optimise.
Solutions:
You can use qzip. Apparently, it won't bring load times down to seconds. But you will see good improvements in load time.
Write an handler which returns results in set of 100's and display results using jQuery asynchronously as in Facebook, where when you move down, more stories are feed, you can do a similar thing for your website, or you can have a "Load More" button which does the same thing except the user has to press the "Load More" button instead.
Note: Implementing the above is not that hard.
probably you need to find an third party grid control which have on-demand virtual paging support.
In my mathematical application I am using timers to regularly perform certain actions. These actions can also be configured by my users. Now I don't want these actions to be executed if there is already another action busy.
E.g. if the user just started a complex calculation by selecting a menu entry, I don't want to execute the actions behind my timers.
Problem is that the user can execute an action via a lot of different ways (via the menu, by clicking somewhere, via popup menu, via drag-and-drop, ...). What I effectively want is to prevent the timers from going off if the application is currently not in the main event loop.
I will give a more concrete example to make it clearer:
At startup I create the timers
If a timer goes off, I execute some actions which, in practice, could access almost every bit in may application's data structure.
Now suppose the user starts a mathematical algorithm (via the menu, by clicking or by dragging elements on the screen, it doesn't matter how he started it).
The algorithm will perform lots of calculations (in the main thread). Since they are executed in the main thread, the timer events will not go off.
Now the algorithm shows a message box (could be a warning or a question).
While the message box is open, events are processed again, including my timer events, which could possibly perform incorrect calculations because there is already another algorithm running.
Reworking my application so that I move logic to a separate worker thread, or adding checks to all of my actions isn't possible at this moment. So please don't suggest to completely rework my application.
What I tried so far is the following:
Using postEvent to send an event, hoping that this event would only be executed in the main event loop. Unfortunately, also the message box's event loop seems to process posted events.
Using the QEvent::WindowBlocked and QEvent::WindowUnblocked events to see when a modal dialog was opened. In my timer-event-logic I can check whether we are between QEvent::WindowBlocked-QEvent::WindowUnblocked calls or not. Unfortunately, these events only work for modal dialogs created by Qt itself, not for other dialogs (e.g. the Windows MessageBox, or the system's printer configuration dialog). Also, this trick would not help if there would be other event loops created by sub routines.
What I actually need to solve my problem is a simple function, that:
If the application is handling an event in the main event loop returns true
If the application is handling an event in another [sub] event loop, it returns false
An alternative could be to return a level that indicates the 'depth' of the handled event.
Anyone suggestions?
You could hook into the event loop of your main thread/application using QAbstractEventDispatcher. Conditionaly filter out QTimer-events based on your application state.
I have a ASPX page which queries from a database. Once we have the dataset it is bound to a gridview and displayed on the page. All this happens in the Page_Load event.
Ofcourse this a simplistic approach. What is the best way to inform the user that data is being retrieved and when we have the data to update the page with the results in the dataset.
I want all this to happen within the same ASPX page and do not want to hop around pages to achieve this. I looked at update panels however it wasn't clear to me how this could be done with an update panel without having a control which triggers the update for the update panel. There are no controls on my page whhich initiate the database query, it occurs as the page is loaded.
If I do the query in a worker thread and then call the Update method on a UpdatePanel with the gridview as part of it, it doesn't work. Nothing happens.
Any thoughts or help? Thanks.
Well, this is a good question. Personally I have two pretty similar methods to do this:
Have a java script that will make an UpdatePanel reload with a short interval. This will create a series of post-backs to the server. During each post-back you should chek you worker thread and return immediately with the state report, usually one of error, pending, success + data
With a java script, make an asynchronous request to a web-service that will block until the data is fetched. This method brings no latency as compared to the previous one (the time between polls), but may suffer from some browsers/servers attitude to hanging open connections. This is normally solved by some interval (say, 1 minute) introduced, so that the hanging request will return with a message like need more time, in which case the java script should simply repeat the request.