Im working on a silverlight application where a user can create, edit, delete objects. The changes they make are placed in a queue which is processed every 4 minutes. When it is processed, the updates are sent over an async web method call to be saved in a sql database, one at a time. When the first update finishes, the next starts.
Im having a problem when a user makes a change and then exits the browser app before the 4 minute timer has expired. Currently the changes are getting lost.
Ive built on what the guy working on this before me has done, and explored the Dispose and Finalize methods, trying to start the update process when the factory is being shut down, but that isnt working due to the async nature of the web service calls. I get errors saying needed objects have already been disposed of.
Im looking for a way to save the data in the updatequeue using a webmethod when the user tries to close or refresh the webpage. Im not expecting the queue to be packed full with updates. This is an application that would usually be run for several hours at a time.
You can use Javascript to stop the user leaving the page. StackOverflow does it (try editing an answer and leaving the page). That works on browser close as well as page navigation. From Javascript you can also notify the Silverlight app to save any queued data (Silverlight support exposing methods to Javascript).
Q. Saving every 4 minutes is slightly odd behaviour for a Silverlight App. I am guessing it is only deigned to be run by one user at a time. What restricts you from saving more frequently?
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I have built a react native app/game where a user has 30 mins to finish a task....when they start task, the 30 mins starts to countdown and it is registered in DB (Firebase) that user is "in play". When they complete task (or 30 mins run out) then DB is again updated to "not in play".
Countdown function is operating on phone and not on server.
Problem is that if the user exits the app, then the counter on the phone ceases (the user is no longer "in play") but the DB does not know about it.....there appears to be no "user has exited app" event/handler that I can use to let DB know that user has quit.
I was thinking maybe the countdown logic should be running on backend but I cant think how.....any ideas?
Currently there is no way to handle app terminated in React Native so I think your best shot is to implement it on the backend.
How about when the user starts, you save the time the user started, and if the time difference between now and when the countdown was started surpasses 30 minutes the user is no longer "in play".
One way to detect that the user has left the game would be with Firebase's onDisconnect handler. With this call you register a write operation on the database that is executed when the server detects that the client is gone.
The server can detect this in two ways:
If the client disconnects cleanly, it sends a message to the server that it is disconnecting and the server runs the disconnect handlers for that client straight away.
If the client disconnects in another way, the server will detect that the client is gone when the socket times out, which may take a few minutes.
So in your case you could use an onDisconnect handler to either remove the player from the game, or otherwise mark them as "gone".
The only problem with this approach is that dirty disconnects may take a few minutes, which might be too long for your scenario.
An alternative would be to have the client write a message into the database periodically to signify that it's still here, e.g. a lastUpdated timestamp.
You can then in any code that reads the data use that timestamp to detect if the player was still recently playing, and consider them "gone" after a certain period that works well for your game. This code can then remove the player from the database.
This code can run in a server-side component if you want, but I've in the past also run this type of code in the client and then used (server-side) security rules to ensure it can only remove users that are "gone".
I have a serious problem, is that I can not launch any query on clicking on some link in my website until the first request is finished:
I have a musical website in which I generate waveform on click on the track, the problem is that generating the waveform take some sometime (about 12 seconds) to be finished, so if I click on another track it will not start untill the generation (the call to the webservice) is not yet finished.
I have seen in FRONT calls but the problem seems to be in backend, because even in the logs of apache, it says that the first query was called at x time, when it finishes apache write down in the log the second call.
The strange thing is that the time of the second call written by apache is the x + some micro seconds, as the apache also was blocked waiting for the first request also to be finished.
Please help me.
BTW : the website is secured by a password so I must have contact with someone to see the problem
Ask me what ever you want for more details.
Kind regards.
I have a timer that talks to java objects through LS2J. It has only to call some getters of the java objects and to update the GUI with new values. This causes the GUI in iNotes Client to show the "Busy" cursor very shortly when the timer ticks. I is really annoying because it occurs even when another window is open and even in the designer.
I actually have to expect that the functionality in the timer event will get more complicated in the future, so I don't want to solve the problem by making my handler lighter.
Is there a way to tell iNotes client not to show this cursor or even an alternative way to make this regular check without timers?
The NotesTimer class in Notes client (not iNotes) does take over the foreground when it triggers, so there will be a bit of a delay if you do something that takes time to execute. It's possible to set up the Notes client to execute background scheduled agents in local database replicas, so that might be an option. You can to the heavy lifting in background and deposit the results somewhere -- say, in a profile document -- that can be accessed quickly by the UI code.
Alternately, you could try a XPages in the client application. I believe it can do partial refreshes while other stuff is going on.
For the record, I simplified the functionality of the Java call by preparing the data so that the timer only has to read the results. I also made the timer run every 3 seconds instead of 1.
Now I don't see any flicker!
I have created a web-service app and i want to populate my view controllers according to the response i fetch(via GET) in main thread. But i want to create a scheduled timer which will go and control my server, if there becomes any difference(let's say if the count of an array has changed) i will create a local notification. As far as i read from here and some google results, i cant run my app in background more then ten minutes expect from some special situations(Audio, Vo-IP, GPS).. But i need to control the server at least one per minute.. Can anyone offer some idea-or link please?
EDIT
I will not sell the app in store, just for a local area network. Let's say, from the server i will send some text messages to the users and if a new message comes, the count of messages array will increment, in this situation i will create a notification. I need to keep this 'controlling' routing alive forever, whether in foreground or background. Does GCD give such a solution do anyone have any idea?
Just simply play a mute audio file in loop in the background, OR, ping the user's location in the background. Yes, that will drain the battery a bit, but it's a simple hack for in-home applications. Just remember to enable the background types in your Info.plist!
Note: "[...] I fetch (via GET) in main thread." This is not a good approach. You should never fetch any network resources on the main thread. Why? Because your GUI, which is maintained by the main thread, will become unresponsive whenever a fetch isn't instantaneous. Any lag spike on the network results in a less than desirable user experience.
Answer: Aside from the listed special situations, you can't run background apps. The way I see it:
Don't put the app in the background. (crappy solution)
Try putting another "entity" between the app and the "server". I don't know why you "need to control the server at least one per minute" but perhaps you can delegate this "control" to another process outside the device?
.
iOS app -> some form of proxy server -> server which requires
"babysitting" every minute.
When my application loads, using the didFinishLaunchingWithOptionsi parse data from the internet to nsarrays. My question is, when the user exists the application by using the 'home' button, and then loads the application again how can the data be re-loaded? (because if the data does not reload - if there are any updates on websites, the new updates will not be seen).
Add an applicationWillEnterForeground method to your app delegate. Load the data there, or start a thread to load it if you like.
You should probably also periodically check for new data even while the app remains open, because the user could go idle for a long time.
As an aside, you shouldn't do anything which might block in applicationDidFinishLaunchingWithOptions. If you are using synchronous NSURLConnection APIs there is a danger the OS might kill your app for taking too long to launch. Best to either use the asynchronous/NSURLConnectionDelegate APIs or do the networking on a background thread and call back to the main thread when you need to update UI (UIKit does NOT like being called from background threads, as it is not thread safe. It might appear to work sometimes, but it will come back to bite you sooner or later).