When my app is running in Windows 8 WINRT can I prevent the OS to go to locked screen/sleep mode?
You can use the DisplayRequest class to indicate that you are busy playing back something that requires the display to stay active and un-dimmed. A good how-to article with sample code is available here. Don't use it frivolously, it is quite detrimental to power consumption. Good odds that the Store will reject your app if you use it for no obvious benefit to the user.
You cannot prevent OS to go to lock screen/sleep/shut-down etc. If you want your application to run behind the scenes, you may want to create a Background Task application. You can find more information at: MSDN Link
Related
I'm in the process of designing an application that will run on a headless Windows CE 6.0 device. The idea is to make an application that will be started at startup and run until powered off. (Basically it will look like a service, but an application is easier to debug without the complete hassle to stop/deploy/start/attach to process procedure)
My concern is what will happen during development. If I debug/deploy the application I see no way of closing it in a friendly and easy way. (Feel free to suggest if this can be done in a better/user friendly way) I will just stop the debugger and the result will be WSACleanup is not called.
Now, the question. What is the consequence of not calling WSACleanup? Will I be able to start and run the winsock application again using the debugger? Or will there be a resource leak preventing me to do so?
Thanks in advance,
Jef
I think that Harry Johnston comment is correct.
Even if your application has no UI you can find a way to close it gracefully. I suppose that you have one or more threads in loops, you can add a named manual reset event that is checked (or can be used for waits instead of Sleep()) inside the loop condition and build a small application that opens the event using the same name, sets it and quits. This would force also your service app to close.
It may not be needed for debugging, but it may be useful also if you'll need to update your software and this requires that your main service is not running.
well this has been bugging me for a couple of days on and off. I am at a clients site where they have a number of bespoke, written in house, services running on a Windows 2008R2 IIS server. The problem is that a couple of these services keep hanging, they are stuck in a “Stopping” state and the only way to kill them off is to open process explorer and kill the threads. Before anyone says anything about using ‘runas’, or logging on as the local admin, or the service owner, etc we’ve been through all of that.
The problem lies with the executable itselfs. The development team, in another country are going to look at this but it will take 4-5 months minimum, and we’re not certain they’ll get it right then.
I have a Powershell script to check the services on a regular basis which has the ability to ensure the services are running and if not, the force a stop and restart of the service, then it sends an email to confirm the actions. However with these specific services mentioned it can do nothing. They can’t be killed in task manager, taskkill, or process explorer (unless one kills the threads) it just says access denied. It is possible to change the permissions in process explorer and kill it but that’s a lengthier process than killing the threads.
To make things a little more difficult I can’t use the process name as on this server there are two other websites using an exe with the same name, just in a different folder.
What I’m after is a way to find and kill the threads of a processID, which I’ve already obtained via the script I have, so the rest of the script can complete the task of restarting the said service. At the moment this service dies on an inconsistent basis throughout the day and night, and the support guys have to RDP onto the server, open process explorer, find the offending process and kill the threads off then restart the services. A bit too much hassle for these already over worked guys especially if we can get powershell to do it automatically.
Hope someone can help on this. Thanks in advance.
Low level thread handling is likely to require native Win32 API usage. Powershell might help with P/Invoke, but the process is going to be complex. For starters, find out if the following tools can be used to identify the stuck thread. Maybe you can combine this info with some Sysinternals tools like handle.exe to find out what really blocks the thread.
The .Net framework has some tools available via System.Diagnostics.Process namespace. A list for threads for named process is available like so,
$ps = [diagnostics.process]::getProcessesByName("iexplore")
$p = $ps[0]
$p.Threads[0]
Full documentation is in MSDN. There is no method for killing a thread, but this should be kind of starting point for identifying the stuck one.
Another a way is to use WMI to get win32_thread data like so,
$threads = gwmi win32_thread
The output is quite different and some filtering is needed. Some examples are available. Another a WMI solution attempt might be based on Win32_process that has Terminate method.
I am new to mobile website development, and facing this issue where I want to refresh data on the website in every 30 sec which is invoked from the client side and server provides the data in response. Problem is when I close the browser or when the browser goes in background it stops working. Is there any thing we can do to make this thing possible?
Have a look at the Android Developers - Processes and Threads guide. You'll get a deeper introduction to how process life-cycles work and what the difference is between the states for background- and foreground processes.
You could embed your web app in a WebView. This way you could deal with the closing browser case: you could provide a means to "exit" the app that involves closing only your container activity. That way the timers you have registered in javascript will still be running in the 'WebViewCoreThread'. This is an undesirable behavior and a source of problems, but you can take advantage of it if you want (just make sure you don't run UI-related code there). I've never tested this in Kit Kat (which uses a different WebView based on Chrome) but works for previous versions, as I described here.
Now the user can always close any app. Even without user interaction, the OS can kill your app on low memory. So just give up on long-running apps that never end, because the OS is designed in such a way this is simply not possible.
You could go native and schedule Alarms using the AlarmManager.
Just checked this out on the Android KitKat WebView and as per Mister Smith's comments the javascript will continue executing in the background until the Activity is killed off:
Just tested with this running in a WebView:
http://jsbin.com/EwEjIyaY/3/edit
My gut instinct is that if the user has moved your application into the background, there seems little value in performing updates every 30 seconds, it makes more sense to just start updating again once the user opens the device up and cache what information you currently have available to you.
As far as Chrome for Android goes the same is happening, as Chrome falls into the background the javascript is still running.
If you are experiencing different behaviour then what exactly are you seeing and can you give us an example?
How do you disable closing an application when it is not responding and just wait till it recovers back?
What you're asking is not just impossible (any user with sufficient priviledges can terminate a process...no matter what OS), it's a horrible User Experience (UX) decision.
Think about it from the User's point of view. You're sitting there looking at an application. The application doesn't appear to be doing anything and isn't providing you any visual feedback that it is doing work. You'd think the application was hung and you'd restart it.
You could do anything from showing a scrolling progress bar to having the long running process update some piece of information on the UI thread (think of an installer in mid-install...it's constantly telling you which files it's putting where rather than just making you wait). In any case, you should be providing some visual feedback to the user so they know your application is still running.
Have the GUI work in a separate thread so that it is (hopefully) never "not responding".
If this is a question about programming, your program should never be in that state since you've tied up the GUI thread somehow. And you can't (and shouldn't) stop Windows or the user from closing your program. They've detected your code is rubbish and have every right to forcefully toss it out of their valuable address space.
In any case, your program's too busy doing other stuff - if it can't respond to the user, it probably can't waste time protecting itself either.
At some point, developers need to get it through their thick skulls that the computer belongs to the user, not them.
Of course, if you're talking about how to configure Windows to prevent this (such as on your PC), then this question belongs on serverfault.
Don't. No matter how important you think your application is, your users' ability to control their own systems is more important.
You can always terminate applications from task manager if you have the privileges. You can just disable or not show the system menu options that has the close icon and close menu option in the application window but that is not going to prevent the user from terminating it from task manager as mentioned before. Instead, I would just show some busy processing icon in the application so the user understands what is going on.
Only thing you can do is disable the close button. Users can still kill it from task manager or similar tool, to way around that. You could make killing it harder by launching it as a privileged process, but that comes with many more problems of its own.
Even with a poor network connection?
Specifically, I've written code which launches a separate thread (from the UI) that attempts to upload a file via HTTP POST. I've found, however, that if the connection is bad, the processor gets stuck on outputstream.close() or httpconnection.getheaderfield() or any read/write which forces data over the network. This causes not only the thread to get stuck, but steals the entire processor, so even the user interface becomes unresponsive.
I've tried lowering the priority of the thread, to no avail.
My theory is that there is no easy way of avoiding this behavior, which is why all the j2me tutorial instruct developers to create a ‘sending data over the network…’ screen, instead of just sending everything in a background thread. If someone can prove me wrong, that would be fantastic.
Thanks!
One important aspect is you need to have a generic UI or screen that can be displayed when the network call in background fails. It is pretty much a must on any mobile app, J2ME or otherwise.
As Honza said, it depends on the design, there are so many things that can be done, like pre-fetching data on app startup, or pre-fetching data based on the screen that is loaded (i.e navigation path), or having a default data set built in into the app etc.
Another thing that you can try is a built-in timer mechanism that retries data download after certain amount of time, and aborting after say 5 tries or 1-2 minutes and displaying generic screen or error message.
Certain handsets in J2ME allow detection of airplane mode, if possible you can detect that and promptly display an appropriate screen.
Also one design that has worked for me is synchronizing UI and networking threads, so that they dont lock up each other (take this bit of advice with heavy dose of salt as I have had quite a few interesting bugs on some samsung and sanyo handsets because of this)
All in all no good answer for you, but different strategies.
It pretty much depends on how you write the code and where you run it. On CLDC the concept of threading is pretty limited and if any thread is doing some long lasting operation other threads might be (and usualy are) blocked by it as well. You should take that into account when designing your application.
You can divide your file data into chunks and then upload with multiple retries on failure. This depends on your application strategy . If your priority is to upload a bulk data with out failure. You need to have assemble the chunks on server to build back your data . This may have the overhead for making connections but the chance is high for your data will get uploaded . If you are not uploading files concurrently this will work with ease .