I'm creating a GStreamer application based on XULRunner. To achieve this created an XPCOM component that makes some of the GStreamer functionality available in a XUL application. However, GStreamer normally makes use of a message loop (GMainLoop) which enables one to receive bus messages. Because XULRunner already has its own message loop I can't create a GMainLoop. So I need another way of getting those messages. One way is to use the gst_bus_poll call. I would need to call it frequently to prevent the message queue from being flooded. So I'm thinking that a timer is the correct solution here.
To make a long story short: how do I create a timer in an XPCOM component?
Take a look at nsITimer.
And you might be interested in the code in this bug about implementing a GStreamer backend for <video>.
Related
I am trying to make a chat app using XMPP protocol. The app is working fine except it doesn't show message notification when the app is in background. In Android I have used a Service for this purpose, however in Windows Phone I couldn't find anything similar to this.
I am trying Background Tasks for this, but as far as I have understood, they're made to run on prespecified trigger and I cannot add any custom trigger to it. In Android I have put my socket connection and parsing message calls in the service itself so that they can run on background too and the socket doesn't get closed even when the app is stopped.
So my question is, is there any similar way to do it in Windows Phone 8.1 (WinRT, not silverlight) or if Background Task is the only option, can you suggest a way to implement the notification functionality. I don't need the exact code, I just need a push to the right direction.
First: You cannot run a network connection in background.
Suggested way is using PushNotifications:
Either directly with a Toast Notification
Or with a PushTrigger to handle a Raw Notification, work out what to do
with it (who was it from, prepare data, etc.) and then create a ShellToast from it. Adds flexibility and improves user experience, but is quite complex.
Known downside: You have to use a server.
Only workarounds: Background-Tasks that checks for new messages about every 30 Minutes.
i am working on an application for windows mobile 6.5, which need to know whenever any application is launched.
Is there any way to get notified when any application is launched?
Can we do something like this?
ManagementEventWatcher
I don't think there is a way to get an event when a new process is created. However, you can get a list of processes using the ToolHelp API, so it should be possible to get the necessary information, but you need to continuously poll in order to detect when a process is started.
Access to the ToolHelp API is not provided in compact framework but you can use the native API instead. An example can be found here: http://msdn.microsoft.com/en-us/library/aa446560.aspx
I think you're going to have to poll for the available processes using Allan's suggestion. I've worked on custom Windows CE shells, and they use the RegisterTaskBar(HWND) to receive notification when windows are created, raised, and destroyed. But that doesn't means every process has a window.
Using the iPhone and objective C, is there a way to stall or perform a timing loop to allow for the GPS to catch up and return a valid set of coordinates?
Currently, the application runs too quickly and the GPS cannot supply the coordinates fast enough...
Since you said you're on iPhone, you're using CLLocationManager. Just set a delegate on the manager and wait for the locationManager:didUpdateToLocation:fromLocation: message to know when the GPS data is ready.
Assuming your GPS polling is running in a different thread to the User Interface, you can call the static NSThread functions sleepForTimeInterval or sleepUntilDate from the thread that is waiting for the GPS data.
If your mobile application is using GPS, your application should be prepared for location updates, even if your application doesn't track movements..
A common case would be where the user put your application in background and activate it later on a completely different location.
On iOS, create an implementation of CLLocationManagerDelegate like Anomie wrote. And use the timestamp of the update to evaluate the freshness of the location.
Don't sleep & poll like other people suggested.
Either block to wait for data or don't update anything if no data received. There is of course usleep(), but without showing code and specifically how your loop is executed and by what mechanism (threaded or not) we can only answer in general terms.
I have to design and implement a way to deal with long running processes in a client/server application. A typical long running process would/could take 2-3 minutes. I also need to report progress to the UI in the meantime and keep the UI responsive.
Having these in my mind I though of a few solutions:
One async request to start the process which starts the server-side process and returns an assigned LRPID (Long Running Process ID) then poll periodically from the client using that LRPID. (Pro: simple to deploy, no firewall messing around Con: Unelegant, resource consuming etc.)
Use a duplex binding (such as NetTcpBinding) and initiate callbacks from the server as progress is being made (Pro: Elegant, efficient, Con: Deployment nightmare)
[Your suggestion???]
What would be your take on this?
Here is a post by Dan Wahlin about how to create a WCF Progress Indicator for a Silverlight Application. This should be of some help.
If you do not want to have to worry about the client's firewall, etc... I would probably go with your first solution and use a BackGroundWorker to make the call in order to keep from blocking the UI thread. I did this recently for an app where a request to generate a report is put on a queue and is retrieved once it is done. It seems to work well.
Another way (without having to change the WCF binding) is to use a WebBrowser control in the WPF client, and SignalR to post progress messages from the server to that control.
Note that to avoid javascript errors that happen with the WebBrowser control (because by default it seems to use Internet Explorer version 7 which doesn't seem to be compatible with jQuery.js), you will need to add keys to the registry on the client machine to change the default for the client app to use IE10 or later - see http://weblog.west-wind.com/posts/2011/May/21/Web-Browser-Control-Specifying-the-IE-Version).
This could be a deployment nuisance (because admin rights seem to be needed - eg on a 64 bit Windows 8.1 pc - to add the registry keys).
Also, it still seems necessary to call the long running WCF method in a separate thread, otherwise the WebBrowser control doesn't seem to update its display to show the SignalR messages it is receiving. (This makes sense because the UI thread would otherwise have to wait until the WCF call had finished).
But I mention it as an alternative approach using a newer tool (SignalR) :)
I have an application that needs to "poll" a webservice to see if the user has any new messages waiting. I have no control over the webservice so I cannot switch to a "push" mechanism, I'm stuck making a request every X number of seconds to see what's available.
I am using a System.Threading.Timer to make the request every so often, but am encountering a few problems. The biggest is that it stops running when the phone is sent into "standby" mode (screen off, but still able to get calls and email/txt notifications).
I'd really like it to behave like other background applications. What can I do to make it work without being too big of a drain on the battery?
Hate to answer my own question, but I was pointed to this, which was able to perform even when the device is asleep. Looks like it's working perfectly.
There's nothing you can do, AFAIK. Standby mode is meant to suspend the processor to save power, and there's no way your code can execute if the processor isn't running. There are things your application can do to prevent the device from going into standby mode, but this really isn't advisable at all.
Yep. Similar to how MusiGenesis has answered, you won't be able to do much without keeping the device up and running. Similar to how some phones will notify that "Game/App Running" and thus your battery is being slapped around.
What about writing an interface from your phone to leverage text messaging (which still works) and get it to send a text message to the web service? Would that be possible? I'm guessing that sort of method might also stop running, but I figure it's a thought?
I'm not sure about compact framework, but in Win32 there is WaitableTimer that can wake up computer from standby. It takes some native calls though as there's no wrapper in .Net.
Although you can't modify the webservice, you might be able to add a second "shadow" webservice in between your clients and the original webservice. The shadow webservice could poll the original webservice and then "push" anything it finds out to the PDAs.
I think you might still have the same problem, though. I've never done "push" from a webservice, but I think it's basically implemented by having the client make an initial call to a webservice method that takes a delegate to a method in the client, which the webservice then hangs onto. When the webservice needs to push something, it calls that delegate. If the client has gone into standby mode in the meantime, the attempt to call the delegate from the server will fail.