I have a RAP application which we deploy into a Tomcat instance. The application does some additional stuff during it's first startup.
Currently when the first user opens the webpage in a Browser, it takes quite a while until the application is ready because of this one-time initialization work.
This is bad for usability as the first user needs to wait a long time until this startup-work is done.
Is there a way to trigger or simulate a first session after the Tomcat is started so we can warmup the application and the first user receives feedback quickly?
I tried to do some simple URL-requests via URLConnection to simulate a browser, but it seems the protocol to trigger a new session is non-trivial.
I also tried to use HtmlUnit to request the page with JavaScript enabled, this works to some degree, but HtmlUnit is quite heavy for this simple step.
So is there an official API or at least some sort of workaround that allows me to pre-start and initialize the application?
Unless this initialization requires a UI session (i.e. a user), the configure method of your ApplicationConfiguration could be a suitable place. However, at this point, the ApplicationContext has not been completely set up, so it could be too early. Also, if your application is based on the workbench and extension points, you won't have an ApplicationConfiguration of your own.
Would you mind opening a bug report (http://eclipse.org/rap/bugs) and describe your use case? I think we should provide some kind of hook for applications to setup and clean up, e.g. an ApplicationContextListener?
Related
In some of my my viewmodels and some background running services, I need a second tick for all sorts of actions such as Statemachine progression etc..
To avoid having to create a Timer for every occasion, I have one TimerService which publishes a Messenger plugin message every second.
Those viewmodels or Services that need it just subscribe to this message.
This has worked well for over a year. Recently I noticed a rather long startup time of my app. After some debugging I found that after the launch of the first Viewmodel (it is correctly displayed), it takes about 25secs before the subscriptions start picking up on this message. Seems like something is holding back the publishing of these messages.
During those 20+ secs there is no activity by MvvmCross at all. Nothing is logged by Mvvmcross at all.
What could cause such behaviour ? When in the startup sequence does the messenger plugin start distributing its messages ?
I apologise for not posting code here, as it is a phenomenon that is just happening across the whole application. None of the singleton services that run in the background pick up these messages until after 20secs everything starts working properly.
EDIT: MvvmCross V3.5 is used along with latests stable updates of Xamarin. Problem occurs on every Android version tested.
After some experimenting (and reading all the MvxMessenger docs again) I tried using the SubscribeOnThreadPoolThread method instead of simple subscribe for one of the published messages that typically triggers updating the properties of a viewmodel on a regular basis in its handlers. This made the problem go away.
Normally the handling if this viewrefresh message is fast and doesn't require more then copying repository values (that are updated by a background service) to the visible viewmodel properties. I guess there's somewhere a synchronous call in one of the refresh handlers that make the messenger system block.Haven't found it yet.
What are typical situations that can make the Messenger plugin block ? I would be very interested to understand that a little better.
I have a personal WinRT app I'm working on, and when the app is suspended, I would like to have it relaunch itself with different launch parameters.
I know you can kind of already do this with toast notifications, but I would like to know if it's possible to do without any user interactions.
Thanks!
Wow. I never thought of this before. Your only hope would have been to re-launch your application during the suspending event using protocol activation. But what happens is it is not re-launched, it is reactivated while in the suspending state and the activation is denied. You can't delay the re-activation either because all thread schedules are suspended once the app is terminated, too. I tried this in a test app just now and I'm right.
There's also no option with somehow triggering a background task. Though the ApplicationTrigger is coming with Windows 10, the rule still remains that a background task cannot invoke any UI. So, you can't use a background task.
Then I thought about file activation. Then I realized that file activation is identical to protocol activation and the result would be the same, too.
Yes, the idea of using a timed toast or scheduled reminder would sort of work. It would certainly require the user to tap the toast, and if toast were disabled, or the user didn't tap them (they are transient), you are left not running and nothing going to start you.
There is one more thing you can do. Since there isn't a WinRT solution here, remember there's almost always a Win32 solution. There is nothing wrong with a Win32 in-memory app listening for your app to be terminated and starting it again (like by using protocol activation). Your problem is solved unless you are running this on an ARM device - hopefully not.
I talk about protocol activation here:
http://blog.jerrynixon.com/2012/10/walkthrough-using-windows-8-custom.html
Best of luck!
I have a Vaadin v6 application that uses the embed component to show a JSP page from another application (JPivot, in this case). Both applications are running in the same application server (Tomcat). I need both applications to communicate and I'm trying to do this by using session attributes. However, each application has its own session and so one is ignorant of the other attributes. My question is how to make these applications communicate without using a database or an external file? It can be other solution than session attributes.
What you wish to do is either IPC between two web apps,
or sharing some informations between them.
If you have a cache available (memcached or similar) you could
store/retrieve the information there.
If no cache is available, then CrossContext=true might help you.
With this you can call "the other" webapp from inside the servlet/request.
Here is a simple explanation how this works
http://lukaszbudnik.blogspot.ch/2009/06/session-sharing-in-apache-tomcat.html
If you google for "tomcat session sharing" you will get many more results.
Please note that this CrossContext stuff only works as long as they are in the same tomcat instance.
As soon as you add another tomcat instance for load balancing or high availability this will break. In that case you should use some sort of message bus or message queue.
I've been writing an extension that allows the user to issue voice commands to control their browser, and things were going great until I hit a catastrophic problem. It goes like this:
The speech recognition object is in continuous mode, and whenever the onerror: 'no-speech' or onend events fire, it restarts. This way, the extension is constantly waiting to accept input and reacts whenever a command is issued, even after 5 minutes of silence.
After a few days of of development, today I reached the point where I was testing it in practical use, and I found that after a little while (and with no change to anything on my part), my onend event started firing constantly. As in, looking at the console, I would see 18,000 requests being made in the space of three seconds, all being instantly denied, thus triggering onend and restarting the request.
I'm aware that it would be optimal to wait for sound before sending a request, or to have local speech recognition capabilities without the need for a remote server, but the present API does not allow that.
Are my suspicions correct? Am I getting request limited?
Are my suspicions correct? Am I getting request limited?
Yes
I'm aware that it would be optimal to wait for sound before sending a request, or to have local speech recognition capabilities without the need for a remote server, but the present API does not allow that.
To hide the IP source of your request you can use anonymizer networks like Tor, though it will not be fast.
It's naive to assume Google will spend resources to process all audio being recorded on your system. In your application development it is better to rely on API which provides at least some guarantees. It could be either commercial API or open source implementation like CMUSphinx.
With CMUSphinx, you can also properly implement command keyword detection and increase accuracy by specifying the grammar of the commands.
You could also use a Voice Activity Detection (VAD) algorithm to detect when a user is talking. This can be done by either setting a volume threshold or a frequency threshold (Human speech is usually less than 400hz for example). This way, you won't send useless requests to Google unless those conditions are meant. I would not recommend using Tor as this would significantly increase latency. CMUSphinx is probably the best local system option, but if still want to use a web-based service, I would recommend either using a Voice Activity Detection algorithm or finding a different web-based software.
Is there a way to register code to be run when Flash is about to close (e.g., when the user closes the browser or when DOM manipulation causes the embedded player to be removed)?
In particular, I'd like for my application to send a closing packet to a remote service so the user's peers know that the user has no chance of coming back without having to wait for a timeout. I'm using URLLoader and URLRequest to maintain a BOSH connection, so I welcome solutions applicable to this specific case. However, if there are NetConnection-specific solutions, I'm sure I can learn from them too.
I'm happy to accept that this callback won't be run on a kill -9 but it would be nice to have the more graceful exit paths allow for some code execution.
It seems like the better solution would be to do this via the server side no? The server should be able to detect the disconnection, where you could then invalidate the session.
However, you could go with a client/socket based solution, albeit much more overhead. Using FMS or some other rtm real time server you could dispatch events to your web server that a connection has dropped, (though you might have issues in the case of low network connectivity, or an internet drop). I would suggest going against this though, as in my experience, FMS sucks :)
Is setting extremely low timeouts not a possibility? (i.e. < 10 seconds)