In Apple's docs I have found an article how to execute a finite-length task when exiting the application. I am looking for a way to adopt that in MonoTouch.
The idea is to process some data if the user pushes the app into background, but that processing takes longer than the time I'm granted by default, hence I want to use the functionality describe here: http://developer.apple.com/library/ios/#documentation/iphone/conceptual/iphoneosprogrammingguide/BackgroundExecution/BackgroundExecution.html to get more time.
How does the code translate into MT? Has anybody an example?
I have a blog post with an example for MonoTouch: http://software.tavlikos.com/2010/12/08/multitasking-in-ios-the-monotouch-way-part-i/
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I am writing payroll management web application in nodejs for my organisation. In many cases application shall involve cpu intensive mathematical calculation for calculating the figures and that too with many users trying to do this simulatenously.
If i plainly write the logic (setting aside the fact that i already did my best from algorithm and data structure point of view to contain the complexity) it will run synchronously blocking the event loop and make request, response slow.
How to resolve this scenario? What are the possible options to do this asynchronously? I also want to mention that this calculation stuff can be let to run in the background and later i can choose to tell user via notification about the status. I have searched for the solution all over this places and i found some solutions but only in theory & i haven't tested them all by implementing. Mentioning below:
Clustering the node server
Use worker threads
Use an alternate server and do some load balancing.
Use a message queue and couple it with worker thread to do backgound tasks.
Can someone suggest me some tried and battle tested advice on this scenario? and also some tutorial links associated with that.
You might wanna try web workers,easy to use and documented.
https://developer.mozilla.org/en-US/docs/Web/API/Web_Workers_API/Using_web_workers
Could anybody give idea on how to create thread pool without using java built-in api (without Executor Class) and will be better if you could take example of Servlet's and write sample code explaining how multiple request's are handled through code.
Just to inform i'v tried many article on Google but most of them talk either theory or Executor framework.
Thanks
If writing a real application I would strongly recommend using the standard Java classes. These ideas are apparently simple on the surface but the fine details of error handling and efficiency are hard to get right.
The Servlet Engine itself is effectively a thread-dispatcher, so in a Servlet we do not need to consider the processing of multiple requests, our servlet Get or Post method sees one request at a time.
So for your example I would simply use the Executor framework. If your intention is to understand the intricacies of how this could be implemented then I'd suggest looking at the source of the Executor Framwork.
I have an VOIP application i'd like to implement, that requires me to process the audio from a call in real time during the call.
Currently, I'm using Asterisk to handle my calls, and it looks like there's a functionality built in called Audiohooks which is designed to let me access the audiostream, and process it from the dialplay
However, I can not find any documentation whatsoever on how to actually create my own audio hook, nor any recent examples on how it should be done. Are there resources that show how I could use this?
Thanks
That api is availible when you do c/c++ modules for asterisk. No external API.
For examples you can check MixMonitor,func_volume,app_conference and other similar application already developed.
Hint: after work done, you have test for memory leaks and hi-load/concurrent load. Code must be thread-safe.
I'm completely new to the Windows Azure and Windows Workflow scope of things.
But basically, what I'm trying to implement is the Cloud web-app that's going to be responsible for pushing down tile updates/badge/toast notifications to my Winodws 8 application.
The code to run to send down the tile notification etc is fine, but needs to be executed every hour or so.
I decided the most straight forward approach was to make an MVC application that would have a WebAPI, this WebAPI will be responsible for receiving the ChannelURI from the ModernApplication that sends it to it, and will be stored on SQL Azure.
There will then be a class that has a static method which does the logic for gathering the new data and generating a new Tile/Badge/Toast.
I've created a simple Activity workflow, that has a Sequence with a DoWhile(true) activity. Inside the body of this DoWhile, contains a Sequence which has InvokeMethod and Delay, the InvokeMethod will call my class that contains the static method. The delay is set to one hour.
So that seems to be all okay. I then start this Activity via the Application_Start in Global.asax with the following line:
this.ActivityInvoker = new WorkflowInvoker(new NotificationActivity());
this.ActivityInvoker.InvokeAsync();
So I just tested it with that and it seems to be running my custom static method at the set interval.
That's all good, but now I have three questions in relation to this way of handling it:
Is this the correct/best approach to do this? If not, what are some other ways I should look into.
If a new instance is spun up on Azure, how do I ensure that the running Workflow for both instances won't step on each other's foot? i.e. how do I make sure that the InvokeMethod won't run two times, I only want it to run once an hour regardless of how many instances there are.
How do I ensure that if the instances crash/go-down that the state of it is maintained?
Any help, guidance, etc is much appreciated.
A couple of good questions that I would love to answer, however trying to do some on a forum like this would be difficult. But let's give it a crack. To start with at least.
1) There is nothing wrong with your approach for implementing a scheduled task. I can think of a few other ways of doing it. Like running a simple Worker Role with a Do{Thread.Sleep(); ...} simple, but effective. There are more complex / elegant ways too including using external libraries and frameworks for scheduling tasks in Azure.
2) You would need to implement some sort of Singleton type pattern in your workflow / job processing engine. You could for instance acquire a lease on a 1Kb blob record when your job starts, and not allow another instance to start etc.
For more detailed answers I suggest we take this offline and have a Skype call and discuss in detail your requirements. You know how to get hold of me via email :) look forward to it.
Just to confirm if multithreading is supported in iPad and iPhone. I need to write an application that calls a web service on a background thread while user can still interact with the UI.
Yes, it has threads.
Also, you don't need to spawn your own threads for most tasks. A lot of the Apple Frameworks (Cocoa Touch Foundation frameworks) have built-in code that will do this for you.
Also, if you're consuming data from a Web API (HTTP Request), I highly recommend you take a look at ASIHTTPRequest, which is built on top of NSOperation (an operation class that easily handles background processing).
Finally, if you need help on program design/flow using the Model-View-Controller pattern, I've written a blog entry describing how to consume Web API data and present it to the end-user in a table format.
iOS has always supported multi-threading, just as Mac OS X did before it. Here's Apple's excellent overview documentation on the subject:
Concurrency Programming Guide