Background task windows phone 7

When the agent start it can determine in which context it is running and behave appropriatly. Creating tasks in visual studio Creating an application Lets Create a captians log application which will be a simple logging application.

Users can type log entries which are timestamped and stored in an isolated storage. The tracking feature will be added using background agent. The start tracking button click will fire up the background agent will be track the location of the captain and add it to the log.

So the agent will update the position even when the program is not active. Create a Windows Phone application solution and develop the foreground tasks and applications. This will contain code will run when the agent is active. Here is the solution file for the captians log which has got two projects: Captians Log — The Windows Phone Silverlight Project which is the main application.

LocationTaskAgent — The background agent to perform the tracking. Solutions may contain differnt projects and when the soltion is build all the assembly file outputs will be combined and sent to the phone. Before this works we need to refernce the LocationTaskAgent Project in Captains Log And when we do this the application manifest file adds a little bit of text to hold the description of the background agent and this is how the background agent is bound to the application.

Here is the text added to the application manifest file. So below is the code that will run when the agent wakes up so we need fill this OnInvoke method with our code that the agent will run. At the end to this code we need to call the method notify complete whcih will will notify the runtime system that it is done.

The Captains log datafile is shared between the application and agent and the first thing that the agent will do is load this datafile from the isolated storage. Now we make use of GPS traking to find out the current loaction. So we make GeoCoordinateWatcher and start it and use it to get the location.

Now before you start thinking about the performance hit this does i would like to tell you that there is a special version of this class provided for Background Agents which uses cached location data which is stored every 15 minutes. And then agent just stores back this location to the application and goes to sleep.

Finally a notification is displayed to the user on which the user can click and go to the main application. The transfer will take place when the application is not running. An application monitor the state of downloads and display their status Files can be transferred from http or https hosts ftp is not suppoerted currently The system maintains a queue of active transfers and services each one in turn.

Applications can query the state of active transfers. Background Transfer Namespace The background transfer namespace is : All the background transfer services are provided from the BackgroundTransfer namspace Most instertingly you dont need to create additional projects to manage background transfers. For example, a there's no way I want to wait around minutes to see if my Periodic Task will run correctly.

Fortunately, you can use LaunchForTest to schedule a task when you're in debug mode. If you're running background processes, you may need to alert your users when things happen - completed task, failed task, significant task progress, etc. You can do that using ShellToast.

Here's the podcast with Jesse Liberty, Peter Torr, and me talking about background services and agents in Windows Phone:. Code samples from my demos are available here.

A question. Can i actually create a Scheduled Task to run every 3 minutes or so? It won't do anything fancy, probably be done in under 5 seconds. I know this web site provides quality dependent articles and other information, is there any other website which offers these stuff in quality? Can i make periodic task run when wp8 application is closed and navigate to page in app. Toggle navigation Microsoft Jon Galloway. Home About Archives Sign In. Side note: why you, Jon? Background Services - Start with the right mindset You want your Windows Phone applications to do useful work in the background, but you don't want the background processes to affect the end user's phone experience.

By experience, I mean: You don't want them to interrupt or slow down foreground tasks especially talking on the phone in any way, ever You don't want them to run down the battery You don't want them to run up expensive bandwidth charges or interfere with foreground network usage You don't want anyone to have to think about them at all Rather than hope developers will keep the user and the above values in mind and do the right thing, Windows Phone background services provide a great framework for you to work within, and they automatically make sure you're playing within the rules.

Overview of services Windows Phone background services are easier to understand when you get the idea of how they all fit together. Color coding explanation: Purple are custom tasks Green are pre-built, specialized tasks Blue are general types Scheduled or Resource Intensive? Resource Intensive Tasks Resource Intensive agents run for a relatively long period of time when the phone meets a set of requirements relating to processor activity , power source , and network connection.

Background Audio Background Audio lets you queue and play audio while your device isn't active or even running. Background Audio Tips Here are a few good things to keep in mind when developing background audio applications. If you have audio you need to move to Isolated Storage, see Jesse's post on how to do that. A few things to be aware of here: The service won't run until conditions are met. The operating system imposes some, and you can add additional restrictions. The important thing to realize here is that the conditions may never be met, so the file transfer will never happen.

If you've requested a large file download which exceeds the cellular limits, but you have a user who never uses a wi-fi connection, they'll never get the file.

So the responsibility is on your application to handle those exceptions. You get both progress and completion events, so your UI can display status to users if they'd be interested. You don't need a separate agent here. You register a TransferRequest with the service and subscribe to the events, but you don't need a service because the transfer service doesn't need you to respond to anything if your application's shut down.

Custom Resource Intensive Tasks If you need to do something resource intensive - other than audio or file transfers - you can create your own Scheduled Task Agent. My main takeaway is that you can do some neat things with these, but you need to account for two things: You don't know when - or if at all - your user's phone will run your task. If your task misbehaves, it will be terminated. Just like that. Notifications You've got two types here: Alarms and Reminders.

There are a few minor differences between the two: Alarms will always have a title that says "Alarm" while Reminders can have a custom title Alarms can play a custom sound, while Reminders will always play the system reminder tone Tapping on an Alarm will launch the app and take you to the initial page of the application, as if it were just being launched. Reminders can include a navigation URI to a page inside your phone application, and it can contain querystring information as well.

AddSeconds 10 ; r. CurrentSource; ScheduledActionService. Add periodicTask ; A couple of tricks Removing tasks before adding them There are a few tricks to be aware of. Add periodicTask ; Launch for testing Many of these things would be tough to test in normal conditions. LaunchForTest task. Name, TimeSpan. FromSeconds 60 ; endif Toast If you're running background processes, you may need to alert your users when things happen - completed task, failed task, significant task progress, etc.

Comments have been disabled for this content. With great power comes great responsibility. For Android you use the same APIs to write platform code and application code, though there are some APIs which are for internal use only. Dianne Hackborn from Google has been constantly answering somewhat tough background task related questions.

The document leaves some questions, such as thread priority issues unanswered, but is definitely a good starting point. For Windows Phone Mango you are restricted to use the dedicated background APIs to manage certain use cases such as audio playback with heavy restrictions on resource usage. The Mango approach is somewhat safer when it comes to the thousands of applications that users can download from the different marketplaces. Microsoft is making a great effort to make it impossible for an application developer to write an application that eats up all resources.

It will be interesting to see where we will be about a year from now - will the APIs still be the same for both platforms and what kind of porting issues we are likely to bump into when we port code from Android to Windows Phone that is supposed to run in the "background".

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