How do you start a background task on device/application startup for windows WinRT/c#

Question

How can I start a background task that implements IBackgroundTask in a universal app for windows/windows phone?

I am using cordova to create an app for ios, android, wp8 and windows. Each platform seems to run a native class before the application starts, so you can add code here to start a task/service. When a windows project is created by cordova, it is created as a javascript project so there is no c# file to start with.

Is my only option to add winJs code to start the background task?

Answer 1

In the end, i got round this by creating it as a cordova plugin. So my plugin has a method called init, which i call when the app starts up. Using the plugin, i can call services in iOS, Android or Windows.

Once i created the plugin, i then started my windows service from within the WindowProxy.js file, which is part of the cordova plugin.

Note, that your service itself must be in a separate Library, and that library must have the output type set as Windows Runtime Component.

Sample code to start the service is as follows

Code in WindowsProxy.js file

init: function (successCallback, errorCallback) {

        var taskRegistered = false;
        var taskName = "Your Background Task Name";
        var background = Windows.ApplicationModel.Background;
        var iter = background.BackgroundTaskRegistration.allTasks.first();

        // check if service already started
        while (iter.hasCurrent) {
            var task = iter.current.value;

            if (task.name === taskName) {
                taskRegistered = true;
                break;
            }

            iter.moveNext();
        }

        if (taskRegistered) {
            successCallback();
        } else {
            Windows.ApplicationModel.Background.BackgroundExecutionManager.requestAccessAsync().then(function () {
                var builder = new Windows.ApplicationModel.Background.BackgroundTaskBuilder();

                builder.name = taskName;
                builder.taskEntryPoint = "CordovaApp.Library.UploadTask"; // namespace of my windows runtime component library
                builder.setTrigger(new Windows.ApplicationModel.Background.TimeTrigger(15, false));
                builder.addCondition(new Windows.ApplicationModel.Background.SystemCondition(Windows.ApplicationModel.Background.SystemConditionType.internetAvailable));

                return builder.register();
            }).done(function () {
                successCallback();
            }, function (err) {
                errorCallback(err);
            });
        }

    },