So what happened?
Initially, with a couple statistics being logged, everything seemed promising so I started sprinkling my version of Mark's AnalyticsTracker throughout my code mostly replacing the spots where I had used RTI. I launched the debugger on the Emulator and....it exited. I thought that was weird. Since I was using the debugger, I expected any exception to break into Visual Studio. You may have experienced this before--an exception occurs early in your program and it seems as if the debugger's not all hooked up by the time it happens. What was a little more perplexing was that, occasionally, it would launch without issue. This made me suspect a race condition...but with what?
The Race is on
Considering what code I had just added, I figured the AnalyticsTracker was being used before the AnalyticsService had started. This was easy to verify by making the tracker check for the existence of the service and verify it was initialized.
So what to do about the events that occur too early? I'm not too fond of just rearranging things until it works as it seems like a lurking issue that may show up on just the right device. Instead, I made my AnalyticsTracker buffer the events that occur early on.
Here's the updated AnaylticsTracker class:
/// <summary> /// Creates an analytics tracker which can be used to send events through the analytics provider. /// NOTE: Instances of this class should not be kept around and reused over time b/c initialization in /// the constructor may fail if it's created too soon and, if it does, events will be deferred continually. /// You can use it in such a scenario but only if you call <see cref="Connect"/> when <see cref="IsConnected"/> is false. /// </summary> public class AnalyticsTracker { /// <summary> /// Indicates whether tracking is enabled. For debugging mostly. /// </summary> public static bool Enabled { get; set; } static readonly Queue<AnalyticsEvent> deferred = new Queue<AnalyticsEvent>(); static AnalyticsTracker() { Enabled = true; } /// <summary> /// Creates a default instance. /// </summary> public AnalyticsTracker() { Connect(); } /// <summary> /// [Re]attempts to connect to the analytics service. /// </summary> public void Connect() { if (!Enabled) return; // If already connected, we're good. if (IsConnected) return; var service = Application.Current.ApplicationLifetimeObjects.OfType<AnalyticsService>().SingleOrDefault(); if (service != null && !service.IsStarted) return; try { CompositionInitializerEx.SatisfyImports(this); // Flush any premature events. Flush(); } catch (Exception ex) { Debug.WriteLine("Error creating analytics event. Deferring. {0}", ExceptionFormatter.FormatMessage(ex)); } } /// <summary> /// Indicates whether this tracker is connected to the service. /// </summary> public bool IsConnected { get { return Log != null; } } /// <summary> /// Import from the analytics service provider. Do not access directly. /// </summary> [Import("Log")] public Action<AnalyticsEvent> Log { get; set; } /// <summary> /// Logs or defers logging of an event. /// </summary> /// <remarks>If the analytics service is not yet up, the events are queued.</remarks> public void Track(string category, string name, string actionValue = null) { var analyticsEvent = new AnalyticsEvent { Category = category, Name = name, ObjectName = actionValue }; if (Log == null) { lock (deferred) deferred.Enqueue(analyticsEvent); } else Log(analyticsEvent); } /// <summary> /// Track an exception. /// </summary> public void Track(Exception error) { Track("Errors", ExceptionFormatter.FormatName(error), error.ToString()); } /// <summary> /// Flush deferred events. /// </summary> void Flush() { // Check before locking unnecessarily. if (deferred.Count <= 0) return; lock (deferred) { while (deferred.Count > 0) Log(deferred.Dequeue()); } } }
Issues with XAML Approach
There is a TrackAction trigger you can use in XAML. I didn't like how this ended up impacting the organization of my data. If you use this approach, you might want to take a look at the data coming into your provider before settling on it especially considering localization.
Other Things to Watch Out for
The Composition namespace. This was frustrating. Somehow I ended up adding a reference to the wrong Composition container. If MEF can't find your imports, keep this in mind. I noticed they included a CompositionInitializerEx in the WebAnalytics namespace. I'd stick with this one to be sure you're using what they're using.
Don't use localized strings. I touched on this above. If any of the strings you use for your analytics are localized, you might find it hard to aggregate the data disregarding language. For example, it'd be easy enough to track the current tool your users are choosing by its name (say CurrentTool.Name) but consider using the type instead if the tool's name is localized (e.g., CurrentTool.GetType().Name or CurrentTool.ToString()).
Wrapping Up
I hope this saves you time if you have any of these issues. There are many more things to consider once you get analytics pumping. For example, you might want to log the language your app is launched with. By default, there's something logged automatically but there are issues. I'll try to cover this in a more specific post. In the meantime, try to think ahead about what you'll want to know.
