MINE for Facebook - a case studyKevin Dockx, @KevinDockx, RealDolmen

What are we talking about?

A little story…

Five essentials, and how to achieve them

Agenda

A LITTLE STORY…

THE FACEBOOK API

… voted “Worst API of 2011” in developer survey

“buggy”

“unreliable”

“lack of documentation”

“slow response times”

“neverending API changes”

Five essentials, and how to achieve themFOCUS.LOOKS.RELIABILITY.PERFORMANCE.STATISTICS & LOGS.

FOCUS

LOOKS

Start hub

Story feed

Single story

RELIABILITY

Architecture

MINE.FacebookSDKBroker

MINE.Framework

MINE.Framework.WinRTComponent

MINE.FacebookClient

MINE.FacebookClient.BackgroundTask

MINE.FacebookClient.Common

What’s used inside those components?MVVM => MVVM Light

Data format & parsing => JSON .NET

Connecting to Facebook => Facebook C# SDK

Architecture & components

MINE.FacebookSDKBroker

MINE.Framework

MINE.Framework.WinRTComponent

MINE.FacebookClient

MINE.FacebookClient.BackgroundTask

MINE.FacebookClient.Common

MVVM Light, JSON .NET, FB SDK

JSON .NET, FB SDK

JSON .NET

Advantages of this architectureProven components, backed by community

Reuse in & outside of current project, WinRT component or otherwise

Takes a bit of time initially, but saves tremendous amounts of time after a while

One more tip: assume failure

Failunless

(condition A)

or(condition

B)

if (condition Z) Fail

else if (condition A)

do Aelse …

PERFORMANCE

Cancellation of tasksProblem: tasks run when I don’t need them anymore.

Solution: support Cancellation- Built-in- What about your own methods?

– Accept a Cancellation Token in your method signature– Check for cancellation in that method– Handle OperationCancelledException

Produce, Consume, Consume, ProduceProblem: different parts of code need access to objects from different threads

Solution: Producer/Consumer pattern- BlockingCollection<T>- TryAdd to add to collection- TryTake to take from collection- CompleteAdding to notify end of adding

•

Performance – the usual suspects- Offload long-running tasks to the background- Cancel Tasks when they’re no longer needed- Use async/await, Task.WhenAny, Task.WhenAll- Use an extended splash screen- Prefetch when possible- Show progress, determinate or indeterminate

- Profile your app using the performance profiler

Performance - the illusion of performance

Perception beats reality. Always.

Performance case: the story feed- “Show me the next 20 items”

- Easy, right? Fetch items, translate them, return them, add to bound collection

- What was done?- Prefetch with producer/consumer- On scroll, items often are in backing collection => immediate return- Consumer asks for items one by one instead of 20 at the same time- Results in perception of faster performance

Performance: reduce memory consumption- Well, hello captain obvious. Obvious? Yes, but for an additional reason

- The less memory your app uses, the more likely it is to stay in memory instead of being terminated, ensuring a faster restart after being suspended

XAML PerformanceDo not load resources that aren’t necessary• Resource Dictionaries are fully parsed, even though your page might

only use one resource of it• Your start page shouldn’t use application-wide dictionaries• If you use a resource throughout your app, put it in Application (through

a resource dictionary)• If you don’t, only reference that dictionary on the pages it is used, or

even in the page-specific resource dictionary

XAML PerformanceOptimize element count• Don’t write this:

<Grid> <Rectangle Fill="Black"/>

</Grid>

• But write this:

<Grid Background=“Black” />

XAML PerformanceReuse brushesDon’t write this:

<TextBox> <TextBox.Foreground> <SolidColorBrush Color="#FF3F42CC"/>

</TextBox.Foreground> </TextBox> <Button Content="Submit"><Button.Foreground>

<SolidColorBrush Color="#FF3F42CC"/> </Button.Foreground> </Button>

Write this:<TextBox Foreground="{StaticResource TextColor}" />

<Button Content="Submit" Foreground="{StaticResource TextColor}" />

XAML PerformanceMinimize redrawing to the same place on the screenDon’t write this

<Grid Background="Black"> <Grid.RowDefinitions>

<RowDefinition Height="*"/> <RowDefinition Height="*"/>

</Grid.RowDefinitions> <Rectangle Grid.Row="1" Fill="White" Opacity=".5"/> </Grid>

XAML PerformanceBut write this:

<Grid> <Grid.RowDefinitions> <RowDefinition Height="*"/> <RowDefinition Height="*"/> </Grid.RowDefinitions> <Rectangle Grid.Row="1" Fill="Black"/> <Rectangle Grid.Row="1" Fill="#FF7F7F7F"/></Grid>

There’s more: http://msdn.microsoft.com/en-us/library/windows/apps/hh994641.aspx

STATISTICS & LOGS

Marked Up- User statistics

- Sessions, users, app installations, …

- Crashes, errors & diagnostics- Custom logging, exceptions, crashes, including full stacktraces

- Usage statistics- Time spent in the application, page views, custom events, …

- Commerce statistics

Marked Up – how?- Init

MarkedUp.AnalyticClient.Initialize(“key");

- Catch navigation

MarkedUp.AnalyticClient.RegisterNavigationFrame(rootFrame);

- Log excepMarkedUp.AnalyticClient.LogLastChanceException(e);tions

SummaryFOCUS.

LOOKS.

RELIABILITY.

PERFORMANCE.

STATISTICS & LOGS.

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http://msdn.be/apps

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