Azure Mobile Services error: "The request could not be completed. ()"

Having just published my first (Windows Phone - obviously) app using Azure Mobile Services, I thought I'd share something I learnt in the process. When first testing on an actual device (always test on actual devices!) I hit an issue where the MobileServicesClient was failing with the following message being intercepted by the Application level UnhandledExceptionHandler:

"The request could not be completed. ()"

Notice the empty brackets at the end. In most cases (based on similar exceptions that others have reported and Google helped me find) these would include an indicator of the issue. Such as "(Internal Server Error)" or "(Send failure)".

The call stack wasn't much help either:


   at Microsoft.WindowsAzure.MobileServices.MobileServiceClient.CreateMobileServiceException(String errorMessage, IServiceFilterRequest request, IServiceFilterResponse response)
   at Microsoft.WindowsAzure.MobileServices.MobileServiceClient.ThrowInvalidResponse(IServiceFilterRequest request, IServiceFilterResponse response, JToken body)
   at Microsoft.WindowsAzure.MobileServices.MobileServiceClient.<RequestAsync>d__f.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter`1.GetResult()
   at Microsoft.WindowsAzure.MobileServices.MobileServiceTable.<SendInsertAsync>d__8.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter`1.GetResult()
   at Microsoft.WindowsAzure.MobileServices.MobileServiceTable`1.<InsertAsync>d__21.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.GetResult()
   at RadioNow.MainPage.<OnNavigatedTo>d__8.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.CompilerServices.AsyncMethodBuilderCore.<ThrowAsync>b__0(Object state)


Even when I wrapped all my uses of the client in try..catch blocks this exception was still only getting caught at the application level unhandled exception handler.

Anyway, the issue came down to the devicenot having Wi-Fi enabled and for some reason it wasn't using 3G ro USB passthrough to connect instead.

So, 2 lessons:
1. The WP8 AMS client might throw errors, based on connectivity, that you'll have to catch and deal with at an application level.
2. Be sure to check/test Wi-Fi connections on devices when tethered.

AccentComplimentBrush v2.0

Yesterday I showed my new AccentComplimentBrush as a way of having a second color that can be used within an app and will work with whatever accent color has been chosen.

There was one big issue though. It only worked with the default accent colors in Windows Phone 8.

I've just pushed a new version to GitHub that is both forwards and backwards compatible.

It now works on both Windows Phone 7.X and Windows Phone 8.
It also works with operator and manufacturer defined accent colors. In fact it will work with any accent color whatsoever (yes, even for the people who've hacked in their own colors) as it now determines the compliment on the fly, rather than relying on a precomputed list of compliments.

Please enjoy.

Using a complimentary accent color

Sometimes you may want to use two colors in an app. If it was just one then I'm sure you'd just go with the Accent color.
The acccent colors all work well when on Black or White.
The problem though is that there is no single other color that can be combined well with any accent color and you probably want black and white elsewhere on the page. What you really want to avoid is a design that looks bad with one (or more) accent color(s).

If only there was a way to have another brush resource available that would adjust to the selected accent color and work in compliment to it.

Introducing the AccentComplimentBrush
It lets you have another SolidColorBrush available via a an Application wide resource that will work with any of the default accent colors. The complimentary color is based on the exact opposite position on the color wheel. See how the two pairs all go together:

The accent color above and it's compliment below.

How do you use it?
Just 2 simple steps

1. Add the resource.
Get the file, add it to your project and then reference it. (Either at the application level or on a specific page.)

    <phone:PhoneApplicationPage.Resources>
        <mrlacey:AccentComplimentBrush x:Key="MustBeSetButCanBeAnything" />
    </phone:PhoneApplicationPage.Resources>

Note the key value I've used above. Resources must have a key, but we don't actually ever use it. Because of this, ReSharper (or equivelent) might try and tell you that the resource isn't used. It is. Usage just can't automatically be detected at design time it because it's implemented with some run time trickery.

2. Use it!
Just refer to it in the XAML.

    <TextBlock Text="accent"
                Foreground="{StaticResource PhoneAccentBrush}" />
    <TextBlock Text="compliment"
                Foreground="{StaticResource AccentComplimentBrush}" />

or in code:

(SolidColorBrush)Application.Current.Resources["AccentComplimentBrush"];


Important!
1. It currently only works with the default accent colors, not any added by the operator or OEM. If you use this and want some help with adding support for any accent color let me know.
2. Because it uses "run time trickery" it doesn't work with the designer (in Visual Studio or Blend). If you know a way that would allow design time support I'd love to hear it.


What do you think? Useful?

Update I've now made a version 2.0 of this code which supports 7.X too and will even work with OEM/MO defined accent colors.

Telford: done! Next it's Bristol.

Last month I talked about Windows Phone 8 development at the university in Telford. Next week it's the UWE in Bristol.

The feedback from Telford was very positive.
There were 3 questions on the feedback form and each was marked on a scale of 1 to 10.

The talk was well delivered and I could understand the concepts discussed: 9.1 / 10
I got something out of this that I could use in a project, either in work or as a hobby project: 8.5 / 10
I would attend one of your talks again: 8.9 / 10


I'm particularly proud of those results considering only 1 person in the room with a Windows Phone 8 device and no one there had any previous experience developing for Windows Phone.


If you're in the Bristol area next Tuesday and are interested in hearing about Windows Phone 8 development,why not come along. More details, registration, etc.

NCLDR on Windows Phone 8

Earlier this week, uber-UK-community-bod and I18n expert, Guy Smith-Ferrier announced the alpha launch of NCLDR.

If you're not familiar with CLDR you can think of it as being like a version of the Globalization parts of the .net framework with lots of added extras. NCLDR is a .net port that allows access to all these lovely goodies.

As is my way and because I was interested if I could use the data in a phone app so I attempted a port/conversion to Windows Phone 8. It's just a POC at the moment, but look, I can get a regex for validating postcodes for each (well most) supported culture(s). If you're capturing a postal or zip code in your app this would allow you to validate it on the device, regardless of which country it was in.

I'll be honest, it wasn't as simple as I'd hoped. There was a lot more work and work arounds needed to get it to work than I would have liked and if Windows Phone support was to be officially added it would be better to add it in early and maybe remove use of some of the types and methods which are not supported on the phone, to aid greater cross platform code reuse.

Here's the changes I had to make to get it to work:

Biggest issue: WP doesn't support BinaryFormatter.
Second but related issue: By switching to using a JSON serializer I was potentially making the data file even bigger. I countered this by only including the minimum I needed in the generated file. This no only made the data file smaller but meant I had to load less and so save on precious memory consumption.

Add missing System elements:

• CultureTypes
• DigitShapes
• ICloneable
• SerializableAttribute

Replace use of HashTable with Dictionary<string, string>. In:

• Culture.cs
• Numbers.cs

Replace verison of string.Compare that was used with a WindowsPhone supported version. In:

• Calendar.cs
• CultureData.cs
• Currency.cs
• CurrencyPeriod.cs
• Language.cs
• MessageSet.cs
• NumberingSystem.cs
• NumberingSystemType.cs
• Numbers.cs
• PluralRule.cs
• Region.cs
• RegionMeasuringSystem.cs
• CultureInfoExtensions.cs
• RegionInfoExtensions.cs

Added some null exception handling/wrapping/suppressing to the following (but didn't really look into why it was needed):

• Language.cs
• Calendar.cs
• Region.cs
• CurrencyPeriod.cs
• NumberingSystem.cs
• Script.cs

Hopefully unnecessary disclaimer: This is a quickly hacked together proof of concept on top of alpha code. Use at your own risk...