Using Azure MobileServices library with my own LAN WebApi

Question

I am currently doing some research for the development of a mobile application for our company that should support offline data sync (on an iPad). We have explored many possibilities including PhoneGap/Cordova, Xamarin and simply native iOS development. Xamarin, for many different reasons, seems to be our best choice, so my question will assume we will develop in Xamarin.

I was looking into a library for managing offline data synchronization and the most obvious solution is Microsoft Azure MobileServices. However, my company is Canadian, and apparently it's hard to trust (legally) our data to clouds based in the US. Since we already deployed internally our WebApi on our intranet, I figured there was probably a way to point the MobileServices library to our own WebApi. I have read about the Azure Hybrid Connection possibility, but our data still conveying through Microsoft servers might not be a possibility. So, my question is this:

Is there a way to configure the Microsoft.WindowsAzure.MobileServices Client library to point directly to our intranet, RESTful WebApi backend, without going through any Microsoft Azure servers ?

I understand that, in order to be able to use the Client librairies seamlessly, we probably would have to adapt our WebApi to implement the necessary .net Backend interfaces. I'm mostly wondering if it's even possible as the MSDN documentation on the libraries all seem to point to direct connections to their servers (no possibilities to configure your own connection strings) and all instructions redirect you to their Azure Mobile Services website.

Thank you.

Answer 1

If you look at the API for your mobile client, you'll notice that the Azure Mobile Services Client SDK only cares about two things:

new AzureMobileClient( url, appkey)

...where it's hosted shouldn't be a concern. Everything else is just configuration.

If you want to host the Azure Mobile Services Backend on your own servers, technically you could do this, but there are likely a few caveats. Microsoft has announced that they will be launching a Canadian Azure data center, but we won't see it until 2016.

In the meantime, here's how you can host the services locally. Note that I have not tried to emulate all of the features of Azure Mobile Services (aka Zumo) so your mileage (or kilometerage) will vary.

Hosting Locally:

From a technical feasibility, you absolutely can run the services locally. I know this because you can create the Azure Mobile Services Backend project from within Visual Studio and run it locally for development purposes. This is what our development team does for testing their mobile applications.

Note that you can create the Azure Mobile Service backend directly from within Visual Studio: New Project -> Cloud -> Azure Mobile Service. You can also download the exact same template (pre-configured with your URL and ApplicationKey) directly from the Azure dashboard: Create -> Mobile Service.

Obviously, if you're hosting it on your server it will be up to you to configure and use a proper SSL certificate for your site.

ZUMO Permissions:

By default, the security roles on the server are turned off. So if you're locking down any of your methods using the [AuthorizeLevel] attribute these settings will be ignored at runtime. If you need to enable this feature you can do so by modifying the WebApiConfig.Register() method and marking the site as self-hosted: config.SetSelfHosted(true).

Configuration:

From a configuration perspective, the Azure Mobile Service dashboard provides several tabs for configuring Identity, Push Notifications, Connection Strings and App Settings. Sadly, you won't have a dashboard, but all of these settings have a corresponding value in the local web.config. Any value you provide here is automatically overwritten in Azure, but they're used when running locally.

The minimum settings you'll need to configure are listed here. The ApplicationKey you can distribute with your ZuMo client, but the MasterKey is for the Admin authorization level so you'll want to keep that secret. The MobileServiceName is used by the EntityFramework for your database schema and what appears in the URL of your site.

<add key="MS_MobileServiceName" value="myzumosite" /> <add key="MS_MasterKey" value="masterkey" /> <add key="MS_ApplicationKey" value="appkey" />

Values that start with a MS_ prefix map to corresponding values in the Azure Portal. MS_GoogleClientID and MS_GoogleClientSecret map to the Google Identity values in the dashboard, for example.

Any other value in the AppSettings node is immediately accessible via the ApiServices.Settings property and corresponds to the Settings node in the Azure dashboard.

Database connection strings continue to exist in the connectionStrings node. The same is true for azure notification hub.

Database:

Obviously, the database you configure will be up to you as well. Permissions and User accounts are also obvious. There may be some minor differences between the SQL Azure syntax for Entity Framework database migration scripts that you'll need to worry about. (I've discovered the database migration scripts don't work from the Package Manager, but they do work when the database scripts are run when your website starts)

Caveats:

• You will not have a nice dashboard for monitoring performance of your site, reviewing logs or changing runtime settings
• You will not be able to scale out your site immediately; Scaling and deployment will be your problem
• Deployment configuration is your responsibility (Project -> Publish won't be available unless you configure it)
• Not sure if you'll be able to use Azure Active Directory as an authentication scheme, though from the sounds of it that won't be a concern. You can write your own authentication providers: Microsoft's Zumo library only supports a handful, but the underlying Owin.Security package that Microsoft uses supports several dozen systems!
• Your site will need to be publically visible to your mobile clients
• Push Notifications should work, but you will be using Azure's notification hub for this.
• I have no idea where ApiServices.Log will go

The easiest path to take would be to:

1. Create the Mobile Service in Azure to get the notification hub and settings preconfigured
2. Download the starter site from the dashboard
3. Configure the web.config as mentioned here.

Answer 2

It's not possible to simply configure WAMS Client library to work with your own WebApi Backend. But WAMS library is available at github, so I'm sure you can reuse a lot of code from the WAMS project, especially if you want to use a PCL project. To route your data securly through Azure, you could think about setting up express route. Additionally, for last weeks update, it's possible to apply a custom domain to the WAMS Backend, including your own certificate to secure your connection.