Month: February 2014

Connecting To and Using a Windows Azure SQL Database via a Cloud Service

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One of the most prominent features of Windows Azure is no doubt Windows Azure SQL Databases, which allows us to have a database on the cloud and benefit from the advantages of cloud computing, such as high-availability and scalability. Azure’s portal interface allows us to easily manage the database, and by using a cloud service as an API for our backend we can quickly access the database from any platform.

In this step by step article, we’ll create a Windows Azure SQL Database, create a web service which connects to this database and allows us to perform specific operations on it and then use that web service in a Windows Store app.

1) Creating the Windows Azure SQL Database

Obviously, you’ll need to have an Azure account to do this. You can go to http://www.windowsazure.com and click on the Free Trial option on the upper right and follow the instructions to get a free 1 month trial. Keep in mind that although it is free, you still need to enter a valid credit card information for validation purposes.

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After you get an Azure account (or if you already have one), click “Portal” on the upper right or go to http://manage.windowsazure.com and log into the Management Portal.

➤ This database – web service – client configuration is a very effective way of creating applications

Template-Binding in WinRT

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In XAML, styles are resources which define the appearance of a control. By creating new styles (or modifying existing ones), you can customize how a control looks to have a more creative and beautiful interface. Since styles are resources, you can just create one that suits your needs and apply it to any suitable control you want.

However, when you create (or modify) a style, if you define everything in it explicity, you will be left with a very inflexible control which you can not further customize. For example, assume we have a bubbly button which has many small circles around it that represents the bubbles, like this:

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I’ve added these bubbles explicitly with white color, so they will stay white no matter what. But what if I decide to use the button with a different background color in different parts of the app?

The circles are barely visible now.

The circles are barely visible now.

A solution to that would be creating a different style for each different color you would use, but that would be tedious and ineffective to say the least. Instead, why don’t we tell the bubbles to have the same color with the Button object’s Foreground property? This way, the style would just add the bubbles without specifying their color and we could set the color of each individual Button object the way we want. Sounds good, right?

Well, what I just described is called template-binding. Within a style or template, you can tell a property to get its value from the object that the template or style is applied to. You can template-bind any compatible properties together to achieve your desired effect.

And in this article, we’ll create a sample project which uses template-binding in order to create… EVIL BUTTONS!!1 *insert evil laugh here*

This is an evil button with horns. Notice that the horns get their fill and border colors from the Button object.

This is an evil button with horns. Notice that the horns get their fill and border colors from the Button object.

➤ If you look at the default style of a control, you’ll see that everything you set on the control is actually template-binded in the style…

Encrypting The “web.config” File of an Azure Cloud Service

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The web.config file contains the configuration options for a web service, some of which could contain sensitive information that you don’t want to be kept in plain text. For example, it is very likely that you’ll connect to a database in your web service, and the connection string you use will be kept in the web.config file. The connection string includes the username and password used in the database server, so if you plan to keep your web service in a 3rd party server or if someone that you don’t want to learn the database credentials needs to work on the source code, you could add an extra layer of security by encrypting this data.

<connectionStrings>
  <add name="DatabaseConnectionString" connectionString="Data Source=blablabla.database.windows.net;Initial Catalog=BlaBlaDB;User ID=yourusername;Password=yourpassword"
    providerName="System.Data.SqlClient" />
</connectionStrings>

.NET Framework provides a feature called “protected configuration” which prevents our data from being shown like in the code above, by encrpyting the configuration data using DpapiProtectedConfigurationProvider or RsaProtectedConfigurationProvider classes. However, both of these two encryption methods need to be applied on the server that hosts the web service, because the encrpytion process uses a machine-specific key. Since we can’t do this on Azure… what can we do to encrypt the web.config of our cloud services?

Well, if we want to encrpyt our web.config files in Azure cloud services, we need to use a special “protected configuration provider”. In this article, we’ll create a .pfx certificate and use “Pkcs12 Protected Configuration Provider” which performs the encryption using a certificate and Windows Azure Certificate Store, to encrypt our web.config file.

➤ Anyone with the connection string can access your database, and you definitely do not want that…