Month: November 2013

Using SSL (Https) in an Azure Cloud Service – Boredom Challenge Final Day

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Any person that has a basic computer knowledge can go ahead and use Microsoft Network Monitor, Fiddler or any other similar application to monitor his/her own network traffic, whereupon he/she will see that the applications which use HTTP have their data displayed plainly. And people with a little more technical knowledge can go further and use other applications (such as Cain and Abel) to sniff the whole network, which will include packages from every computer connected to it. So, someone just logged in to a website that used HTTP while you were listening to the network? Well, tough luck for him/her, because you’ve just sniffed the username and password.

For demonstration, I’ve created an Azure Cloud Service that has a method which returns the number of characters for a given string. And as you see, Fiddler directly catches my request to the web method and its response:

This is what I sent to the web method.

This is what I sent to the web method.

And this is what the web method returned.

And this is what the web method returned.

Of course, a competent developer would take precautions against this. We use hashing and salting for username – passwords so they are not displayed plainly, but still, we don’t want people to get the hashed version either, because then they could try decrypting it or use that hashed version to make calls to our service themselves. Therefore, we need more security.

This is where HTTPS comes in, which is actually the HTTP protocol with SSL on top. SSL (Secure Socket Layer) uses certificates for encryption and authorization, therefore allowing a secure communication over the network. Many applications (such as e-mail, instant messaging or voice-over-IP applications) use this to ensure security, and in this article, we’ll see how we can use it in our own Azure Cloud Service.

➤ For bonus points, use Fiddler to check other apps’ web method calls. It’s quite entertaining to see how they work. 🙂

Creating a “Page Turning” Effect in Blend – Boredom Challenge Day 29

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Animations, when done properly, are a guaranteed way of increasing the visual appeal of an app. In my previous blog posts, we’ve seen how we can make simple animations in Blend, and later we’ve seen how we can combine these simple animations to make a card flip effect. So, contiuning on in this trend, I’ve set my eyes on the another such frequently used and nice-looking effect: Turning a page.

If you look at the card flip effect example, you can see that we can actually use it for turning a page by changing the center of rotation of the objects. However, this will result in stiff looking rectangle pages which lack the curvy edges of a real page. So, how can we turn that page more realistically?

Unfortunately, we can't make it look as good as this. At least, not easily.

Unfortunately, we can’t make it look as good as this. At least, not easily.

It is not possible to create an effect in Blend like shown in the screenshot. You can, however, create such an effect in code, using bezier curves and whatnot. But it looks quite complicated, and I’ve seen people suggesting to use Direct2D instead of creating such animations in code. Also, while searching, I’ve come across some code examples or custom user controls but they were generally for WPF (I’ve only found one custom control for WinRT, and it wasn’t free).

So our best bet would be animating curves in codebehind, or learning Direct2D. Unfortunately, ain’t nobody got time for that.

If you are muttering to yourself “But.. but, I just wanted to turn a simple page, nothing fancy!”, then you are at the right place. We can play around in Blend a little to make it “sort of” curvy and look just like shown in the video below:

In this article, we’ll create an example app which will have a book where the user can turn the pages with the animation shown above.

➤ Here I am, on the road again.. There I am, up on the stage..

Integrating Twitter in Windows Store Apps with “Linq to Twitter” – Boredom Challenge Day 28

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In this previous blog post I’ve talked about why integrating Twitter in our apps is a good idea and then created a sample app which fetched a public Twitter feed without requiring the user to log in. However, this was just a small feature, and we may wish to take it a step further and allow the user to login to Twitter and publish tweets directly from our app, or maybe make the user follow a specific Twitter user, display favorite tweets or allow the user retweet and so on.

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If you try to use Twitter’s REST API to do this, however, you are in for quite a ride. Because of security reasons, trying to do some operations may cause you to mutter “wtf” to yourself several times in a short time span, such as constructing the HTTP request for authorization, since it only accepts parameters that require specific encryptions and encodings (see for yourself). It is, of course, not impossible, but it is time consuming. Therefore, we’ll be going the easy way, by using an open source 3rd party library called Linq to Twitter that does these operations itself and allows us to reach every function of the Twitter API way more easily. Linq to Twitter also allows us to query Twitter using Linq syntax (hence the name), which I really liked.

So, in this article we’ll create a Windows Store app that allows the user to sign in with his/her Twitter account, get and display the user’s basic information, and let the user send a tweet from inside the app.

➤ Twitter API is actually quite nice as it allows you to do anything you could on the website itself