Getting to Know Azure Mobile App Cont.

Microsoft Azure Mobile App has recently gone GA (General Availability) and has definitely captured my attention. Mobile App is a tremendous accelerator that enables us to go from an idea to a functional prototype quickly. Then, we can continue to build on that initial investment to create a robust production ready app. Finally, this post is all about using Visual Studio Team Services (VSTS) to build and publish apps to HockeyApp, so that we can test and assess quality before our apps make it to our favorite app Stores.

Refreshing Authentication Tokens

Authentication Tokens are short-lived and having users login to the App frequently can cause friction. This is definitely undesirable and can be dealt with by identifying when a Token is no longer valid. When this condition is met, we can attempt to refresh the Authentication Token by calling the Azure App Service Token Store APIs.

Getting to Know Azure Mobile App

Microsoft Azure Mobile App has recently gone GA (General Availability) and has definitely captured my attention. Mobile App is a tremendous accelerator that enables us to go from an idea to a functional prototype quickly. Then, we can continue to build on that initial investment to create a robust production ready app. Finally, using Visual Studio Team Services and Release Management, we can publish our apps to our favorite app Stores.

Why Mobile App

These are reasons why you should consider Mobile App on your next project. They certainly contributed to my agility throughout my adventure.

• Build native and cross platform apps
• Connect to your enterprise systems
• Connect to SaaS APIs easily
• Build offline-ready apps with sync
• Push Notifications to millions in seconds
• Automatically scale-out to handle any incoming customer load.
• Build low friction server-side REST services.
• Benefit from a simplified data access layer.
• Deliver functional prototypes with minimal effort.

Using PowerShell to Authenticate Against OAuth

From development to deployment, PowerShell is becoming the ‘go to’ automation technology on Microsoft Azure. So, I decided to use PowerShell to perform automated tests against a Web API (a.k.a REST service). These tests are built to run during the execution of a Continuous Release cycle and confirm that the API is responding as expected.

Are You Getting a 403 (Forbidden) From Windows Azure Storage Services?

If your development computer isn’t set to the correct date / time and you are working with Windows Azure you might end up like this guy! I know I did!

Recently I tried to shift back the clock on my developer computer so that I could test a caching mechanism.

After setting the clock back one day, I was unable to connect to Windows Azure services like Blob Storage Service, Queue Storage Service and Table Storage Service. I constantly got HTTP Status Code 403 Forbidden.

I logged into the Windows Azure Management Portal and saw that everything was as it should. I checked the Windows Azure Service Dashboard to see if any services were down… I even check that my storage keys had not been regenerated.

I fired up fiddler and got nothing more than I already knew… then it came to me, whenever http calls are made, the client sends a timestamp to the server and whenever the client and the server are out of sync, calls are often refused. So I set my clock back to the right time and the problem went away.

All in all, this was my fault, I tried to fool the system and I got caught.

Everything boils down to the fact that the Authentication for the Windows Azure Storage Services accept request timestamps who’s date times that are within 15 minutes of the services’ current time.

All authenticated requests must include the Coordinated Universal Time (UTC) timestamp for the request. You can specify the timestamp either in the x-ms-date header, or in the standard HTTP/HTTPS Date header. If both headers are specified on the request, the value of x-ms-date is used as the request’s time of creation.

The storage services ensure that a request is no older than 15 minutes by the time it reaches the service. This guards against certain security attacks, including replay attacks. When this check fails, the server returns response code 403 (Forbidden).