###BeginCaseStudy###
Case Study: 3
Video Transcoding Service
Background

You are developing a video transcoding service. This service is used by customers to upload
video files, convert video to other formats, and view the converted files. This service is used
by customers all over the world.
Business Requirements
The user-facing portion of the application is an ASP.NET MVC application. It provides an
interface for administrators to upload video and schedule transcoding. It also enables
administrators and users to download the transcoded videos.
When videos are uploaded, they are populated with metadata used to identify the video. The
video metadata is gathered by only one system when the video upload is complete.
Customers require support for Microsoft Internet Explorer 7 and later.
The application contains a header that is visible on every page.
If the logged-on user is an administrator, then the header will contain links to administrative
functions. This information is read from a cookie that is set on the server. The administrative
links must not be present if an error condition is present.
Technical Requirements
User Experience:
 The front-end web application enables a user to view a list of videos.
 The main view of the application is the web page that displays the list of videos.
 HTML elements other than the list of videos are changed with every request
requiring the page to reload.
Compatibility:
 Some customers use browsers that do not support the HTTP DELETE verb.
 These browsers send a POST request with an HTTP header of X-Delete when the
intended action is to delete.
Transcoding:
 The video transcoding occurs on a set of Windows Azure worker roles.
 The transcoding is performed by a third-party command line tool named
transcode.exe. When the tool is installed, an Environment variable named transcode
contains the path to the utility.
 A variable named license contains the license key. The license for the transcoding
utility requires that it be unregistered when it is not in use.
 The transcoding utility requires a significant amount of resources. A maximum of 10
instances of the utility can be running at any one time. If an instance of the role
cannot process an additional video, it must not prevent any other roles from
processing that video.
 The utility logs errors to a Logs directory under the utilities path.
 A local Azure directory resource named perf is used to capture performance data.
Development:
 Developers must use Microsoft Remote Desktop Protocol (RDP) to view errors
generated by the transcode.exe utility.
 An x509 certificate has been created and distributed to the developers for this
purpose.

 Developers must be able to use only RDP and not any other administrative
functions.
Application Structure

###EndCaseStudy###

You are creating a new authentication system that uses an HTTP header value.
The existing authentication system must continue to operate normally.
You need to implement the custom authentication.
What should you do? (Each correct answer presents a complete solution. Choose all that apply.)

A.
Create a class derived from ActionResult and check for a valid HTTP header value in the
ExecuteResult method. Change all actions to return this new class.

B.
Create an HttpHandler to check for a valid HTTP header value in the ProcessRequest method.

C.
Create an HttpModule and check for a valid HTTP header value in the AuthenticateRequest event.

D.
Create a class derived from AuthorizeAttribute and check for a valid HTTP header value in the
AuthorizeCore method. Change usages of the existing AuthorizeAttribute to use the new class.

Explanation: