Design the application architecture - Objective 1.3: Design and implement the Windows Azure role life cycle

Question 1

What are the three different types of solutions offered in Windows Azure?

Answer 1

Virtual machines, web sites and cloud services.

Question 2

What does a Windows Azure virtual machine provide?

Answer 2

The same functionality as any virtual machine hosted locally.

Question 3

What does a Windows Azure web site provide?

Answer 3

A way to host ASP.Net web sites without the overhead of maintaining a virtual machine along with automatic scalability, fast deployment and almost immediate startup.

Question 4

What does a Windows Azure cloud service provide?

Answer 4

It is the original Windows Azure Platform as a Service (PaaS) offering.

Question 5

What are Windows Azure startup tasks?

Answer 5

They are actions that are performed before a role starts.

Question 6

What are the three types of roles in Windows Azure?

Answer 6

Web, worker and VM

Question 7

If you are simply going to run a web site in IIS in Windows Azure, which role should you use?

Answer 7

Web role

Question 8

If you are going to run a middle-tier application without IIS in Windows Azure, which role should you use?

Answer 8

Worker role

Question 9

Which Windows Azure roles can use startup tasks?

Answer 9

Web and worker roles

Question 10

Where are startup tasks defined?

Answer 10

In the Task element of the Startup element of the ServiceDefinition.csdef file

Question 11

When do startup tasks run?

Answer 11

Whenever a role recycles or a server reboots.

Question 12

What error code must a startup task return before the startup process will complete successfully?

Answer 12

Zero

Question 13

What happens when a startup task returns a non-zero error code?

Answer 13

The role does not start

Question 14

When multiple startup tasks are defined for a role, how are they executed in relation to each other?

Answer 14

They are executed according to their taskType attribute. Simple tasks are executed synchronously. Background and foreground tasks are started asynchronously in parallel to the startup of the role.

Question 15

Which tool is used in Windows Azure to manage IIS settings at startup?

Answer 15

AppCmd.exe

Question 16

Why should you take care in modifying the web.config section in the startup task?

Answer 16

Startup tasks can be run more than once and modifying the web.config file could cause runtime errors.

An example would be adding a section to the web.config file which when run more than once would cause a runtime error.

Question 17

What is the error code returned from AppCmd.exe when you try to add the same section to the web.config file more than once?

Answer 17

183

Question 18

What is the error code returned from AppCmd.exe when you get an “Access Denied” error?

Answer 18

5

Question 19

What types of programs can startup tasks run?

Answer 19

Executables, batch files and PowerShell scripts.

Question 20

In Windows Azure, how are application pools normally named?

Answer 20

They are usually named with a GUID

Question 21

In Windows Azure, how are web sites typically named?

Answer 21

rolename_roleinstancenumber

This ensures each website name is different for each version of the role.

Question 22

In Windows Azure, why must registry changes be added to startup tasks?

Answer 22

Windows Azure virtual machines are stateless and the registry changes would not be saved when the role restarts.

Question 23

In Windows Azure, how do you install third-party applications that your web site may depend on?

Answer 23

They must be installed with startup tasks.

Question 24

What 6 steps are taken when a role starts?

Answer 24

1. Instance is marked as Starting. It will no longer receive traffic.
2. Startup tasks are executed according to their taskType attribute: Simple tasks are executed synchronously. Background and foreground tasks are started asynchronously. This is in parallel with the startup task.
3. The role host process is started and the site is created in IIS.
4. The task calls the Microsoft.WindowsAzure.ServiceRuntime.RoleEntryPoint.OnStart method.
5. The instance is marked as Ready and tra􏰟fic is routed to the instance.
6. The task calls the Microsoft.WindowsAzure.ServiceRuntime.RoleEntryPoint.Run method.

Question 25

What are the similarities between the OnStart method and a startup task?

Answer 25

1. They both have the same timeout.
2. They are executed again if the role is recycled.
3. You can configure both to run ahead of the role.

Question 26

What are the differences between the OnStart method and a startup task?

Answer 26

1. A startup task runs in a different process which allows it to run under different privileges.
2. State can be shared between the OnStart method and the Run method because they are in the same application domain.
3. A startup task can be configured as either a background or foreground task that runs in parallel to the role.

Question 27

Which three major events can you override after startup tasks are completed?

Answer 27

OnStart, Run and OnEnd

Question 28

What value must be returned from the OnStart method to indicate success?

Answer 28

true

Question 29

What happens if you override the Run method and return from the function?

Answer 29

The role shuts down

Question 30

When should you override the Run method?

Answer 30

When you want to run code for the life of the role instance

Question 31

When is the ASP.Net Application_Start method called?

Answer 31

Immediately after the OnStart method.

Question 32

What is the hard time limit of the OnStop method?

Answer 32

Five minutes

Question 33

What happens if the OnStop method does not complete by the end of the time limit?

Answer 33

The process is terminated