.NET Interview Questions

1. Write a simple Windows Forms MessageBox statement.

System.Windows.Forms.MessageBox.Show ("Hello, Windows Forms");

2. Can you write a class without specifying namespace? Which namespace does it belong to by default??

Yes, you can, then the class belongs to global namespace which has no name. For commercial products, naturally, you wouldn’t want global namespace.

3. You are designing a GUI application with a window and several widgets on it. The user then resizes the app window and sees a lot of grey space, while the widgets stay in place. What’s the problem?

One should use anchoring for correct resizing. Otherwise the default property of a widget on a form is top-left, so it stays at the same location when resized.

4. How can you save the desired properties of Windows Forms application?
.config files in .NET are supported through the API to allow storing and retrieving information.

They are nothing more than simple XML files, sort of like what .ini files were before for Win32 apps.

5. So how do you retrieve the customized properties of a .NET application from XML .config file?

Initialize an instance of AppSettingsReader class. Call the GetValue method of AppSettingsReader class, passing in the name of the property and the type expected. Assign the result to the appropriate variable.

6. Can you automate this process?

In Visual Studio yes, use Dynamic Properties for automatic .config creation, storage and retrieval.

7. My progress bar freezes up and dialog window shows blank, when an intensive background process takes over.

Yes, you should’ve multi-threaded your GUI, with taskbar and main form being one thread, and the background process being the other.

8. What’s the safest way to deploy a Windows Forms app?

Web deployment: the user always downloads the latest version of the code; the program runs within security sandbox, properly written app will not require additional security privileges.

9. Why is it not a good idea to insert code into InitializeComponent method when working with Visual Studio?

The designer will likely throw it away; most of the code inside InitializeComponent is auto-generated.

10. What’s the difference between WindowsDefaultLocation and WindowsDefaultBounds?

WindowsDefaultLocation tells the form to start up at a location selected by OS, but with internally specified size. WindowsDefaultBounds delegates both size and starting position choices to the OS.

11. What’s the difference between Move and LocationChanged? Resize and SizeChanged?

Both methods do the same, Move and Resize are the names adopted from VB to ease migration to C#.

12. How would you create a non-rectangular window, let’s say an ellipse?

Create a rectangular form, set the TransparencyKey property to the same value as BackColor, which will effectively make the background of the form transparent. Then set the FormBorderStyle to FormBorderStyle.None, which will remove the contour and contents of the form.

13. How do you create a separator in the Menu Designer?

A hyphen ‘-’ would do it. Also, an ampersand ‘&\’ would underline the next letter.

14. How’s anchoring different from docking?

Anchoring treats the component as having the absolute size and adjusts its location relative to the parent form. Docking treats the component location as absolute and disregards the component size. So if a status bar must always be at the bottom no matter what, use docking. If a button should be on the top right, but change its position with the form being resized, use anchoring.

.NET Remoting Interview Questions

1. What’s a Windows process?

It’s an application that’s running and had been allocated memory.

2. What’s typical about a Windows process in regards to memory allocation?

Each process is allocated its own block of available RAM space, no process can access another process’ code or data. If the process crashes, it dies alone without taking the entire OS or a bunch of other applications down.

3. Why do you call it a process? What’s different between process and application in .NET, not common computer usage, terminology?

A process is an instance of a running application. An application is an executable on the hard drive or network. There can be numerous processes launched of the same application (5 copies of Word running), but 1 process can run just 1 application.

4. What distributed process frameworks outside .NET do you know?

Distributed Computing Environment/Remote Procedure Calls (DEC/RPC), Microsoft Distributed Component Object Model (DCOM), Common Object Request Broker Architecture (CORBA), and Java Remote Method Invocation (RMI).

5. What are possible implementations of distributed applications in .NET?

.NET Remoting and ASP.NET Web Services. If we talk about the Framework Class Library, noteworthy classes are in System.Runtime.Remoting and System.Web.Services.

6. When would you use .NET Remoting and when Web services?

Use remoting for more efficient exchange of information when you control both ends of the application. Use Web services for open-protocol-based information exchange when you are just a client or a server with the other end belonging to someone else.

7. What’s a proxy of the server object in .NET Remoting?

It’s a fake copy of the server object that resides on the client side and behaves as if it was the server. It handles the communication between real server object and the client object. This process is also known as marshaling.

8. What are remotable objects in .NET Remoting?

Remotable objects are the objects that can be marshaled across the application domains. You can marshal by value, where a deep copy of the object is created and then passed to the receiver. You can also marshal by reference, where just a reference to an existing object is passed.

9. What are channels in .NET Remoting?

Channels represent the objects that transfer the other serialized objects from one application domain to another and from one computer to another, as well as one process to another on the same box. A channel must exist before an object can be transferred.

10. What security measures exist for .NET Remoting in System.Runtime.Remoting?

None. Security should be taken care of at the application level. Cryptography and other security techniques can be applied at application or server level.

11. What is a formatter?

A formatter is an object that is responsible for encoding and serializing data into messages on one end, and deserializing and decoding messages into data on the other end.

12. Choosing between HTTP and TCP for protocols and Binary and SOAP for formatters, what are the trade-offs?

Binary over TCP is the most effiecient, SOAP over HTTP is the most interoperable.

13. What’s SingleCall activation mode used for?

If the server object is instantiated for responding to just one single request, the request should be made in SingleCall mode.

14. What’s Singleton activation mode?

A single object is instantiated regardless of the number of clients accessing it. Lifetime of this object is determined by lifetime lease.

15. How do you define the lease of the object?

By implementing ILease interface when writing the class code.

16. Can you configure a .NET Remoting object via XML file?

Yes, via machine.config and application level .config file (or web.config in ASP.NET). Application-level XML settings take precedence over machine.config.

17. How can you automatically generate interface for the remotable object in .NET with Microsoft tools?

Use the Soapsuds tool.