Way 2 Freshers

What is the difference between boxing and unboxing ?

Boxing allows us to convert value types to reference types. Basically, the runtime creates a temporary reference-type box for the object on heap.
Eg:
int i=20;
object o=i;

Describe the difference between a Thread and a Process?

Answer1:
Thread - is used to execute more than one program at a time.
process - executes single program

Answer2:
A thread is a path of execution that run on CPU, a proccess is a collection of threads that share the same virtual memory. A process have at least one thread of execution, and a thread always run in a process context.

Answer3:
The operating system creates a process for the purpose of running a program. Each process executes a single program. Processes own resources allocated by the operating system. Resources include memory, file handles, sockets, device handles, and windows. Processes do not share address spaces or file resources except through explicit methods such as inheriting file handles or shared memory segments, or mapping the same file in a shared way.
Threads allow a program to do multiple things concurrently. At least one thread exists within each process. If multiple threads can exist within a process, then they share the same memory and file resources.

Answer4:
Thread is a light weight process, which is initialized itself by a process. Light weigt processes does not loads resources required by it itself, these are loaded by its parent process which has generated it.

What is a Windows Service and how does its lifecycle differ from a “standard” EXE?

Windows Service applications are long-running applications that are ideal for use in server environments. The applications do not have a user interface or produce any visual output; it is instead used by other programs or the system to perform operations. Any user messages are typically written to the Windows Event Log. Services can be automatically started when the computer is booted. This makes services ideal for use on a server or whenever you need long-running functionality that does not interfere with other users who are working on the same computer. They do not require a logged in user in order to execute and can run under the context of any user including the system. Windows Services are controlled through the Service Control Manager where they can be stopped, paused, and started as needed.

What is the difference between an EXE and a DLL?

An EXE can run independently, whereas DLL will run within an EXE. DLL is an in-process file and EXE is an out-process file

What is strong-typing versus weak-typing? Which is preferred? Why?

Strong type is checking the types of variables as soon as possible, usually at compile time. While weak typing is delaying checking the types of the system as late as possible, usually to run-time. Which is preferred depends on what you want. For scripts & quick stuff you’ll usually want weak typing, because you want to write as much less code as possible. In big programs, strong typing can reduce errors at compile time.
What are PDBs? Where must they be located for debugging to work?

Answer1:
To debug precompiled components such as business objects and code-behind modules, you need to generate debug symbols. To do this, compile the components with the debug flags by using either Visual Studio .NET or a command line compiler such as Csc.exe (for Microsoft Visual C# .NET) or Vbc.exe (for Microsoft Visual Basic .NET).

Using Visual Studio .NET
1. Open the ASP.NET Web Application project in Visual Studio .NET.
2. Right-click the project in the Solution Explorer and click Properties.
3. In the Properties dialog box, click the Configuration Properties folder.
4. In the left pane, select Build.
5. Set Generate Debugging Information to true.
6. Close the Properties dialog box.
7. Right-click the project and click Build to compile the project and generate symbols (.pdb files).

Answer2:
A program database (PDB) file holds debugging and project state information that allows incremental linking of a Debug configuration of your program.
The linker creates project.PDB, which contains debug information for the project’s EXE file. The project.PDB contains full debug information, including function prototypes, not just the type information found in VCx0.PDB. Both PDB files allow incremental updates.
They should be located at bin\Debug directory

What is cyclomatic complexity and why is it important?

Cyclomatic complexity is a computer science metric (measurement) developed by Thomas McCabe used to generally measure the complexity of a program. It directly measures the number of linearly independent paths through a program’s source code.

The concept, although not the method, is somewhat similar to that of general text complexity measured by the Flesch-Kincaid Readability Test.

Cyclomatic complexity is computed using a graph that describes the control flow of the program. The nodes of the graph correspond to the commands of a program. A directed edge connects two nodes, if the second command might be executed immediately after the first command. By definition,

CC = E - N + P

where
CC = cyclomatic complexity
E = the number of edges of the graph
N = the number of nodes of the graph
P = the number of connected components.

What is FullTrust? Do GAC’ed assemblies have FullTrust?

Your code is allowed to do anything in the framework, meaning that all (.Net) permissions are granted. The GAC has FullTrust because it’s on the local HD, and that has FullTrust by default, you can change that using caspol

What does this do? gacutil /l | find /i “about”

Answer1:
This command is used to install strong typed assembly in GAC

Answer2:
gacutil.exe is used to install strong typed assembly in GAC. gacutil.exe /l is used to lists the contents of the global assembly cache. |(pipe) symbol is used to filter the output with another command. find /i “about” is to find the text “about” on gacutil output. If any lines contains the text “about” then that line will get displayed on console window.

Contrast OOP and SOA. What are tenets of each

Service Oriented Architecture. In SOA you create an abstract layer that your applications use to access various “services” and can aggregate the services. These services could be databases, web services, message queues or other sources. The Service Layer provides a way to access these services that the applications do not need to know how the access is done. For example, to get a full customer record, I might need to get data from a SGL Server database, a web service and a message queue. The Service layer hides this from the calling application. All the application knows is that it asked for a full customer record. It doesn’t know what system or systems it came from or how it was retrieved.

How does the XmlSerializer work? What ACL permissions does a process using it require?

XmlSerializer requires write permission to the system’s TEMP directory.