In .NET, which class is typically used as a project installer to install a Windows service on a target system?

Introduction / Context:
Installing a Windows service requires more than just copying an executable file. In .NET, you usually create installer components so that tools and setup projects can register the service properly with the operating system. This question checks if you know which class is used in installer code to install a Windows service.

Given Data / Assumptions:

• We are working with .NET Windows services.
• A service project needs an installer so that installation utilities can register it.
• The class is part of the System.ServiceProcess namespace.
• We are choosing among several candidate classes.

Concept / Approach:
When you add an installer to a Windows service project in Visual Studio, the environment generates classes based on ServiceInstaller and ServiceProcessInstaller. ServiceInstaller represents the installer for the actual service, controlling properties like ServiceName and StartType. ServiceProcessInstaller defines the account under which the service runs. The key class referenced in many interview questions is ServiceInstaller, which is used to install a Windows service.

Step-by-Step Solution:
Step 1: Recall that Windows service projects often contain a ProjectInstaller that inherits from Installer. Step 2: Within this installer, there is typically a ServiceInstaller component representing the specific service configuration. Step 3: Recognise that SqlConnection, ProcessStartInfo, and StreamWriter have completely different purposes unrelated to service installation. Step 4: Select ServiceInstaller as the correct class used to install a Windows service.

Verification / Alternative check:
You can verify this by creating a Windows service in Visual Studio, adding an installer, and inspecting the generated code. You will see a class that instantiates ServiceInstaller and ServiceProcessInstaller objects. Documentation for Windows service deployment also references ServiceInstaller as the project installer for services.

Why Other Options Are Wrong:
Option b: SqlConnection is used for database connectivity and does not relate to service installation.

Option c: ProcessStartInfo configures how a new process starts, but does not install anything as a service.

Option d: StreamWriter is used for writing text to streams and files and is unrelated to service registration with Windows.

Common Pitfalls:
Learners sometimes confuse the ServiceBase class, which you inherit to implement service logic, with installer classes. ServiceBase defines how the service behaves at runtime, while ServiceInstaller and ServiceProcessInstaller define how it is installed. It is also easy to forget that installers are typically used by installation tools and not called directly from application code.

Final Answer:
The ServiceInstaller class is the .NET class commonly used as a project installer to install a Windows service on a target system.