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.NET windows services development interview questions
1) Explain
Windows service. You often need programs that run
continuously in the background. For example, an email server
is expected to listen continuously on a network port for
incoming email messages, a print spooler is expected to
listen continuously to print requests, and so on.
What’s the
Unix name for a Windows service equivalent? Daemon.
So basically a Windows service application is just another
executable? What’s different about a Windows service as
compared to a regular application? Windows services must
support the interface of the Service Control Manager (SCM).
A Windows service must be installed in the Windows service
database before it can be launched.
How is development of a Windows service different from a
Windows Forms application? A Windows service typically does
not have a user interface, it supports a set of commands and
can have a GUI that’s built later to allow for easier access
to those commands.
How do you give a Windows service specific permissions?
Windows service always runs under someone’s identity. Can be
System or Administrator account, but if you want to restrict
the behavior of a Windows service, the best bet is to create
a new user account, assign and deny necessary privileges to
that account, and then associate the Windows service with
that new account.
Can you share processes between Windows services? Yes.
Where’s Windows service database located? HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services
What does SCM do? SCM is Windows Service Control Manager.
Its responsibilities are as follows:
Accepts requests to install and uninstall Windows services
from the Windows service database.
To start Windows services either on system startup or
requested by the user.
To enumerate installed Windows services.
To maintain status information for currently running Windows
services.
To transmits control messages (such as Start, Stop, Pause,
and Continue) to available Windows services.
To lock/unlock Windows service database.
vice on a box? Use Windows Service Installer, do not go
through Add/Remove Programs or MSI file, as you would
normally go with applications.
When developing a Windows service for .NET, which namespace
do you typically look in for required classes?
System.ServiceProcess. The classes are ServiceBase,
ServiceProcessInstaller, ServiceInstaller and
ServiceController.
How do you handle Start, Pause, Continue and Stop calls from
SCM within your application? By implementing OnStart,
OnPause, OnContinue and OnStop methods.
Describe the start-up process for a Windows service. Main()
is executed to create an instance of a Web service, then
Run() to launch it, then OnStart() from within the instance
is executed.
I want to write a Windows service that cannot be paused,
only started and stopped. How do I accomplish that? Set
CanPauseAndContinue attribute to false.
What application do you use to install a Windows service?
installutil.exe
I am trying to install my Windows service under
NetworkService account, but keep getting an error. The
LocalService and NetworkService accounts are only available
on Windows XP and Windows Server 2003. These accounts do not
exist on Windows 2000 or older operating systems.
How can you see which services are running on a Windows box?
Admin Tools -> Computer Management -> Services and
Application -> Services. You can also open the Computer
Management tool by right-clicking on My Computer and
selecting Manage from the popup menu.
How do you start, pause, continue or stop a Windows service
off the command line? net start ServiceName, net pause
ServiceName and so on. Also sc.exe provides a command-line
interface for Windows services. View the OS documentation or
proper book chapters on using sc.exe.
Can I write an MMC snap-in for my Windows service? Yes, use
classes from the System.Management.Instrumentation
namespace. Also see Managing Applications Using WMI from
.NET Framework SDK. |
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