NAME

Win32::Daemon - Extension enabling Win32 Perl scripts to run as a true Win32 service.

SYNOPSIS

use Win32::Daemon;
Win32::Daemon::StartService();
# ...process Perl code...
Win32::Daemon::StopService();

DESCRIPTION

This extension enables a Win32 Perl script to act as a true Win32 service.

FUNCTIONS

Function List

AcceptedControls()

CallbackTimer()

CreateService()

ConfigureService()

QueryServiceConfig()

DeleteService()

GetLastError()

GetSecurity()

GetServiceHandle()

HideService()

QueryLastMessage()

RegisterCallbacks()

RestoreService()

SetSecurity()

SetServiceBits()

ShowService()

StartService()

State()

StopService()

Timeout()

Function Descriptions

• AcceptedControls( [$NewControls] )

  This function queries (and optionally sets) the current list of controls that the service registers for. By registering for a control the script is notifying the SCM that it is accepting the specified control messages. For example, if you specify the SERVICE_ACCEPT_PAUSE_CONTINUE control then the SCM knows that the script will accept and process any attempt to pause and continue (resume from paused state) the service.

  Recognized accepted controls:

  SERVICE_ACCEPT_STOP............The service accepts messages to stop.
  SERVICE_ACCEPT_PAUSE_CONTINUE..The service accepts messages to pause
                                 and continue.
  SERVICE_ACCEPT_SHUTDOWN........The service accepts messages to
                                 shutdown the system: when the OS is
                                 shutting down the service will be
                                 notified when it has accepted this
                                 control.

  Following controls are only recognized on Windows 2000 and higher:

  SERVICE_ACCEPT_PARAMCHANGE.....The service accepts messages
                                 notifying it of any parameter change
                                 made to the service.
  SERVICE_ACCEPT_NETBINDCHANGE...The service accepts messages
                                 notifying it of any network binding
                                 changes.
  

  By default all of these controls are accepted. To change this pass in a value consisting of any of these values OR'ed together.

  NOTE: You can query and set these controls at any time. However it is only supported to set them before you start the service (calling the StartService() function).

• CallbackTimer( [ $NewTimerValue ] )

  This function returns the value of the callback timer. The value is in milliseconds. This value indicates how often the "Running" callback subroutine will be called. Note that the calling of this routine will be blocked by any other callback.

  If you pass in a value it will reset the timer to the specified frequency. Passing in a 0 will disable all "Running" callbacks. Passing in -1 will toggle the state between calling the "Running" callback subroutine and not calling it.

• CreateService ( \%ServiceInfo )

  This function creates a new service in the system configuration. The return is TRUE if the service was created, and FALSE otherwise. If an error occurred, call GetLastError to retrieve the actual error code.

  NOTE: This function will fail if the script is not running with administrator privileges.

  The hash describes the service to be created. The keys are:

  • name

    The 'internal' service name; that is, the name of the registry key used to store the information on this service.

  • display

    The 'display' service name; that is, the name displayed by the services control panel or MMC plugin.

  • path

    The full path name to the executable. This should be the path to your Perl executable, which will normally be the contents of $^X.

    NOTE: If you are using a compiled perl script (such as one generated with PerlApp) as opposed to a text based perl script file then this value must point to the actual compiled script's executable (eg. MyCompiledPerlService.exe) instead of ($^X which usually points to perl.exe). You can specify any parameters to pass into the service using the parameters key.

  • user

    The username the service is to run under; this is optional.

  • password

    The password to be used to log in the service; this is technically optional, but needs to be specified if user is.

  • parameters

    The parameters to be passed to Perl; in other words, the command line you would execute interactively, but without the leading ``perl ''. The parameters key value is appended to the path key when starting the service. Typically this will be something like:

    MyPerlScript.pl /a /b /c
    

  • machine

    The name of the machine to create the service on. Omission or an empty string specify the machine executing the call.

  • service_type

    An integer representing the type of the service; defaults to SERVICE_WIN32_OWN_PROCESS.

  • start_type

    An integer specifying how (or whether) the service is to be started. The default is SERVICE_AUTO_START.

  • error_control

    An integer specifying how the Service Control Manager is to react if the service fails to start. The default is SERVICE_ERROR_IGNORE, which in fact gets you an error log entry.

  • load_order

    The name of the load order group of which this service is a member. The default is membership in no group. See value ServiceGroupOrder in registry key HKEY_LOCAL_MACHINE\System\CurrentControlSet\Control for the names.

  • tag_id

    An integer representing the startup order of the service within its load ordering group.

  • dependencies

    A reference to the internal names of services and/or load ordering groups upon which this service depends. The default is no dependencies. Load order group names are prefixed with a '+' to distinguish them from service names.

  • description

    A short text description of the service, displayed (at least) as flyover help by the MMC "services" plugin.

• ConfigureService( \%ServiceInfo )

  Modify a service created with CreateService. Same arguments as CreateService.

  If you specify a parameters key you MUST specify a path key.

• DeleteService ($Machine, $ServiceName )

  This function deletes an existing service. The return is TRUE if the service was deleted, and FALSE otherwise. If an error occurred, call GetLastError to retrieve the actual error code.

  The arguments are the name of the machine (an empty string specifies the machine executing the call), and the 'internal' service name (i.e. the string passed in the name element when the service was created).

  A running service may not be deleted.

• GetSecurity( $Machine, $ServiceName )

  This will return a binary Security Descriptor (SD) that is associated with the specified service on the specified machine.

  The SD is in self-relative format. It can be imported into a [Win32::Perms](https://metacpan.org/pod/Win32%3A%3APerms) object using the Win32::Perms object's Import() method.

• RegisterCallbacks( $CodeRef | \%Hash )

  This will register specified code subroutines that will be called when specified events take place. For example if you register a subroutine with the pause event then this routine will be called when there is an attempt to pause the service. Not all events must have callbacks registered.

  If only a reference to a subroutine is passed in then it will be called for each and every event. You can pass in a hash containing particular key names (listed below) with code references.

  Possible hash key names:

  Key Name                 Event
  -------------            --------------------------------------
  start....................The service is starting.
  pause....................The service is entering a paused state.
  continue.................The service is resuming from a paused
                           state.
  stop.....................The service is stopping (see note below).
  running..................The service is running (see note below).
  interrogate..............The service is being queried for
                           information.
  shutdown.................The system is being shut down.
  preshutdown..............The system is about to begin shutting
                           down (Vista+ only).
  param_change.............There has been a parameter change to
                           the system.
  net_bind_add.............A new network binding has been made.
  net_bind_remove..........A network binding has been removed.
  net_bind_enable..........A network binding has been enabled.
  net_bind_disable.........A network binding has been disabled.
  device_event.............A device has generated some event.
  hardware_profile_change..A change has been made to the system's
                           hardware profile.
  power_event..............A power event has occured (eg change to
                           battery power).
  session_change...........There has been a change in session.
  user_defined.............A user defined event has been sent to
                           the service.

  NOTES:

  • The Stop state

    When a service calls into the registered "stop" callback routine the script should call the StopService() function. This tells the service to terminate and return back to the Perl script. This is the only way for the service to know that it must stop.

  • The Running state

    Periodically the extension will call into a registered "Running" subroutine. This allows the script to process data. This routine should be fast and return quickly otherwise it will block other callback events from being run. The frequency of calling the "Running" subroutine is dictated by the callback timer value passed into StartService() and any changes made to this value by calling into CallbackTimer().

• SetSecurity( $Machine, $ServiceName, $BinarySD | $Win32PermsObject )

  This applies the specified Security Descriptor (SD) to the specified service on the specified machine. You must have appropriate permissions to call this function.

  The specified SD can be either a binary SD (in self-relative or absolute format) or it can be a Win32::Perms object.

  This only sets the DACL and SACL. The owner and group are not set even if they are specified in the SD.

• StartService( [ \%Context, $CallbackTimer ] )

  This starts a new service thread. The script should call this as soon as possible. When the service manager starts the service Perl is started and the script is loaded.

  This function returns the thread handle of the service thread. If you call into this more than once it will only return the thread handle (it won't create another new service thread).

  • Callback Mode

    If the script has already registered callback routines (using RegisterCallbacks()) then the call into StartService() will not return until the service has stopped. However callbacks will be made for each state change and callback timer timeout (refer to RegisterCallbacks()).

• StopService()

  This will instruct the service to terminate.

• Timeout( [$TimeoutValue] )

  This function sets the new timeout value indicating how long a command will wait before Win32::Daemon tells the Service Control Manager that the command failed.

• QueryLastMessage( [$fResetMessage] )

  This function returns the last message that the service manager has sent to the service.

  Pass in a non zero value to reset the pending message to SERVICE_CONTROL_NONE. This way your script can tell when two of the same messages come in.

  Occasionally the service manager will send messages to the service. These messages typically request the service to change from one state to another. It is important that the Perl script responds to each message otherwise the service manager becomes confused about the current state of the service. For example, if the service manager is submits a SERVICE_PAUSE_PENDING then it expects the Perl script to recognize the change to a paused state and submit the new state by calling State( SERVICE_PAUSED ).

  You can update the service manager with the current status using the State() function.

  Possible values returned are:

  Valid Service Control Messages
  ------------------------------
  SERVICE_CONTROL_NONE............No message is pending.
  SERVICE_CONTROL_STOP............The SCM is requesting the service to
                                  stop. This results in State()
                                  reporting SERVICE_STOP_PENDING.
  SERVICE_CONTROL_PAUSE...........The SCM is requesting the service to
                                  pause. This results in State()
                                  reporting SERVICE_PAUSE_PENDING.
  SERVICE_CONTROL_CONTINUE........The SCM is requesting the service to
                                  continue from a paused state. This
                                  results in State() reporting
                                  SERVICE_CONTINUE_PENDING.
  SERVICE_CONTROL_INTERROGATE.....The service manager is querying the
                                  service's state
  
  SERVICE_CONTROL_USER_DEFINED....This is a user defined control.
                                  There are 127 of these beginning
                                  with SERVICE_CONTROL_USER_DEFINED
                                  as the base.

  Windows 2000 specific messages:

  SERVICE_CONTROL_SHUTDOWN........The machine is shutting down. This
                                  indicates that the service has
                                  roughly 20 seconds to clean up and
                                  terminate. This time can be extended
                                  by submitting SERVICE_STOP_PENDING
                                  via the State() function.
  SERVICE_CONTROL_PARAMCHANGE.....Service parameters have been
                                  modified.
  SERVICE_CONTROL_NETBINDADD......A network binding as been added.
  SERVICE_CONTROL_NETBINDREMOVE...A network binding has been removed.
  SERVICE_CONTROL_NETBINDENABLE...A network binding has been enabled.
  SERVICE_CONTROL_NETBINDDISABLE..A network binding has been disabled.
  SERVICE_CONTROL_DEVICEEVENT.....A device has generated some event.
  SERVICE_CONTROL_HARDWAREPROFILECHANGE
                                  A change has been made to the
                                  system's hardware profile.
  SERVICE_CONTROL_POWEREVENT......A power event has occured (eg change
                                  to battery power).
  SERVICE_CONTROL_SESSIONCHANGE...There has been a change in session.

  Windows Vista+ specific messages:

  SERVICE_CONTROL_PRESHUTDOWN ....The machine is about to shut down.
                                  This provides the service much more
                                  time to shutdown than
                                  SERVICE_CONTROL_SHUTDOWN.
  

  Note: When the system shuts down it will send a SERVICE_CONTROL_SHUTDOWN message. The Perl script has approximately 20 seconds to perform any shutdown activities before the Control Manger stops the service. If more time is needed call the State() function passing in the SERVICE_STOP_PENDING control message along with how many seconds it will take to shutdown the service. This time value is only an estimate. When the service is finally ready to stop it must submit the SERVICE_STOPPED message as in:

  if( SERVICE_CONTROL_SHUTDOWN == State() )
  {
      Win32::Daemon::State( SERVICE_STOP_PENDING, 30_000 );
      #...process code...
      Win32::Daemon::State( SERVICE_STOPPED );
  }
  

• State([$NewState [, $Hint ] || \%Hash ] )

  This function returns the current state of the service. It can optionally update the status of the service as well. This is the last status reported to the service manager.

  Optionally you can pass in a value that will be sent to the service manager. Optionally you can pass in a numeric value indicating the "hint". This is the number of milliseconds the SCM can expect to wait before the service responds to the request. For example, if your service script reports a hint of 30,000 milliseconds means that the SCM will have to wait for 30 seconds for the script to change the service's state before deciding that the script is non responsive.

  If you are setting/updating the state instead of passing in the state and wait hint you could pass in a hash reference. This allows you to specify the state, wait hint and error state. You can use the following keys:

  Hash Key
  --------
  state..........Valid service state (see table below).
  waithint.......A wait hint explained above. This is in milliseconds.
  error..........Any 32 bit error code. This is what will be reported
                 if an application queries the error state of the
                 service. It is also what is reported if a call to
                 start the services fails.
                 To reset an error state pass in NO_ERROR.
                 The only invalid error value is 0xFFFFFFFF.
  

  Example of passing in an error:

  Win32::Daemon::State( { error => 0x12345678 } );
  # Later to reset the error:
  Win32::Daemon::State( { error => NO_ERROR } );

  Possible values returned (or submitted):

  Valid Service States
  --------------------
  SERVICE_NOT_READY..........The SCM has not yet been initialized. If
                             the SCM is slow or busy then this value
                             will result from a call to State().
                             If you get this value, just keep calling
                             State() until you get
                             SERVICE_START_PENDING.
  SERVICE_STOPPED............The service is stopped.
  SERVICE_RUNNING............The service is running.
  SERVICE_PAUSED.............The service is paused.
  SERVICE_START_PENDING......The service manager is attempting to
                             start the service.
  SERVICE_STOP_PENDING.......The service manager is attempting to
                             stop the service.
  SERVICE_CONTINUE_PENDING...The service manager is attempting to
                             resume the service.
  SERVICE_PAUSE_PENDING......The service manager is attempting to
                             pause the service.

Callbacks

Callbacks were introduced in version v20030617.

The Win32::Daemon supports the concept of event callbacks. This allows a script to register a particular subroutine with a particular event. When the event occurs it will call the Perl subroutine registered with that event. This can make it very simple to write scripts.

You register a callback subroutine by calling into the RegisterCallbacks() function. You can pass in a code reference or a hash. A code reference will register the specified subroutine with all events. A hash allows you to pick which events you want to register for which subroutines. You do not have to register all events. If an event is not registered for a subroutine then the script will not be notified when the event occurs.

At a minimum a script should register for the 'Start' and 'Running' states. This enables the script to actually start and to periodically process data.

When an event callback occurs the subroutine should change the state accordingly by passing in the new state into State(). For example the 'Start' callback would call State( SERVICE_RUNNING ) to inform the service that it is officially running. Another example is the 'Pause' state should call State( SERVICE_PAUSED ) to inform the service that it is officially paused.

Once callback subroutines are registered the script enters the service mode by calling StartService(). This will being the process of calling the event callback routines. Note that when callback routines are registered the StartService() function will not return until a callback routine calls StopService() (typically the 'Stop' event callback would call StopService().

When calling into StartService() you can pass in a hash reference. This reference is known as a "context" hash. For every callback the hash will be passed into the callback routine. This enables a script to query and set data in the hash--essentially letting you pass information across to different callback events. This context hash is not required.

When a callback is made it always passes two parameters in: $State and $Context. $State is simply the state change that caused the callback. This represents the event that took place (e.g. SERVICE_PAUSE_PENDING, SERVICE_START_PENDING, etc). The $Context is a reference to the context hash that was passed into the StartService() function.

A typical callback routine should look similar to:

sub Callback_Start
{
    my( $Event, $Context ) = @_;
    $Context->{last_event} = $Event;

    # ...do some work here...

    # Tell the service manager that we have now
    # entered the running state.
    Win32::Daemon::State( SERVICE_RUNNING );
    return();
}

Refer to Example 4: Using a single callback and Example 5: Using different callback routines for an example of using callbacks.

COMPILED PERL APPLICATIONS

Many users like to compile their perl scripts into executable programs. This way it is much easier to copy them around from machine to machine since all necessary files, packages and binaries are compiled into one .exe file. These compiled perl scripts are compatible with Win32::Deamon as long as you install it correctly.

If you are going to compile your Win32::Daemon based perl script into an .exe there is nothing unique you need to do to your Win32::Daemon code with one single exception of the call into Win32::Daemon::CreateService(). When passing in the 'path' and 'parameters' values into CreateService() observe the following simple rules:

• If using a Perl script

  path........The full path to the Perl interpeter ($^X).
              This is typically:
                c:\perl\bin\perl.exe
  
  parameters..This value MUST start with the full path to the perl
              script file and append any parameters
              that you want passed into the service. For
              Example:
                c:\scripts\myPerlService.pl -param1 -param2 "c:\\Param2Path"

• If using a compiled Perl application

  path........The full path to the compiled Perl application.
              For example:
                c:\compiledscripts\myPerlService.exe
  
  parameters..This value is just the list of  parameters
              that you want passed into the service. For
              Example:
                -param1 -param2 "c:\\Param2Path"

Refer to "Example 3: Install the service" for an example.

EXAMPLES

Example 1: Simple Service

This example service will delete all .tmp files from the c:\temp directory every time it starts. It will immediately terminate.

use Win32::Daemon;

# Tell the OS to start processing the service...
Win32::Daemon::StartService();

# Wait until the service manager is ready for us to continue...
while( SERVICE_START_PENDING != Win32::Daemon::State() )
{
    sleep( 1 );
}

# Now let the service manager know that we are running...
Win32::Daemon::State( SERVICE_RUNNING );

# Okay, go ahead and process stuff...
unlink( glob( "c:\\temp\\*.tmp" ) );

# Tell the OS that the service is terminating...
Win32::Daemon::StopService();

This particular example does not really illustrate the capabilities of a Perl based service.

Example 2: Typical skeleton code

# This style of Win32::Daemon use is obsolete. It still works but the
# callback model is more efficient and easier to use. Refer to examples 4
#and 5.
use Win32;
use Win32::Daemon;
$SERVICE_SLEEP_TIME = 20; # 20 milliseconds
$PrevState = SERVICE_START_PENDING;
Win32::Daemon::StartService();
while( SERVICE_STOPPED != ( $State = Win32::Daemon::State() ) )
{
  if( SERVICE_START_PENDING == $State )
  {
      # Initialization code
      Win32::Daemon::State( SERVICE_RUNNING );
      $PrevState = SERVICE_RUNNING;
  }
  elsif( SERVICE_STOP_PENDING == $State )
  {
    Win32::Daemon::State( SERVICE_STOPPED );
  }
  elsif( SERVICE_PAUSE_PENDING == $State )
  {
    # "Pausing...";
    Win32::Daemon::State( SERVICE_PAUSED );
    $PrevState = SERVICE_PAUSED;
    next;
  }
  elsif( SERVICE_CONTINUE_PENDING == $State )
  {
    # "Resuming...";
    Win32::Daemon::State( SERVICE_RUNNING );
    $PrevState = SERVICE_RUNNING;
    next;
  }
  elsif( SERVICE_STOP_PENDING == $State )
  {
    # "Stopping...";
    Win32::Daemon::State( SERVICE_STOPPED );
    $PrevState = SERVICE_STOPPED;
    next;
  }
  elsif( SERVICE_RUNNING == $State )
  {
    # The service is running as normal...
    # ...add the main code here...

  }
  else
  {
    # Got an unhandled control message. Set the state to
    # whatever the previous state was.
    Win32::Daemon::State( $PrevState );
  }

  # Check for any outstanding commands. Pass in a non zero value
  # and it resets the Last Message to SERVICE_CONTROL_NONE.
  if( SERVICE_CONTROL_NONE != ( my $Message = Win32::Daemon::QueryLastMessage( 1 ) ) )
  {
    if( SERVICE_CONTROL_INTERROGATE == $Message )
    {
      # Got here if the Service Control Manager is requesting
      # the current state of the service. This can happen for
      # a variety of reasons. Report the last state we set.
      Win32::Daemon::State( $PrevState );
    }
    elsif( SERVICE_CONTROL_SHUTDOWN == $Message )
    {
      # Yikes! The system is shutting down. We had better clean up
      # and stop.
      # Tell the SCM that we are preparing to shutdown and that we
      # expect it to take 25 seconds (so don't terminate us for at
      # least 25 seconds)...
      Win32::Daemon::State( SERVICE_STOP_PENDING, 25000 );
    }
  }
  # Snooze for awhile so we don't suck up cpu time...
  Win32::Sleep( $SERVICE_SLEEP_TIME );
}
# We are done so close down...
Win32::Daemon::StopService();

Example 3: Install the service

For the 'path' key the $^X equates to the full path of the perl executable. Since no user is specified it defaults to the LocalSystem.

use Win32::Daemon;
# If using a compiled perl script (eg. myPerlService.exe) then
# $ServicePath must be the path to the .exe as in:
#    $ServicePath = 'c:\CompiledPerlScripts\myPerlService.exe';
# Otherwise it must point to the Perl interpreter (perl.exe) which
# is conviently provided by the $^X variable...
my $ServicePath = $^X;

# If using a compiled perl script then $ServiceParams
# must be the parameters to pass into your Perl service as in:
#    $ServiceParams = '-param1 -param2 "c:\\Param2Path"';
# OTHERWISE
# it MUST point to the perl script file that is the service such as:
my $ServiceParams = 'c:\perl\scripts\myPerlService.pl -param1 -param2 "c:\\Param2Path"';


my %service_info = (
    machine =>  '',
    name    =>  'PerlTest',
    display =>  'Oh my GOD, Perl is a service!',
    path    =>  $ServicePath,
    user    =>  '',
    pwd     =>  '',
    description => 'Some text description of this service',
    parameters => $ServiceParams
);
if( Win32::Daemon::CreateService( \%service_info ) )
{
    print "Successfully added.\n";
}
else
{
    print "Failed to add service: " . Win32::FormatMessage( Win32::Daemon::GetLastError() ) . "\n";
}

Example 4: Using a single callback

In this example only one subroutine is used for all callbacks. The CallbackRoutine() subroutine will receive all event callbacks. Basically this callback routine will have to do essentially the same thing that the main while loop in "Example 2: Typical skeleton code" does.

use Win32::Daemon;
Win32::Daemon::RegisterCallbacks( \&CallbackRoutine );
%Context = (
    count   =>  0,
    start_time => time(),
);
# Start the service passing in a context and
# indicating to callback using the "Running" event
# every 2000 milliseconds (2 seconds).
Win32::Daemon::StartService( \%Context, 2000 );

sub CallbackRoutine
{
    my( $Event, $Context ) = @_;

    $Context->{last_event} = $Event;
    if( SERVICE_RUNNING == $Event )
    {
        # ... process your main stuff here...
        # ... note that here there is no need to
        #     change the state

    }
    elsif( SERVICE_START_PENDING == $Event )
    {
        # Initialization code
        # ...do whatever you need to do to start...

        $Context->{last_state} = SERVICE_RUNNING;
        Win32::Daemon::State( SERVICE_RUNNING );
    }
    elsif( SERVICE_PAUSE_PENDING == $Event )
    {
        $Context->{last_state} = SERVICE_PAUSED;
        Win32::Daemon::State( SERVICE_PAUSED );

    }
    elsif( SERVICE_CONTINUE_PENDING == $Event )
    {
        $Context->{last_state} = SERVICE_RUNNING;
        Win32::Daemon::State( SERVICE_RUNNING );
    }
    elsif( SERVICE_STOP_PENDING == $Event )
    {
        $Context->{last_state} = SERVICE_STOPPED;
        Win32::Daemon::State( SERVICE_STOPPED );

        # We need to notify the Daemon that we want to stop callbacks
        # and the service.
        Win32::Daemon::StopService();
    }
    else
    {
        # Take care of unhandled states by setting the State()
        # to whatever the last state was we set...
        Win32::Daemon::State( $Context->{last_state} );
    }
    return();
}

Example 5: Using different callback routines

use Win32::Daemon;
Win32::Daemon::RegisterCallbacks( {
    start       =>  \&Callback_Start,
    running     =>  \&Callback_Running,
    stop        =>  \&Callback_Stop,
    pause       =>  \&Callback_Pause,
    continue    =>  \&Callback_Continue,
} );

my %Context = (
    last_state => SERVICE_STOPPED,
    start_time => time(),
);

# Start the service passing in a context and
# indicating to callback using the "Running" event
# every 2000 milliseconds (2 seconds).
Win32::Daemon::StartService( \%Context, 2000 );

sub Callback_Running
{
    my( $Event, $Context ) = @_;

    # Note that here you want to check that the state
    # is indeed SERVICE_RUNNING. Even though the Running
    # callback is called it could have done so before
    # calling the "Start" callback.
    if( SERVICE_RUNNING == Win32::Daemon::State() )
    {
        # ... process your main stuff here...
        # ... note that here there is no need to
        #     change the state
    }
}

sub Callback_Start
{
    my( $Event, $Context ) = @_;
    # Initialization code
    # ...do whatever you need to do to start...

    $Context->{last_state} = SERVICE_RUNNING;
    Win32::Daemon::State( SERVICE_RUNNING );
}

sub Callback_Pause
{
    my( $Event, $Context ) = @_;
    $Context->{last_state} = SERVICE_PAUSED;
    Win32::Daemon::State( SERVICE_PAUSED );
}

sub Callback_Continue
{
    my( $Event, $Context ) = @_;
    $Context->{last_state} = SERVICE_RUNNING;
    Win32::Daemon::State( SERVICE_RUNNING );
}

sub Callback_Stop
{
    my( $Event, $Context ) = @_;
    $Context->{last_state} = SERVICE_STOPPED;
    Win32::Daemon::State( SERVICE_STOPPED );

    # We need to notify the Daemon that we want to stop callbacks and the service.
    Win32::Daemon::StopService();
}

NOTES

Timer/Running Callbacks:

Starting with build 20080321 the "running" callback is deprecated and replaced with the "timer" callback. Scripts should no longer test for a state of SERVICE_RUNNING but instead check for the state of SERVICE_CONTROL_TIMER to indicate whether or not a callback has occurred due to a timer.

If a script...

• ...registers for the "running" callback it will continue to work as expected: timer expiration results in a callback to the subroutine registered for the "running" callback passing in a value of SERVICE_RUNNING.
• ...registers for the "timer" callback then timer expiration results in a callback to the subroutine registered for the "timer" callback, passing in a value of SERVICE_CONTROL_TIMER.
• ...registers for both "running" and "timer" then only Win32::Daemon treats it as if only "timer" was registered (see above for behavior).
• ...registers for everything by passing one subroutine reference into Win32::Daemon::Callback() then both "running" and "timer" are registered and only "timer" is recognized (see previous 2 behaviors above).

Legacy scripts which call Win32::Daemon::Callback() passing in only one catchall subroutine reference will be most impacted as they will expect.

SEE ALSO

MSDN: Service Control Manager

MSDN: Service Functions

AUTHOR

Dave Roth, Roth Consulting, http://www.roth.net/

CONTRIBUTORS

Haiko Strotbek haiko@strotbek.com

Jan Dubois jand@activestate.com

Marc Pijnappels marc.pijnappels@nec-computers.com

Olivier Mengué dolmen@cpan.org

SUPPORT

Dave has retired from active development of this module. It is now being maintained as part of the libwin32 project libwin32@perl.org.

COPYRIGHT

Copyright © 1998 - 2011 the Win32::Daemon "AUTHOR" and "CONTRIBUTORS" as listed above.

LICENSE

This library is free software and may be distributed under the same terms as perl itself.