SERVICE

SERVICE

1. Process

   • provide a service
   • rely Win API
   • Ever running

2. Components

   • Service App
   • Service Control Program
     • Services.msc
   • Service Control Manager

3. How is create?

   • 1. El instalador del program debe registrar su servicio
     • 2. Setup call a Advapi32.dll function
       • CreateService
         • Specify: Type (single,share), Path, Display Name, Account - context security, Startup Type(Manual,Automatic), Error Code (how react?)
       • 3. A message is sended to SCM
         • 4. SCM crea key in Registry
           • HKLM\System\ CurrentControlSet\Services
             • Save all parameters
               • Note The SCM does not access a service’s Parameters subkey until the service is deleted, at which time the SCM deletes the service’s entire key, including subkeys like Parameters.

4. How Start a service?

   • SCM send Start command
     • Process main thread run StartServiceCtrlDispatcher
       • Accet List of services point
         • Named pipe communication to SCM
           • Service thread
             • Is Running?
               • YES
                 • Call RegisterServiceCtrlHandler --> save the Service Control Handler in the main process
                   • Implemented for manage a lot of SCM commands
                   • Inicialyze SERVICE
                     • SCM ask its progress
                     • Service thread --> Loop waiting REQUESTS from CLIENT APPs
               • NO
                 • Return to the main function
                   • Free resources before out

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