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xpcservice.plist(5)         BSD File Formats Manual        xpcservice.plist(5)


NAME

     xpcservice.plist -- XPC Service configuration keys and values


DESCRIPTION

     This document describes the keys-value pairs which configure an XPC Ser-
     vice.  An XPC Service is a process which implments the server-side of an
     XPC connection.  The service program is conntained insided a Mac OS X
     bundle.  The bundle contains an Info.plist.  The XPC Service configura-
     tion settings are specified by keys and values defined in a dictionary
     included within the Info.plist.


OVERVIEW

     An application has a namespace which maps a service name to a running
     instance of the service program.  The namespace is created dynamically
     and is unique to each application.  The namespace is populated with the
     set services embedded in the application bundle and embedded in the
     frameworks used by the application.

     System frameworks may have embedded XPC Services.  Typically, an devel-
     oper would not connect to this service directly.  Instead, the developer
     would call an API function in the framework and that would contact the
     service.  However, the name of XPC Service must be in the application's
     namespace so that the framework code can "see" and connect to the ser-
     vice.

     XPC Services are "launched-on-demand". They are only started when an
     application creates a connection to the service and sends a message to
     it. The service process can be terminated when it is inactive and has
     been idle for a a period of time.  The service process can be started
     again upon receipt of a new message or connection request.  XPC Services
     should be state-less so that they can come and go as needed.

     The results of a connection request to an XPC Service from two different
     applications depends upon the type of the service.  The service type con-
     trols the policy used to create a new instance of the service.  For exam-
     ple, a new connection request from two different applications to an
     Application-type service in a framework will result in a new instance of
     the service being created for each application.  However, if two applica-
     tions request the same User-type service, then only one instance of the
     service will be created for each user.

     Services embedded in an application bundle will only be visible to the
     containning application and will be, by definition, Applicaton-type ser-
     vices. A subsequent connection request from an application to a service
     will result in a new connection to an existing service.


CF Bundle Keys

     These top-level Info.plist keys are required to be defined in the
     Info.plist file:

     CFBundleIdentifier <string>
     This key defines the name of the service; clients use this name to con-
     nect to the service.

     CFBundlePackageType "XPC!"
     This key identifies the bundle as being an XPC Service.

     XPCService <dictionary>
     This key defines a dictionary which contains the settings to configure
     the XPC Service.


XPCService Dictionary Keys

     The XPC Service may be configured by setting these keys in the XPCService
     dictionary:

     ServiceType <string> (default: Application)
     The type of the XPC Service specifies how the service is instanciated.
     The values are:

     o   Application
         Each application will have a unique instance of this service.

     o   User
         There is one instance of the service process created for each user.

     o   System
         There is one instance of the service process for the whole system.
         System XPC Services are restricted to reside in system frameworks and
         must be owned by root.

     RunLoopType <string> (default: dispatch_main)
     The RunLoop type specifies which style of runloop will be started once
     xpc_main has finished initializing. The values are:

     o   dispatch_main
         xpc_main will call dispatch_main().

     o   NSRunLoop
         xpc_main will call [[NSRunLoop currentRunLoop] run].

     JoinExistingSession <bool> (default: False)
     By default XPC Services are placed into there own unique audit session.
     If this key is true, then the service is placed into the session of the
     application requesting a connection to the service.

     EnvironmentVariables <dictionary> (default: none)
     A dictionary containing environment variables (represented as key-value
     pairs) which are set in the environment of the service process.


SEE ALSO

     plist(5)

Darwin                         February 8, 2011                         Darwin

Mac OS X 10.7 - Generated Wed Aug 24 20:32:56 CDT 2011
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