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