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Twisted programs usually work with twisted.application.service.Application
. This class usually holds all persistent configuration of a running server, such as:
- ports to bind to,
- places where connections to must be kept or attempted,
- periodic actions to do,
- and almost everything else to do with your
twisted.application.service.Application <Application>
.
It is the root object in a tree of services implementing twisted.application.service.IService
.
Other howtos describe how to write custom code for Application
s, but this one describes how to use already written code (which can be part of Twisted or from a third-party Twisted plugin developer). The Twisted distribution comes with an important tool to deal with Application
s: twistd(1)
.
Application
s are just Python objects, which can be created and manipulated in the same ways as any other object.
The Twisted Daemon is a program that knows how to run twisted.application.service.Application <Application>
s. Strictly speaking, twistd
is not necessary. Fetching the application, getting the IService
component, calling startService()
, scheduling stopService()
when the reactor shuts down, and then calling reactor.run()
could be done manually.
However, twistd
supplies many options which are highly useful for program set up:
- choosing a reactor (for more on reactors, see
Choosing a Reactor <choosing-reactor>
), - logging configuration (see the
logger <logger>
documentation for more), - daemonizing (forking to the background),
- and
more <application>
.
twistd
supports all Applications mentioned above -- and an additional one. Sometimes it is convenient to write the code for building a class in straight Python. One big source of such Python files is the examples <../examples/index>
directory. When a straight Python file which defines an Application
object called application
is used, use the -y
option.
When twistd
runs, it records its process id in a twistd.pid
file (this can be configured via a command line switch). In order to shutdown the twistd
process, kill that pid. The usual way to do this would be:
kill `cat twistd.pid`
To prevent twistd
from daemonizing, you can pass it the --no-daemon
option (or -n
, in conjunction with other short options).
As always, the gory details are in the manual page.