Perl объект ортасы: POE нұсқасы

the Mach variant

The Perl Object Environment (POE) is a library of Perl modules written in the Perl programming language by Rocco Caputo et al. From CPAN:
"POE originally was developed as the core of a persistent object server and runtime environment. It has evolved into a general purpose multitasking and networking framework, encompassing and providing a consistent interface to other event loops such as Event and the Tk and Gtk toolkits."

POE, The Perl Object Environment can be thought of as a tiny modular operating system. One or more POE programs or instances can be run concurrently and are generally well suited for cooperative multitasking. The POE package consists of namespaces and abstractions that guide future development of POE in an open ended CPAN style convention.

The informal architecture consists of a set of layers with a kernel on the bottom. This tiny kernel represents the events layer which operates as the main loop of each running POE instance. The first call is to the "event dispatcher" POE::Kernel. The POE::Kernel namespace contains a suite of functions which are plugged into the kernel itself. These loop abstractions are designed after POE's standardized event loop bridge interface POE::Loop. These can be mixed and matched as needed to provide runtime services and a lean facility for interprocess communication. The basic functions are POE::Loop::Event, POE::Loop::Poll and POE::Loop::Select. Also available are POE::Loop::Tk and POE::Loop::Gtk which offer hooks into other loop bridges in the external environment. If that isn't enough, the POE::Loop kernel abstraction provides reusable signal callbacks, time or alarm callbacks, and filehandle activity callbacks as well as administrative functions such as initializing, executing, and finalizing event loops. There is also a higher level packaging framework POE::Macro and a debugging utility for testing them called POE::Preprocessor. This framework has yielded POE::Macro::UseBytes. NOTE: As the Perl tradition mandates, POE is also a moving target. Always check CPAN to see what new goodies the community has placed in the archive. ( and remember Perl's Motto: "There's more than one way to do it" per Larry)

The Running Kernel operates through primordial finite state machines constructed from another set of abstractions ruled by the POE::Session architecture. A POE::Session is almost trivially defined as a map of events to the functions, class methods, and/or object methods that handle them. POE::Session objects also contain a storage space shared by all its event handlers, called a heap. Any way you slice them the states are solidly identified and clearly defined. A more featureful event handler is a POE::Session subclass called POE::NFA an event driven Nondeterministic finite automaton (a smarter finite state machine). This event handler moves from one strictly defined state to another as events, polls, user selections, or other external events require. This state machine acts to encapsulate a wide range of generic event driven threads allowing much tighter tracking along the execution path than the relatively informal POE::Session.

The Kernel's next requirement is for Input Output handlers that exist in a single I/O layer called Wheels. Wheels initiate actions, handle their resulting low level events, and produce higher level events for the sessions that use them. Wheels, like Sessions and Loops are built from a uniform set of abstractions POE::Wheel that sit on top of the Kernel. There are seven highly specialized and well defined Wheels in POE's base distribution:
POE::Wheel::Run Creates and interacts with child processes using pipe , fork , and sometimes exec Interaction is done through the child's standard input and output. POE::Wheel::SocketFactory A way to create client and server sockets without blocking to wait for their establishment. POE::Wheel::Curses A handler for non blocking input from the Curses text interface library. CPAN components such as Curses::UI::POE and Term::Visual build upon it. POE::Wheel::FollowTail Tracks an ever growing file, such as a log or a collaborative document, by keeping a handle on its tail. POE::Wheel::ListenAccept A subset of POE::Wheel::SocketFactory used for listening on existing server sockets and accepting connections from remote clients. POE::Wheel::ReadLine A non blocking, event driven analogue to Term::ReadLine. POE::Wheel::ReadWrite A high performance NBIO file handler for POE that uses POE's drivers and filters to perform buffered read and write on filehandles which draws on the next layer POE's own little file system.

The Acme::POE::Knee module on the CPAN. A number of silly acronym expansions at the end of What POE Is.