NAME

    Zing - Multi-Process Management System

ABSTRACT

    Actor Toolkit and Multi-Process Management System

SYNOPSIS

      use Zing;
    
      my $zing = Zing->new(scheme => ['MyApp', [], 1]);
    
      # $zing->execute;

DESCRIPTION

    This distribution includes an actor-model architecture toolkit and
    multi-process management system which provides primatives for building
    resilient, reactive, concurrent, distributed message-driven
    applications in Perl 5. If you're unfamiliar with this architectural
    pattern, learn more about "the actor model"
    <https://en.wikipedia.org/wiki/Actor_model>.

INHERITS

    This package inherits behaviors from:

    Zing::Kernel

LIBRARIES

    This package uses type constraints from:

    Zing::Types

ATTRIBUTES

    This package has the following attributes:

 scheme

      scheme(Scheme)

    This attribute is read-only, accepts (Scheme) values, and is required.

METHODS

    This package implements the following methods:

 start

      start() : Kernel

    The start method prepares the Zing::Kernel and executes its event-loop.

    start example #1

        # given: synopsis
      
        $zing->start;

COMMANDS

    Given the following process (actor):

      # in lib/MyApp.pm
    
      package MyApp;
    
      use parent 'Zing::Single';
    
      sub perform {
        # do something (once)
      }
    
      1;

    With an application cartridge specifying 4 forks:

      # in app/myapp
    
      ['MyApp', [], 4]

    The zing command-line application lets you manage Zing applications
    from the command-line using these commands:

 start

      $ zing start app/myapp

    The start command loads an application cartridge which returns a
    "scheme" and runs it as a daemon.

 stop

      $ zing stop app/myapp

    The stop command finds a running application by its PID (process ID)
    and terminates the process.

 logs

      $ zing logs --level fatal

    The logs command taps the centralized log source and outputs new events
    to STDOUT (standard output).

PRIMATIVES

    This distribution provides a collection of actor-model primitives which
    can be used to create sophisticated and powerful distributed systems,
    organized within intricate process topologies. The following is a
    directory of those primitives listed by classification:

 messaging

    These classes facilitate message-passing and communications:

      * Zing::Channel: Shared Communication

      * Zing::Data: Process Data

      * Zing::Domain: Aggregate Root

      * Zing::Dropbox: Transient Store

      * Zing::KeyVal: Key/Value Store

      * Zing::Mailbox: Process Mailbox

      * Zing::PubSub: Pub/Sub Store

      * Zing::Queue: Message Queue

      * Zing::Registry: Process Registry

      * Zing::Repo: Generic Store

      * Zing::Store: Storage Abstraction

 processes

    These base classes implement the underlying process (actor) logic:

      * Zing: Process Wrapper

      * Zing::Kernel: Kernel Process

      * Zing::Launcher: Scheme Launcher

      * Zing::Process: Processing Unit

      * Zing::Ring: Process Ring

      * Zing::Scheduler: Scheme Launcher

      * Zing::Simple: Simple Process

      * Zing::Single: Single Process

      * Zing::Spawner: Scheme Spawner

      * Zing::Timer: Timer Process

      * Zing::Watcher: Watcher Process

      * Zing::Worker: Worker Process

 ready-made

    These classes are ready-made process implementations using callbacks:

      * Zing::Zang: Process Implementation

      * Zing::Zang::Launcher: Process Launcher

      * Zing::Zang::Simple: Process Performer

      * Zing::Zang::Single: Single-Task Process

      * Zing::Zang::Spawner: Process Spawner

      * Zing::Zang::Timer: Timer Process

      * Zing::Zang::Watcher: Process Watcher

      * Zing::Zang::Worker: Worker Process

FEATURES

    All features are implemented using classes and objects. The following
    is a list of features currently enabled by this toolkit:

 actor-model

      use Zing::Process;
    
      my $p1 = Zing::Process->new(name => 'p1');
      my $p2 = Zing::Process->new(name => 'p2');
    
      $p1->mailbox->send($p2->mailbox->term, { action => 'greeting' });

    This distribution provides a toolkit for creating processes (actors)
    which can be run in isolation and which communicate with other
    processes through message-passing.

 asynchronous

      # in process (1)
      use Zing::Domain;
      use Zing::Process;
    
      my $d1 = Zing::Domain->new(name => 'peers');
      my $p1 = Zing::Process->new(name => 'p1');
    
      $d1->push('mailboxes', $p1->mailbox->term);
      $p1->execute;
    
      # in process (2)
      use Zing::Domain;
      use Zing::Process;
    
      my $d2 = Zing::Domain->new(name => 'peers');
      my $p2 = Zing::Process->new(name => 'p2');
    
      my $mailboxes = $d2->get('mailboxes');
    
      for my $address (@$mailboxes) {
        # send each registered process a message
        $p2->send($address, { discovery => $p2->mailbox->term });
      }
    
      $p2->execute;

    This distribution provides a multi-process management system which
    allows processes to be deployed and managed separately having the
    ability to communicate across threads of execution.

 atomicity

      # in process (1)
      use Zing::KeyVal;
    
      my $i = 0;
      my $kv = Zing::KeyVal->new(name => 'stash');
    
      while ($i < 1_000) {
        $kv->send('random', { value => 1 });
    
        # my $data = $kv->recv('random');
      }
    
      # in process (2)
      use Zing::KeyVal;
    
      my $i = 0;
      my $kv = Zing::KeyVal->new(name => 'stash');
    
      while ($i < 1_000) {
        $kv->send('random', { value => 2 });
    
        # my $data = $kv->recv('random');
      }

    This distribution provides data storage abstractions which perform
    atomic reads and write by leveraging Redis <https://redis.io> as the
    default data storage backend.

 chainable

      use Zing::Process;
      use Zing::Ring;
    
      my $p1 = Zing::Process->new(name => 'p1');
      my $p2 = Zing::Process->new(name => 'p2');
    
      my $ring = Zing::Ring->new(processes => [$p1, $p2]);
    
      $ring->execute;

    This distribution provides a mechanism for chaining (i.e. joining) two
    or more processes together and executing them in a turn-based manner.
    This ability allows you to design complex hierarchical process
    topologies.

 channels

      # in process (1)
      use Zing::Channel;
    
      my $chan = Zing::Channel->new(name => 'chat');
    
      while (1) {
        if (my $data = $chan->recv) {
          # broadcast received
          warn $data->{text};
        }
      }
    
      # in process (2)
      use Zing::Channel;
    
      my $chan = Zing::Channel->new(name => 'chat');
    
      while (1) {
        if (my $data = $chan->recv) {
          # broadcast received
          warn $data->{text};
        }
      }

    This distribution provides the means for braodcasting and communicating
    to multiple processes simulaneously through channels which are similar
    to FIFO queues.

 clusterable

      # in process (1) on cluster (1)
      use Zing::Queue;
    
      my $queue = Zing::Queue->new(name => 'tasks', target => 'global');
    
      # pull from global queue
      $queue->recv;
    
      # in process (1) on cluster (2)
      use Zing::Queue;
    
      my $queue = Zing::Queue->new(name => 'tasks', target => 'global');
    
      # pull from global queue
      $queue->recv;

    This distribution provides support cross-cluster communication and thus
    operations. Using federated Redis as the data storage backend means you
    can scale your deployments without changing your implementations.

 configuration

      # configure the namespace (defaults to "main")
      ZING_NS=app
    
      # enable process debugging tracing
      ZING_DEBUG=1
    
      # configure where the command-line tool finds catridges
      ZING_HOME=/tmp
    
      # configure the hostname used in process registration
      ZING_HOST=0.0.0.0
      ZING_HOST=68.80.90.100
    
      # configure the system datastore (defaults to 'Zing::Redis')
      ZING_STORE='Zing::Redis'
    
      # configure Redis driver without touching your source code
      ZING_REDIS='server=127.0.0.1:6379'
      ZING_REDIS='every=1_000_000,reconnect=60'
      ZING_REDIS='sentinels=127.0.0.1:12345|127.0.0.1:23456,sentinels_cnx_timeout=0.1'
      ZING_REDIS='server=192.168.0.1:6379,debug=0'
    
      # configure where the command-line tool finds catridges and PID files
      ZING_APPDIR=./
      ZING_PIDDIR=/tmp

    This distribution provides environment variables that let you customize
    how Zing operates and behaves without the need to modify source code.
    These attributes are not required and fallback to sane defaults.

 distributed

      # in process (1..n) on cluster (1)
      use Zing;
    
      my $zing = Zing->new(scheme => ['MyApp', [], 16]);
    
      $zing->execute;
    
      # in process (1..n) on cluster (2)
      use Zing;
    
      my $zing = Zing->new(scheme => ['MyApp', [], 16]);
    
      $zing->execute;
    
      # in process (1..n) on cluster (3)
      use Zing;
    
      my $zing = Zing->new(scheme => ['MyApp', [], 16]);
    
      $zing->execute;

    This distribution provides a collection of actor-model primitives which
    can be used to create sophisticated and powerful distributed systems,
    organized within intricate process topologies.

 event-driven

      # in process (1)
      package MyApp::FileUpoad;
    
      use parent 'Zing::Process';
    
      sub receive {
        my ($self, $from, $data) = @_;
    
        # react to file-upload events
    
        return;
      }
    
      my $p1 = MyApp::FileUpoad->new;
    
      $p1->execute;
    
      # in process (2)
      package MyApp::TextTranslate;
    
      use parent 'Zing::Process';
    
      sub receive {
        my ($self, $from, $data) = @_;
    
        # react to text-translate events
    
        return;
      }
    
      my $p2 = MyApp::TextTranslate->new;
    
      $p2->execute;

    This distribution provides all the prerequisites needed to develop
    scalable reactive event-driven applications distributed across one or
    several servers.

 fifo-queues

      # in process (1)
      use Zing::Queue;
    
      my $queue = Zing::Queue->new(name => 'tasks');
    
      # pull from queue
      $queue->send({ command => { ... } });
      $queue->send({ command => { ... } });
      $queue->send({ command => { ... } });
      $queue->send({ command => { ... } });
    
      # in process (2)
      use Zing::Queue;
    
      my $queue = Zing::Queue->new(name => 'tasks');
    
      # pull from FIFO queue
      $queue->recv;

    This distribution provides high-performance FIFO message queues which
    enhance messaging across processes when the order of operations and
    events is critical and where duplicates can't be tolerated.

 hot-reloadable

      use Zing;
      use Zing::Daemon;
    
      my $daemon = Zing::Daemon->new(
        name => 'myapp-sleep',
        app => Zing->new(scheme => ['MyApp::Sleep', [], 4])
      );
    
      $daemon->execute; # pid 12345
    
      # $ kill -USR2 12345

    This distribution provides zero-downtime through hot-reloading which is
    where the process watchers (supervisors) keep the app running and
    gracefully reload child processes at runtime.

 log-shipping

      use Zing::Zang;
    
      my $zang = Zing::Zang->new(on_perform => sub {
        my ($self) = @_;
    
        $self->log->fatal('something went wrong');
    
        return;
      });
    
      $zang->execute;
    
      # tap the logs using the command-line tool
    
      # $ zing logs

    This distribution provides the ability to ship the logs of individual
    processes to a specific centralized channel which can be tapped
    asynchronously, especially by the command-line tool.

 mailboxes

      use Zing::Process;
    
      my $p1 = Zing::Process->new(name => 'p1');
      my $p2 = Zing::Process->new(name => 'p2');
    
      $p1->mailbox->send($p2->mailbox->term, { say => 'ehlo' });
    
      my $message = $p2->mailbox->recv;
    
      $p2->mailbox->reply($message, { say => 'helo' });

    This distribution provides every process with its own unique mailbox
    which can receive messages from other processes as a means of
    cooperating through message passing.

 management

      use Zing::Kernel;
    
      my $kernel = Zing::Kernel->new(scheme => ['MyApp::Logger', [], 2]);
    
      $kernel->execute;

    This distribution provides a kernel process that can be used to manage
    the deployment of child processes and is used to wrap cartridges by the
    command-line tool when daemonizing process.

 multitasking

      use Zing::Zang;
    
      my $zang = Zing::Zang->new(
        on_perform => sub {
          # do something
        },
        on_receive => sub {
          # handle something
        },
      );
    
      $zang->execute;

    This distribution provides all processes with an event-loop that allows
    them to perform multiple operations in sequence and supports operating
    in a non-blocking manner.

 non-blocking

      use Zing::Zang;
    
      my $zang = Zing::Zang->new(
        on_perform => sub {
          my ($self) = @_;
    
          $self->defer({ command => {...} }) and return;
    
          return;
        },
        on_receive => sub {
          my ($self, $from, $data) = @_;
    
          return unless $self->term eq $from; # from myself
    
          # do something
    
          return;
        }
      );
    
      $zang->exercise;

    This distribution provides features that allow processes to operate in
    a non-blocking manner, yielding and deferring operations, and chunking
    workloads.

 parallelism

      use Zing::Process;
    
      my $p1 = Zing::Process->new;
    
      my $f1 = $p1->spawn(['MyApp', [id => 12345] 1]);
      my $f2 = $p1->spawn(['MyApp', [id => 12346] 1]);

    This distribution provides multiple ways of executing operations in
    parallel, including spawning processes via forking with the guarantee
    of not creating zombie processes.

 supervisors

      use Zing::Zang::Watcher;
    
      my $zang = Zing::Zang::Watcher->new(
        scheme => ['MyApp', [] 8]
      );
    
      $zang->exercise;

    This distribution provides watcher processes which to supervise child
    processes but also are capable of multitasking and performing other
    operations while monitoring supervised processes.

 virtual-actors

      use Zing::Zang::Spawner;
    
      my $zang = Zing::Zang::Spawner->new(
        queues => ['schemes']
      );
    
      $zang->exercise;

    This distribution provides the ability to use virtual actors, which are
    processes (actors) created on-demand as a result of some system event.
    This feature is enabled by the Zing::Launcher and Zing::Spawner
    superclasses.

SEE ALSO

    The Actor Model <https://en.wikipedia.org/wiki/Actor_model>

    Concurrent Computation
    <https://www.amazon.com/Actors-Concurrent-Computation-Distributed-Systems/dp/026251141X>

    Concurrency in Go/Erlang <https://www.youtube.com/watch?v=2yiKUIDFc2I>

    The Akka Project <https://github.com/akka/akka>

    The Actorkit Project <https://github.com/influx6/actorkit>

    The Orleans Project <http://dotnet.github.io/orleans>

    The Pyakka Project <https://github.com/jodal/pykka>

    The Reactive Manifesto <http://www.reactivemanifesto.org>

DISCLOSURES

    The following is a list of all the known ways Zing is not like a
    traditional actor-model system:

      * In Zing, actors act independently and aren't beholden to a system
      manager.

      * In Zing, actors are always active (each runs its own infinite
      event-loop).

      * In Zing, actors can communicate unrestricted (no approved
      communicators).

      * In Zing, actors can block using poll but do not block by default.

      * In Zing, the default datastore/backend is Redis <https://redis.io>
      which means the system is (by default) subject to the guarantees and
      limitations of that system. Data is serialized as JSON
      <https://json.org> and stored in plain-text.

AUTHOR

    Al Newkirk, awncorp@cpan.org

LICENSE

    Copyright (C) 2011-2019, Al Newkirk, et al.

    This is free software; you can redistribute it and/or modify it under
    the terms of the The Apache License, Version 2.0, as elucidated in the
    "license file"
    <https://github.com/iamalnewkirk/zing/blob/master/LICENSE>.

PROJECT

    Wiki <https://github.com/iamalnewkirk/zing/wiki>

    Project <https://github.com/iamalnewkirk/zing>

    Initiatives <https://github.com/iamalnewkirk/zing/projects>

    Milestones <https://github.com/iamalnewkirk/zing/milestones>

    Contributing
    <https://github.com/iamalnewkirk/zing/blob/master/CONTRIBUTE.md>

    Issues <https://github.com/iamalnewkirk/zing/issues>

