[ViewVC] Diff of: cvs/AnyEvent-MP/MP.pm

Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.80 by root, Fri Sep 4 22:30:29 2009 UTC vs.
Revision 1.119 by root, Sun Feb 26 10:29:59 2012 UTC

…		…
1	=head1 NAME	1	=head1 NAME
2		2
3	AnyEvent::MP - multi-processing/message-passing framework	3	AnyEvent::MP - erlang-style multi-processing/message-passing framework
4		4
5	=head1 SYNOPSIS	5	=head1 SYNOPSIS
6		6
7	use AnyEvent::MP;	7	use AnyEvent::MP;
8		8
30	rcv $port, pong => sub { warn "pong received\n" };	30	rcv $port, pong => sub { warn "pong received\n" };
31		31
32	# create a port on another node	32	# create a port on another node
33	my $port = spawn $node, $initfunc, @initdata;	33	my $port = spawn $node, $initfunc, @initdata;
34		34
		35	# destroy a port again
		36	kil $port; # "normal" kill
		37	kil $port, my_error => "everything is broken"; # error kill
		38
35	# monitoring	39	# monitoring
36	mon $port, $cb->(@msg) # callback is invoked on death	40	mon $localport, $cb->(@msg) # callback is invoked on death
37	mon $port, $otherport # kill otherport on abnormal death	41	mon $localport, $otherport # kill otherport on abnormal death
38	mon $port, $otherport, @msg # send message on death	42	mon $localport, $otherport, @msg # send message on death
		43
		44	# temporarily execute code in port context
		45	peval $port, sub { die "kill the port!" };
		46
		47	# execute callbacks in $SELF port context
		48	my $timer = AE::timer 1, 0, psub {
		49	die "kill the port, delayed";
		50	};
39		51
40	=head1 CURRENT STATUS	52	=head1 CURRENT STATUS
41		53
42	bin/aemp - stable.	54	bin/aemp - stable.
43	AnyEvent::MP - stable API, should work.	55	AnyEvent::MP - stable API, should work.
44	AnyEvent::MP::Intro - explains most concepts.	56	AnyEvent::MP::Intro - explains most concepts.
45	AnyEvent::MP::Kernel - mostly stable.	57	AnyEvent::MP::Kernel - mostly stable API.
46	AnyEvent::MP::Global - stable but incomplete, protocol not yet final.	58	AnyEvent::MP::Global - stable API.
47
48	stay tuned.
49		59
50	=head1 DESCRIPTION	60	=head1 DESCRIPTION
51		61
52	This module (-family) implements a simple message passing framework.	62	This module (-family) implements a simple message passing framework.
53		63
…		…
68		78
69	Ports allow you to register C<rcv> handlers that can match all or just	79	Ports allow you to register C<rcv> handlers that can match all or just
70	some messages. Messages send to ports will not be queued, regardless of	80	some messages. Messages send to ports will not be queued, regardless of
71	anything was listening for them or not.	81	anything was listening for them or not.
72		82
		83	Ports are represented by (printable) strings called "port IDs".
		84
73	=item port ID - C<nodeid#portname>	85	=item port ID - C<nodeid#portname>
74		86
75	A port ID is the concatenation of a node ID, a hash-mark (C<#>) as	87	A port ID is the concatenation of a node ID, a hash-mark (C<#>) as
76	separator, and a port name (a printable string of unspecified format).	88	separator, and a port name (a printable string of unspecified format).
77		89
…		…
81	which enables nodes to manage each other remotely, and to create new	93	which enables nodes to manage each other remotely, and to create new
82	ports.	94	ports.
83		95
84	Nodes are either public (have one or more listening ports) or private	96	Nodes are either public (have one or more listening ports) or private
85	(no listening ports). Private nodes cannot talk to other private nodes	97	(no listening ports). Private nodes cannot talk to other private nodes
86	currently.	98	currently, but all nodes can talk to public nodes.
87		99
		100	Nodes is represented by (printable) strings called "node IDs".
		101
88	=item node ID - C<[a-za-Z0-9_\-.:]+>	102	=item node ID - C<[A-Za-z0-9_\-.:]*>
89		103
90	A node ID is a string that uniquely identifies the node within a	104	A node ID is a string that uniquely identifies the node within a
91	network. Depending on the configuration used, node IDs can look like a	105	network. Depending on the configuration used, node IDs can look like a
92	hostname, a hostname and a port, or a random string. AnyEvent::MP itself	106	hostname, a hostname and a port, or a random string. AnyEvent::MP itself
93	doesn't interpret node IDs in any way.	107	doesn't interpret node IDs in any way except to uniquely identify a node.
94		108
95	=item binds - C<ip:port>	109	=item binds - C<ip:port>
96		110
97	Nodes can only talk to each other by creating some kind of connection to	111	Nodes can only talk to each other by creating some kind of connection to
98	each other. To do this, nodes should listen on one or more local transport	112	each other. To do this, nodes should listen on one or more local transport
		113	endpoints - binds.
		114
99	endpoints - binds. Currently, only standard C<ip:port> specifications can	115	Currently, only standard C<ip:port> specifications can be used, which
100	be used, which specify TCP ports to listen on.	116	specify TCP ports to listen on. So a bind is basically just a tcp socket
		117	in listening mode thta accepts conenctions form other nodes.
101		118
		119	=item seed nodes
		120
		121	When a node starts, it knows nothing about the network it is in - it
		122	needs to connect to at least one other node that is already in the
		123	network. These other nodes are called "seed nodes".
		124
		125	Seed nodes themselves are not special - they are seed nodes only because
		126	some other node I<uses> them as such, but any node can be used as seed
		127	node for other nodes, and eahc node cna use a different set of seed nodes.
		128
		129	In addition to discovering the network, seed nodes are also used to
		130	maintain the network - all nodes using the same seed node form are part of
		131	the same network. If a network is split into multiple subnets because e.g.
		132	the network link between the parts goes down, then using the same seed
		133	nodes for all nodes ensures that eventually the subnets get merged again.
		134
		135	Seed nodes are expected to be long-running, and at least one seed node
		136	should always be available. They should also be relatively responsive - a
		137	seed node that blocks for long periods will slow down everybody else.
		138
		139	For small networks, it's best if every node uses the same set of seed
		140	nodes. For large networks, it can be useful to specify "regional" seed
		141	nodes for most nodes in an area, and use all seed nodes as seed nodes for
		142	each other. What's important is that all seed nodes connections form a
		143	complete graph, so that the network cannot split into separate subnets
		144	forever.
		145
		146	Seed nodes are represented by seed IDs.
		147
102	=item seeds - C<host:port>	148	=item seed IDs - C<host:port>
103		149
104	When a node starts, it knows nothing about the network. To teach the node	150	Seed IDs are transport endpoint(s) (usually a hostname/IP address and a
105	about the network it first has to contact some other node within the	151	TCP port) of nodes that should be used as seed nodes.
106	network. This node is called a seed.
107		152
108	Seeds are transport endpoint(s) of as many nodes as one wants. Those nodes	153	=item global nodes
109	are expected to be long-running, and at least one of those should always
110	be available. When nodes run out of connections (e.g. due to a network
111	error), they try to re-establish connections to some seednodes again to
112	join the network.
113		154
114	Apart from being sued for seeding, seednodes are not special in any way -	155	An AEMP network needs a discovery service - nodes need to know how to
115	every public node can be a seednode.	156	connect to other nodes they only know by name. In addition, AEMP offers a
		157	distributed "group database", which maps group names to a list of strings
		158	- for example, to register worker ports.
		159
		160	A network needs at least one global node to work, and allows every node to
		161	be a global node.
		162
		163	Any node that loads the L<AnyEvent::MP::Global> module becomes a global
		164	node and tries to keep connections to all other nodes. So while it can
		165	make sense to make every node "global" in small networks, it usually makes
		166	sense to only make seed nodes into global nodes in large networks (nodes
		167	keep connections to seed nodes and global nodes, so makign them the same
		168	reduces overhead).
116		169
117	=back	170	=back
118		171
119	=head1 VARIABLES/FUNCTIONS	172	=head1 VARIABLES/FUNCTIONS
120		173
…		…
132		185
133	use AE ();	186	use AE ();
134		187
135	use base "Exporter";	188	use base "Exporter";
136		189
137	our $VERSION = $AnyEvent::MP::Kernel::VERSION;	190	our $VERSION = '1.30';
138		191
139	our @EXPORT = qw(	192	our @EXPORT = qw(
140	NODE $NODE *SELF node_of after	193	NODE $NODE *SELF node_of after
141	configure	194	configure
142	snd rcv mon mon_guard kil reg psub spawn	195	snd rcv mon mon_guard kil psub peval spawn cal
143	port	196	port
144	);	197	);
145		198
146	our $SELF;	199	our $SELF;
147		200
…		…
167		220
168	Before a node can talk to other nodes on the network (i.e. enter	221	Before a node can talk to other nodes on the network (i.e. enter
169	"distributed mode") it has to configure itself - the minimum a node needs	222	"distributed mode") it has to configure itself - the minimum a node needs
170	to know is its own name, and optionally it should know the addresses of	223	to know is its own name, and optionally it should know the addresses of
171	some other nodes in the network to discover other nodes.	224	some other nodes in the network to discover other nodes.
		225
		226	The key/value pairs are basically the same ones as documented for the
		227	F<aemp> command line utility (sans the set/del prefix).
172		228
173	This function configures a node - it must be called exactly once (or	229	This function configures a node - it must be called exactly once (or
174	never) before calling other AnyEvent::MP functions.	230	never) before calling other AnyEvent::MP functions.
175		231
176	=over 4	232	=over 4
…		…
210	used, meaning the node will bind on a dynamically-assigned port on every	266	used, meaning the node will bind on a dynamically-assigned port on every
211	local IP address it finds.	267	local IP address it finds.
212		268
213	=item step 3, connect to seed nodes	269	=item step 3, connect to seed nodes
214		270
215	As the last step, the seeds list from the profile is passed to the	271	As the last step, the seed ID list from the profile is passed to the
216	L<AnyEvent::MP::Global> module, which will then use it to keep	272	L<AnyEvent::MP::Global> module, which will then use it to keep
217	connectivity with at least one node at any point in time.	273	connectivity with at least one node at any point in time.
218		274
219	=back	275	=back
220		276
221	Example: become a distributed node using the locla node name as profile.	277	Example: become a distributed node using the local node name as profile.
222	This should be the most common form of invocation for "daemon"-type nodes.	278	This should be the most common form of invocation for "daemon"-type nodes.
223		279
224	configure	280	configure
225		281
226	Example: become an anonymous node. This form is often used for commandline	282	Example: become an anonymous node. This form is often used for commandline
…		…
360	msg1 => sub { ... },	416	msg1 => sub { ... },
361	...	417	...
362	;	418	;
363		419
364	Example: temporarily register a rcv callback for a tag matching some port	420	Example: temporarily register a rcv callback for a tag matching some port
365	(e.g. for a rpc reply) and unregister it after a message was received.	421	(e.g. for an rpc reply) and unregister it after a message was received.
366		422
367	rcv $port, $otherport => sub {	423	rcv $port, $otherport => sub {
368	my @reply = @_;	424	my @reply = @_;
369		425
370	rcv $SELF, $otherport;	426	rcv $SELF, $otherport;
…		…
383	if (ref $_[0]) {	439	if (ref $_[0]) {
384	if (my $self = $PORT_DATA{$portid}) {	440	if (my $self = $PORT_DATA{$portid}) {
385	"AnyEvent::MP::Port" eq ref $self	441	"AnyEvent::MP::Port" eq ref $self
386	or Carp::croak "$port: rcv can only be called on message matching ports, caught";	442	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
387		443
388	$self->[2] = shift;	444	$self->[0] = shift;
389	} else {	445	} else {
390	my $cb = shift;	446	my $cb = shift;
391	$PORT{$portid} = sub {	447	$PORT{$portid} = sub {
392	local $SELF = $port;	448	local $SELF = $port;
393	eval { &$cb }; _self_die if $@;	449	eval { &$cb }; _self_die if $@;
394	};	450	};
395	}	451	}
396	} elsif (defined $_[0]) {	452	} elsif (defined $_[0]) {
397	my $self = $PORT_DATA{$portid} \|\|= do {	453	my $self = $PORT_DATA{$portid} \|\|= do {
398	my $self = bless [$PORT{$port} \|\| sub { }, { }, $port], "AnyEvent::MP::Port";	454	my $self = bless [$PORT{$portid} \|\| sub { }, { }, $port], "AnyEvent::MP::Port";
399		455
400	$PORT{$portid} = sub {	456	$PORT{$portid} = sub {
401	local $SELF = $port;	457	local $SELF = $port;
402		458
403	if (my $cb = $self->[1]{$_[0]}) {	459	if (my $cb = $self->[1]{$_[0]}) {
…		…
425	}	481	}
426		482
427	$port	483	$port
428	}	484	}
429		485
		486	=item peval $port, $coderef[, @args]
		487
		488	Evaluates the given C<$codref> within the contetx of C<$port>, that is,
		489	when the code throews an exception the C<$port> will be killed.
		490
		491	Any remaining args will be passed to the callback. Any return values will
		492	be returned to the caller.
		493
		494	This is useful when you temporarily want to execute code in the context of
		495	a port.
		496
		497	Example: create a port and run some initialisation code in it's context.
		498
		499	my $port = port { ... };
		500
		501	peval $port, sub {
		502	init
		503	or die "unable to init";
		504	};
		505
		506	=cut
		507
		508	sub peval($$) {
		509	local $SELF = shift;
		510	my $cb = shift;
		511
		512	if (wantarray) {
		513	my @res = eval { &$cb };
		514	_self_die if $@;
		515	@res
		516	} else {
		517	my $res = eval { &$cb };
		518	_self_die if $@;
		519	$res
		520	}
		521	}
		522
430	=item $closure = psub { BLOCK }	523	=item $closure = psub { BLOCK }
431		524
432	Remembers C<$SELF> and creates a closure out of the BLOCK. When the	525	Remembers C<$SELF> and creates a closure out of the BLOCK. When the
433	closure is executed, sets up the environment in the same way as in C<rcv>	526	closure is executed, sets up the environment in the same way as in C<rcv>
434	callbacks, i.e. runtime errors will cause the port to get C<kil>ed.	527	callbacks, i.e. runtime errors will cause the port to get C<kil>ed.
		528
		529	The effect is basically as if it returned C<< sub { peval $SELF, sub {
		530	BLOCK }, @_ } >>.
435		531
436	This is useful when you register callbacks from C<rcv> callbacks:	532	This is useful when you register callbacks from C<rcv> callbacks:
437		533
438	rcv delayed_reply => sub {	534	rcv delayed_reply => sub {
439	my ($delay, @reply) = @_;	535	my ($delay, @reply) = @_;
…		…
512	delivered again.	608	delivered again.
513		609
514	Inter-host-connection timeouts and monitoring depend on the transport	610	Inter-host-connection timeouts and monitoring depend on the transport
515	used. The only transport currently implemented is TCP, and AnyEvent::MP	611	used. The only transport currently implemented is TCP, and AnyEvent::MP
516	relies on TCP to detect node-downs (this can take 10-15 minutes on a	612	relies on TCP to detect node-downs (this can take 10-15 minutes on a
517	non-idle connection, and usually around two hours for idle conenctions).	613	non-idle connection, and usually around two hours for idle connections).
518		614
519	This means that monitoring is good for program errors and cleaning up	615	This means that monitoring is good for program errors and cleaning up
520	stuff eventually, but they are no replacement for a timeout when you need	616	stuff eventually, but they are no replacement for a timeout when you need
521	to ensure some maximum latency.	617	to ensure some maximum latency.
522		618
…		…
554	}	650	}
555		651
556	$node->monitor ($port, $cb);	652	$node->monitor ($port, $cb);
557		653
558	defined wantarray	654	defined wantarray
559	and AnyEvent::Util::guard { $node->unmonitor ($port, $cb) }	655	and ($cb += 0, AnyEvent::Util::guard { $node->unmonitor ($port, $cb) })
560	}	656	}
561		657
562	=item $guard = mon_guard $port, $ref, $ref...	658	=item $guard = mon_guard $port, $ref, $ref...
563		659
564	Monitors the given C<$port> and keeps the passed references. When the port	660	Monitors the given C<$port> and keeps the passed references. When the port
…		…
587		683
588	=item kil $port[, @reason]	684	=item kil $port[, @reason]
589		685
590	Kill the specified port with the given C<@reason>.	686	Kill the specified port with the given C<@reason>.
591		687
592	If no C<@reason> is specified, then the port is killed "normally" (ports	688	If no C<@reason> is specified, then the port is killed "normally" -
593	monitoring other ports will not necessarily die because a port dies	689	monitor callback will be invoked, but the kil will not cause linked ports
594	"normally").	690	(C<mon $mport, $lport> form) to get killed.
595		691
596	Otherwise, linked ports get killed with the same reason (second form of	692	If a C<@reason> is specified, then linked ports (C<mon $mport, $lport>
597	C<mon>, see above).	693	form) get killed with the same reason.
598		694
599	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks	695	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks
600	will be reported as reason C<< die => $@ >>.	696	will be reported as reason C<< die => $@ >>.
601		697
602	Transport/communication errors are reported as C<< transport_error =>	698	Transport/communication errors are reported as C<< transport_error =>
…		…
621	the package, then the package above the package and so on (e.g.	717	the package, then the package above the package and so on (e.g.
622	C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function	718	C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function
623	exists or it runs out of package names.	719	exists or it runs out of package names.
624		720
625	The init function is then called with the newly-created port as context	721	The init function is then called with the newly-created port as context
626	object (C<$SELF>) and the C<@initdata> values as arguments.	722	object (C<$SELF>) and the C<@initdata> values as arguments. It I<must>
		723	call one of the C<rcv> functions to set callbacks on C<$SELF>, otherwise
		724	the port might not get created.
627		725
628	A common idiom is to pass a local port, immediately monitor the spawned	726	A common idiom is to pass a local port, immediately monitor the spawned
629	port, and in the remote init function, immediately monitor the passed	727	port, and in the remote init function, immediately monitor the passed
630	local port. This two-way monitoring ensures that both ports get cleaned up	728	local port. This two-way monitoring ensures that both ports get cleaned up
631	when there is a problem.	729	when there is a problem.
…		…
655		753
656	sub _spawn {	754	sub _spawn {
657	my $port = shift;	755	my $port = shift;
658	my $init = shift;	756	my $init = shift;
659		757
		758	# rcv will create the actual port
660	local $SELF = "$NODE#$port";	759	local $SELF = "$NODE#$port";
661	eval {	760	eval {
662	&{ load_func $init }	761	&{ load_func $init }
663	};	762	};
664	_self_die if $@;	763	_self_die if $@;
…		…
699	? $action[0]()	798	? $action[0]()
700	: snd @action;	799	: snd @action;
701	};	800	};
702	}	801	}
703		802
		803	=item cal $port, @msg, $callback[, $timeout]
		804
		805	A simple form of RPC - sends a message to the given C<$port> with the
		806	given contents (C<@msg>), but adds a reply port to the message.
		807
		808	The reply port is created temporarily just for the purpose of receiving
		809	the reply, and will be C<kil>ed when no longer needed.
		810
		811	A reply message sent to the port is passed to the C<$callback> as-is.
		812
		813	If an optional time-out (in seconds) is given and it is not C<undef>,
		814	then the callback will be called without any arguments after the time-out
		815	elapsed and the port is C<kil>ed.
		816
		817	If no time-out is given (or it is C<undef>), then the local port will
		818	monitor the remote port instead, so it eventually gets cleaned-up.
		819
		820	Currently this function returns the temporary port, but this "feature"
		821	might go in future versions unless you can make a convincing case that
		822	this is indeed useful for something.
		823
		824	=cut
		825
		826	sub cal(@) {
		827	my $timeout = ref $_[-1] ? undef : pop;
		828	my $cb = pop;
		829
		830	my $port = port {
		831	undef $timeout;
		832	kil $SELF;
		833	&$cb;
		834	};
		835
		836	if (defined $timeout) {
		837	$timeout = AE::timer $timeout, 0, sub {
		838	undef $timeout;
		839	kil $port;
		840	$cb->();
		841	};
		842	} else {
		843	mon $_[0], sub {
		844	kil $port;
		845	$cb->();
		846	};
		847	}
		848
		849	push @_, $port;
		850	&snd;
		851
		852	$port
		853	}
		854
704	=back	855	=back
705		856
706	=head1 AnyEvent::MP vs. Distributed Erlang	857	=head1 AnyEvent::MP vs. Distributed Erlang
707		858
708	AnyEvent::MP got lots of its ideas from distributed Erlang (Erlang node	859	AnyEvent::MP got lots of its ideas from distributed Erlang (Erlang node
709	== aemp node, Erlang process == aemp port), so many of the documents and	860	== aemp node, Erlang process == aemp port), so many of the documents and
710	programming techniques employed by Erlang apply to AnyEvent::MP. Here is a	861	programming techniques employed by Erlang apply to AnyEvent::MP. Here is a
711	sample:	862	sample:
712		863
713	http://www.Erlang.se/doc/programming_rules.shtml	864	http://www.erlang.se/doc/programming_rules.shtml
714	http://Erlang.org/doc/getting_started/part_frame.html # chapters 3 and 4	865	http://erlang.org/doc/getting_started/part_frame.html # chapters 3 and 4
715	http://Erlang.org/download/Erlang-book-part1.pdf # chapters 5 and 6	866	http://erlang.org/download/erlang-book-part1.pdf # chapters 5 and 6
716	http://Erlang.org/download/armstrong_thesis_2003.pdf # chapters 4 and 5	867	http://erlang.org/download/armstrong_thesis_2003.pdf # chapters 4 and 5
717		868
718	Despite the similarities, there are also some important differences:	869	Despite the similarities, there are also some important differences:
719		870
720	=over 4	871	=over 4
721		872
722	=item * Node IDs are arbitrary strings in AEMP.	873	=item * Node IDs are arbitrary strings in AEMP.
723		874
724	Erlang relies on special naming and DNS to work everywhere in the same	875	Erlang relies on special naming and DNS to work everywhere in the same
725	way. AEMP relies on each node somehow knowing its own address(es) (e.g. by	876	way. AEMP relies on each node somehow knowing its own address(es) (e.g. by
726	configuration or DNS), but will otherwise discover other odes itself.	877	configuration or DNS), and possibly the addresses of some seed nodes, but
		878	will otherwise discover other nodes (and their IDs) itself.
727		879
728	=item * Erlang has a "remote ports are like local ports" philosophy, AEMP	880	=item * Erlang has a "remote ports are like local ports" philosophy, AEMP
729	uses "local ports are like remote ports".	881	uses "local ports are like remote ports".
730		882
731	The failure modes for local ports are quite different (runtime errors	883	The failure modes for local ports are quite different (runtime errors
…		…
740	ports being the special case/exception, where transport errors cannot	892	ports being the special case/exception, where transport errors cannot
741	occur.	893	occur.
742		894
743	=item * Erlang uses processes and a mailbox, AEMP does not queue.	895	=item * Erlang uses processes and a mailbox, AEMP does not queue.
744		896
745	Erlang uses processes that selectively receive messages, and therefore	897	Erlang uses processes that selectively receive messages out of order, and
746	needs a queue. AEMP is event based, queuing messages would serve no	898	therefore needs a queue. AEMP is event based, queuing messages would serve
747	useful purpose. For the same reason the pattern-matching abilities of	899	no useful purpose. For the same reason the pattern-matching abilities
748	AnyEvent::MP are more limited, as there is little need to be able to	900	of AnyEvent::MP are more limited, as there is little need to be able to
749	filter messages without dequeuing them.	901	filter messages without dequeuing them.
750		902
751	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).	903	This is not a philosophical difference, but simply stems from AnyEvent::MP
		904	being event-based, while Erlang is process-based.
		905
		906	You cna have a look at L<Coro::MP> for a more Erlang-like process model on
		907	top of AEMP and Coro threads.
752		908
753	=item * Erlang sends are synchronous, AEMP sends are asynchronous.	909	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
754		910
755	Sending messages in Erlang is synchronous and blocks the process (and	911	Sending messages in Erlang is synchronous and blocks the process until
		912	a conenction has been established and the message sent (and so does not
756	so does not need a queue that can overflow). AEMP sends are immediate,	913	need a queue that can overflow). AEMP sends return immediately, connection
757	connection establishment is handled in the background.	914	establishment is handled in the background.
758		915
759	=item * Erlang suffers from silent message loss, AEMP does not.	916	=item * Erlang suffers from silent message loss, AEMP does not.
760		917
761	Erlang makes few guarantees on messages delivery - messages can get lost	918	Erlang implements few guarantees on messages delivery - messages can get
762	without any of the processes realising it (i.e. you send messages a, b,	919	lost without any of the processes realising it (i.e. you send messages a,
763	and c, and the other side only receives messages a and c).	920	b, and c, and the other side only receives messages a and c).
764		921
765	AEMP guarantees correct ordering, and the guarantee that after one message	922	AEMP guarantees (modulo hardware errors) correct ordering, and the
766	is lost, all following ones sent to the same port are lost as well, until	923	guarantee that after one message is lost, all following ones sent to the
767	monitoring raises an error, so there are no silent "holes" in the message	924	same port are lost as well, until monitoring raises an error, so there are
768	sequence.	925	no silent "holes" in the message sequence.
		926
		927	If you want your software to be very reliable, you have to cope with
		928	corrupted and even out-of-order messages in both Erlang and AEMP. AEMP
		929	simply tries to work better in common error cases, such as when a network
		930	link goes down.
769		931
770	=item * Erlang can send messages to the wrong port, AEMP does not.	932	=item * Erlang can send messages to the wrong port, AEMP does not.
771		933
772	In Erlang it is quite likely that a node that restarts reuses a process ID	934	In Erlang it is quite likely that a node that restarts reuses an Erlang
773	known to other nodes for a completely different process, causing messages	935	process ID known to other nodes for a completely different process,
774	destined for that process to end up in an unrelated process.	936	causing messages destined for that process to end up in an unrelated
		937	process.
775		938
776	AEMP never reuses port IDs, so old messages or old port IDs floating	939	AEMP does not reuse port IDs, so old messages or old port IDs floating
777	around in the network will not be sent to an unrelated port.	940	around in the network will not be sent to an unrelated port.
778		941
779	=item * Erlang uses unprotected connections, AEMP uses secure	942	=item * Erlang uses unprotected connections, AEMP uses secure
780	authentication and can use TLS.	943	authentication and can use TLS.
781		944
…		…
784		947
785	=item * The AEMP protocol is optimised for both text-based and binary	948	=item * The AEMP protocol is optimised for both text-based and binary
786	communications.	949	communications.
787		950
788	The AEMP protocol, unlike the Erlang protocol, supports both programming	951	The AEMP protocol, unlike the Erlang protocol, supports both programming
789	language independent text-only protocols (good for debugging) and binary,	952	language independent text-only protocols (good for debugging), and binary,
790	language-specific serialisers (e.g. Storable). By default, unless TLS is	953	language-specific serialisers (e.g. Storable). By default, unless TLS is
791	used, the protocol is actually completely text-based.	954	used, the protocol is actually completely text-based.
792		955
793	It has also been carefully designed to be implementable in other languages	956	It has also been carefully designed to be implementable in other languages
794	with a minimum of work while gracefully degrading functionality to make the	957	with a minimum of work while gracefully degrading functionality to make the
795	protocol simple.	958	protocol simple.
796		959
797	=item * AEMP has more flexible monitoring options than Erlang.	960	=item * AEMP has more flexible monitoring options than Erlang.
798		961
799	In Erlang, you can chose to receive I<all> exit signals as messages	962	In Erlang, you can chose to receive I<all> exit signals as messages or
800	or I<none>, there is no in-between, so monitoring single processes is	963	I<none>, there is no in-between, so monitoring single Erlang processes is
801	difficult to implement. Monitoring in AEMP is more flexible than in	964	difficult to implement.
802	Erlang, as one can choose between automatic kill, exit message or callback	965
803	on a per-process basis.	966	Monitoring in AEMP is more flexible than in Erlang, as one can choose
		967	between automatic kill, exit message or callback on a per-port basis.
804		968
805	=item * Erlang tries to hide remote/local connections, AEMP does not.	969	=item * Erlang tries to hide remote/local connections, AEMP does not.
806		970
807	Monitoring in Erlang is not an indicator of process death/crashes, in the	971	Monitoring in Erlang is not an indicator of process death/crashes, in the
808	same way as linking is (except linking is unreliable in Erlang).	972	same way as linking is (except linking is unreliable in Erlang).
…		…
830	overhead, as well as having to keep a proxy object everywhere.	994	overhead, as well as having to keep a proxy object everywhere.
831		995
832	Strings can easily be printed, easily serialised etc. and need no special	996	Strings can easily be printed, easily serialised etc. and need no special
833	procedures to be "valid".	997	procedures to be "valid".
834		998
835	And as a result, a miniport consists of a single closure stored in a	999	And as a result, a port with just a default receiver consists of a single
836	global hash - it can't become much cheaper.	1000	code reference stored in a global hash - it can't become much cheaper.
837		1001
838	=item Why favour JSON, why not a real serialising format such as Storable?	1002	=item Why favour JSON, why not a real serialising format such as Storable?
839		1003
840	In fact, any AnyEvent::MP node will happily accept Storable as framing	1004	In fact, any AnyEvent::MP node will happily accept Storable as framing
841	format, but currently there is no way to make a node use Storable by	1005	format, but currently there is no way to make a node use Storable by
…		…
857		1021
858	L<AnyEvent::MP::Intro> - a gentle introduction.	1022	L<AnyEvent::MP::Intro> - a gentle introduction.
859		1023
860	L<AnyEvent::MP::Kernel> - more, lower-level, stuff.	1024	L<AnyEvent::MP::Kernel> - more, lower-level, stuff.
861		1025
862	L<AnyEvent::MP::Global> - network maintainance and port groups, to find	1026	L<AnyEvent::MP::Global> - network maintenance and port groups, to find
863	your applications.	1027	your applications.
		1028
		1029	L<AnyEvent::MP::DataConn> - establish data connections between nodes.
		1030
		1031	L<AnyEvent::MP::LogCatcher> - simple service to display log messages from
		1032	all nodes.
864		1033
865	L<AnyEvent>.	1034	L<AnyEvent>.
866		1035
867	=head1 AUTHOR	1036	=head1 AUTHOR
868		1037

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Comparing AnyEvent-MP/MP.pm (file contents): Revision 1.80 by root, Fri Sep 4 22:30:29 2009 UTC vs. Revision 1.119 by root, Sun Feb 26 10:29:59 2012 UTC

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Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.80 by root, Fri Sep 4 22:30:29 2009 UTC vs.
Revision 1.119 by root, Sun Feb 26 10:29:59 2012 UTC