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

Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.83 by root, Tue Sep 8 01:38:16 2009 UTC vs.
Revision 1.123 by root, Thu Mar 1 19:37:59 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<#>)
76	separator, and a port name (a printable string of unspecified format).	88	as separator, and a port name (a printable string of unspecified
		89	format created by AnyEvent::MP).
77		90
78	=item node	91	=item node
79		92
80	A node is a single process containing at least one port - the node port,	93	A node is a single process containing at least one port - the node port,
81	which enables nodes to manage each other remotely, and to create new	94	which enables nodes to manage each other remotely, and to create new
82	ports.	95	ports.
83		96
84	Nodes are either public (have one or more listening ports) or private	97	Nodes are either public (have one or more listening ports) or private
85	(no listening ports). Private nodes cannot talk to other private nodes	98	(no listening ports). Private nodes cannot talk to other private nodes
86	currently.	99	currently, but all nodes can talk to public nodes.
87		100
		101	Nodes is represented by (printable) strings called "node IDs".
		102
88	=item node ID - C<[a-za-Z0-9_\-.:]+>	103	=item node ID - C<[A-Za-z0-9_\-.:]*>
89		104
90	A node ID is a string that uniquely identifies the node within a	105	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	106	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	107	hostname, a hostname and a port, or a random string. AnyEvent::MP itself
93	doesn't interpret node IDs in any way.	108	doesn't interpret node IDs in any way except to uniquely identify a node.
94		109
95	=item binds - C<ip:port>	110	=item binds - C<ip:port>
96		111
97	Nodes can only talk to each other by creating some kind of connection to	112	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	113	each other. To do this, nodes should listen on one or more local transport
		114	endpoints - binds.
		115
99	endpoints - binds. Currently, only standard C<ip:port> specifications can	116	Currently, only standard C<ip:port> specifications can be used, which
100	be used, which specify TCP ports to listen on.	117	specify TCP ports to listen on. So a bind is basically just a tcp socket
		118	in listening mode thta accepts conenctions form other nodes.
101		119
102	=item seed nodes	120	=item seed nodes
103		121
104	When a node starts, it knows nothing about the network. To teach the node	122	When a node starts, it knows nothing about the network it is in - it
105	about the network it first has to contact some other node within the	123	needs to connect to at least one other node that is already in the
106	network. This node is called a seed.	124	network. These other nodes are called "seed nodes".
107		125
108	Apart from the fact that other nodes know them as seed nodes and they have	126	Seed nodes themselves are not special - they are seed nodes only because
109	to have fixed listening addresses, seed nodes are perfectly normal nodes -	127	some other node I<uses> them as such, but any node can be used as seed
110	any node can function as a seed node for others.	128	node for other nodes, and eahc node cna use a different set of seed nodes.
111		129
112	In addition to discovering the network, seed nodes are also used to	130	In addition to discovering the network, seed nodes are also used to
113	maintain the network and to connect nodes that otherwise would have	131	maintain the network - all nodes using the same seed node form are part of
114	trouble connecting. They form the backbone of the AnyEvent::MP network.	132	the same network. If a network is split into multiple subnets because e.g.
		133	the network link between the parts goes down, then using the same seed
		134	nodes for all nodes ensures that eventually the subnets get merged again.
115		135
116	Seed nodes are expected to be long-running, and at least one seed node	136	Seed nodes are expected to be long-running, and at least one seed node
117	should always be available.	137	should always be available. They should also be relatively responsive - a
		138	seed node that blocks for long periods will slow down everybody else.
118		139
		140	For small networks, it's best if every node uses the same set of seed
		141	nodes. For large networks, it can be useful to specify "regional" seed
		142	nodes for most nodes in an area, and use all seed nodes as seed nodes for
		143	each other. What's important is that all seed nodes connections form a
		144	complete graph, so that the network cannot split into separate subnets
		145	forever.
		146
		147	Seed nodes are represented by seed IDs.
		148
119	=item seeds - C<host:port>	149	=item seed IDs - C<host:port>
120		150
121	Seeds are transport endpoint(s) (usually a hostname/IP address and a	151	Seed IDs are transport endpoint(s) (usually a hostname/IP address and a
122	TCP port) of nodes thta should be used as seed nodes.	152	TCP port) of nodes that should be used as seed nodes.
123		153
124	The nodes listening on those endpoints are expected to be long-running,	154	=item global nodes
125	and at least one of those should always be available. When nodes run out	155
126	of connections (e.g. due to a network error), they try to re-establish	156	An AEMP network needs a discovery service - nodes need to know how to
127	connections to some seednodes again to join the network.	157	connect to other nodes they only know by name. In addition, AEMP offers a
		158	distributed "group database", which maps group names to a list of strings
		159	- for example, to register worker ports.
		160
		161	A network needs at least one global node to work, and allows every node to
		162	be a global node.
		163
		164	Any node that loads the L<AnyEvent::MP::Global> module becomes a global
		165	node and tries to keep connections to all other nodes. So while it can
		166	make sense to make every node "global" in small networks, it usually makes
		167	sense to only make seed nodes into global nodes in large networks (nodes
		168	keep connections to seed nodes and global nodes, so makign them the same
		169	reduces overhead).
128		170
129	=back	171	=back
130		172
131	=head1 VARIABLES/FUNCTIONS	173	=head1 VARIABLES/FUNCTIONS
132		174
…		…
134		176
135	=cut	177	=cut
136		178
137	package AnyEvent::MP;	179	package AnyEvent::MP;
138		180
		181	use AnyEvent::MP::Config ();
139	use AnyEvent::MP::Kernel;	182	use AnyEvent::MP::Kernel;
		183	use AnyEvent::MP::Kernel qw(%NODE %PORT %PORT_DATA $UNIQ $RUNIQ $ID);
140		184
141	use common::sense;	185	use common::sense;
142		186
143	use Carp ();	187	use Carp ();
144		188
145	use AE ();	189	use AE ();
146		190
147	use base "Exporter";	191	use base "Exporter";
148		192
149	our $VERSION = $AnyEvent::MP::Kernel::VERSION;	193	our $VERSION = $AnyEvent::MP::Config::VERSION;
150		194
151	our @EXPORT = qw(	195	our @EXPORT = qw(
152	NODE $NODE *SELF node_of after	196	NODE $NODE *SELF node_of after
153	configure	197	configure
154	snd rcv mon mon_guard kil reg psub spawn	198	snd rcv mon mon_guard kil psub peval spawn cal
155	port	199	port
156	);	200	);
157		201
158	our $SELF;	202	our $SELF;
159		203
…		…
182	to know is its own name, and optionally it should know the addresses of	226	to know is its own name, and optionally it should know the addresses of
183	some other nodes in the network to discover other nodes.	227	some other nodes in the network to discover other nodes.
184		228
185	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
186	never) before calling other AnyEvent::MP functions.	230	never) before calling other AnyEvent::MP functions.
		231
		232	The key/value pairs are basically the same ones as documented for the
		233	F<aemp> command line utility (sans the set/del prefix), with two additions:
		234
		235	=over 4
		236
		237	=item norc => $boolean (default false)
		238
		239	If true, then the rc file (e.g. F<~/.perl-anyevent-mp>) will I<not>
		240	be consulted - all configuraiton options must be specified in the
		241	C<configure> call.
		242
		243	=item force => $boolean (default false)
		244
		245	IF true, then the values specified in the C<configure> will take
		246	precedence over any values configured via the rc file. The default is for
		247	the rc file to override any options specified in the program.
		248
		249	=back
187		250
188	=over 4	251	=over 4
189		252
190	=item step 1, gathering configuration from profiles	253	=item step 1, gathering configuration from profiles
191		254
…		…
205	That means that the values specified in the profile have highest priority	268	That means that the values specified in the profile have highest priority
206	and the values specified directly via C<configure> have lowest priority,	269	and the values specified directly via C<configure> have lowest priority,
207	and can only be used to specify defaults.	270	and can only be used to specify defaults.
208		271
209	If the profile specifies a node ID, then this will become the node ID of	272	If the profile specifies a node ID, then this will become the node ID of
210	this process. If not, then the profile name will be used as node ID. The	273	this process. If not, then the profile name will be used as node ID, with
211	special node ID of C<anon/> will be replaced by a random node ID.	274	a slash (C</>) attached.
		275
		276	If the node ID (or profile name) ends with a slash (C</>), then a random
		277	string is appended to make it unique.
212		278
213	=item step 2, bind listener sockets	279	=item step 2, bind listener sockets
214		280
215	The next step is to look up the binds in the profile, followed by binding	281	The next step is to look up the binds in the profile, followed by binding
216	aemp protocol listeners on all binds specified (it is possible and valid	282	aemp protocol listeners on all binds specified (it is possible and valid
…		…
222	used, meaning the node will bind on a dynamically-assigned port on every	288	used, meaning the node will bind on a dynamically-assigned port on every
223	local IP address it finds.	289	local IP address it finds.
224		290
225	=item step 3, connect to seed nodes	291	=item step 3, connect to seed nodes
226		292
227	As the last step, the seeds list from the profile is passed to the	293	As the last step, the seed ID list from the profile is passed to the
228	L<AnyEvent::MP::Global> module, which will then use it to keep	294	L<AnyEvent::MP::Global> module, which will then use it to keep
229	connectivity with at least one node at any point in time.	295	connectivity with at least one node at any point in time.
230		296
231	=back	297	=back
232		298
233	Example: become a distributed node using the locla node name as profile.	299	Example: become a distributed node using the local node name as profile.
234	This should be the most common form of invocation for "daemon"-type nodes.	300	This should be the most common form of invocation for "daemon"-type nodes.
235		301
236	configure	302	configure
237		303
238	Example: become an anonymous node. This form is often used for commandline	304	Example: become an anonymous node. This form is often used for commandline
239	clients.	305	clients.
240		306
241	configure nodeid => "anon/";	307	configure nodeid => "anon/";
242		308
243	Example: configure a node using a profile called seed, which si suitable	309	Example: configure a node using a profile called seed, which is suitable
244	for a seed node as it binds on all local addresses on a fixed port (4040,	310	for a seed node as it binds on all local addresses on a fixed port (4040,
245	customary for aemp).	311	customary for aemp).
246		312
247	# use the aemp commandline utility	313	# use the aemp commandline utility
248	# aemp profile seed nodeid anon/ binds '*:4040'	314	# aemp profile seed binds '*:4040'
249		315
250	# then use it	316	# then use it
251	configure profile => "seed";	317	configure profile => "seed";
252		318
253	# or simply use aemp from the shell again:	319	# or simply use aemp from the shell again:
…		…
323	sub _kilme {	389	sub _kilme {
324	die "received message on port without callback";	390	die "received message on port without callback";
325	}	391	}
326		392
327	sub port(;&) {	393	sub port(;&) {
328	my $id = "$UNIQ." . $ID++;	394	my $id = $UNIQ . ++$ID;
329	my $port = "$NODE#$id";	395	my $port = "$NODE#$id";
330		396
331	rcv $port, shift \|\| \&_kilme;	397	rcv $port, shift \|\| \&_kilme;
332		398
333	$port	399	$port
…		…
372	msg1 => sub { ... },	438	msg1 => sub { ... },
373	...	439	...
374	;	440	;
375		441
376	Example: temporarily register a rcv callback for a tag matching some port	442	Example: temporarily register a rcv callback for a tag matching some port
377	(e.g. for a rpc reply) and unregister it after a message was received.	443	(e.g. for an rpc reply) and unregister it after a message was received.
378		444
379	rcv $port, $otherport => sub {	445	rcv $port, $otherport => sub {
380	my @reply = @_;	446	my @reply = @_;
381		447
382	rcv $SELF, $otherport;	448	rcv $SELF, $otherport;
…		…
395	if (ref $_[0]) {	461	if (ref $_[0]) {
396	if (my $self = $PORT_DATA{$portid}) {	462	if (my $self = $PORT_DATA{$portid}) {
397	"AnyEvent::MP::Port" eq ref $self	463	"AnyEvent::MP::Port" eq ref $self
398	or Carp::croak "$port: rcv can only be called on message matching ports, caught";	464	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
399		465
400	$self->[2] = shift;	466	$self->[0] = shift;
401	} else {	467	} else {
402	my $cb = shift;	468	my $cb = shift;
403	$PORT{$portid} = sub {	469	$PORT{$portid} = sub {
404	local $SELF = $port;	470	local $SELF = $port;
405	eval { &$cb }; _self_die if $@;	471	eval { &$cb }; _self_die if $@;
406	};	472	};
407	}	473	}
408	} elsif (defined $_[0]) {	474	} elsif (defined $_[0]) {
409	my $self = $PORT_DATA{$portid} \|\|= do {	475	my $self = $PORT_DATA{$portid} \|\|= do {
410	my $self = bless [$PORT{$port} \|\| sub { }, { }, $port], "AnyEvent::MP::Port";	476	my $self = bless [$PORT{$portid} \|\| sub { }, { }, $port], "AnyEvent::MP::Port";
411		477
412	$PORT{$portid} = sub {	478	$PORT{$portid} = sub {
413	local $SELF = $port;	479	local $SELF = $port;
414		480
415	if (my $cb = $self->[1]{$_[0]}) {	481	if (my $cb = $self->[1]{$_[0]}) {
…		…
437	}	503	}
438		504
439	$port	505	$port
440	}	506	}
441		507
		508	=item peval $port, $coderef[, @args]
		509
		510	Evaluates the given C<$codref> within the contetx of C<$port>, that is,
		511	when the code throews an exception the C<$port> will be killed.
		512
		513	Any remaining args will be passed to the callback. Any return values will
		514	be returned to the caller.
		515
		516	This is useful when you temporarily want to execute code in the context of
		517	a port.
		518
		519	Example: create a port and run some initialisation code in it's context.
		520
		521	my $port = port { ... };
		522
		523	peval $port, sub {
		524	init
		525	or die "unable to init";
		526	};
		527
		528	=cut
		529
		530	sub peval($$) {
		531	local $SELF = shift;
		532	my $cb = shift;
		533
		534	if (wantarray) {
		535	my @res = eval { &$cb };
		536	_self_die if $@;
		537	@res
		538	} else {
		539	my $res = eval { &$cb };
		540	_self_die if $@;
		541	$res
		542	}
		543	}
		544
442	=item $closure = psub { BLOCK }	545	=item $closure = psub { BLOCK }
443		546
444	Remembers C<$SELF> and creates a closure out of the BLOCK. When the	547	Remembers C<$SELF> and creates a closure out of the BLOCK. When the
445	closure is executed, sets up the environment in the same way as in C<rcv>	548	closure is executed, sets up the environment in the same way as in C<rcv>
446	callbacks, i.e. runtime errors will cause the port to get C<kil>ed.	549	callbacks, i.e. runtime errors will cause the port to get C<kil>ed.
		550
		551	The effect is basically as if it returned C<< sub { peval $SELF, sub {
		552	BLOCK }, @_ } >>.
447		553
448	This is useful when you register callbacks from C<rcv> callbacks:	554	This is useful when you register callbacks from C<rcv> callbacks:
449		555
450	rcv delayed_reply => sub {	556	rcv delayed_reply => sub {
451	my ($delay, @reply) = @_;	557	my ($delay, @reply) = @_;
…		…
524	delivered again.	630	delivered again.
525		631
526	Inter-host-connection timeouts and monitoring depend on the transport	632	Inter-host-connection timeouts and monitoring depend on the transport
527	used. The only transport currently implemented is TCP, and AnyEvent::MP	633	used. The only transport currently implemented is TCP, and AnyEvent::MP
528	relies on TCP to detect node-downs (this can take 10-15 minutes on a	634	relies on TCP to detect node-downs (this can take 10-15 minutes on a
529	non-idle connection, and usually around two hours for idle conenctions).	635	non-idle connection, and usually around two hours for idle connections).
530		636
531	This means that monitoring is good for program errors and cleaning up	637	This means that monitoring is good for program errors and cleaning up
532	stuff eventually, but they are no replacement for a timeout when you need	638	stuff eventually, but they are no replacement for a timeout when you need
533	to ensure some maximum latency.	639	to ensure some maximum latency.
534		640
…		…
566	}	672	}
567		673
568	$node->monitor ($port, $cb);	674	$node->monitor ($port, $cb);
569		675
570	defined wantarray	676	defined wantarray
571	and AnyEvent::Util::guard { $node->unmonitor ($port, $cb) }	677	and ($cb += 0, AnyEvent::Util::guard { $node->unmonitor ($port, $cb) })
572	}	678	}
573		679
574	=item $guard = mon_guard $port, $ref, $ref...	680	=item $guard = mon_guard $port, $ref, $ref...
575		681
576	Monitors the given C<$port> and keeps the passed references. When the port	682	Monitors the given C<$port> and keeps the passed references. When the port
…		…
599		705
600	=item kil $port[, @reason]	706	=item kil $port[, @reason]
601		707
602	Kill the specified port with the given C<@reason>.	708	Kill the specified port with the given C<@reason>.
603		709
604	If no C<@reason> is specified, then the port is killed "normally" (ports	710	If no C<@reason> is specified, then the port is killed "normally" -
605	monitoring other ports will not necessarily die because a port dies	711	monitor callback will be invoked, but the kil will not cause linked ports
606	"normally").	712	(C<mon $mport, $lport> form) to get killed.
607		713
608	Otherwise, linked ports get killed with the same reason (second form of	714	If a C<@reason> is specified, then linked ports (C<mon $mport, $lport>
609	C<mon>, see above).	715	form) get killed with the same reason.
610		716
611	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks	717	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks
612	will be reported as reason C<< die => $@ >>.	718	will be reported as reason C<< die => $@ >>.
613		719
614	Transport/communication errors are reported as C<< transport_error =>	720	Transport/communication errors are reported as C<< transport_error =>
…		…
680	}	786	}
681		787
682	sub spawn(@) {	788	sub spawn(@) {
683	my ($nodeid, undef) = split /#/, shift, 2;	789	my ($nodeid, undef) = split /#/, shift, 2;
684		790
685	my $id = "$RUNIQ." . $ID++;	791	my $id = $RUNIQ . ++$ID;
686		792
687	$_[0] =~ /::/	793	$_[0] =~ /::/
688	or Carp::croak "spawn init function must be a fully-qualified name, caught";	794	or Carp::croak "spawn init function must be a fully-qualified name, caught";
689		795
690	snd_to_func $nodeid, "AnyEvent::MP::_spawn" => $id, @_;	796	snd_to_func $nodeid, "AnyEvent::MP::_spawn" => $id, @_;
691		797
692	"$nodeid#$id"	798	"$nodeid#$id"
693	}	799	}
		800
694		801
695	=item after $timeout, @msg	802	=item after $timeout, @msg
696		803
697	=item after $timeout, $callback	804	=item after $timeout, $callback
698		805
…		…
714	? $action[0]()	821	? $action[0]()
715	: snd @action;	822	: snd @action;
716	};	823	};
717	}	824	}
718		825
		826	=item cal $port, @msg, $callback[, $timeout]
		827
		828	A simple form of RPC - sends a message to the given C<$port> with the
		829	given contents (C<@msg>), but adds a reply port to the message.
		830
		831	The reply port is created temporarily just for the purpose of receiving
		832	the reply, and will be C<kil>ed when no longer needed.
		833
		834	A reply message sent to the port is passed to the C<$callback> as-is.
		835
		836	If an optional time-out (in seconds) is given and it is not C<undef>,
		837	then the callback will be called without any arguments after the time-out
		838	elapsed and the port is C<kil>ed.
		839
		840	If no time-out is given (or it is C<undef>), then the local port will
		841	monitor the remote port instead, so it eventually gets cleaned-up.
		842
		843	Currently this function returns the temporary port, but this "feature"
		844	might go in future versions unless you can make a convincing case that
		845	this is indeed useful for something.
		846
		847	=cut
		848
		849	sub cal(@) {
		850	my $timeout = ref $_[-1] ? undef : pop;
		851	my $cb = pop;
		852
		853	my $port = port {
		854	undef $timeout;
		855	kil $SELF;
		856	&$cb;
		857	};
		858
		859	if (defined $timeout) {
		860	$timeout = AE::timer $timeout, 0, sub {
		861	undef $timeout;
		862	kil $port;
		863	$cb->();
		864	};
		865	} else {
		866	mon $_[0], sub {
		867	kil $port;
		868	$cb->();
		869	};
		870	}
		871
		872	push @_, $port;
		873	&snd;
		874
		875	$port
		876	}
		877
719	=back	878	=back
720		879
721	=head1 AnyEvent::MP vs. Distributed Erlang	880	=head1 AnyEvent::MP vs. Distributed Erlang
722		881
723	AnyEvent::MP got lots of its ideas from distributed Erlang (Erlang node	882	AnyEvent::MP got lots of its ideas from distributed Erlang (Erlang node
724	== aemp node, Erlang process == aemp port), so many of the documents and	883	== aemp node, Erlang process == aemp port), so many of the documents and
725	programming techniques employed by Erlang apply to AnyEvent::MP. Here is a	884	programming techniques employed by Erlang apply to AnyEvent::MP. Here is a
726	sample:	885	sample:
727		886
728	http://www.Erlang.se/doc/programming_rules.shtml	887	http://www.erlang.se/doc/programming_rules.shtml
729	http://Erlang.org/doc/getting_started/part_frame.html # chapters 3 and 4	888	http://erlang.org/doc/getting_started/part_frame.html # chapters 3 and 4
730	http://Erlang.org/download/Erlang-book-part1.pdf # chapters 5 and 6	889	http://erlang.org/download/erlang-book-part1.pdf # chapters 5 and 6
731	http://Erlang.org/download/armstrong_thesis_2003.pdf # chapters 4 and 5	890	http://erlang.org/download/armstrong_thesis_2003.pdf # chapters 4 and 5
732		891
733	Despite the similarities, there are also some important differences:	892	Despite the similarities, there are also some important differences:
734		893
735	=over 4	894	=over 4
736		895
737	=item * Node IDs are arbitrary strings in AEMP.	896	=item * Node IDs are arbitrary strings in AEMP.
738		897
739	Erlang relies on special naming and DNS to work everywhere in the same	898	Erlang relies on special naming and DNS to work everywhere in the same
740	way. AEMP relies on each node somehow knowing its own address(es) (e.g. by	899	way. AEMP relies on each node somehow knowing its own address(es) (e.g. by
741	configuration or DNS), but will otherwise discover other odes itself.	900	configuration or DNS), and possibly the addresses of some seed nodes, but
		901	will otherwise discover other nodes (and their IDs) itself.
742		902
743	=item * Erlang has a "remote ports are like local ports" philosophy, AEMP	903	=item * Erlang has a "remote ports are like local ports" philosophy, AEMP
744	uses "local ports are like remote ports".	904	uses "local ports are like remote ports".
745		905
746	The failure modes for local ports are quite different (runtime errors	906	The failure modes for local ports are quite different (runtime errors
…		…
755	ports being the special case/exception, where transport errors cannot	915	ports being the special case/exception, where transport errors cannot
756	occur.	916	occur.
757		917
758	=item * Erlang uses processes and a mailbox, AEMP does not queue.	918	=item * Erlang uses processes and a mailbox, AEMP does not queue.
759		919
760	Erlang uses processes that selectively receive messages, and therefore	920	Erlang uses processes that selectively receive messages out of order, and
761	needs a queue. AEMP is event based, queuing messages would serve no	921	therefore needs a queue. AEMP is event based, queuing messages would serve
762	useful purpose. For the same reason the pattern-matching abilities of	922	no useful purpose. For the same reason the pattern-matching abilities
763	AnyEvent::MP are more limited, as there is little need to be able to	923	of AnyEvent::MP are more limited, as there is little need to be able to
764	filter messages without dequeuing them.	924	filter messages without dequeuing them.
765		925
766	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).	926	This is not a philosophical difference, but simply stems from AnyEvent::MP
		927	being event-based, while Erlang is process-based.
		928
		929	You cna have a look at L<Coro::MP> for a more Erlang-like process model on
		930	top of AEMP and Coro threads.
767		931
768	=item * Erlang sends are synchronous, AEMP sends are asynchronous.	932	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
769		933
770	Sending messages in Erlang is synchronous and blocks the process (and	934	Sending messages in Erlang is synchronous and blocks the process until
		935	a conenction has been established and the message sent (and so does not
771	so does not need a queue that can overflow). AEMP sends are immediate,	936	need a queue that can overflow). AEMP sends return immediately, connection
772	connection establishment is handled in the background.	937	establishment is handled in the background.
773		938
774	=item * Erlang suffers from silent message loss, AEMP does not.	939	=item * Erlang suffers from silent message loss, AEMP does not.
775		940
776	Erlang makes few guarantees on messages delivery - messages can get lost	941	Erlang implements few guarantees on messages delivery - messages can get
777	without any of the processes realising it (i.e. you send messages a, b,	942	lost without any of the processes realising it (i.e. you send messages a,
778	and c, and the other side only receives messages a and c).	943	b, and c, and the other side only receives messages a and c).
779		944
780	AEMP guarantees correct ordering, and the guarantee that after one message	945	AEMP guarantees (modulo hardware errors) correct ordering, and the
781	is lost, all following ones sent to the same port are lost as well, until	946	guarantee that after one message is lost, all following ones sent to the
782	monitoring raises an error, so there are no silent "holes" in the message	947	same port are lost as well, until monitoring raises an error, so there are
783	sequence.	948	no silent "holes" in the message sequence.
		949
		950	If you want your software to be very reliable, you have to cope with
		951	corrupted and even out-of-order messages in both Erlang and AEMP. AEMP
		952	simply tries to work better in common error cases, such as when a network
		953	link goes down.
784		954
785	=item * Erlang can send messages to the wrong port, AEMP does not.	955	=item * Erlang can send messages to the wrong port, AEMP does not.
786		956
787	In Erlang it is quite likely that a node that restarts reuses a process ID	957	In Erlang it is quite likely that a node that restarts reuses an Erlang
788	known to other nodes for a completely different process, causing messages	958	process ID known to other nodes for a completely different process,
789	destined for that process to end up in an unrelated process.	959	causing messages destined for that process to end up in an unrelated
		960	process.
790		961
791	AEMP never reuses port IDs, so old messages or old port IDs floating	962	AEMP does not reuse port IDs, so old messages or old port IDs floating
792	around in the network will not be sent to an unrelated port.	963	around in the network will not be sent to an unrelated port.
793		964
794	=item * Erlang uses unprotected connections, AEMP uses secure	965	=item * Erlang uses unprotected connections, AEMP uses secure
795	authentication and can use TLS.	966	authentication and can use TLS.
796		967
…		…
799		970
800	=item * The AEMP protocol is optimised for both text-based and binary	971	=item * The AEMP protocol is optimised for both text-based and binary
801	communications.	972	communications.
802		973
803	The AEMP protocol, unlike the Erlang protocol, supports both programming	974	The AEMP protocol, unlike the Erlang protocol, supports both programming
804	language independent text-only protocols (good for debugging) and binary,	975	language independent text-only protocols (good for debugging), and binary,
805	language-specific serialisers (e.g. Storable). By default, unless TLS is	976	language-specific serialisers (e.g. Storable). By default, unless TLS is
806	used, the protocol is actually completely text-based.	977	used, the protocol is actually completely text-based.
807		978
808	It has also been carefully designed to be implementable in other languages	979	It has also been carefully designed to be implementable in other languages
809	with a minimum of work while gracefully degrading functionality to make the	980	with a minimum of work while gracefully degrading functionality to make the
810	protocol simple.	981	protocol simple.
811		982
812	=item * AEMP has more flexible monitoring options than Erlang.	983	=item * AEMP has more flexible monitoring options than Erlang.
813		984
814	In Erlang, you can chose to receive I<all> exit signals as messages	985	In Erlang, you can chose to receive I<all> exit signals as messages or
815	or I<none>, there is no in-between, so monitoring single processes is	986	I<none>, there is no in-between, so monitoring single Erlang processes is
816	difficult to implement. Monitoring in AEMP is more flexible than in	987	difficult to implement.
817	Erlang, as one can choose between automatic kill, exit message or callback	988
818	on a per-process basis.	989	Monitoring in AEMP is more flexible than in Erlang, as one can choose
		990	between automatic kill, exit message or callback on a per-port basis.
819		991
820	=item * Erlang tries to hide remote/local connections, AEMP does not.	992	=item * Erlang tries to hide remote/local connections, AEMP does not.
821		993
822	Monitoring in Erlang is not an indicator of process death/crashes, in the	994	Monitoring in Erlang is not an indicator of process death/crashes, in the
823	same way as linking is (except linking is unreliable in Erlang).	995	same way as linking is (except linking is unreliable in Erlang).
…		…
845	overhead, as well as having to keep a proxy object everywhere.	1017	overhead, as well as having to keep a proxy object everywhere.
846		1018
847	Strings can easily be printed, easily serialised etc. and need no special	1019	Strings can easily be printed, easily serialised etc. and need no special
848	procedures to be "valid".	1020	procedures to be "valid".
849		1021
850	And as a result, a miniport consists of a single closure stored in a	1022	And as a result, a port with just a default receiver consists of a single
851	global hash - it can't become much cheaper.	1023	code reference stored in a global hash - it can't become much cheaper.
852		1024
853	=item Why favour JSON, why not a real serialising format such as Storable?	1025	=item Why favour JSON, why not a real serialising format such as Storable?
854		1026
855	In fact, any AnyEvent::MP node will happily accept Storable as framing	1027	In fact, any AnyEvent::MP node will happily accept Storable as framing
856	format, but currently there is no way to make a node use Storable by	1028	format, but currently there is no way to make a node use Storable by
…		…
872		1044
873	L<AnyEvent::MP::Intro> - a gentle introduction.	1045	L<AnyEvent::MP::Intro> - a gentle introduction.
874		1046
875	L<AnyEvent::MP::Kernel> - more, lower-level, stuff.	1047	L<AnyEvent::MP::Kernel> - more, lower-level, stuff.
876		1048
877	L<AnyEvent::MP::Global> - network maintainance and port groups, to find	1049	L<AnyEvent::MP::Global> - network maintenance and port groups, to find
878	your applications.	1050	your applications.
		1051
		1052	L<AnyEvent::MP::DataConn> - establish data connections between nodes.
879		1053
880	L<AnyEvent::MP::LogCatcher> - simple service to display log messages from	1054	L<AnyEvent::MP::LogCatcher> - simple service to display log messages from
881	all nodes.	1055	all nodes.
882		1056
883	L<AnyEvent>.	1057	L<AnyEvent>.

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Comparing AnyEvent-MP/MP.pm (file contents): Revision 1.83 by root, Tue Sep 8 01:38:16 2009 UTC vs. Revision 1.123 by root, Thu Mar 1 19:37:59 2012 UTC

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Revision 1.83 by root, Tue Sep 8 01:38:16 2009 UTC vs.
Revision 1.123 by root, Thu Mar 1 19:37:59 2012 UTC