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

Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.43 by root, Sun Aug 9 16:08:16 2009 UTC vs.
Revision 1.55 by root, Fri Aug 14 23:17:17 2009 UTC

…		…
9	$NODE # contains this node's noderef	9	$NODE # contains this node's noderef
10	NODE # returns this node's noderef	10	NODE # returns this node's noderef
11	NODE $port # returns the noderef of the port	11	NODE $port # returns the noderef of the port
12		12
13	$SELF # receiving/own port id in rcv callbacks	13	$SELF # receiving/own port id in rcv callbacks
		14
		15	# initialise the node so it can send/receive messages
		16	initialise_node; # -OR-
		17	initialise_node "localhost:4040"; # -OR-
		18	initialise_node "slave/", "localhost:4040"
14		19
15	# ports are message endpoints	20	# ports are message endpoints
16		21
17	# sending messages	22	# sending messages
18	snd $port, type => data...;	23	snd $port, type => data...;
19	snd $port, @msg;	24	snd $port, @msg;
20	snd @msg_with_first_element_being_a_port;	25	snd @msg_with_first_element_being_a_port;
21		26
22	# miniports	27	# creating/using ports, the simple way
23	my $miniport = port { my @msg = @_; 0 };	28	my $simple_port = port { my @msg = @_; 0 };
24		29
25	# full ports	30	# creating/using ports, tagged message matching
26	my $port = port;	31	my $port = port;
27	rcv $port, smartmatch => $cb->(@msg);
28	rcv $port, ping => sub { snd $_[0], "pong"; 0 };	32	rcv $port, ping => sub { snd $_[0], "pong"; 0 };
29	rcv $port, pong => sub { warn "pong received\n"; 0 };	33	rcv $port, pong => sub { warn "pong received\n"; 0 };
30		34
31	# remote ports	35	# create a port on another node
32	my $port = spawn $node, $initfunc, @initdata;	36	my $port = spawn $node, $initfunc, @initdata;
33
34	# more, smarter, matches (_any_ is exported by this module)
35	rcv $port, [child_died => $pid] => sub { ...
36	rcv $port, [_any_, _any_, 3] => sub { .. $_[2] is 3
37		37
38	# monitoring	38	# monitoring
39	mon $port, $cb->(@msg) # callback is invoked on death	39	mon $port, $cb->(@msg) # callback is invoked on death
40	mon $port, $otherport # kill otherport on abnormal death	40	mon $port, $otherport # kill otherport on abnormal death
41	mon $port, $otherport, @msg # send message on death	41	mon $port, $otherport, @msg # send message on death
42		42
		43	=head1 CURRENT STATUS
		44
		45	AnyEvent::MP - stable API, should work
		46	AnyEvent::MP::Intro - outdated
		47	AnyEvent::MP::Kernel - WIP
		48	AnyEvent::MP::Transport - mostly stable
		49
		50	stay tuned.
		51
43	=head1 DESCRIPTION	52	=head1 DESCRIPTION
44		53
45	This module (-family) implements a simple message passing framework.	54	This module (-family) implements a simple message passing framework.
46		55
47	Despite its simplicity, you can securely message other processes running	56	Despite its simplicity, you can securely message other processes running
…		…
50	For an introduction to this module family, see the L<AnyEvent::MP::Intro>	59	For an introduction to this module family, see the L<AnyEvent::MP::Intro>
51	manual page.	60	manual page.
52		61
53	At the moment, this module family is severly broken and underdocumented,	62	At the moment, this module family is severly broken and underdocumented,
54	so do not use. This was uploaded mainly to reserve the CPAN namespace -	63	so do not use. This was uploaded mainly to reserve the CPAN namespace -
55	stay tuned! The basic API should be finished, however.	64	stay tuned!
56		65
57	=head1 CONCEPTS	66	=head1 CONCEPTS
58		67
59	=over 4	68	=over 4
60		69
61	=item port	70	=item port
62		71
63	A port is something you can send messages to (with the C<snd> function).	72	A port is something you can send messages to (with the C<snd> function).
64		73
65	Some ports allow you to register C<rcv> handlers that can match specific	74	Ports allow you to register C<rcv> handlers that can match all or just
66	messages. All C<rcv> handlers will receive messages they match, messages	75	some messages. Messages will not be queued.
67	will not be queued.
68		76
69	=item port id - C<noderef#portname>	77	=item port id - C<noderef#portname>
70		78
71	A port id is normaly the concatenation of a noderef, a hash-mark (C<#>) as	79	A port ID is the concatenation of a noderef, a hash-mark (C<#>) as
72	separator, and a port name (a printable string of unspecified format). An	80	separator, and a port name (a printable string of unspecified format). An
73	exception is the the node port, whose ID is identical to its node	81	exception is the the node port, whose ID is identical to its node
74	reference.	82	reference.
75		83
76	=item node	84	=item node
77		85
78	A node is a single process containing at least one port - the node	86	A node is a single process containing at least one port - the node port,
79	port. You can send messages to node ports to find existing ports or to	87	which provides nodes to manage each other remotely, and to create new
80	create new ports, among other things.	88	ports.
81		89
82	Nodes are either private (single-process only), slaves (connected to a	90	Nodes are either private (single-process only), slaves (connected to a
83	master node only) or public nodes (connectable from unrelated nodes).	91	master node only) or public nodes (connectable from unrelated nodes).
84		92
85	=item noderef - C<host:port,host:port...>, C<id@noderef>, C<id>	93	=item noderef - C<host:port,host:port...>, C<id@noderef>, C<id>
…		…
105		113
106	=cut	114	=cut
107		115
108	package AnyEvent::MP;	116	package AnyEvent::MP;
109		117
110	use AnyEvent::MP::Base;	118	use AnyEvent::MP::Kernel;
111		119
112	use common::sense;	120	use common::sense;
113		121
114	use Carp ();	122	use Carp ();
115		123
116	use AE ();	124	use AE ();
117		125
118	use base "Exporter";	126	use base "Exporter";
119		127
120	our $VERSION = $AnyEvent::MP::Base::VERSION;	128	our $VERSION = $AnyEvent::MP::Kernel::VERSION;
121		129
122	our @EXPORT = qw(	130	our @EXPORT = qw(
123	NODE $NODE *SELF node_of _any_	131	NODE $NODE *SELF node_of _any_
124	resolve_node initialise_node	132	resolve_node initialise_node
125	snd rcv mon kil reg psub spawn	133	snd rcv mon kil reg psub spawn
…		…
134	kil $SELF, die => $msg;	142	kil $SELF, die => $msg;
135	}	143	}
136		144
137	=item $thisnode = NODE / $NODE	145	=item $thisnode = NODE / $NODE
138		146
139	The C<NODE> function returns, and the C<$NODE> variable contains	147	The C<NODE> function returns, and the C<$NODE> variable contains the
140	the noderef of the local node. The value is initialised by a call	148	noderef of the local node. The value is initialised by a call to
141	to C<become_public> or C<become_slave>, after which all local port	149	C<initialise_node>.
142	identifiers become invalid.
143		150
144	=item $noderef = node_of $port	151	=item $noderef = node_of $port
145		152
146	Extracts and returns the noderef from a portid or a noderef.	153	Extracts and returns the noderef from a port ID or a noderef.
147		154
148	=item initialise_node $noderef, $seednode, $seednode...	155	=item initialise_node $noderef, $seednode, $seednode...
149		156
150	=item initialise_node "slave/", $master, $master...	157	=item initialise_node "slave/", $master, $master...
151		158
…		…
154	it should know the noderefs of some other nodes in the network.	161	it should know the noderefs of some other nodes in the network.
155		162
156	This function initialises a node - it must be called exactly once (or	163	This function initialises a node - it must be called exactly once (or
157	never) before calling other AnyEvent::MP functions.	164	never) before calling other AnyEvent::MP functions.
158		165
159	All arguments are noderefs, which can be either resolved or unresolved.	166	All arguments (optionally except for the first) are noderefs, which can be
		167	either resolved or unresolved.
		168
		169	The first argument will be looked up in the configuration database first
		170	(if it is C<undef> then the current nodename will be used instead) to find
		171	the relevant configuration profile (see L<aemp>). If none is found then
		172	the default configuration is used. The configuration supplies additional
		173	seed/master nodes and can override the actual noderef.
160		174
161	There are two types of networked nodes, public nodes and slave nodes:	175	There are two types of networked nodes, public nodes and slave nodes:
162		176
163	=over 4	177	=over 4
164		178
165	=item public nodes	179	=item public nodes
166		180
167	For public nodes, C<$noderef> must either be a (possibly unresolved)	181	For public nodes, C<$noderef> (supplied either directly to
168	noderef, in which case it will be resolved, or C<undef> (or missing), in	182	C<initialise_node> or indirectly via a profile or the nodename) must be a
169	which case the noderef will be guessed.	183	noderef (possibly unresolved, in which case it will be resolved).
170		184
171	Afterwards, the node will bind itself on all endpoints and try to connect	185	After resolving, the node will bind itself on all endpoints and try to
172	to all additional C<$seednodes> that are specified. Seednodes are optional	186	connect to all additional C<$seednodes> that are specified. Seednodes are
173	and can be used to quickly bootstrap the node into an existing network.	187	optional and can be used to quickly bootstrap the node into an existing
		188	network.
174		189
175	=item slave nodes	190	=item slave nodes
176		191
177	When the C<$noderef> is the special string C<slave/>, then the node will	192	When the C<$noderef> (either as given or overriden by the config file)
		193	is the special string C<slave/>, then the node will become a slave
178	become a slave node. Slave nodes cannot be contacted from outside and will	194	node. Slave nodes cannot be contacted from outside and will route most of
179	route most of their traffic to the master node that they attach to.	195	their traffic to the master node that they attach to.
180		196
181	At least one additional noderef is required: The node will try to connect	197	At least one additional noderef is required (either by specifying it
182	to all of them and will become a slave attached to the first node it can	198	directly or because it is part of the configuration profile): The node
183	successfully connect to.	199	will try to connect to all of them and will become a slave attached to the
		200	first node it can successfully connect to.
184		201
185	=back	202	=back
186		203
187	This function will block until all nodes have been resolved and, for slave	204	This function will block until all nodes have been resolved and, for slave
188	nodes, until it has successfully established a connection to a master	205	nodes, until it has successfully established a connection to a master
189	server.	206	server.
190		207
191	Example: become a public node listening on the default node.	208	Example: become a public node listening on the guessed noderef, or the one
		209	specified via C<aemp> for the current node. This should be the most common
		210	form of invocation for "daemon"-type nodes.
192		211
193	initialise_node;	212	initialise_node;
		213
		214	Example: become a slave node to any of the the seednodes specified via
		215	C<aemp>. This form is often used for commandline clients.
		216
		217	initialise_node "slave/";
		218
		219	Example: become a slave node to any of the specified master servers. This
		220	form is also often used for commandline clients.
		221
		222	initialise_node "slave/", "master1", "192.168.13.17", "mp.example.net";
194		223
195	Example: become a public node, and try to contact some well-known master	224	Example: become a public node, and try to contact some well-known master
196	servers to become part of the network.	225	servers to become part of the network.
197		226
198	initialise_node undef, "master1", "master2";	227	initialise_node undef, "master1", "master2";
…		…
201		230
202	initialise_node 4041;	231	initialise_node 4041;
203		232
204	Example: become a public node, only visible on localhost port 4044.	233	Example: become a public node, only visible on localhost port 4044.
205		234
206	initialise_node "locahost:4044";	235	initialise_node "localhost:4044";
207
208	Example: become a slave node to any of the specified master servers.
209
210	initialise_node "slave/", "master1", "192.168.13.17", "mp.example.net";
211		236
212	=item $cv = resolve_node $noderef	237	=item $cv = resolve_node $noderef
213		238
214	Takes an unresolved node reference that may contain hostnames and	239	Takes an unresolved node reference that may contain hostnames and
215	abbreviated IDs, resolves all of them and returns a resolved node	240	abbreviated IDs, resolves all of them and returns a resolved node
…		…
252	=item snd $port, type => @data	277	=item snd $port, type => @data
253		278
254	=item snd $port, @msg	279	=item snd $port, @msg
255		280
256	Send the given message to the given port ID, which can identify either	281	Send the given message to the given port ID, which can identify either
257	a local or a remote port, and can be either a string or soemthignt hat	282	a local or a remote port, and must be a port ID.
258	stringifies a sa port ID (such as a port object :).
259		283
260	While the message can be about anything, it is highly recommended to use a	284	While the message can be about anything, it is highly recommended to use a
261	string as first element (a portid, or some word that indicates a request	285	string as first element (a port ID, or some word that indicates a request
262	type etc.).	286	type etc.).
263		287
264	The message data effectively becomes read-only after a call to this	288	The message data effectively becomes read-only after a call to this
265	function: modifying any argument is not allowed and can cause many	289	function: modifying any argument is not allowed and can cause many
266	problems.	290	problems.
…		…
271	that Storable can serialise and deserialise is allowed, and for the local	295	that Storable can serialise and deserialise is allowed, and for the local
272	node, anything can be passed.	296	node, anything can be passed.
273		297
274	=item $local_port = port	298	=item $local_port = port
275		299
276	Create a new local port object that can be used either as a pattern	300	Create a new local port object and returns its port ID. Initially it has
277	matching port ("full port") or a single-callback port ("miniport"),	301	no callbacks set and will throw an error when it receives messages.
278	depending on how C<rcv> callbacks are bound to the object.
279		302
280	=item $port = port { my @msg = @_; $finished }	303	=item $local_port = port { my @msg = @_ }
281		304
282	Creates a "miniport", that is, a very lightweight port without any pattern	305	Creates a new local port, and returns its ID. Semantically the same as
283	matching behind it, and returns its ID. Semantically the same as creating
284	a port and calling C<rcv $port, $callback> on it.	306	creating a port and calling C<rcv $port, $callback> on it.
285		307
286	The block will be called for every message received on the port. When the	308	The block will be called for every message received on the port, with the
287	callback returns a true value its job is considered "done" and the port	309	global variable C<$SELF> set to the port ID. Runtime errors will cause the
288	will be destroyed. Otherwise it will stay alive.	310	port to be C<kil>ed. The message will be passed as-is, no extra argument
		311	(i.e. no port ID) will be passed to the callback.
289		312
290	The message will be passed as-is, no extra argument (i.e. no port id) will	313	If you want to stop/destroy the port, simply C<kil> it:
291	be passed to the callback.
292		314
293	If you need the local port id in the callback, this works nicely:	315	my $port = port {
294		316	my @msg = @_;
295	my $port; $port = port {	317	...
296	snd $otherport, reply => $port;	318	kil $SELF;
297	};	319	};
298		320
299	=cut	321	=cut
300		322
301	sub rcv($@);	323	sub rcv($@);
		324
		325	sub _kilme {
		326	die "received message on port without callback";
		327	}
302		328
303	sub port(;&) {	329	sub port(;&) {
304	my $id = "$UNIQ." . $ID++;	330	my $id = "$UNIQ." . $ID++;
305	my $port = "$NODE#$id";	331	my $port = "$NODE#$id";
306		332
307	if (@_) {	333	rcv $port, shift \|\| \&_kilme;
308	rcv $port, shift;
309	} else {
310	$PORT{$id} = sub { }; # nop
311	}
312		334
313	$port	335	$port
314	}	336	}
315		337
316	=item reg $port, $name
317
318	=item reg $name
319
320	Registers the given port (or C<$SELF><<< if missing) under the name
321	C<$name>. If the name already exists it is replaced.
322
323	A port can only be registered under one well known name.
324
325	A port automatically becomes unregistered when it is killed.
326
327	=cut
328
329	sub reg(@) {
330	my $port = @_ > 1 ? shift : $SELF \|\| Carp::croak 'reg: called with one argument only, but $SELF not set,';
331
332	$REG{$_[0]} = $port;
333	}
334
335	=item rcv $port, $callback->(@msg)	338	=item rcv $local_port, $callback->(@msg)
336		339
337	Replaces the callback on the specified miniport (after converting it to	340	Replaces the default callback on the specified port. There is no way to
338	one if required).	341	remove the default callback: use C<sub { }> to disable it, or better
339		342	C<kil> the port when it is no longer needed.
340	=item rcv $port, tagstring => $callback->(@msg), ...
341
342	=item rcv $port, $smartmatch => $callback->(@msg), ...
343
344	=item rcv $port, [$smartmatch...] => $callback->(@msg), ...
345
346	Register callbacks to be called on matching messages on the given full
347	port (after converting it to one if required) and return the port.
348
349	The callback has to return a true value when its work is done, after
350	which is will be removed, or a false value in which case it will stay
351	registered.
352		343
353	The global C<$SELF> (exported by this module) contains C<$port> while	344	The global C<$SELF> (exported by this module) contains C<$port> while
354	executing the callback.	345	executing the callback. Runtime errors during callback execution will
		346	result in the port being C<kil>ed.
355		347
356	Runtime errors during callback execution will result in the port being	348	The default callback received all messages not matched by a more specific
357	C<kil>ed.	349	C<tag> match.
358		350
359	If the match is an array reference, then it will be matched against the	351	=item rcv $local_port, tag => $callback->(@msg_without_tag), ...
360	first elements of the message, otherwise only the first element is being
361	matched.
362		352
363	Any element in the match that is specified as C<_any_> (a function	353	Register (or replace) callbacks to be called on messages starting with the
364	exported by this module) matches any single element of the message.	354	given tag on the given port (and return the port), or unregister it (when
		355	C<$callback> is C<$undef> or missing). There can only be one callback
		356	registered for each tag.
365		357
366	While not required, it is highly recommended that the first matching	358	The original message will be passed to the callback, after the first
367	element is a string identifying the message. The one-string-only match is	359	element (the tag) has been removed. The callback will use the same
368	also the most efficient match (by far).	360	environment as the default callback (see above).
369		361
370	Example: create a port and bind receivers on it in one go.	362	Example: create a port and bind receivers on it in one go.
371		363
372	my $port = rcv port,	364	my $port = rcv port,
373	msg1 => sub { ...; 0 },	365	msg1 => sub { ... },
374	msg2 => sub { ...; 0 },	366	msg2 => sub { ... },
375	;	367	;
376		368
377	Example: create a port, bind receivers and send it in a message elsewhere	369	Example: create a port, bind receivers and send it in a message elsewhere
378	in one go:	370	in one go:
379		371
380	snd $otherport, reply =>	372	snd $otherport, reply =>
381	rcv port,	373	rcv port,
382	msg1 => sub { ...; 0 },	374	msg1 => sub { ... },
383	...	375	...
384	;	376	;
		377
		378	Example: temporarily register a rcv callback for a tag matching some port
		379	(e.g. for a rpc reply) and unregister it after a message was received.
		380
		381	rcv $port, $otherport => sub {
		382	my @reply = @_;
		383
		384	rcv $SELF, $otherport;
		385	};
385		386
386	=cut	387	=cut
387		388
388	sub rcv($@) {	389	sub rcv($@) {
389	my $port = shift;	390	my $port = shift;
390	my ($noderef, $portid) = split /#/, $port, 2;	391	my ($noderef, $portid) = split /#/, $port, 2;
391		392
392	($NODE{$noderef} \|\| add_node $noderef) == $NODE{""}	393	($NODE{$noderef} \|\| add_node $noderef) == $NODE{""}
393	or Carp::croak "$port: rcv can only be called on local ports, caught";	394	or Carp::croak "$port: rcv can only be called on local ports, caught";
394		395
395	if (@_ == 1) {	396	while (@_) {
		397	if (ref $_[0]) {
		398	if (my $self = $PORT_DATA{$portid}) {
		399	"AnyEvent::MP::Port" eq ref $self
		400	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
		401
		402	$self->[2] = shift;
		403	} else {
396	my $cb = shift;	404	my $cb = shift;
397	delete $PORT_DATA{$portid};
398	$PORT{$portid} = sub {	405	$PORT{$portid} = sub {
399	local $SELF = $port;	406	local $SELF = $port;
400	eval {	407	eval { &$cb }; _self_die if $@;
401	&$cb	408	};
402	and kil $port;
403	};	409	}
404	_self_die if $@;	410	} elsif (defined $_[0]) {
405	};
406	} else {
407	my $self = $PORT_DATA{$portid} \|\|= do {	411	my $self = $PORT_DATA{$portid} \|\|= do {
408	my $self = bless {	412	my $self = bless [$PORT{$port} \|\| sub { }, { }, $port], "AnyEvent::MP::Port";
409	id => $port,
410	}, "AnyEvent::MP::Port";
411		413
412	$PORT{$portid} = sub {	414	$PORT{$portid} = sub {
413	local $SELF = $port;	415	local $SELF = $port;
414		416
415	eval {
416	for (@{ $self->{rc0}{$_[0]} }) {	417	if (my $cb = $self->[1]{$_[0]}) {
417	$_ && &{$_->[0]}	418	shift;
418	&& undef $_;	419	eval { &$cb }; _self_die if $@;
419	}	420	} else {
420
421	for (@{ $self->{rcv}{$_[0]} }) {
422	$_ && [@_[1 .. @{$_->[1]}]] ~~ $_->[1]
423	&& &{$_->[0]}	421	&{ $self->[0] };
424	&& undef $_;
425	}
426
427	for (@{ $self->{any} }) {
428	$_ && [@_[0 .. $#{$_->[1]}]] ~~ $_->[1]
429	&& &{$_->[0]}
430	&& undef $_;
431	}	422	}
432	};	423	};
433	_self_die if $@;	424
		425	$self
434	};	426	};
435		427
436	$self
437	};
438
439	"AnyEvent::MP::Port" eq ref $self	428	"AnyEvent::MP::Port" eq ref $self
440	or Carp::croak "$port: rcv can only be called on message matching ports, caught";	429	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
441		430
442	while (@_) {
443	my ($match, $cb) = splice @_, 0, 2;	431	my ($tag, $cb) = splice @_, 0, 2;
444		432
445	if (!ref $match) {	433	if (defined $cb) {
446	push @{ $self->{rc0}{$match} }, [$cb];	434	$self->[1]{$tag} = $cb;
447	} elsif (("ARRAY" eq ref $match && !ref $match->[0])) {
448	my ($type, @match) = @$match;
449	@match
450	? push @{ $self->{rcv}{$match->[0]} }, [$cb, \@match]
451	: push @{ $self->{rc0}{$match->[0]} }, [$cb];
452	} else {	435	} else {
453	push @{ $self->{any} }, [$cb, $match];	436	delete $self->[1]{$tag};
454	}	437	}
455	}	438	}
456	}	439	}
457		440
458	$port	441	$port
…		…
683	my $id = "$RUNIQ." . $ID++;	666	my $id = "$RUNIQ." . $ID++;
684		667
685	$_[0] =~ /::/	668	$_[0] =~ /::/
686	or Carp::croak "spawn init function must be a fully-qualified name, caught";	669	or Carp::croak "spawn init function must be a fully-qualified name, caught";
687		670
688	($NODE{$noderef} \|\| add_node $noderef)	671	snd_to_func $noderef, "AnyEvent::MP::_spawn" => $id, @_;
689	->send (["", "AnyEvent::MP::_spawn" => $id, @_]);
690		672
691	"$noderef#$id"	673	"$noderef#$id"
692	}	674	}
693		675
694	=back	676	=back
…		…
762	convenience functionality.	744	convenience functionality.
763		745
764	This means that AEMP requires a less tightly controlled environment at the	746	This means that AEMP requires a less tightly controlled environment at the
765	cost of longer node references and a slightly higher management overhead.	747	cost of longer node references and a slightly higher management overhead.
766		748
		749	=item * Erlang has a "remote ports are like local ports" philosophy, AEMP
		750	uses "local ports are like remote ports".
		751
		752	The failure modes for local ports are quite different (runtime errors
		753	only) then for remote ports - when a local port dies, you I<know> it dies,
		754	when a connection to another node dies, you know nothing about the other
		755	port.
		756
		757	Erlang pretends remote ports are as reliable as local ports, even when
		758	they are not.
		759
		760	AEMP encourages a "treat remote ports differently" philosophy, with local
		761	ports being the special case/exception, where transport errors cannot
		762	occur.
		763
767	=item * Erlang uses processes and a mailbox, AEMP does not queue.	764	=item * Erlang uses processes and a mailbox, AEMP does not queue.
768		765
769	Erlang uses processes that selctively receive messages, and therefore	766	Erlang uses processes that selectively receive messages, and therefore
770	needs a queue. AEMP is event based, queuing messages would serve no useful	767	needs a queue. AEMP is event based, queuing messages would serve no
771	purpose.	768	useful purpose. For the same reason the pattern-matching abilities of
		769	AnyEvent::MP are more limited, as there is little need to be able to
		770	filter messages without dequeing them.
772		771
773	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).	772	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).
774		773
775	=item * Erlang sends are synchronous, AEMP sends are asynchronous.	774	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
776		775
777	Sending messages in Erlang is synchronous and blocks the process. AEMP	776	Sending messages in Erlang is synchronous and blocks the process (and
778	sends are immediate, connection establishment is handled in the	777	so does not need a queue that can overflow). AEMP sends are immediate,
779	background.	778	connection establishment is handled in the background.
780		779
781	=item * Erlang can silently lose messages, AEMP cannot.	780	=item * Erlang suffers from silent message loss, AEMP does not.
782		781
783	Erlang makes few guarantees on messages delivery - messages can get lost	782	Erlang makes few guarantees on messages delivery - messages can get lost
784	without any of the processes realising it (i.e. you send messages a, b,	783	without any of the processes realising it (i.e. you send messages a, b,
785	and c, and the other side only receives messages a and c).	784	and c, and the other side only receives messages a and c).
786		785
…		…
798	eventually be killed - it cannot happen that a node detects a port as dead	797	eventually be killed - it cannot happen that a node detects a port as dead
799	and then later sends messages to it, finding it is still alive.	798	and then later sends messages to it, finding it is still alive.
800		799
801	=item * Erlang can send messages to the wrong port, AEMP does not.	800	=item * Erlang can send messages to the wrong port, AEMP does not.
802		801
803	In Erlang it is quite possible that a node that restarts reuses a process	802	In Erlang it is quite likely that a node that restarts reuses a process ID
804	ID known to other nodes for a completely different process, causing	803	known to other nodes for a completely different process, causing messages
805	messages destined for that process to end up in an unrelated process.	804	destined for that process to end up in an unrelated process.
806		805
807	AEMP never reuses port IDs, so old messages or old port IDs floating	806	AEMP never reuses port IDs, so old messages or old port IDs floating
808	around in the network will not be sent to an unrelated port.	807	around in the network will not be sent to an unrelated port.
809		808
810	=item * Erlang uses unprotected connections, AEMP uses secure	809	=item * Erlang uses unprotected connections, AEMP uses secure
…		…
846	This also saves round-trips and avoids sending messages to the wrong port	845	This also saves round-trips and avoids sending messages to the wrong port
847	(hard to do in Erlang).	846	(hard to do in Erlang).
848		847
849	=back	848	=back
850		849
		850	=head1 RATIONALE
		851
		852	=over 4
		853
		854	=item Why strings for ports and noderefs, why not objects?
		855
		856	We considered "objects", but found that the actual number of methods
		857	thatc an be called are very low. Since port IDs and noderefs travel over
		858	the network frequently, the serialising/deserialising would add lots of
		859	overhead, as well as having to keep a proxy object.
		860
		861	Strings can easily be printed, easily serialised etc. and need no special
		862	procedures to be "valid".
		863
		864	And a a miniport consists of a single closure stored in a global hash - it
		865	can't become much cheaper.
		866
		867	=item Why favour JSON, why not real serialising format such as Storable?
		868
		869	In fact, any AnyEvent::MP node will happily accept Storable as framing
		870	format, but currently there is no way to make a node use Storable by
		871	default.
		872
		873	The default framing protocol is JSON because a) JSON::XS is many times
		874	faster for small messages and b) most importantly, after years of
		875	experience we found that object serialisation is causing more problems
		876	than it gains: Just like function calls, objects simply do not travel
		877	easily over the network, mostly because they will always be a copy, so you
		878	always have to re-think your design.
		879
		880	Keeping your messages simple, concentrating on data structures rather than
		881	objects, will keep your messages clean, tidy and efficient.
		882
		883	=back
		884
851	=head1 SEE ALSO	885	=head1 SEE ALSO
852		886
853	L<AnyEvent>.	887	L<AnyEvent>.
854		888
855	=head1 AUTHOR	889	=head1 AUTHOR

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Comparing AnyEvent-MP/MP.pm (file contents): Revision 1.43 by root, Sun Aug 9 16:08:16 2009 UTC vs. Revision 1.55 by root, Fri Aug 14 23:17:17 2009 UTC

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Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.43 by root, Sun Aug 9 16:08:16 2009 UTC vs.
Revision 1.55 by root, Fri Aug 14 23:17:17 2009 UTC