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

Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.29 by root, Tue Aug 4 23:16:57 2009 UTC vs.
Revision 1.35 by root, Thu Aug 6 10:21:48 2009 UTC

…		…
23		23
24	# more, smarter, matches (_any_ is exported by this module)	24	# more, smarter, matches (_any_ is exported by this module)
25	rcv $port, [child_died => $pid] => sub { ...	25	rcv $port, [child_died => $pid] => sub { ...
26	rcv $port, [_any_, _any_, 3] => sub { .. $_[2] is 3	26	rcv $port, [_any_, _any_, 3] => sub { .. $_[2] is 3
27		27
		28	# linking two ports, so they both crash together
		29	lnk $port1, $port2;
		30
		31	# monitoring
		32	mon $port, $cb->(@msg) # callback is invoked on death
		33	mon $port, $otherport # kill otherport on abnormal death
		34	mon $port, $otherport, @msg # send message on death
		35
28	=head1 DESCRIPTION	36	=head1 DESCRIPTION
29		37
30	This module (-family) implements a simple message passing framework.	38	This module (-family) implements a simple message passing framework.
31		39
32	Despite its simplicity, you can securely message other processes running	40	Despite its simplicity, you can securely message other processes running
…		…
53		61
54	=item port id - C<noderef#portname>	62	=item port id - C<noderef#portname>
55		63
56	A port id is normaly the concatenation of a noderef, a hash-mark (C<#>) as	64	A port id is normaly the concatenation of a noderef, a hash-mark (C<#>) as
57	separator, and a port name (a printable string of unspecified format). An	65	separator, and a port name (a printable string of unspecified format). An
58	exception is the the node port, whose ID is identical to it's node	66	exception is the the node port, whose ID is identical to its node
59	reference.	67	reference.
60		68
61	=item node	69	=item node
62		70
63	A node is a single process containing at least one port - the node	71	A node is a single process containing at least one port - the node
…		…
103	use base "Exporter";	111	use base "Exporter";
104		112
105	our $VERSION = '0.1';	113	our $VERSION = '0.1';
106	our @EXPORT = qw(	114	our @EXPORT = qw(
107	NODE $NODE *SELF node_of _any_	115	NODE $NODE *SELF node_of _any_
108	resolve_node	116	resolve_node initialise_node
109	become_slave become_public
110	snd rcv mon kil reg psub	117	snd rcv mon kil reg psub
111	port	118	port
112	);	119	);
113		120
114	our $SELF;	121	our $SELF;
…		…
124	The C<NODE> function returns, and the C<$NODE> variable contains	131	The C<NODE> function returns, and the C<$NODE> variable contains
125	the noderef of the local node. The value is initialised by a call	132	the noderef of the local node. The value is initialised by a call
126	to C<become_public> or C<become_slave>, after which all local port	133	to C<become_public> or C<become_slave>, after which all local port
127	identifiers become invalid.	134	identifiers become invalid.
128		135
129	=item $noderef = node_of $portid	136	=item $noderef = node_of $port
130		137
131	Extracts and returns the noderef from a portid or a noderef.	138	Extracts and returns the noderef from a portid or a noderef.
		139
		140	=item initialise_node $noderef, $seednode, $seednode...
		141
		142	=item initialise_node "slave/", $master, $master...
		143
		144	Before a node can talk to other nodes on the network it has to initialise
		145	itself - the minimum a node needs to know is it's own name, and optionally
		146	it should know the noderefs of some other nodes in the network.
		147
		148	This function initialises a node - it must be called exactly once (or
		149	never) before calling other AnyEvent::MP functions.
		150
		151	All arguments are noderefs, which can be either resolved or unresolved.
		152
		153	There are two types of networked nodes, public nodes and slave nodes:
		154
		155	=over 4
		156
		157	=item public nodes
		158
		159	For public nodes, C<$noderef> must either be a (possibly unresolved)
		160	noderef, in which case it will be resolved, or C<undef> (or missing), in
		161	which case the noderef will be guessed.
		162
		163	Afterwards, the node will bind itself on all endpoints and try to connect
		164	to all additional C<$seednodes> that are specified. Seednodes are optional
		165	and can be used to quickly bootstrap the node into an existing network.
		166
		167	=item slave nodes
		168
		169	When the C<$noderef> is the special string C<slave/>, then the node will
		170	become a slave node. Slave nodes cannot be contacted from outside and will
		171	route most of their traffic to the master node that they attach to.
		172
		173	At least one additional noderef is required: The node will try to connect
		174	to all of them and will become a slave attached to the first node it can
		175	successfully connect to.
		176
		177	=back
		178
		179	This function will block until all nodes have been resolved and, for slave
		180	nodes, until it has successfully established a connection to a master
		181	server.
		182
		183	Example: become a public node listening on the default node.
		184
		185	initialise_node;
		186
		187	Example: become a public node, and try to contact some well-known master
		188	servers to become part of the network.
		189
		190	initialise_node undef, "master1", "master2";
		191
		192	Example: become a public node listening on port C<4041>.
		193
		194	initialise_node 4041;
		195
		196	Example: become a public node, only visible on localhost port 4044.
		197
		198	initialise_node "locahost:4044";
		199
		200	Example: become a slave node to any of the specified master servers.
		201
		202	initialise_node "slave/", "master1", "192.168.13.17", "mp.example.net";
132		203
133	=item $cv = resolve_node $noderef	204	=item $cv = resolve_node $noderef
134		205
135	Takes an unresolved node reference that may contain hostnames and	206	Takes an unresolved node reference that may contain hostnames and
136	abbreviated IDs, resolves all of them and returns a resolved node	207	abbreviated IDs, resolves all of them and returns a resolved node
…		…
168		239
169	Due to some quirks in how perl exports variables, it is impossible to	240	Due to some quirks in how perl exports variables, it is impossible to
170	just export C<$SELF>, all the symbols called C<SELF> are exported by this	241	just export C<$SELF>, all the symbols called C<SELF> are exported by this
171	module, but only C<$SELF> is currently used.	242	module, but only C<$SELF> is currently used.
172		243
173	=item snd $portid, type => @data	244	=item snd $port, type => @data
174		245
175	=item snd $portid, @msg	246	=item snd $port, @msg
176		247
177	Send the given message to the given port ID, which can identify either	248	Send the given message to the given port ID, which can identify either
178	a local or a remote port, and can be either a string or soemthignt hat	249	a local or a remote port, and can be either a string or soemthignt hat
179	stringifies a sa port ID (such as a port object :).	250	stringifies a sa port ID (such as a port object :).
180		251
…		…
190	JSON is used, then only strings, numbers and arrays and hashes consisting	261	JSON is used, then only strings, numbers and arrays and hashes consisting
191	of those are allowed (no objects). When Storable is used, then anything	262	of those are allowed (no objects). When Storable is used, then anything
192	that Storable can serialise and deserialise is allowed, and for the local	263	that Storable can serialise and deserialise is allowed, and for the local
193	node, anything can be passed.	264	node, anything can be passed.
194		265
195	=item kil $portid[, @reason]
196
197	Kill the specified port with the given C<@reason>.
198
199	If no C<@reason> is specified, then the port is killed "normally" (linked
200	ports will not be kileld, or even notified).
201
202	Otherwise, linked ports get killed with the same reason (second form of
203	C<mon>, see below).
204
205	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks
206	will be reported as reason C<< die => $@ >>.
207
208	Transport/communication errors are reported as C<< transport_error =>
209	$message >>.
210
211	=item $guard = mon $portid, $cb->(@reason)
212
213	=item $guard = mon $portid, $otherport
214
215	=item $guard = mon $portid, $otherport, @msg
216
217	Monitor the given port and do something when the port is killed.
218
219	In the first form, the callback is simply called with any number
220	of C<@reason> elements (no @reason means that the port was deleted
221	"normally"). Note also that I<< the callback B<must> never die >>, so use
222	C<eval> if unsure.
223
224	In the second form, the other port will be C<kil>'ed with C<@reason>, iff
225	a @reason was specified, i.e. on "normal" kils nothing happens, while
226	under all other conditions, the other port is killed with the same reason.
227
228	In the last form, a message of the form C<@msg, @reason> will be C<snd>.
229
230	Example: call a given callback when C<$port> is killed.
231
232	mon $port, sub { warn "port died because of <@_>\n" };
233
234	Example: kill ourselves when C<$port> is killed abnormally.
235
236	mon $port, $self;
237
238	Example: send us a restart message another C<$port> is killed.
239
240	mon $port, $self => "restart";
241
242	=cut
243
244	sub mon {
245	my ($noderef, $port, $cb) = ((split /#/, shift, 2), shift);
246
247	my $node = $NODE{$noderef} \|\| add_node $noderef;
248
249	#TODO: ports must not be references
250	if (!ref $cb or "AnyEvent::MP::Port" eq ref $cb) {
251	if (@_) {
252	# send a kill info message
253	my (@msg) = ($cb, @_);
254	$cb = sub { snd @msg, @_ };
255	} else {
256	# simply kill other port
257	my $port = $cb;
258	$cb = sub { kil $port, @_ if @_ };
259	}
260	}
261
262	$node->monitor ($port, $cb);
263
264	defined wantarray
265	and AnyEvent::Util::guard { $node->unmonitor ($port, $cb) }
266	}
267
268	=item $guard = mon_guard $port, $ref, $ref...
269
270	Monitors the given C<$port> and keeps the passed references. When the port
271	is killed, the references will be freed.
272
273	Optionally returns a guard that will stop the monitoring.
274
275	This function is useful when you create e.g. timers or other watchers and
276	want to free them when the port gets killed:
277
278	$port->rcv (start => sub {
279	my $timer; $timer = mon_guard $port, AE::timer 1, 1, sub {
280	undef $timer if 0.9 < rand;
281	});
282	});
283
284	=cut
285
286	sub mon_guard {
287	my ($port, @refs) = @_;
288
289	mon $port, sub { 0 && @refs }
290	}
291
292	=item lnk $port1, $port2
293
294	Link two ports. This is simply a shorthand for:
295
296	mon $port1, $port2;
297	mon $port2, $port1;
298
299	It means that if either one is killed abnormally, the other one gets
300	killed as well.
301
302	=item $local_port = port	266	=item $local_port = port
303		267
304	Create a new local port object that supports message matching.	268	Create a new local port object that can be used either as a pattern
		269	matching port ("full port") or a single-callback port ("miniport"),
		270	depending on how C<rcv> callbacks are bound to the object.
305		271
306	=item $portid = port { my @msg = @_; $finished }	272	=item $port = port { my @msg = @_; $finished }
307		273
308	Creates a "mini port", that is, a very lightweight port without any	274	Creates a "miniport", that is, a very lightweight port without any pattern
309	pattern matching behind it, and returns its ID.	275	matching behind it, and returns its ID. Semantically the same as creating
		276	a port and calling C<rcv $port, $callback> on it.
310		277
311	The block will be called for every message received on the port. When the	278	The block will be called for every message received on the port. When the
312	callback returns a true value its job is considered "done" and the port	279	callback returns a true value its job is considered "done" and the port
313	will be destroyed. Otherwise it will stay alive.	280	will be destroyed. Otherwise it will stay alive.
314		281
315	The message will be passed as-is, no extra argument (i.e. no port id) will	282	The message will be passed as-is, no extra argument (i.e. no port id) will
316	be passed to the callback.	283	be passed to the callback.
317		284
318	If you need the local port id in the callback, this works nicely:	285	If you need the local port id in the callback, this works nicely:
319		286
320	my $port; $port = miniport {	287	my $port; $port = port {
321	snd $otherport, reply => $port;	288	snd $otherport, reply => $port;
322	};	289	};
323		290
324	=cut	291	=cut
		292
		293	sub rcv($@);
325		294
326	sub port(;&) {	295	sub port(;&) {
327	my $id = "$UNIQ." . $ID++;	296	my $id = "$UNIQ." . $ID++;
328	my $port = "$NODE#$id";	297	my $port = "$NODE#$id";
329		298
330	if (@_) {	299	if (@_) {
		300	rcv $port, shift;
		301	} else {
		302	$PORT{$id} = sub { }; # nop
		303	}
		304
		305	$port
		306	}
		307
		308	=item reg $port, $name
		309
		310	Registers the given port under the name C<$name>. If the name already
		311	exists it is replaced.
		312
		313	A port can only be registered under one well known name.
		314
		315	A port automatically becomes unregistered when it is killed.
		316
		317	=cut
		318
		319	sub reg(@) {
		320	my ($port, $name) = @_;
		321
		322	$REG{$name} = $port;
		323	}
		324
		325	=item rcv $port, $callback->(@msg)
		326
		327	Replaces the callback on the specified miniport (after converting it to
		328	one if required).
		329
		330	=item rcv $port, tagstring => $callback->(@msg), ...
		331
		332	=item rcv $port, $smartmatch => $callback->(@msg), ...
		333
		334	=item rcv $port, [$smartmatch...] => $callback->(@msg), ...
		335
		336	Register callbacks to be called on matching messages on the given full
		337	port (after converting it to one if required).
		338
		339	The callback has to return a true value when its work is done, after
		340	which is will be removed, or a false value in which case it will stay
		341	registered.
		342
		343	The global C<$SELF> (exported by this module) contains C<$port> while
		344	executing the callback.
		345
		346	Runtime errors wdurign callback execution will result in the port being
		347	C<kil>ed.
		348
		349	If the match is an array reference, then it will be matched against the
		350	first elements of the message, otherwise only the first element is being
		351	matched.
		352
		353	Any element in the match that is specified as C<_any_> (a function
		354	exported by this module) matches any single element of the message.
		355
		356	While not required, it is highly recommended that the first matching
		357	element is a string identifying the message. The one-string-only match is
		358	also the most efficient match (by far).
		359
		360	=cut
		361
		362	sub rcv($@) {
		363	my $port = shift;
		364	my ($noderef, $portid) = split /#/, $port, 2;
		365
		366	($NODE{$noderef} \|\| add_node $noderef) == $NODE{""}
		367	or Carp::croak "$port: rcv can only be called on local ports, caught";
		368
		369	if (@_ == 1) {
331	my $cb = shift;	370	my $cb = shift;
		371	delete $PORT_DATA{$portid};
332	$PORT{$id} = sub {	372	$PORT{$portid} = sub {
333	local $SELF = $port;	373	local $SELF = $port;
334	eval {	374	eval {
335	&$cb	375	&$cb
336	and kil $id;	376	and kil $port;
337	};	377	};
338	_self_die if $@;	378	_self_die if $@;
339	};	379	};
340	} else {	380	} else {
		381	my $self = $PORT_DATA{$portid} \|\|= do {
341	my $self = bless {	382	my $self = bless {
342	id => "$NODE#$id",	383	id => $port,
343	}, "AnyEvent::MP::Port";	384	}, "AnyEvent::MP::Port";
344		385
345	$PORT_DATA{$id} = $self;
346	$PORT{$id} = sub {	386	$PORT{$portid} = sub {
347	local $SELF = $port;	387	local $SELF = $port;
348		388
349	eval {	389	eval {
350	for (@{ $self->{rc0}{$_[0]} }) {	390	for (@{ $self->{rc0}{$_[0]} }) {
351	$_ && &{$_->[0]}	391	$_ && &{$_->[0]}
352	&& undef $_;	392	&& undef $_;
353	}	393	}
354		394
355	for (@{ $self->{rcv}{$_[0]} }) {	395	for (@{ $self->{rcv}{$_[0]} }) {
356	$_ && [@_[1 .. @{$_->[1]}]] ~~ $_->[1]	396	$_ && [@_[1 .. @{$_->[1]}]] ~~ $_->[1]
357	&& &{$_->[0]}	397	&& &{$_->[0]}
358	&& undef $_;	398	&& undef $_;
359	}	399	}
360		400
361	for (@{ $self->{any} }) {	401	for (@{ $self->{any} }) {
362	$_ && [@_[0 .. $#{$_->[1]}]] ~~ $_->[1]	402	$_ && [@_[0 .. $#{$_->[1]}]] ~~ $_->[1]
363	&& &{$_->[0]}	403	&& &{$_->[0]}
364	&& undef $_;	404	&& undef $_;
		405	}
365	}	406	};
		407	_self_die if $@;
366	};	408	};
367	_self_die if $@;	409
		410	$self
368	};	411	};
369	}
370		412
371	$port
372	}
373
374	=item reg $portid, $name
375
376	Registers the given port under the name C<$name>. If the name already
377	exists it is replaced.
378
379	A port can only be registered under one well known name.
380
381	A port automatically becomes unregistered when it is killed.
382
383	=cut
384
385	sub reg(@) {
386	my ($portid, $name) = @_;
387
388	$REG{$name} = $portid;
389	}
390
391	=item rcv $portid, tagstring => $callback->(@msg), ...
392
393	=item rcv $portid, $smartmatch => $callback->(@msg), ...
394
395	=item rcv $portid, [$smartmatch...] => $callback->(@msg), ...
396
397	Register callbacks to be called on matching messages on the given port.
398
399	The callback has to return a true value when its work is done, after
400	which is will be removed, or a false value in which case it will stay
401	registered.
402
403	The global C<$SELF> (exported by this module) contains C<$portid> while
404	executing the callback.
405
406	Runtime errors wdurign callback execution will result in the port being
407	C<kil>ed.
408
409	If the match is an array reference, then it will be matched against the
410	first elements of the message, otherwise only the first element is being
411	matched.
412
413	Any element in the match that is specified as C<_any_> (a function
414	exported by this module) matches any single element of the message.
415
416	While not required, it is highly recommended that the first matching
417	element is a string identifying the message. The one-string-only match is
418	also the most efficient match (by far).
419
420	=cut
421
422	sub rcv($@) {
423	my ($noderef, $port) = split /#/, shift, 2;
424
425	($NODE{$noderef} \|\| add_node $noderef) == $NODE{""}
426	or Carp::croak "$noderef#$port: rcv can only be called on local ports, caught";
427
428	my $self = $PORT_DATA{$port}
429	or Carp::croak "$noderef#$port: rcv can only be called on message matching ports, caught";
430
431	"AnyEvent::MP::Port" eq ref $self	413	"AnyEvent::MP::Port" eq ref $self
432	or Carp::croak "$noderef#$port: rcv can only be called on message matching ports, caught";	414	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
433		415
434	while (@_) {	416	while (@_) {
435	my ($match, $cb) = splice @_, 0, 2;	417	my ($match, $cb) = splice @_, 0, 2;
436		418
437	if (!ref $match) {	419	if (!ref $match) {
438	push @{ $self->{rc0}{$match} }, [$cb];	420	push @{ $self->{rc0}{$match} }, [$cb];
439	} elsif (("ARRAY" eq ref $match && !ref $match->[0])) {	421	} elsif (("ARRAY" eq ref $match && !ref $match->[0])) {
440	my ($type, @match) = @$match;	422	my ($type, @match) = @$match;
441	@match	423	@match
442	? push @{ $self->{rcv}{$match->[0]} }, [$cb, \@match]	424	? push @{ $self->{rcv}{$match->[0]} }, [$cb, \@match]
443	: push @{ $self->{rc0}{$match->[0]} }, [$cb];	425	: push @{ $self->{rc0}{$match->[0]} }, [$cb];
444	} else {	426	} else {
445	push @{ $self->{any} }, [$cb, $match];	427	push @{ $self->{any} }, [$cb, $match];
		428	}
446	}	429	}
447	}	430	}
		431
		432	$port
448	}	433	}
449		434
450	=item $closure = psub { BLOCK }	435	=item $closure = psub { BLOCK }
451		436
452	Remembers C<$SELF> and creates a closure out of the BLOCK. When the	437	Remembers C<$SELF> and creates a closure out of the BLOCK. When the
…		…
483	$res	468	$res
484	}	469	}
485	}	470	}
486	}	471	}
487		472
488	=back	473	=item $guard = mon $port, $cb->(@reason)
489		474
490	=head1 FUNCTIONS FOR NODES	475	=item $guard = mon $port, $otherport
491		476
492	=over 4	477	=item $guard = mon $port, $otherport, @msg
493		478
494	=item become_public $noderef	479	Monitor the given port and do something when the port is killed.
495		480
496	Tells the node to become a public node, i.e. reachable from other nodes.	481	In the first form, the callback is simply called with any number
		482	of C<@reason> elements (no @reason means that the port was deleted
		483	"normally"). Note also that I<< the callback B<must> never die >>, so use
		484	C<eval> if unsure.
497		485
498	The first argument is the (unresolved) node reference of the local node	486	In the second form, the other port will be C<kil>'ed with C<@reason>, iff
499	(if missing then the empty string is used).	487	a @reason was specified, i.e. on "normal" kils nothing happens, while
		488	under all other conditions, the other port is killed with the same reason.
500		489
501	It is quite common to not specify anything, in which case the local node	490	In the last form, a message of the form C<@msg, @reason> will be C<snd>.
502	tries to listen on the default port, or to only specify a port number, in
503	which case AnyEvent::MP tries to guess the local addresses.
504		491
		492	Example: call a given callback when C<$port> is killed.
		493
		494	mon $port, sub { warn "port died because of <@_>\n" };
		495
		496	Example: kill ourselves when C<$port> is killed abnormally.
		497
		498	mon $port, $self;
		499
		500	Example: send us a restart message another C<$port> is killed.
		501
		502	mon $port, $self => "restart";
		503
505	=cut	504	=cut
		505
		506	sub mon {
		507	my ($noderef, $port) = split /#/, shift, 2;
		508
		509	my $node = $NODE{$noderef} \|\| add_node $noderef;
		510
		511	my $cb = shift;
		512
		513	unless (ref $cb) {
		514	if (@_) {
		515	# send a kill info message
		516	my (@msg) = ($cb, @_);
		517	$cb = sub { snd @msg, @_ };
		518	} else {
		519	# simply kill other port
		520	my $port = $cb;
		521	$cb = sub { kil $port, @_ if @_ };
		522	}
		523	}
		524
		525	$node->monitor ($port, $cb);
		526
		527	defined wantarray
		528	and AnyEvent::Util::guard { $node->unmonitor ($port, $cb) }
		529	}
		530
		531	=item $guard = mon_guard $port, $ref, $ref...
		532
		533	Monitors the given C<$port> and keeps the passed references. When the port
		534	is killed, the references will be freed.
		535
		536	Optionally returns a guard that will stop the monitoring.
		537
		538	This function is useful when you create e.g. timers or other watchers and
		539	want to free them when the port gets killed:
		540
		541	$port->rcv (start => sub {
		542	my $timer; $timer = mon_guard $port, AE::timer 1, 1, sub {
		543	undef $timer if 0.9 < rand;
		544	});
		545	});
		546
		547	=cut
		548
		549	sub mon_guard {
		550	my ($port, @refs) = @_;
		551
		552	mon $port, sub { 0 && @refs }
		553	}
		554
		555	=item lnk $port1, $port2
		556
		557	Link two ports. This is simply a shorthand for:
		558
		559	mon $port1, $port2;
		560	mon $port2, $port1;
		561
		562	It means that if either one is killed abnormally, the other one gets
		563	killed as well.
		564
		565	=item kil $port[, @reason]
		566
		567	Kill the specified port with the given C<@reason>.
		568
		569	If no C<@reason> is specified, then the port is killed "normally" (linked
		570	ports will not be kileld, or even notified).
		571
		572	Otherwise, linked ports get killed with the same reason (second form of
		573	C<mon>, see below).
		574
		575	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks
		576	will be reported as reason C<< die => $@ >>.
		577
		578	Transport/communication errors are reported as C<< transport_error =>
		579	$message >>.
506		580
507	=back	581	=back
508		582
509	=head1 NODE MESSAGES	583	=head1 NODE MESSAGES
510		584
…		…
552		626
553	=back	627	=back
554		628
555	=head1 AnyEvent::MP vs. Distributed Erlang	629	=head1 AnyEvent::MP vs. Distributed Erlang
556		630
557	AnyEvent::MP got lots of its ideas from distributed erlang (erlang node	631	AnyEvent::MP got lots of its ideas from distributed Erlang (Erlang node
558	== aemp node, erlang process == aemp port), so many of the documents and	632	== aemp node, Erlang process == aemp port), so many of the documents and
559	programming techniques employed by erlang apply to AnyEvent::MP. Here is a	633	programming techniques employed by Erlang apply to AnyEvent::MP. Here is a
560	sample:	634	sample:
561		635
562	http://www.erlang.se/doc/programming_rules.shtml	636	http://www.Erlang.se/doc/programming_rules.shtml
563	http://erlang.org/doc/getting_started/part_frame.html # chapters 3 and 4	637	http://Erlang.org/doc/getting_started/part_frame.html # chapters 3 and 4
564	http://erlang.org/download/erlang-book-part1.pdf # chapters 5 and 6	638	http://Erlang.org/download/Erlang-book-part1.pdf # chapters 5 and 6
565	http://erlang.org/download/armstrong_thesis_2003.pdf # chapters 4 and 5	639	http://Erlang.org/download/armstrong_thesis_2003.pdf # chapters 4 and 5
566		640
567	Despite the similarities, there are also some important differences:	641	Despite the similarities, there are also some important differences:
568		642
569	=over 4	643	=over 4
570		644
…		…
581		655
582	Erlang uses processes that selctively receive messages, and therefore	656	Erlang uses processes that selctively receive messages, and therefore
583	needs a queue. AEMP is event based, queuing messages would serve no useful	657	needs a queue. AEMP is event based, queuing messages would serve no useful
584	purpose.	658	purpose.
585		659
586	(But see L<Coro::MP> for a more erlang-like process model on top of AEMP).	660	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).
587		661
588	=item * Erlang sends are synchronous, AEMP sends are asynchronous.	662	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
589		663
590	Sending messages in erlang is synchronous and blocks the process. AEMP	664	Sending messages in Erlang is synchronous and blocks the process. AEMP
591	sends are immediate, connection establishment is handled in the	665	sends are immediate, connection establishment is handled in the
592	background.	666	background.
593		667
594	=item * Erlang can silently lose messages, AEMP cannot.	668	=item * Erlang can silently lose messages, AEMP cannot.
595		669
…		…
598	and c, and the other side only receives messages a and c).	672	and c, and the other side only receives messages a and c).
599		673
600	AEMP guarantees correct ordering, and the guarantee that there are no	674	AEMP guarantees correct ordering, and the guarantee that there are no
601	holes in the message sequence.	675	holes in the message sequence.
602		676
603	=item * In erlang, processes can be declared dead and later be found to be	677	=item * In Erlang, processes can be declared dead and later be found to be
604	alive.	678	alive.
605		679
606	In erlang it can happen that a monitored process is declared dead and	680	In Erlang it can happen that a monitored process is declared dead and
607	linked processes get killed, but later it turns out that the process is	681	linked processes get killed, but later it turns out that the process is
608	still alive - and can receive messages.	682	still alive - and can receive messages.
609		683
610	In AEMP, when port monitoring detects a port as dead, then that port will	684	In AEMP, when port monitoring detects a port as dead, then that port will
611	eventually be killed - it cannot happen that a node detects a port as dead	685	eventually be killed - it cannot happen that a node detects a port as dead
612	and then later sends messages to it, finding it is still alive.	686	and then later sends messages to it, finding it is still alive.
613		687
614	=item * Erlang can send messages to the wrong port, AEMP does not.	688	=item * Erlang can send messages to the wrong port, AEMP does not.
615		689
616	In erlang it is quite possible that a node that restarts reuses a process	690	In Erlang it is quite possible that a node that restarts reuses a process
617	ID known to other nodes for a completely different process, causing	691	ID known to other nodes for a completely different process, causing
618	messages destined for that process to end up in an unrelated process.	692	messages destined for that process to end up in an unrelated process.
619		693
620	AEMP never reuses port IDs, so old messages or old port IDs floating	694	AEMP never reuses port IDs, so old messages or old port IDs floating
621	around in the network will not be sent to an unrelated port.	695	around in the network will not be sent to an unrelated port.
…		…
627	securely authenticate nodes.	701	securely authenticate nodes.
628		702
629	=item * The AEMP protocol is optimised for both text-based and binary	703	=item * The AEMP protocol is optimised for both text-based and binary
630	communications.	704	communications.
631		705
632	The AEMP protocol, unlike the erlang protocol, supports both	706	The AEMP protocol, unlike the Erlang protocol, supports both
633	language-independent text-only protocols (good for debugging) and binary,	707	language-independent text-only protocols (good for debugging) and binary,
634	language-specific serialisers (e.g. Storable).	708	language-specific serialisers (e.g. Storable).
635		709
636	It has also been carefully designed to be implementable in other languages	710	It has also been carefully designed to be implementable in other languages
637	with a minimum of work while gracefully degrading fucntionality to make the	711	with a minimum of work while gracefully degrading fucntionality to make the
638	protocol simple.	712	protocol simple.
639		713
		714	=item * AEMP has more flexible monitoring options than Erlang.
		715
		716	In Erlang, you can chose to receive I<all> exit signals as messages
		717	or I<none>, there is no in-between, so monitoring single processes is
		718	difficult to implement. Monitoring in AEMP is more flexible than in
		719	Erlang, as one can choose between automatic kill, exit message or callback
		720	on a per-process basis.
		721
		722	=item * Erlang has different semantics for monitoring and linking, AEMP has the same.
		723
		724	Monitoring in Erlang is not an indicator of process death/crashes,
		725	as linking is (except linking is unreliable in Erlang). In AEMP, the
		726	semantics of monitoring and linking are identical, linking is simply
		727	two-way monitoring with automatic kill.
		728
640	=back	729	=back
641		730
642	=head1 SEE ALSO	731	=head1 SEE ALSO
643		732
644	L<AnyEvent>.	733	L<AnyEvent>.

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Revision 1.35 by root, Thu Aug 6 10:21:48 2009 UTC