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

Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.31 by root, Wed Aug 5 19:55:58 2009 UTC vs.
Revision 1.36 by root, Thu Aug 6 10:46:48 2009 UTC

…		…
22	snd $port2, ping => $port1;	22	snd $port2, ping => $port1;
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
		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, $otherport, @msg # send message on death
27		35
28	=head1 DESCRIPTION	36	=head1 DESCRIPTION
29		37
30	This module (-family) implements a simple message passing framework.	38	This module (-family) implements a simple message passing framework.
31		39
…		…
123	The C<NODE> function returns, and the C<$NODE> variable contains	131	The C<NODE> function returns, and the C<$NODE> variable contains
124	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
125	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
126	identifiers become invalid.	134	identifiers become invalid.
127		135
128	=item $noderef = node_of $portid	136	=item $noderef = node_of $port
129		137
130	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";
131		203
132	=item $cv = resolve_node $noderef	204	=item $cv = resolve_node $noderef
133		205
134	Takes an unresolved node reference that may contain hostnames and	206	Takes an unresolved node reference that may contain hostnames and
135	abbreviated IDs, resolves all of them and returns a resolved node	207	abbreviated IDs, resolves all of them and returns a resolved node
…		…
167		239
168	Due to some quirks in how perl exports variables, it is impossible to	240	Due to some quirks in how perl exports variables, it is impossible to
169	just export C<$SELF>, all the symbols called C<SELF> are exported by this	241	just export C<$SELF>, all the symbols called C<SELF> are exported by this
170	module, but only C<$SELF> is currently used.	242	module, but only C<$SELF> is currently used.
171		243
172	=item snd $portid, type => @data	244	=item snd $port, type => @data
173		245
174	=item snd $portid, @msg	246	=item snd $port, @msg
175		247
176	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
177	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
178	stringifies a sa port ID (such as a port object :).	250	stringifies a sa port ID (such as a port object :).
179		251
…		…
189	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
190	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
191	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
192	node, anything can be passed.	264	node, anything can be passed.
193		265
194	=item kil $portid[, @reason]
195
196	Kill the specified port with the given C<@reason>.
197
198	If no C<@reason> is specified, then the port is killed "normally" (linked
199	ports will not be kileld, or even notified).
200
201	Otherwise, linked ports get killed with the same reason (second form of
202	C<mon>, see below).
203
204	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks
205	will be reported as reason C<< die => $@ >>.
206
207	Transport/communication errors are reported as C<< transport_error =>
208	$message >>.
209
210	=item $guard = mon $portid, $cb->(@reason)
211
212	=item $guard = mon $portid, $otherport
213
214	=item $guard = mon $portid, $otherport, @msg
215
216	Monitor the given port and do something when the port is killed.
217
218	In the first form, the callback is simply called with any number
219	of C<@reason> elements (no @reason means that the port was deleted
220	"normally"). Note also that I<< the callback B<must> never die >>, so use
221	C<eval> if unsure.
222
223	In the second form, the other port will be C<kil>'ed with C<@reason>, iff
224	a @reason was specified, i.e. on "normal" kils nothing happens, while
225	under all other conditions, the other port is killed with the same reason.
226
227	In the last form, a message of the form C<@msg, @reason> will be C<snd>.
228
229	Example: call a given callback when C<$port> is killed.
230
231	mon $port, sub { warn "port died because of <@_>\n" };
232
233	Example: kill ourselves when C<$port> is killed abnormally.
234
235	mon $port, $self;
236
237	Example: send us a restart message another C<$port> is killed.
238
239	mon $port, $self => "restart";
240
241	=cut
242
243	sub mon {
244	my ($noderef, $port) = split /#/, shift, 2;
245
246	my $node = $NODE{$noderef} \|\| add_node $noderef;
247
248	my $cb = shift;
249
250	unless (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 can be used either as a pattern	268	Create a new local port object that can be used either as a pattern
305	matching port ("full port") or a single-callback port ("miniport"),	269	matching port ("full port") or a single-callback port ("miniport"),
306	depending on how C<rcv> callbacks are bound to the object.	270	depending on how C<rcv> callbacks are bound to the object.
307		271
308	=item $portid = port { my @msg = @_; $finished }	272	=item $port = port { my @msg = @_; $finished }
309		273
310	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
311	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.
312		277
313	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
314	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
315	will be destroyed. Otherwise it will stay alive.	280	will be destroyed. Otherwise it will stay alive.
316		281
…		…
323	snd $otherport, reply => $port;	288	snd $otherport, reply => $port;
324	};	289	};
325		290
326	=cut	291	=cut
327		292
		293	sub rcv($@);
		294
328	sub port(;&) {	295	sub port(;&) {
329	my $id = "$UNIQ." . $ID++;	296	my $id = "$UNIQ." . $ID++;
330	my $port = "$NODE#$id";	297	my $port = "$NODE#$id";
331		298
332	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	=item reg $name
		311
		312	Registers the given port (or C<$SELF><<< if missing) under the name
		313	C<$name>. If the name already exists it is replaced.
		314
		315	A port can only be registered under one well known name.
		316
		317	A port automatically becomes unregistered when it is killed.
		318
		319	=cut
		320
		321	sub reg(@) {
		322	my $port = @_ > 1 ? shift : $SELF \|\| Carp::croak 'reg: called with one argument only, but $SELF not set,';
		323
		324	$REG{$_[0]} = $port;
		325	}
		326
		327	=item rcv $port, $callback->(@msg)
		328
		329	Replaces the callback on the specified miniport (after converting it to
		330	one if required).
		331
		332	=item rcv $port, tagstring => $callback->(@msg), ...
		333
		334	=item rcv $port, $smartmatch => $callback->(@msg), ...
		335
		336	=item rcv $port, [$smartmatch...] => $callback->(@msg), ...
		337
		338	Register callbacks to be called on matching messages on the given full
		339	port (after converting it to one if required) and return the port.
		340
		341	The callback has to return a true value when its work is done, after
		342	which is will be removed, or a false value in which case it will stay
		343	registered.
		344
		345	The global C<$SELF> (exported by this module) contains C<$port> while
		346	executing the callback.
		347
		348	Runtime errors wdurign callback execution will result in the port being
		349	C<kil>ed.
		350
		351	If the match is an array reference, then it will be matched against the
		352	first elements of the message, otherwise only the first element is being
		353	matched.
		354
		355	Any element in the match that is specified as C<_any_> (a function
		356	exported by this module) matches any single element of the message.
		357
		358	While not required, it is highly recommended that the first matching
		359	element is a string identifying the message. The one-string-only match is
		360	also the most efficient match (by far).
		361
		362	Example: create a port and bind receivers on it in one go.
		363
		364	my $port = rcv port,
		365	msg1 => sub { ...; 0 },
		366	msg2 => sub { ...; 0 },
		367	;
		368
		369	Example: create a port, bind receivers and send it in a message elsewhere
		370	in one go:
		371
		372	snd $otherport, reply =>
		373	rcv port,
		374	msg1 => sub { ...; 0 },
		375	...
		376	;
		377
		378	=cut
		379
		380	sub rcv($@) {
		381	my $port = shift;
		382	my ($noderef, $portid) = split /#/, $port, 2;
		383
		384	($NODE{$noderef} \|\| add_node $noderef) == $NODE{""}
		385	or Carp::croak "$port: rcv can only be called on local ports, caught";
		386
		387	if (@_ == 1) {
333	my $cb = shift;	388	my $cb = shift;
		389	delete $PORT_DATA{$portid};
334	$PORT{$id} = sub {	390	$PORT{$portid} = sub {
335	local $SELF = $port;	391	local $SELF = $port;
336	eval {	392	eval {
337	&$cb	393	&$cb
338	and kil $id;	394	and kil $port;
339	};	395	};
340	_self_die if $@;	396	_self_die if $@;
341	};	397	};
342	} else {	398	} else {
		399	my $self = $PORT_DATA{$portid} \|\|= do {
343	my $self = bless {	400	my $self = bless {
344	id => "$NODE#$id",	401	id => $port,
345	}, "AnyEvent::MP::Port";	402	}, "AnyEvent::MP::Port";
346		403
347	$PORT_DATA{$id} = $self;
348	$PORT{$id} = sub {	404	$PORT{$portid} = sub {
349	local $SELF = $port;	405	local $SELF = $port;
350		406
351	eval {	407	eval {
352	for (@{ $self->{rc0}{$_[0]} }) {	408	for (@{ $self->{rc0}{$_[0]} }) {
353	$_ && &{$_->[0]}	409	$_ && &{$_->[0]}
354	&& undef $_;	410	&& undef $_;
355	}	411	}
356		412
357	for (@{ $self->{rcv}{$_[0]} }) {	413	for (@{ $self->{rcv}{$_[0]} }) {
358	$_ && [@_[1 .. @{$_->[1]}]] ~~ $_->[1]	414	$_ && [@_[1 .. @{$_->[1]}]] ~~ $_->[1]
359	&& &{$_->[0]}	415	&& &{$_->[0]}
360	&& undef $_;	416	&& undef $_;
361	}	417	}
362		418
363	for (@{ $self->{any} }) {	419	for (@{ $self->{any} }) {
364	$_ && [@_[0 .. $#{$_->[1]}]] ~~ $_->[1]	420	$_ && [@_[0 .. $#{$_->[1]}]] ~~ $_->[1]
365	&& &{$_->[0]}	421	&& &{$_->[0]}
366	&& undef $_;	422	&& undef $_;
		423	}
367	}	424	};
		425	_self_die if $@;
368	};	426	};
369	_self_die if $@;	427
		428	$self
370	};	429	};
371	}
372		430
373	$port
374	}
375
376	=item reg $portid, $name
377
378	Registers the given port under the name C<$name>. If the name already
379	exists it is replaced.
380
381	A port can only be registered under one well known name.
382
383	A port automatically becomes unregistered when it is killed.
384
385	=cut
386
387	sub reg(@) {
388	my ($portid, $name) = @_;
389
390	$REG{$name} = $portid;
391	}
392
393	=item rcv $portid, $callback->(@msg)
394
395	Replaces the callback on the specified miniport (or newly created port
396	object, see C<port>). Full ports are configured with the following calls:
397
398	=item rcv $portid, tagstring => $callback->(@msg), ...
399
400	=item rcv $portid, $smartmatch => $callback->(@msg), ...
401
402	=item rcv $portid, [$smartmatch...] => $callback->(@msg), ...
403
404	Register callbacks to be called on matching messages on the given port.
405
406	The callback has to return a true value when its work is done, after
407	which is will be removed, or a false value in which case it will stay
408	registered.
409
410	The global C<$SELF> (exported by this module) contains C<$portid> while
411	executing the callback.
412
413	Runtime errors wdurign callback execution will result in the port being
414	C<kil>ed.
415
416	If the match is an array reference, then it will be matched against the
417	first elements of the message, otherwise only the first element is being
418	matched.
419
420	Any element in the match that is specified as C<_any_> (a function
421	exported by this module) matches any single element of the message.
422
423	While not required, it is highly recommended that the first matching
424	element is a string identifying the message. The one-string-only match is
425	also the most efficient match (by far).
426
427	=cut
428
429	sub rcv($@) {
430	my $portid = shift;
431	my ($noderef, $port) = split /#/, $port, 2;
432
433	($NODE{$noderef} \|\| add_node $noderef) == $NODE{""}
434	or Carp::croak "$noderef#$port: rcv can only be called on local ports, caught";
435
436	my $self = $PORT_DATA{$port}
437	or Carp::croak "$noderef#$port: rcv can only be called on message matching ports, caught";
438
439	"AnyEvent::MP::Port" eq ref $self	431	"AnyEvent::MP::Port" eq ref $self
440	or Carp::croak "$noderef#$port: rcv can only be called on message matching ports, caught";	432	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
441		433
442	while (@_) {	434	while (@_) {
443	my ($match, $cb) = splice @_, 0, 2;	435	my ($match, $cb) = splice @_, 0, 2;
444		436
445	if (!ref $match) {	437	if (!ref $match) {
446	push @{ $self->{rc0}{$match} }, [$cb];	438	push @{ $self->{rc0}{$match} }, [$cb];
447	} elsif (("ARRAY" eq ref $match && !ref $match->[0])) {	439	} elsif (("ARRAY" eq ref $match && !ref $match->[0])) {
448	my ($type, @match) = @$match;	440	my ($type, @match) = @$match;
449	@match	441	@match
450	? push @{ $self->{rcv}{$match->[0]} }, [$cb, \@match]	442	? push @{ $self->{rcv}{$match->[0]} }, [$cb, \@match]
451	: push @{ $self->{rc0}{$match->[0]} }, [$cb];	443	: push @{ $self->{rc0}{$match->[0]} }, [$cb];
452	} else {	444	} else {
453	push @{ $self->{any} }, [$cb, $match];	445	push @{ $self->{any} }, [$cb, $match];
		446	}
454	}	447	}
455	}	448	}
456		449
457	$portid	450	$port
458	}	451	}
459		452
460	=item $closure = psub { BLOCK }	453	=item $closure = psub { BLOCK }
461		454
462	Remembers C<$SELF> and creates a closure out of the BLOCK. When the	455	Remembers C<$SELF> and creates a closure out of the BLOCK. When the
…		…
493	$res	486	$res
494	}	487	}
495	}	488	}
496	}	489	}
497		490
498	=back	491	=item $guard = mon $port, $cb->(@reason)
499		492
500	=head1 FUNCTIONS FOR NODES	493	=item $guard = mon $port, $rcvport
501		494
502	=over 4	495	=item $guard = mon $port
503		496
504	=item become_public $noderef	497	=item $guard = mon $port, $rcvport, @msg
505		498
506	Tells the node to become a public node, i.e. reachable from other nodes.	499	Monitor the given port and do something when the port is killed, and
		500	optionally return a guard that can be used to stop monitoring again.
507		501
508	The first argument is the (unresolved) node reference of the local node	502	In the first form (callback), the callback is simply called with any
509	(if missing then the empty string is used).	503	number of C<@reason> elements (no @reason means that the port was deleted
		504	"normally"). Note also that I<< the callback B<must> never die >>, so use
		505	C<eval> if unsure.
510		506
511	It is quite common to not specify anything, in which case the local node	507	In the second form (another port given), the other port (C<$rcvport)
512	tries to listen on the default port, or to only specify a port number, in	508	will be C<kil>'ed with C<@reason>, iff a @reason was specified, i.e. on
513	which case AnyEvent::MP tries to guess the local addresses.	509	"normal" kils nothing happens, while under all other conditions, the other
		510	port is killed with the same reason.
514		511
		512	The third form (kill self) is the same as the second form, except that
		513	C<$rvport> defaults to C<$SELF>.
		514
		515	In the last form (message), a message of the form C<@msg, @reason> will be
		516	C<snd>.
		517
		518	Example: call a given callback when C<$port> is killed.
		519
		520	mon $port, sub { warn "port died because of <@_>\n" };
		521
		522	Example: kill ourselves when C<$port> is killed abnormally.
		523
		524	mon $port;
		525
		526	Example: send us a restart message when another C<$port> is killed.
		527
		528	mon $port, $self => "restart";
		529
515	=cut	530	=cut
		531
		532	sub mon {
		533	my ($noderef, $port) = split /#/, shift, 2;
		534
		535	my $node = $NODE{$noderef} \|\| add_node $noderef;
		536
		537	my $cb = @_ ? $_[0] : $SELF \|\| Carp::croak 'mon: called with one argument only, but $SELF not set,';
		538
		539	unless (ref $cb) {
		540	if (@_) {
		541	# send a kill info message
		542	my (@msg) = @_;
		543	$cb = sub { snd @msg, @_ };
		544	} else {
		545	# simply kill other port
		546	my $port = $cb;
		547	$cb = sub { kil $port, @_ if @_ };
		548	}
		549	}
		550
		551	$node->monitor ($port, $cb);
		552
		553	defined wantarray
		554	and AnyEvent::Util::guard { $node->unmonitor ($port, $cb) }
		555	}
		556
		557	=item $guard = mon_guard $port, $ref, $ref...
		558
		559	Monitors the given C<$port> and keeps the passed references. When the port
		560	is killed, the references will be freed.
		561
		562	Optionally returns a guard that will stop the monitoring.
		563
		564	This function is useful when you create e.g. timers or other watchers and
		565	want to free them when the port gets killed:
		566
		567	$port->rcv (start => sub {
		568	my $timer; $timer = mon_guard $port, AE::timer 1, 1, sub {
		569	undef $timer if 0.9 < rand;
		570	});
		571	});
		572
		573	=cut
		574
		575	sub mon_guard {
		576	my ($port, @refs) = @_;
		577
		578	#TODO: mon-less form?
		579
		580	mon $port, sub { 0 && @refs }
		581	}
		582
		583	=item lnk $port1, $port2
		584
		585	=item lnk $otherport
		586
		587	Link two ports. This is simply a shorthand for:
		588
		589	mon $port1, $port2;
		590	mon $port2, $port1;
		591
		592	It means that if either one is killed abnormally, the other one gets
		593	killed as well.
		594
		595	The one-argument form assumes that one port is C<$SELF>.
		596
		597	=cut
		598
		599	sub lnk {
		600	my $port1 = shift;
		601	my $port2 = @_ ? shift : $SELF \|\| Carp::croak 'lnk: called with one argument only, but $SELF not set,';
		602
		603	mon $port1, $port2;
		604	mon $port2, $port1;
		605	}
		606
		607	=item kil $port[, @reason]
		608
		609	Kill the specified port with the given C<@reason>.
		610
		611	If no C<@reason> is specified, then the port is killed "normally" (linked
		612	ports will not be kileld, or even notified).
		613
		614	Otherwise, linked ports get killed with the same reason (second form of
		615	C<mon>, see below).
		616
		617	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks
		618	will be reported as reason C<< die => $@ >>.
		619
		620	Transport/communication errors are reported as C<< transport_error =>
		621	$message >>.
516		622
517	=back	623	=back
518		624
519	=head1 NODE MESSAGES	625	=head1 NODE MESSAGES
520		626
…		…
562		668
563	=back	669	=back
564		670
565	=head1 AnyEvent::MP vs. Distributed Erlang	671	=head1 AnyEvent::MP vs. Distributed Erlang
566		672
567	AnyEvent::MP got lots of its ideas from distributed erlang (erlang node	673	AnyEvent::MP got lots of its ideas from distributed Erlang (Erlang node
568	== aemp node, erlang process == aemp port), so many of the documents and	674	== aemp node, Erlang process == aemp port), so many of the documents and
569	programming techniques employed by erlang apply to AnyEvent::MP. Here is a	675	programming techniques employed by Erlang apply to AnyEvent::MP. Here is a
570	sample:	676	sample:
571		677
572	http://www.erlang.se/doc/programming_rules.shtml	678	http://www.Erlang.se/doc/programming_rules.shtml
573	http://erlang.org/doc/getting_started/part_frame.html # chapters 3 and 4	679	http://Erlang.org/doc/getting_started/part_frame.html # chapters 3 and 4
574	http://erlang.org/download/erlang-book-part1.pdf # chapters 5 and 6	680	http://Erlang.org/download/Erlang-book-part1.pdf # chapters 5 and 6
575	http://erlang.org/download/armstrong_thesis_2003.pdf # chapters 4 and 5	681	http://Erlang.org/download/armstrong_thesis_2003.pdf # chapters 4 and 5
576		682
577	Despite the similarities, there are also some important differences:	683	Despite the similarities, there are also some important differences:
578		684
579	=over 4	685	=over 4
580		686
…		…
591		697
592	Erlang uses processes that selctively receive messages, and therefore	698	Erlang uses processes that selctively receive messages, and therefore
593	needs a queue. AEMP is event based, queuing messages would serve no useful	699	needs a queue. AEMP is event based, queuing messages would serve no useful
594	purpose.	700	purpose.
595		701
596	(But see L<Coro::MP> for a more erlang-like process model on top of AEMP).	702	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).
597		703
598	=item * Erlang sends are synchronous, AEMP sends are asynchronous.	704	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
599		705
600	Sending messages in erlang is synchronous and blocks the process. AEMP	706	Sending messages in Erlang is synchronous and blocks the process. AEMP
601	sends are immediate, connection establishment is handled in the	707	sends are immediate, connection establishment is handled in the
602	background.	708	background.
603		709
604	=item * Erlang can silently lose messages, AEMP cannot.	710	=item * Erlang can silently lose messages, AEMP cannot.
605		711
…		…
608	and c, and the other side only receives messages a and c).	714	and c, and the other side only receives messages a and c).
609		715
610	AEMP guarantees correct ordering, and the guarantee that there are no	716	AEMP guarantees correct ordering, and the guarantee that there are no
611	holes in the message sequence.	717	holes in the message sequence.
612		718
613	=item * In erlang, processes can be declared dead and later be found to be	719	=item * In Erlang, processes can be declared dead and later be found to be
614	alive.	720	alive.
615		721
616	In erlang it can happen that a monitored process is declared dead and	722	In Erlang it can happen that a monitored process is declared dead and
617	linked processes get killed, but later it turns out that the process is	723	linked processes get killed, but later it turns out that the process is
618	still alive - and can receive messages.	724	still alive - and can receive messages.
619		725
620	In AEMP, when port monitoring detects a port as dead, then that port will	726	In AEMP, when port monitoring detects a port as dead, then that port will
621	eventually be killed - it cannot happen that a node detects a port as dead	727	eventually be killed - it cannot happen that a node detects a port as dead
622	and then later sends messages to it, finding it is still alive.	728	and then later sends messages to it, finding it is still alive.
623		729
624	=item * Erlang can send messages to the wrong port, AEMP does not.	730	=item * Erlang can send messages to the wrong port, AEMP does not.
625		731
626	In erlang it is quite possible that a node that restarts reuses a process	732	In Erlang it is quite possible that a node that restarts reuses a process
627	ID known to other nodes for a completely different process, causing	733	ID known to other nodes for a completely different process, causing
628	messages destined for that process to end up in an unrelated process.	734	messages destined for that process to end up in an unrelated process.
629		735
630	AEMP never reuses port IDs, so old messages or old port IDs floating	736	AEMP never reuses port IDs, so old messages or old port IDs floating
631	around in the network will not be sent to an unrelated port.	737	around in the network will not be sent to an unrelated port.
…		…
637	securely authenticate nodes.	743	securely authenticate nodes.
638		744
639	=item * The AEMP protocol is optimised for both text-based and binary	745	=item * The AEMP protocol is optimised for both text-based and binary
640	communications.	746	communications.
641		747
642	The AEMP protocol, unlike the erlang protocol, supports both	748	The AEMP protocol, unlike the Erlang protocol, supports both
643	language-independent text-only protocols (good for debugging) and binary,	749	language-independent text-only protocols (good for debugging) and binary,
644	language-specific serialisers (e.g. Storable).	750	language-specific serialisers (e.g. Storable).
645		751
646	It has also been carefully designed to be implementable in other languages	752	It has also been carefully designed to be implementable in other languages
647	with a minimum of work while gracefully degrading fucntionality to make the	753	with a minimum of work while gracefully degrading fucntionality to make the
648	protocol simple.	754	protocol simple.
649		755
		756	=item * AEMP has more flexible monitoring options than Erlang.
		757
		758	In Erlang, you can chose to receive I<all> exit signals as messages
		759	or I<none>, there is no in-between, so monitoring single processes is
		760	difficult to implement. Monitoring in AEMP is more flexible than in
		761	Erlang, as one can choose between automatic kill, exit message or callback
		762	on a per-process basis.
		763
		764	=item * Erlang has different semantics for monitoring and linking, AEMP has the same.
		765
		766	Monitoring in Erlang is not an indicator of process death/crashes,
		767	as linking is (except linking is unreliable in Erlang). In AEMP, the
		768	semantics of monitoring and linking are identical, linking is simply
		769	two-way monitoring with automatic kill.
		770
650	=back	771	=back
651		772
652	=head1 SEE ALSO	773	=head1 SEE ALSO
653		774
654	L<AnyEvent>.	775	L<AnyEvent>.

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Revision 1.36 by root, Thu Aug 6 10:46:48 2009 UTC