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

Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.77 by elmex, Thu Sep 3 07:57:30 2009 UTC vs.
Revision 1.111 by root, Sat Mar 20 20:12:18 2010 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 prot 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 API, 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
…		…
61		71
62	=over 4	72	=over 4
63		73
64	=item port	74	=item port
65		75
66	A port is something you can send messages to (with the C<snd> function).	76	Not to be confused with a TCP port, a "port" is something you can send
		77	messages to (with the C<snd> function).
67		78
68	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
69	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
70	anything was listening for them or not.	81	anything was listening for them or not.
71		82
…		…
82		93
83	Nodes are either public (have one or more listening ports) or private	94	Nodes are either public (have one or more listening ports) or private
84	(no listening ports). Private nodes cannot talk to other private nodes	95	(no listening ports). Private nodes cannot talk to other private nodes
85	currently.	96	currently.
86		97
87	=item node ID - C<[a-za-Z0-9_\-.:]+>	98	=item node ID - C<[A-Z_][a-zA-Z0-9_\-.:]*>
88		99
89	A node ID is a string that uniquely identifies the node within a	100	A node ID is a string that uniquely identifies the node within a
90	network. Depending on the configuration used, node IDs can look like a	101	network. Depending on the configuration used, node IDs can look like a
91	hostname, a hostname and a port, or a random string. AnyEvent::MP itself	102	hostname, a hostname and a port, or a random string. AnyEvent::MP itself
92	doesn't interpret node IDs in any way.	103	doesn't interpret node IDs in any way.
…		…
96	Nodes can only talk to each other by creating some kind of connection to	107	Nodes can only talk to each other by creating some kind of connection to
97	each other. To do this, nodes should listen on one or more local transport	108	each other. To do this, nodes should listen on one or more local transport
98	endpoints - binds. Currently, only standard C<ip:port> specifications can	109	endpoints - binds. Currently, only standard C<ip:port> specifications can
99	be used, which specify TCP ports to listen on.	110	be used, which specify TCP ports to listen on.
100		111
101	=item seeds - C<host:port>	112	=item seed nodes
102		113
103	When a node starts, it knows nothing about the network. To teach the node	114	When a node starts, it knows nothing about the network. To teach the node
104	about the network it first has to contact some other node within the	115	about the network it first has to contact some other node within the
105	network. This node is called a seed.	116	network. This node is called a seed.
106		117
107	Seeds are transport endpoint(s) of as many nodes as one wants. Those nodes	118	Apart from the fact that other nodes know them as seed nodes and they have
		119	to have fixed listening addresses, seed nodes are perfectly normal nodes -
		120	any node can function as a seed node for others.
		121
		122	In addition to discovering the network, seed nodes are also used to
		123	maintain the network and to connect nodes that otherwise would have
		124	trouble connecting. They form the backbone of an AnyEvent::MP network.
		125
108	are expected to be long-running, and at least one of those should always	126	Seed nodes are expected to be long-running, and at least one seed node
109	be available. When nodes run out of connections (e.g. due to a network	127	should always be available. They should also be relatively responsive - a
110	error), they try to re-establish connections to some seednodes again to	128	seed node that blocks for long periods will slow down everybody else.
111	join the network.
112		129
113	Apart from being sued for seeding, seednodes are not special in any way -	130	=item seeds - C<host:port>
114	every public node can be a seednode.	131
		132	Seeds are transport endpoint(s) (usually a hostname/IP address and a
		133	TCP port) of nodes that should be used as seed nodes.
		134
		135	The nodes listening on those endpoints are expected to be long-running,
		136	and at least one of those should always be available. When nodes run out
		137	of connections (e.g. due to a network error), they try to re-establish
		138	connections to some seednodes again to join the network.
115		139
116	=back	140	=back
117		141
118	=head1 VARIABLES/FUNCTIONS	142	=head1 VARIABLES/FUNCTIONS
119		143
…		…
131		155
132	use AE ();	156	use AE ();
133		157
134	use base "Exporter";	158	use base "Exporter";
135		159
136	our $VERSION = $AnyEvent::MP::Kernel::VERSION;	160	our $VERSION = 1.27;
137		161
138	our @EXPORT = qw(	162	our @EXPORT = qw(
139	NODE $NODE *SELF node_of after	163	NODE $NODE *SELF node_of after
140	configure	164	configure
141	snd rcv mon mon_guard kil reg psub spawn	165	snd rcv mon mon_guard kil psub peval spawn cal
142	port	166	port
143	);	167	);
144		168
145	our $SELF;	169	our $SELF;
146		170
…		…
158		182
159	=item $nodeid = node_of $port	183	=item $nodeid = node_of $port
160		184
161	Extracts and returns the node ID from a port ID or a node ID.	185	Extracts and returns the node ID from a port ID or a node ID.
162		186
		187	=item configure $profile, key => value...
		188
163	=item configure key => value...	189	=item configure key => value...
164		190
165	Before a node can talk to other nodes on the network (i.e. enter	191	Before a node can talk to other nodes on the network (i.e. enter
166	"distributed mode") it has to configure itself - the minimum a node needs	192	"distributed mode") it has to configure itself - the minimum a node needs
167	to know is its own name, and optionally it should know the addresses of	193	to know is its own name, and optionally it should know the addresses of
168	some other nodes in the network to discover other nodes.	194	some other nodes in the network to discover other nodes.
169		195
		196	The key/value pairs are basically the same ones as documented for the
		197	F<aemp> command line utility (sans the set/del prefix).
		198
170	This function configures a node - it must be called exactly once (or	199	This function configures a node - it must be called exactly once (or
171	never) before calling other AnyEvent::MP functions.	200	never) before calling other AnyEvent::MP functions.
172		201
173	=over 4	202	=over 4
174		203
175	=item step 1, gathering configuration from profiles	204	=item step 1, gathering configuration from profiles
176		205
177	The function first looks up a profile in the aemp configuration (see the	206	The function first looks up a profile in the aemp configuration (see the
178	L<aemp> commandline utility). The profile name can be specified via the	207	L<aemp> commandline utility). The profile name can be specified via the
179	named C<profile> parameter. If it is missing, then the nodename (F<uname	208	named C<profile> parameter or can simply be the first parameter). If it is
180	-n>) will be used as profile name.	209	missing, then the nodename (F<uname -n>) will be used as profile name.
181		210
182	The profile data is then gathered as follows:	211	The profile data is then gathered as follows:
183		212
184	First, all remaining key => value pairs (all of which are conveniently	213	First, all remaining key => value pairs (all of which are conveniently
185	undocumented at the moment) will be interpreted as configuration	214	undocumented at the moment) will be interpreted as configuration
…		…
213	L<AnyEvent::MP::Global> module, which will then use it to keep	242	L<AnyEvent::MP::Global> module, which will then use it to keep
214	connectivity with at least one node at any point in time.	243	connectivity with at least one node at any point in time.
215		244
216	=back	245	=back
217		246
218	Example: become a distributed node using the locla node name as profile.	247	Example: become a distributed node using the local node name as profile.
219	This should be the most common form of invocation for "daemon"-type nodes.	248	This should be the most common form of invocation for "daemon"-type nodes.
220		249
221	configure	250	configure
222		251
223	Example: become an anonymous node. This form is often used for commandline	252	Example: become an anonymous node. This form is often used for commandline
…		…
357	msg1 => sub { ... },	386	msg1 => sub { ... },
358	...	387	...
359	;	388	;
360		389
361	Example: temporarily register a rcv callback for a tag matching some port	390	Example: temporarily register a rcv callback for a tag matching some port
362	(e.g. for a rpc reply) and unregister it after a message was received.	391	(e.g. for an rpc reply) and unregister it after a message was received.
363		392
364	rcv $port, $otherport => sub {	393	rcv $port, $otherport => sub {
365	my @reply = @_;	394	my @reply = @_;
366		395
367	rcv $SELF, $otherport;	396	rcv $SELF, $otherport;
…		…
380	if (ref $_[0]) {	409	if (ref $_[0]) {
381	if (my $self = $PORT_DATA{$portid}) {	410	if (my $self = $PORT_DATA{$portid}) {
382	"AnyEvent::MP::Port" eq ref $self	411	"AnyEvent::MP::Port" eq ref $self
383	or Carp::croak "$port: rcv can only be called on message matching ports, caught";	412	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
384		413
385	$self->[2] = shift;	414	$self->[0] = shift;
386	} else {	415	} else {
387	my $cb = shift;	416	my $cb = shift;
388	$PORT{$portid} = sub {	417	$PORT{$portid} = sub {
389	local $SELF = $port;	418	local $SELF = $port;
390	eval { &$cb }; _self_die if $@;	419	eval { &$cb }; _self_die if $@;
391	};	420	};
392	}	421	}
393	} elsif (defined $_[0]) {	422	} elsif (defined $_[0]) {
394	my $self = $PORT_DATA{$portid} \|\|= do {	423	my $self = $PORT_DATA{$portid} \|\|= do {
395	my $self = bless [$PORT{$port} \|\| sub { }, { }, $port], "AnyEvent::MP::Port";	424	my $self = bless [$PORT{$portid} \|\| sub { }, { }, $port], "AnyEvent::MP::Port";
396		425
397	$PORT{$portid} = sub {	426	$PORT{$portid} = sub {
398	local $SELF = $port;	427	local $SELF = $port;
399		428
400	if (my $cb = $self->[1]{$_[0]}) {	429	if (my $cb = $self->[1]{$_[0]}) {
…		…
422	}	451	}
423		452
424	$port	453	$port
425	}	454	}
426		455
		456	=item peval $port, $coderef[, @args]
		457
		458	Evaluates the given C<$codref> within the contetx of C<$port>, that is,
		459	when the code throews an exception the C<$port> will be killed.
		460
		461	Any remaining args will be passed to the callback. Any return values will
		462	be returned to the caller.
		463
		464	This is useful when you temporarily want to execute code in the context of
		465	a port.
		466
		467	Example: create a port and run some initialisation code in it's context.
		468
		469	my $port = port { ... };
		470
		471	peval $port, sub {
		472	init
		473	or die "unable to init";
		474	};
		475
		476	=cut
		477
		478	sub peval($$) {
		479	local $SELF = shift;
		480	my $cb = shift;
		481
		482	if (wantarray) {
		483	my @res = eval { &$cb };
		484	_self_die if $@;
		485	@res
		486	} else {
		487	my $res = eval { &$cb };
		488	_self_die if $@;
		489	$res
		490	}
		491	}
		492
427	=item $closure = psub { BLOCK }	493	=item $closure = psub { BLOCK }
428		494
429	Remembers C<$SELF> and creates a closure out of the BLOCK. When the	495	Remembers C<$SELF> and creates a closure out of the BLOCK. When the
430	closure is executed, sets up the environment in the same way as in C<rcv>	496	closure is executed, sets up the environment in the same way as in C<rcv>
431	callbacks, i.e. runtime errors will cause the port to get C<kil>ed.	497	callbacks, i.e. runtime errors will cause the port to get C<kil>ed.
		498
		499	The effect is basically as if it returned C<< sub { peval $SELF, sub {
		500	BLOCK } } >>.
432		501
433	This is useful when you register callbacks from C<rcv> callbacks:	502	This is useful when you register callbacks from C<rcv> callbacks:
434		503
435	rcv delayed_reply => sub {	504	rcv delayed_reply => sub {
436	my ($delay, @reply) = @_;	505	my ($delay, @reply) = @_;
…		…
472		541
473	Monitor the given port and do something when the port is killed or	542	Monitor the given port and do something when the port is killed or
474	messages to it were lost, and optionally return a guard that can be used	543	messages to it were lost, and optionally return a guard that can be used
475	to stop monitoring again.	544	to stop monitoring again.
476		545
		546	In the first form (callback), the callback is simply called with any
		547	number of C<@reason> elements (no @reason means that the port was deleted
		548	"normally"). Note also that I<< the callback B<must> never die >>, so use
		549	C<eval> if unsure.
		550
		551	In the second form (another port given), the other port (C<$rcvport>)
		552	will be C<kil>'ed with C<@reason>, if a @reason was specified, i.e. on
		553	"normal" kils nothing happens, while under all other conditions, the other
		554	port is killed with the same reason.
		555
		556	The third form (kill self) is the same as the second form, except that
		557	C<$rvport> defaults to C<$SELF>.
		558
		559	In the last form (message), a message of the form C<@msg, @reason> will be
		560	C<snd>.
		561
		562	Monitoring-actions are one-shot: once messages are lost (and a monitoring
		563	alert was raised), they are removed and will not trigger again.
		564
		565	As a rule of thumb, monitoring requests should always monitor a port from
		566	a local port (or callback). The reason is that kill messages might get
		567	lost, just like any other message. Another less obvious reason is that
		568	even monitoring requests can get lost (for example, when the connection
		569	to the other node goes down permanently). When monitoring a port locally
		570	these problems do not exist.
		571
477	C<mon> effectively guarantees that, in the absence of hardware failures,	572	C<mon> effectively guarantees that, in the absence of hardware failures,
478	after starting the monitor, either all messages sent to the port will	573	after starting the monitor, either all messages sent to the port will
479	arrive, or the monitoring action will be invoked after possible message	574	arrive, or the monitoring action will be invoked after possible message
480	loss has been detected. No messages will be lost "in between" (after	575	loss has been detected. No messages will be lost "in between" (after
481	the first lost message no further messages will be received by the	576	the first lost message no further messages will be received by the
482	port). After the monitoring action was invoked, further messages might get	577	port). After the monitoring action was invoked, further messages might get
483	delivered again.	578	delivered again.
484		579
485	Note that monitoring-actions are one-shot: once messages are lost (and a	580	Inter-host-connection timeouts and monitoring depend on the transport
486	monitoring alert was raised), they are removed and will not trigger again.	581	used. The only transport currently implemented is TCP, and AnyEvent::MP
		582	relies on TCP to detect node-downs (this can take 10-15 minutes on a
		583	non-idle connection, and usually around two hours for idle connections).
487		584
488	In the first form (callback), the callback is simply called with any	585	This means that monitoring is good for program errors and cleaning up
489	number of C<@reason> elements (no @reason means that the port was deleted	586	stuff eventually, but they are no replacement for a timeout when you need
490	"normally"). Note also that I<< the callback B<must> never die >>, so use	587	to ensure some maximum latency.
491	C<eval> if unsure.
492
493	In the second form (another port given), the other port (C<$rcvport>)
494	will be C<kil>'ed with C<@reason>, if a @reason was specified, i.e. on
495	"normal" kils nothing happens, while under all other conditions, the other
496	port is killed with the same reason.
497
498	The third form (kill self) is the same as the second form, except that
499	C<$rvport> defaults to C<$SELF>.
500
501	In the last form (message), a message of the form C<@msg, @reason> will be
502	C<snd>.
503
504	As a rule of thumb, monitoring requests should always monitor a port from
505	a local port (or callback). The reason is that kill messages might get
506	lost, just like any other message. Another less obvious reason is that
507	even monitoring requests can get lost (for example, when the connection
508	to the other node goes down permanently). When monitoring a port locally
509	these problems do not exist.
510		588
511	Example: call a given callback when C<$port> is killed.	589	Example: call a given callback when C<$port> is killed.
512		590
513	mon $port, sub { warn "port died because of <@_>\n" };	591	mon $port, sub { warn "port died because of <@_>\n" };
514		592
…		…
542	}	620	}
543		621
544	$node->monitor ($port, $cb);	622	$node->monitor ($port, $cb);
545		623
546	defined wantarray	624	defined wantarray
547	and AnyEvent::Util::guard { $node->unmonitor ($port, $cb) }	625	and ($cb += 0, AnyEvent::Util::guard { $node->unmonitor ($port, $cb) })
548	}	626	}
549		627
550	=item $guard = mon_guard $port, $ref, $ref...	628	=item $guard = mon_guard $port, $ref, $ref...
551		629
552	Monitors the given C<$port> and keeps the passed references. When the port	630	Monitors the given C<$port> and keeps the passed references. When the port
…		…
575		653
576	=item kil $port[, @reason]	654	=item kil $port[, @reason]
577		655
578	Kill the specified port with the given C<@reason>.	656	Kill the specified port with the given C<@reason>.
579		657
580	If no C<@reason> is specified, then the port is killed "normally" (ports	658	If no C<@reason> is specified, then the port is killed "normally" -
581	monitoring other ports will not necessarily die because a port dies	659	monitor callback will be invoked, but the kil will not cause linked ports
582	"normally").	660	(C<mon $mport, $lport> form) to get killed.
583		661
584	Otherwise, linked ports get killed with the same reason (second form of	662	If a C<@reason> is specified, then linked ports (C<mon $mport, $lport>
585	C<mon>, see above).	663	form) get killed with the same reason.
586		664
587	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks	665	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks
588	will be reported as reason C<< die => $@ >>.	666	will be reported as reason C<< die => $@ >>.
589		667
590	Transport/communication errors are reported as C<< transport_error =>	668	Transport/communication errors are reported as C<< transport_error =>
…		…
609	the package, then the package above the package and so on (e.g.	687	the package, then the package above the package and so on (e.g.
610	C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function	688	C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function
611	exists or it runs out of package names.	689	exists or it runs out of package names.
612		690
613	The init function is then called with the newly-created port as context	691	The init function is then called with the newly-created port as context
614	object (C<$SELF>) and the C<@initdata> values as arguments.	692	object (C<$SELF>) and the C<@initdata> values as arguments. It I<must>
		693	call one of the C<rcv> functions to set callbacks on C<$SELF>, otherwise
		694	the port might not get created.
615		695
616	A common idiom is to pass a local port, immediately monitor the spawned	696	A common idiom is to pass a local port, immediately monitor the spawned
617	port, and in the remote init function, immediately monitor the passed	697	port, and in the remote init function, immediately monitor the passed
618	local port. This two-way monitoring ensures that both ports get cleaned up	698	local port. This two-way monitoring ensures that both ports get cleaned up
619	when there is a problem.	699	when there is a problem.
620		700
		701	C<spawn> guarantees that the C<$initfunc> has no visible effects on the
		702	caller before C<spawn> returns (by delaying invocation when spawn is
		703	called for the local node).
		704
621	Example: spawn a chat server port on C<$othernode>.	705	Example: spawn a chat server port on C<$othernode>.
622		706
623	# this node, executed from within a port context:	707	# this node, executed from within a port context:
624	my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF;	708	my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF;
625	mon $server;	709	mon $server;
…		…
639		723
640	sub _spawn {	724	sub _spawn {
641	my $port = shift;	725	my $port = shift;
642	my $init = shift;	726	my $init = shift;
643		727
		728	# rcv will create the actual port
644	local $SELF = "$NODE#$port";	729	local $SELF = "$NODE#$port";
645	eval {	730	eval {
646	&{ load_func $init }	731	&{ load_func $init }
647	};	732	};
648	_self_die if $@;	733	_self_die if $@;
…		…
683	? $action[0]()	768	? $action[0]()
684	: snd @action;	769	: snd @action;
685	};	770	};
686	}	771	}
687		772
		773	=item cal $port, @msg, $callback[, $timeout]
		774
		775	A simple form of RPC - sends a message to the given C<$port> with the
		776	given contents (C<@msg>), but adds a reply port to the message.
		777
		778	The reply port is created temporarily just for the purpose of receiving
		779	the reply, and will be C<kil>ed when no longer needed.
		780
		781	A reply message sent to the port is passed to the C<$callback> as-is.
		782
		783	If an optional time-out (in seconds) is given and it is not C<undef>,
		784	then the callback will be called without any arguments after the time-out
		785	elapsed and the port is C<kil>ed.
		786
		787	If no time-out is given (or it is C<undef>), then the local port will
		788	monitor the remote port instead, so it eventually gets cleaned-up.
		789
		790	Currently this function returns the temporary port, but this "feature"
		791	might go in future versions unless you can make a convincing case that
		792	this is indeed useful for something.
		793
		794	=cut
		795
		796	sub cal(@) {
		797	my $timeout = ref $_[-1] ? undef : pop;
		798	my $cb = pop;
		799
		800	my $port = port {
		801	undef $timeout;
		802	kil $SELF;
		803	&$cb;
		804	};
		805
		806	if (defined $timeout) {
		807	$timeout = AE::timer $timeout, 0, sub {
		808	undef $timeout;
		809	kil $port;
		810	$cb->();
		811	};
		812	} else {
		813	mon $_[0], sub {
		814	kil $port;
		815	$cb->();
		816	};
		817	}
		818
		819	push @_, $port;
		820	&snd;
		821
		822	$port
		823	}
		824
688	=back	825	=back
689		826
690	=head1 AnyEvent::MP vs. Distributed Erlang	827	=head1 AnyEvent::MP vs. Distributed Erlang
691		828
692	AnyEvent::MP got lots of its ideas from distributed Erlang (Erlang node	829	AnyEvent::MP got lots of its ideas from distributed Erlang (Erlang node
693	== aemp node, Erlang process == aemp port), so many of the documents and	830	== aemp node, Erlang process == aemp port), so many of the documents and
694	programming techniques employed by Erlang apply to AnyEvent::MP. Here is a	831	programming techniques employed by Erlang apply to AnyEvent::MP. Here is a
695	sample:	832	sample:
696		833
697	http://www.Erlang.se/doc/programming_rules.shtml	834	http://www.erlang.se/doc/programming_rules.shtml
698	http://Erlang.org/doc/getting_started/part_frame.html # chapters 3 and 4	835	http://erlang.org/doc/getting_started/part_frame.html # chapters 3 and 4
699	http://Erlang.org/download/Erlang-book-part1.pdf # chapters 5 and 6	836	http://erlang.org/download/erlang-book-part1.pdf # chapters 5 and 6
700	http://Erlang.org/download/armstrong_thesis_2003.pdf # chapters 4 and 5	837	http://erlang.org/download/armstrong_thesis_2003.pdf # chapters 4 and 5
701		838
702	Despite the similarities, there are also some important differences:	839	Despite the similarities, there are also some important differences:
703		840
704	=over 4	841	=over 4
705		842
706	=item * Node IDs are arbitrary strings in AEMP.	843	=item * Node IDs are arbitrary strings in AEMP.
707		844
708	Erlang relies on special naming and DNS to work everywhere in the same	845	Erlang relies on special naming and DNS to work everywhere in the same
709	way. AEMP relies on each node somehow knowing its own address(es) (e.g. by	846	way. AEMP relies on each node somehow knowing its own address(es) (e.g. by
710	configuration or DNS), but will otherwise discover other odes itself.	847	configuration or DNS), and possibly the addresses of some seed nodes, but
		848	will otherwise discover other nodes (and their IDs) itself.
711		849
712	=item * Erlang has a "remote ports are like local ports" philosophy, AEMP	850	=item * Erlang has a "remote ports are like local ports" philosophy, AEMP
713	uses "local ports are like remote ports".	851	uses "local ports are like remote ports".
714		852
715	The failure modes for local ports are quite different (runtime errors	853	The failure modes for local ports are quite different (runtime errors
…		…
740	so does not need a queue that can overflow). AEMP sends are immediate,	878	so does not need a queue that can overflow). AEMP sends are immediate,
741	connection establishment is handled in the background.	879	connection establishment is handled in the background.
742		880
743	=item * Erlang suffers from silent message loss, AEMP does not.	881	=item * Erlang suffers from silent message loss, AEMP does not.
744		882
745	Erlang makes few guarantees on messages delivery - messages can get lost	883	Erlang implements few guarantees on messages delivery - messages can get
746	without any of the processes realising it (i.e. you send messages a, b,	884	lost without any of the processes realising it (i.e. you send messages a,
747	and c, and the other side only receives messages a and c).	885	b, and c, and the other side only receives messages a and c).
748		886
749	AEMP guarantees correct ordering, and the guarantee that after one message	887	AEMP guarantees correct ordering, and the guarantee that after one message
750	is lost, all following ones sent to the same port are lost as well, until	888	is lost, all following ones sent to the same port are lost as well, until
751	monitoring raises an error, so there are no silent "holes" in the message	889	monitoring raises an error, so there are no silent "holes" in the message
752	sequence.	890	sequence.
…		…
814	overhead, as well as having to keep a proxy object everywhere.	952	overhead, as well as having to keep a proxy object everywhere.
815		953
816	Strings can easily be printed, easily serialised etc. and need no special	954	Strings can easily be printed, easily serialised etc. and need no special
817	procedures to be "valid".	955	procedures to be "valid".
818		956
819	And as a result, a miniport consists of a single closure stored in a	957	And as a result, a port with just a default receiver consists of a single
820	global hash - it can't become much cheaper.	958	closure stored in a global hash - it can't become much cheaper.
821		959
822	=item Why favour JSON, why not a real serialising format such as Storable?	960	=item Why favour JSON, why not a real serialising format such as Storable?
823		961
824	In fact, any AnyEvent::MP node will happily accept Storable as framing	962	In fact, any AnyEvent::MP node will happily accept Storable as framing
825	format, but currently there is no way to make a node use Storable by	963	format, but currently there is no way to make a node use Storable by
…		…
844	L<AnyEvent::MP::Kernel> - more, lower-level, stuff.	982	L<AnyEvent::MP::Kernel> - more, lower-level, stuff.
845		983
846	L<AnyEvent::MP::Global> - network maintainance and port groups, to find	984	L<AnyEvent::MP::Global> - network maintainance and port groups, to find
847	your applications.	985	your applications.
848		986
		987	L<AnyEvent::MP::DataConn> - establish data connections between nodes.
		988
		989	L<AnyEvent::MP::LogCatcher> - simple service to display log messages from
		990	all nodes.
		991
849	L<AnyEvent>.	992	L<AnyEvent>.
850		993
851	=head1 AUTHOR	994	=head1 AUTHOR
852		995
853	Marc Lehmann <schmorp@schmorp.de>	996	Marc Lehmann <schmorp@schmorp.de>

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Comparing AnyEvent-MP/MP.pm (file contents): Revision 1.77 by elmex, Thu Sep 3 07:57:30 2009 UTC vs. Revision 1.111 by root, Sat Mar 20 20:12:18 2010 UTC

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Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.77 by elmex, Thu Sep 3 07:57:30 2009 UTC vs.
Revision 1.111 by root, Sat Mar 20 20:12:18 2010 UTC