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

Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.36 by root, Thu Aug 6 10:46:48 2009 UTC vs.
Revision 1.91 by root, Tue Sep 22 09:54:42 2009 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
9	$NODE # contains this node's noderef	9	$NODE # contains this node's node ID
10	NODE # returns this node's noderef	10	NODE # returns this node's node ID
11	NODE $port # returns the noderef of the port
12		11
		12	$SELF # receiving/own port id in rcv callbacks
		13
		14	# initialise the node so it can send/receive messages
		15	configure;
		16
		17	# ports are message destinations
		18
		19	# sending messages
13	snd $port, type => data...;	20	snd $port, type => data...;
		21	snd $port, @msg;
		22	snd @msg_with_first_element_being_a_port;
14		23
15	$SELF # receiving/own port id in rcv callbacks	24	# creating/using ports, the simple way
		25	my $simple_port = port { my @msg = @_ };
16		26
17	rcv $port, smartmatch => $cb->($port, @msg);	27	# creating/using ports, tagged message matching
18		28	my $port = port;
19	# examples:
20	rcv $port2, ping => sub { snd $_[0], "pong"; 0 };	29	rcv $port, ping => sub { snd $_[0], "pong" };
21	rcv $port1, pong => sub { warn "pong received\n" };	30	rcv $port, pong => sub { warn "pong received\n" };
22	snd $port2, ping => $port1;
23		31
24	# more, smarter, matches (_any_ is exported by this module)	32	# create a port on another node
25	rcv $port, [child_died => $pid] => sub { ...	33	my $port = spawn $node, $initfunc, @initdata;
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		34
31	# monitoring	35	# monitoring
32	mon $port, $cb->(@msg) # callback is invoked on death	36	mon $localport, $cb->(@msg) # callback is invoked on death
33	mon $port, $otherport # kill otherport on abnormal death	37	mon $localport, $otherport # kill otherport on abnormal death
34	mon $port, $otherport, @msg # send message on death	38	mon $localport, $otherport, @msg # send message on death
		39
		40	=head1 CURRENT STATUS
		41
		42	bin/aemp - stable.
		43	AnyEvent::MP - stable API, should work.
		44	AnyEvent::MP::Intro - explains most concepts.
		45	AnyEvent::MP::Kernel - mostly stable API.
		46	AnyEvent::MP::Global - stable API.
35		47
36	=head1 DESCRIPTION	48	=head1 DESCRIPTION
37		49
38	This module (-family) implements a simple message passing framework.	50	This module (-family) implements a simple message passing framework.
39		51
40	Despite its simplicity, you can securely message other processes running	52	Despite its simplicity, you can securely message other processes running
41	on the same or other hosts.	53	on the same or other hosts, and you can supervise entities remotely.
42		54
43	For an introduction to this module family, see the L<AnyEvent::MP::Intro>	55	For an introduction to this module family, see the L<AnyEvent::MP::Intro>
44	manual page.	56	manual page and the examples under F<eg/>.
45
46	At the moment, this module family is severly broken and underdocumented,
47	so do not use. This was uploaded mainly to reserve the CPAN namespace -
48	stay tuned! The basic API should be finished, however.
49		57
50	=head1 CONCEPTS	58	=head1 CONCEPTS
51		59
52	=over 4	60	=over 4
53		61
54	=item port	62	=item port
55		63
56	A port is something you can send messages to (with the C<snd> function).	64	Not to be confused with a TCP port, a "port" is something you can send
		65	messages to (with the C<snd> function).
57		66
58	Some ports allow you to register C<rcv> handlers that can match specific	67	Ports allow you to register C<rcv> handlers that can match all or just
59	messages. All C<rcv> handlers will receive messages they match, messages	68	some messages. Messages send to ports will not be queued, regardless of
60	will not be queued.	69	anything was listening for them or not.
61		70
62	=item port id - C<noderef#portname>	71	=item port ID - C<nodeid#portname>
63		72
64	A port id is normaly the concatenation of a noderef, a hash-mark (C<#>) as	73	A port ID is the concatenation of a node ID, a hash-mark (C<#>) as
65	separator, and a port name (a printable string of unspecified format). An	74	separator, and a port name (a printable string of unspecified format).
66	exception is the the node port, whose ID is identical to its node
67	reference.
68		75
69	=item node	76	=item node
70		77
71	A node is a single process containing at least one port - the node	78	A node is a single process containing at least one port - the node port,
72	port. You can send messages to node ports to find existing ports or to	79	which enables nodes to manage each other remotely, and to create new
73	create new ports, among other things.	80	ports.
74		81
75	Nodes are either private (single-process only), slaves (connected to a	82	Nodes are either public (have one or more listening ports) or private
76	master node only) or public nodes (connectable from unrelated nodes).	83	(no listening ports). Private nodes cannot talk to other private nodes
		84	currently.
77		85
78	=item noderef - C<host:port,host:port...>, C<id@noderef>, C<id>	86	=item node ID - C<[A-Z_][a-zA-Z0-9_\-.:]*>
79		87
80	A node reference is a string that either simply identifies the node (for	88	A node ID is a string that uniquely identifies the node within a
81	private and slave nodes), or contains a recipe on how to reach a given	89	network. Depending on the configuration used, node IDs can look like a
82	node (for public nodes).	90	hostname, a hostname and a port, or a random string. AnyEvent::MP itself
		91	doesn't interpret node IDs in any way.
83		92
84	This recipe is simply a comma-separated list of C<address:port> pairs (for	93	=item binds - C<ip:port>
85	TCP/IP, other protocols might look different).
86		94
87	Node references come in two flavours: resolved (containing only numerical	95	Nodes can only talk to each other by creating some kind of connection to
88	addresses) or unresolved (where hostnames are used instead of addresses).	96	each other. To do this, nodes should listen on one or more local transport
		97	endpoints - binds. Currently, only standard C<ip:port> specifications can
		98	be used, which specify TCP ports to listen on.
89		99
90	Before using an unresolved node reference in a message you first have to	100	=item seed nodes
91	resolve it.	101
		102	When a node starts, it knows nothing about the network. To teach the node
		103	about the network it first has to contact some other node within the
		104	network. This node is called a seed.
		105
		106	Apart from the fact that other nodes know them as seed nodes and they have
		107	to have fixed listening addresses, seed nodes are perfectly normal nodes -
		108	any node can function as a seed node for others.
		109
		110	In addition to discovering the network, seed nodes are also used to
		111	maintain the network and to connect nodes that otherwise would have
		112	trouble connecting. They form the backbone of an AnyEvent::MP network.
		113
		114	Seed nodes are expected to be long-running, and at least one seed node
		115	should always be available. They should also be relatively responsive - a
		116	seed node that blocks for long periods will slow down everybody else.
		117
		118	=item seeds - C<host:port>
		119
		120	Seeds are transport endpoint(s) (usually a hostname/IP address and a
		121	TCP port) of nodes thta should be used as seed nodes.
		122
		123	The nodes listening on those endpoints are expected to be long-running,
		124	and at least one of those should always be available. When nodes run out
		125	of connections (e.g. due to a network error), they try to re-establish
		126	connections to some seednodes again to join the network.
92		127
93	=back	128	=back
94		129
95	=head1 VARIABLES/FUNCTIONS	130	=head1 VARIABLES/FUNCTIONS
96		131
98		133
99	=cut	134	=cut
100		135
101	package AnyEvent::MP;	136	package AnyEvent::MP;
102		137
103	use AnyEvent::MP::Base;	138	use AnyEvent::MP::Kernel;
104		139
105	use common::sense;	140	use common::sense;
106		141
107	use Carp ();	142	use Carp ();
108		143
109	use AE ();	144	use AE ();
110		145
111	use base "Exporter";	146	use base "Exporter";
112		147
113	our $VERSION = '0.1';	148	our $VERSION = $AnyEvent::MP::Kernel::VERSION;
		149
114	our @EXPORT = qw(	150	our @EXPORT = qw(
115	NODE $NODE *SELF node_of _any_	151	NODE $NODE *SELF node_of after
116	resolve_node initialise_node	152	configure
117	snd rcv mon kil reg psub	153	snd rcv mon mon_guard kil psub spawn cal
118	port	154	port
119	);	155	);
120		156
121	our $SELF;	157	our $SELF;
122		158
…		…
126	kil $SELF, die => $msg;	162	kil $SELF, die => $msg;
127	}	163	}
128		164
129	=item $thisnode = NODE / $NODE	165	=item $thisnode = NODE / $NODE
130		166
131	The C<NODE> function returns, and the C<$NODE> variable contains	167	The C<NODE> function returns, and the C<$NODE> variable contains, the node
132	the noderef of the local node. The value is initialised by a call	168	ID of the node running in the current process. This value is initialised by
133	to C<become_public> or C<become_slave>, after which all local port	169	a call to C<configure>.
134	identifiers become invalid.
135		170
136	=item $noderef = node_of $port	171	=item $nodeid = node_of $port
137		172
138	Extracts and returns the noderef from a portid or a noderef.	173	Extracts and returns the node ID from a port ID or a node ID.
139		174
140	=item initialise_node $noderef, $seednode, $seednode...	175	=item configure $profile, key => value...
141		176
142	=item initialise_node "slave/", $master, $master...	177	=item configure key => value...
143		178
144	Before a node can talk to other nodes on the network it has to initialise	179	Before a node can talk to other nodes on the network (i.e. enter
145	itself - the minimum a node needs to know is it's own name, and optionally	180	"distributed mode") it has to configure itself - the minimum a node needs
146	it should know the noderefs of some other nodes in the network.	181	to know is its own name, and optionally it should know the addresses of
		182	some other nodes in the network to discover other nodes.
147		183
148	This function initialises a node - it must be called exactly once (or	184	This function configures a node - it must be called exactly once (or
149	never) before calling other AnyEvent::MP functions.	185	never) before calling other AnyEvent::MP functions.
150		186
151	All arguments are noderefs, which can be either resolved or unresolved.
152
153	There are two types of networked nodes, public nodes and slave nodes:
154
155	=over 4	187	=over 4
156		188
157	=item public nodes	189	=item step 1, gathering configuration from profiles
158		190
159	For public nodes, C<$noderef> must either be a (possibly unresolved)	191	The function first looks up a profile in the aemp configuration (see the
160	noderef, in which case it will be resolved, or C<undef> (or missing), in	192	L<aemp> commandline utility). The profile name can be specified via the
161	which case the noderef will be guessed.	193	named C<profile> parameter or can simply be the first parameter). If it is
		194	missing, then the nodename (F<uname -n>) will be used as profile name.
162		195
163	Afterwards, the node will bind itself on all endpoints and try to connect	196	The profile data is then gathered as follows:
164	to all additional C<$seednodes> that are specified. Seednodes are optional
165	and can be used to quickly bootstrap the node into an existing network.
166		197
167	=item slave nodes	198	First, all remaining key => value pairs (all of which are conveniently
		199	undocumented at the moment) will be interpreted as configuration
		200	data. Then they will be overwritten by any values specified in the global
		201	default configuration (see the F<aemp> utility), then the chain of
		202	profiles chosen by the profile name (and any C<parent> attributes).
168		203
169	When the C<$noderef> is the special string C<slave/>, then the node will	204	That means that the values specified in the profile have highest priority
170	become a slave node. Slave nodes cannot be contacted from outside and will	205	and the values specified directly via C<configure> have lowest priority,
171	route most of their traffic to the master node that they attach to.	206	and can only be used to specify defaults.
172		207
173	At least one additional noderef is required: The node will try to connect	208	If the profile specifies a node ID, then this will become the node ID of
174	to all of them and will become a slave attached to the first node it can	209	this process. If not, then the profile name will be used as node ID. The
175	successfully connect to.	210	special node ID of C<anon/> will be replaced by a random node ID.
		211
		212	=item step 2, bind listener sockets
		213
		214	The next step is to look up the binds in the profile, followed by binding
		215	aemp protocol listeners on all binds specified (it is possible and valid
		216	to have no binds, meaning that the node cannot be contacted form the
		217	outside. This means the node cannot talk to other nodes that also have no
		218	binds, but it can still talk to all "normal" nodes).
		219
		220	If the profile does not specify a binds list, then a default of C<*> is
		221	used, meaning the node will bind on a dynamically-assigned port on every
		222	local IP address it finds.
		223
		224	=item step 3, connect to seed nodes
		225
		226	As the last step, the seeds list from the profile is passed to the
		227	L<AnyEvent::MP::Global> module, which will then use it to keep
		228	connectivity with at least one node at any point in time.
176		229
177	=back	230	=back
178		231
179	This function will block until all nodes have been resolved and, for slave	232	Example: become a distributed node using the local node name as profile.
180	nodes, until it has successfully established a connection to a master	233	This should be the most common form of invocation for "daemon"-type nodes.
181	server.
182		234
183	Example: become a public node listening on the default node.	235	configure
184		236
185	initialise_node;	237	Example: become an anonymous node. This form is often used for commandline
		238	clients.
186		239
187	Example: become a public node, and try to contact some well-known master	240	configure nodeid => "anon/";
188	servers to become part of the network.
189		241
190	initialise_node undef, "master1", "master2";	242	Example: configure a node using a profile called seed, which si suitable
		243	for a seed node as it binds on all local addresses on a fixed port (4040,
		244	customary for aemp).
191		245
192	Example: become a public node listening on port C<4041>.	246	# use the aemp commandline utility
		247	# aemp profile seed nodeid anon/ binds '*:4040'
193		248
194	initialise_node 4041;	249	# then use it
		250	configure profile => "seed";
195		251
196	Example: become a public node, only visible on localhost port 4044.	252	# or simply use aemp from the shell again:
		253	# aemp run profile seed
197		254
198	initialise_node "locahost:4044";	255	# or provide a nicer-to-remember nodeid
199		256	# aemp run profile seed nodeid "$(hostname)"
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";
203
204	=item $cv = resolve_node $noderef
205
206	Takes an unresolved node reference that may contain hostnames and
207	abbreviated IDs, resolves all of them and returns a resolved node
208	reference.
209
210	In addition to C<address:port> pairs allowed in resolved noderefs, the
211	following forms are supported:
212
213	=over 4
214
215	=item the empty string
216
217	An empty-string component gets resolved as if the default port (4040) was
218	specified.
219
220	=item naked port numbers (e.g. C<1234>)
221
222	These are resolved by prepending the local nodename and a colon, to be
223	further resolved.
224
225	=item hostnames (e.g. C<localhost:1234>, C<localhost>)
226
227	These are resolved by using AnyEvent::DNS to resolve them, optionally
228	looking up SRV records for the C<aemp=4040> port, if no port was
229	specified.
230
231	=back
232		257
233	=item $SELF	258	=item $SELF
234		259
235	Contains the current port id while executing C<rcv> callbacks or C<psub>	260	Contains the current port id while executing C<rcv> callbacks or C<psub>
236	blocks.	261	blocks.
237		262
238	=item SELF, %SELF, @SELF...	263	=item *SELF, SELF, %SELF, @SELF...
239		264
240	Due to some quirks in how perl exports variables, it is impossible to	265	Due to some quirks in how perl exports variables, it is impossible to
241	just export C<$SELF>, all the symbols called C<SELF> are exported by this	266	just export C<$SELF>, all the symbols named C<SELF> are exported by this
242	module, but only C<$SELF> is currently used.	267	module, but only C<$SELF> is currently used.
243		268
244	=item snd $port, type => @data	269	=item snd $port, type => @data
245		270
246	=item snd $port, @msg	271	=item snd $port, @msg
247		272
248	Send the given message to the given port ID, which can identify either	273	Send the given message to the given port, which can identify either a
249	a local or a remote port, and can be either a string or soemthignt hat	274	local or a remote port, and must be a port ID.
250	stringifies a sa port ID (such as a port object :).
251		275
252	While the message can be about anything, it is highly recommended to use a	276	While the message can be almost anything, it is highly recommended to
253	string as first element (a portid, or some word that indicates a request	277	use a string as first element (a port ID, or some word that indicates a
254	type etc.).	278	request type etc.) and to consist if only simple perl values (scalars,
		279	arrays, hashes) - if you think you need to pass an object, think again.
255		280
256	The message data effectively becomes read-only after a call to this	281	The message data logically becomes read-only after a call to this
257	function: modifying any argument is not allowed and can cause many	282	function: modifying any argument (or values referenced by them) is
258	problems.	283	forbidden, as there can be considerable time between the call to C<snd>
		284	and the time the message is actually being serialised - in fact, it might
		285	never be copied as within the same process it is simply handed to the
		286	receiving port.
259		287
260	The type of data you can transfer depends on the transport protocol: when	288	The type of data you can transfer depends on the transport protocol: when
261	JSON is used, then only strings, numbers and arrays and hashes consisting	289	JSON is used, then only strings, numbers and arrays and hashes consisting
262	of those are allowed (no objects). When Storable is used, then anything	290	of those are allowed (no objects). When Storable is used, then anything
263	that Storable can serialise and deserialise is allowed, and for the local	291	that Storable can serialise and deserialise is allowed, and for the local
264	node, anything can be passed.	292	node, anything can be passed. Best rely only on the common denominator of
		293	these.
265		294
266	=item $local_port = port	295	=item $local_port = port
267		296
268	Create a new local port object that can be used either as a pattern	297	Create a new local port object and returns its port ID. Initially it has
269	matching port ("full port") or a single-callback port ("miniport"),	298	no callbacks set and will throw an error when it receives messages.
270	depending on how C<rcv> callbacks are bound to the object.
271		299
272	=item $port = port { my @msg = @_; $finished }	300	=item $local_port = port { my @msg = @_ }
273		301
274	Creates a "miniport", that is, a very lightweight port without any pattern	302	Creates a new local port, and returns its ID. Semantically the same as
275	matching behind it, and returns its ID. Semantically the same as creating
276	a port and calling C<rcv $port, $callback> on it.	303	creating a port and calling C<rcv $port, $callback> on it.
277		304
278	The block will be called for every message received on the port. When the	305	The block will be called for every message received on the port, with the
279	callback returns a true value its job is considered "done" and the port	306	global variable C<$SELF> set to the port ID. Runtime errors will cause the
280	will be destroyed. Otherwise it will stay alive.	307	port to be C<kil>ed. The message will be passed as-is, no extra argument
		308	(i.e. no port ID) will be passed to the callback.
281		309
282	The message will be passed as-is, no extra argument (i.e. no port id) will	310	If you want to stop/destroy the port, simply C<kil> it:
283	be passed to the callback.
284		311
285	If you need the local port id in the callback, this works nicely:	312	my $port = port {
286		313	my @msg = @_;
287	my $port; $port = port {	314	...
288	snd $otherport, reply => $port;	315	kil $SELF;
289	};	316	};
290		317
291	=cut	318	=cut
292		319
293	sub rcv($@);	320	sub rcv($@);
		321
		322	sub _kilme {
		323	die "received message on port without callback";
		324	}
294		325
295	sub port(;&) {	326	sub port(;&) {
296	my $id = "$UNIQ." . $ID++;	327	my $id = "$UNIQ." . $ID++;
297	my $port = "$NODE#$id";	328	my $port = "$NODE#$id";
298		329
299	if (@_) {	330	rcv $port, shift \|\| \&_kilme;
300	rcv $port, shift;
301	} else {
302	$PORT{$id} = sub { }; # nop
303	}
304		331
305	$port	332	$port
306	}	333	}
307		334
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)	335	=item rcv $local_port, $callback->(@msg)
328		336
329	Replaces the callback on the specified miniport (after converting it to	337	Replaces the default callback on the specified port. There is no way to
330	one if required).	338	remove the default callback: use C<sub { }> to disable it, or better
331		339	C<kil> the port when it is no longer needed.
332	=item rcv $port, tagstring => $callback->(@msg), ...
333
334	=item rcv $port, $smartmatch => $callback->(@msg), ...
335
336	=item rcv $port, [$smartmatch...] => $callback->(@msg), ...
337
338	Register callbacks to be called on matching messages on the given full
339	port (after converting it to one if required) and return the port.
340
341	The callback has to return a true value when its work is done, after
342	which is will be removed, or a false value in which case it will stay
343	registered.
344		340
345	The global C<$SELF> (exported by this module) contains C<$port> while	341	The global C<$SELF> (exported by this module) contains C<$port> while
346	executing the callback.	342	executing the callback. Runtime errors during callback execution will
		343	result in the port being C<kil>ed.
347		344
348	Runtime errors wdurign callback execution will result in the port being	345	The default callback received all messages not matched by a more specific
349	C<kil>ed.	346	C<tag> match.
350		347
351	If the match is an array reference, then it will be matched against the	348	=item rcv $local_port, tag => $callback->(@msg_without_tag), ...
352	first elements of the message, otherwise only the first element is being
353	matched.
354		349
355	Any element in the match that is specified as C<_any_> (a function	350	Register (or replace) callbacks to be called on messages starting with the
356	exported by this module) matches any single element of the message.	351	given tag on the given port (and return the port), or unregister it (when
		352	C<$callback> is C<$undef> or missing). There can only be one callback
		353	registered for each tag.
357		354
358	While not required, it is highly recommended that the first matching	355	The original message will be passed to the callback, after the first
359	element is a string identifying the message. The one-string-only match is	356	element (the tag) has been removed. The callback will use the same
360	also the most efficient match (by far).	357	environment as the default callback (see above).
361		358
362	Example: create a port and bind receivers on it in one go.	359	Example: create a port and bind receivers on it in one go.
363		360
364	my $port = rcv port,	361	my $port = rcv port,
365	msg1 => sub { ...; 0 },	362	msg1 => sub { ... },
366	msg2 => sub { ...; 0 },	363	msg2 => sub { ... },
367	;	364	;
368		365
369	Example: create a port, bind receivers and send it in a message elsewhere	366	Example: create a port, bind receivers and send it in a message elsewhere
370	in one go:	367	in one go:
371		368
372	snd $otherport, reply =>	369	snd $otherport, reply =>
373	rcv port,	370	rcv port,
374	msg1 => sub { ...; 0 },	371	msg1 => sub { ... },
375	...	372	...
376	;	373	;
377		374
		375	Example: temporarily register a rcv callback for a tag matching some port
		376	(e.g. for a rpc reply) and unregister it after a message was received.
		377
		378	rcv $port, $otherport => sub {
		379	my @reply = @_;
		380
		381	rcv $SELF, $otherport;
		382	};
		383
378	=cut	384	=cut
379		385
380	sub rcv($@) {	386	sub rcv($@) {
381	my $port = shift;	387	my $port = shift;
382	my ($noderef, $portid) = split /#/, $port, 2;	388	my ($nodeid, $portid) = split /#/, $port, 2;
383		389
384	($NODE{$noderef} \|\| add_node $noderef) == $NODE{""}	390	$NODE{$nodeid} == $NODE{""}
385	or Carp::croak "$port: rcv can only be called on local ports, caught";	391	or Carp::croak "$port: rcv can only be called on local ports, caught";
386		392
387	if (@_ == 1) {	393	while (@_) {
		394	if (ref $_[0]) {
		395	if (my $self = $PORT_DATA{$portid}) {
		396	"AnyEvent::MP::Port" eq ref $self
		397	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
		398
		399	$self->[2] = shift;
		400	} else {
388	my $cb = shift;	401	my $cb = shift;
389	delete $PORT_DATA{$portid};
390	$PORT{$portid} = sub {	402	$PORT{$portid} = sub {
391	local $SELF = $port;	403	local $SELF = $port;
392	eval {	404	eval { &$cb }; _self_die if $@;
393	&$cb	405	};
394	and kil $port;
395	};	406	}
396	_self_die if $@;	407	} elsif (defined $_[0]) {
397	};
398	} else {
399	my $self = $PORT_DATA{$portid} \|\|= do {	408	my $self = $PORT_DATA{$portid} \|\|= do {
400	my $self = bless {	409	my $self = bless [$PORT{$port} \|\| sub { }, { }, $port], "AnyEvent::MP::Port";
401	id => $port,
402	}, "AnyEvent::MP::Port";
403		410
404	$PORT{$portid} = sub {	411	$PORT{$portid} = sub {
405	local $SELF = $port;	412	local $SELF = $port;
406		413
407	eval {
408	for (@{ $self->{rc0}{$_[0]} }) {	414	if (my $cb = $self->[1]{$_[0]}) {
409	$_ && &{$_->[0]}	415	shift;
410	&& undef $_;	416	eval { &$cb }; _self_die if $@;
411	}	417	} else {
412
413	for (@{ $self->{rcv}{$_[0]} }) {
414	$_ && [@_[1 .. @{$_->[1]}]] ~~ $_->[1]
415	&& &{$_->[0]}	418	&{ $self->[0] };
416	&& undef $_;
417	}
418
419	for (@{ $self->{any} }) {
420	$_ && [@_[0 .. $#{$_->[1]}]] ~~ $_->[1]
421	&& &{$_->[0]}
422	&& undef $_;
423	}	419	}
424	};	420	};
425	_self_die if $@;	421
		422	$self
426	};	423	};
427		424
428	$self
429	};
430
431	"AnyEvent::MP::Port" eq ref $self	425	"AnyEvent::MP::Port" eq ref $self
432	or Carp::croak "$port: rcv can only be called on message matching ports, caught";	426	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
433		427
434	while (@_) {
435	my ($match, $cb) = splice @_, 0, 2;	428	my ($tag, $cb) = splice @_, 0, 2;
436		429
437	if (!ref $match) {	430	if (defined $cb) {
438	push @{ $self->{rc0}{$match} }, [$cb];	431	$self->[1]{$tag} = $cb;
439	} elsif (("ARRAY" eq ref $match && !ref $match->[0])) {
440	my ($type, @match) = @$match;
441	@match
442	? push @{ $self->{rcv}{$match->[0]} }, [$cb, \@match]
443	: push @{ $self->{rc0}{$match->[0]} }, [$cb];
444	} else {	432	} else {
445	push @{ $self->{any} }, [$cb, $match];	433	delete $self->[1]{$tag};
446	}	434	}
447	}	435	}
448	}	436	}
449		437
450	$port	438	$port
…		…
486	$res	474	$res
487	}	475	}
488	}	476	}
489	}	477	}
490		478
491	=item $guard = mon $port, $cb->(@reason)	479	=item $guard = mon $port, $cb->(@reason) # call $cb when $port dies
492		480
493	=item $guard = mon $port, $rcvport	481	=item $guard = mon $port, $rcvport # kill $rcvport when $port dies
494		482
495	=item $guard = mon $port	483	=item $guard = mon $port # kill $SELF when $port dies
496		484
497	=item $guard = mon $port, $rcvport, @msg	485	=item $guard = mon $port, $rcvport, @msg # send a message when $port dies
498		486
499	Monitor the given port and do something when the port is killed, and	487	Monitor the given port and do something when the port is killed or
500	optionally return a guard that can be used to stop monitoring again.	488	messages to it were lost, and optionally return a guard that can be used
		489	to stop monitoring again.
501		490
502	In the first form (callback), the callback is simply called with any	491	In the first form (callback), the callback is simply called with any
503	number of C<@reason> elements (no @reason means that the port was deleted	492	number of C<@reason> elements (no @reason means that the port was deleted
504	"normally"). Note also that I<< the callback B<must> never die >>, so use	493	"normally"). Note also that I<< the callback B<must> never die >>, so use
505	C<eval> if unsure.	494	C<eval> if unsure.
506		495
507	In the second form (another port given), the other port (C<$rcvport)	496	In the second form (another port given), the other port (C<$rcvport>)
508	will be C<kil>'ed with C<@reason>, iff a @reason was specified, i.e. on	497	will be C<kil>'ed with C<@reason>, if a @reason was specified, i.e. on
509	"normal" kils nothing happens, while under all other conditions, the other	498	"normal" kils nothing happens, while under all other conditions, the other
510	port is killed with the same reason.	499	port is killed with the same reason.
511		500
512	The third form (kill self) is the same as the second form, except that	501	The third form (kill self) is the same as the second form, except that
513	C<$rvport> defaults to C<$SELF>.	502	C<$rvport> defaults to C<$SELF>.
514		503
515	In the last form (message), a message of the form C<@msg, @reason> will be	504	In the last form (message), a message of the form C<@msg, @reason> will be
516	C<snd>.	505	C<snd>.
517		506
		507	Monitoring-actions are one-shot: once messages are lost (and a monitoring
		508	alert was raised), they are removed and will not trigger again.
		509
		510	As a rule of thumb, monitoring requests should always monitor a port from
		511	a local port (or callback). The reason is that kill messages might get
		512	lost, just like any other message. Another less obvious reason is that
		513	even monitoring requests can get lost (for example, when the connection
		514	to the other node goes down permanently). When monitoring a port locally
		515	these problems do not exist.
		516
		517	C<mon> effectively guarantees that, in the absence of hardware failures,
		518	after starting the monitor, either all messages sent to the port will
		519	arrive, or the monitoring action will be invoked after possible message
		520	loss has been detected. No messages will be lost "in between" (after
		521	the first lost message no further messages will be received by the
		522	port). After the monitoring action was invoked, further messages might get
		523	delivered again.
		524
		525	Inter-host-connection timeouts and monitoring depend on the transport
		526	used. The only transport currently implemented is TCP, and AnyEvent::MP
		527	relies on TCP to detect node-downs (this can take 10-15 minutes on a
		528	non-idle connection, and usually around two hours for idle conenctions).
		529
		530	This means that monitoring is good for program errors and cleaning up
		531	stuff eventually, but they are no replacement for a timeout when you need
		532	to ensure some maximum latency.
		533
518	Example: call a given callback when C<$port> is killed.	534	Example: call a given callback when C<$port> is killed.
519		535
520	mon $port, sub { warn "port died because of <@_>\n" };	536	mon $port, sub { warn "port died because of <@_>\n" };
521		537
522	Example: kill ourselves when C<$port> is killed abnormally.	538	Example: kill ourselves when C<$port> is killed abnormally.
…		…
528	mon $port, $self => "restart";	544	mon $port, $self => "restart";
529		545
530	=cut	546	=cut
531		547
532	sub mon {	548	sub mon {
533	my ($noderef, $port) = split /#/, shift, 2;	549	my ($nodeid, $port) = split /#/, shift, 2;
534		550
535	my $node = $NODE{$noderef} \|\| add_node $noderef;	551	my $node = $NODE{$nodeid} \|\| add_node $nodeid;
536		552
537	my $cb = @_ ? $_[0] : $SELF \|\| Carp::croak 'mon: called with one argument only, but $SELF not set,';	553	my $cb = @_ ? shift : $SELF \|\| Carp::croak 'mon: called with one argument only, but $SELF not set,';
538		554
539	unless (ref $cb) {	555	unless (ref $cb) {
540	if (@_) {	556	if (@_) {
541	# send a kill info message	557	# send a kill info message
542	my (@msg) = @_;	558	my (@msg) = ($cb, @_);
543	$cb = sub { snd @msg, @_ };	559	$cb = sub { snd @msg, @_ };
544	} else {	560	} else {
545	# simply kill other port	561	# simply kill other port
546	my $port = $cb;	562	my $port = $cb;
547	$cb = sub { kil $port, @_ if @_ };	563	$cb = sub { kil $port, @_ if @_ };
…		…
560	is killed, the references will be freed.	576	is killed, the references will be freed.
561		577
562	Optionally returns a guard that will stop the monitoring.	578	Optionally returns a guard that will stop the monitoring.
563		579
564	This function is useful when you create e.g. timers or other watchers and	580	This function is useful when you create e.g. timers or other watchers and
565	want to free them when the port gets killed:	581	want to free them when the port gets killed (note the use of C<psub>):
566		582
567	$port->rcv (start => sub {	583	$port->rcv (start => sub {
568	my $timer; $timer = mon_guard $port, AE::timer 1, 1, sub {	584	my $timer; $timer = mon_guard $port, AE::timer 1, 1, psub {
569	undef $timer if 0.9 < rand;	585	undef $timer if 0.9 < rand;
570	});	586	});
571	});	587	});
572		588
573	=cut	589	=cut
…		…
578	#TODO: mon-less form?	594	#TODO: mon-less form?
579		595
580	mon $port, sub { 0 && @refs }	596	mon $port, sub { 0 && @refs }
581	}	597	}
582		598
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]	599	=item kil $port[, @reason]
608		600
609	Kill the specified port with the given C<@reason>.	601	Kill the specified port with the given C<@reason>.
610		602
611	If no C<@reason> is specified, then the port is killed "normally" (linked	603	If no C<@reason> is specified, then the port is killed "normally" (ports
612	ports will not be kileld, or even notified).	604	monitoring other ports will not necessarily die because a port dies
		605	"normally").
613		606
614	Otherwise, linked ports get killed with the same reason (second form of	607	Otherwise, linked ports get killed with the same reason (second form of
615	C<mon>, see below).	608	C<mon>, see above).
616		609
617	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks	610	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks
618	will be reported as reason C<< die => $@ >>.	611	will be reported as reason C<< die => $@ >>.
619		612
620	Transport/communication errors are reported as C<< transport_error =>	613	Transport/communication errors are reported as C<< transport_error =>
621	$message >>.	614	$message >>.
622		615
623	=back
624
625	=head1 NODE MESSAGES
626
627	Nodes understand the following messages sent to them. Many of them take
628	arguments called C<@reply>, which will simply be used to compose a reply
629	message - C<$reply[0]> is the port to reply to, C<$reply[1]> the type and
630	the remaining arguments are simply the message data.
631
632	While other messages exist, they are not public and subject to change.
633
634	=over 4
635
636	=cut	616	=cut
637		617
638	=item lookup => $name, @reply	618	=item $port = spawn $node, $initfunc[, @initdata]
639		619
640	Replies with the port ID of the specified well-known port, or C<undef>.	620	Creates a port on the node C<$node> (which can also be a port ID, in which
		621	case it's the node where that port resides).
641		622
642	=item devnull => ...	623	The port ID of the newly created port is returned immediately, and it is
		624	possible to immediately start sending messages or to monitor the port.
643		625
644	Generic data sink/CPU heat conversion.	626	After the port has been created, the init function is called on the remote
		627	node, in the same context as a C<rcv> callback. This function must be a
		628	fully-qualified function name (e.g. C<MyApp::Chat::Server::init>). To
		629	specify a function in the main program, use C<::name>.
645		630
646	=item relay => $port, @msg	631	If the function doesn't exist, then the node tries to C<require>
		632	the package, then the package above the package and so on (e.g.
		633	C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function
		634	exists or it runs out of package names.
647		635
648	Simply forwards the message to the given port.	636	The init function is then called with the newly-created port as context
		637	object (C<$SELF>) and the C<@initdata> values as arguments. It I<must>
		638	call one of the C<rcv> functions to set callbacks on C<$SELF>, otherwise
		639	the port might not get created.
649		640
650	=item eval => $string[ @reply]	641	A common idiom is to pass a local port, immediately monitor the spawned
		642	port, and in the remote init function, immediately monitor the passed
		643	local port. This two-way monitoring ensures that both ports get cleaned up
		644	when there is a problem.
651		645
652	Evaluates the given string. If C<@reply> is given, then a message of the	646	C<spawn> guarantees that the C<$initfunc> has no visible effects on the
653	form C<@reply, $@, @evalres> is sent.	647	caller before C<spawn> returns (by delaying invocation when spawn is
		648	called for the local node).
654		649
655	Example: crash another node.	650	Example: spawn a chat server port on C<$othernode>.
656		651
657	snd $othernode, eval => "exit";	652	# this node, executed from within a port context:
		653	my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF;
		654	mon $server;
658		655
659	=item time => @reply	656	# init function on C<$othernode>
		657	sub connect {
		658	my ($srcport) = @_;
660		659
661	Replies the the current node time to C<@reply>.	660	mon $srcport;
662		661
663	Example: tell the current node to send the current time to C<$myport> in a	662	rcv $SELF, sub {
664	C<timereply> message.	663	...
		664	};
		665	}
665		666
666	snd $NODE, time => $myport, timereply => 1, 2;	667	=cut
667	# => snd $myport, timereply => 1, 2, <time>	668
		669	sub _spawn {
		670	my $port = shift;
		671	my $init = shift;
		672
		673	# rcv will create the actual port
		674	local $SELF = "$NODE#$port";
		675	eval {
		676	&{ load_func $init }
		677	};
		678	_self_die if $@;
		679	}
		680
		681	sub spawn(@) {
		682	my ($nodeid, undef) = split /#/, shift, 2;
		683
		684	my $id = "$RUNIQ." . $ID++;
		685
		686	$_[0] =~ /::/
		687	or Carp::croak "spawn init function must be a fully-qualified name, caught";
		688
		689	snd_to_func $nodeid, "AnyEvent::MP::_spawn" => $id, @_;
		690
		691	"$nodeid#$id"
		692	}
		693
		694	=item after $timeout, @msg
		695
		696	=item after $timeout, $callback
		697
		698	Either sends the given message, or call the given callback, after the
		699	specified number of seconds.
		700
		701	This is simply a utility function that comes in handy at times - the
		702	AnyEvent::MP author is not convinced of the wisdom of having it, though,
		703	so it may go away in the future.
		704
		705	=cut
		706
		707	sub after($@) {
		708	my ($timeout, @action) = @_;
		709
		710	my $t; $t = AE::timer $timeout, 0, sub {
		711	undef $t;
		712	ref $action[0]
		713	? $action[0]()
		714	: snd @action;
		715	};
		716	}
		717
		718	=item cal $port, @msg, $callback[, $timeout]
		719
		720	A simple form of RPC - sends a message to the given C<$port> with the
		721	given contents (C<@msg>), but adds a reply port to the message.
		722
		723	The reply port is created temporarily just for the purpose of receiving
		724	the reply, and will be C<kil>ed when no longer needed.
		725
		726	A reply message sent to the port is passed to the C<$callback> as-is.
		727
		728	If an optional time-out (in seconds) is given and it is not C<undef>,
		729	then the callback will be called without any arguments after the time-out
		730	elapsed and the port is C<kil>ed.
		731
		732	If no time-out is given, then the local port will monitor the remote port
		733	instead, so it eventually gets cleaned-up.
		734
		735	Currently this function returns the temporary port, but this "feature"
		736	might go in future versions unless you can make a convincing case that
		737	this is indeed useful for something.
		738
		739	=cut
		740
		741	sub cal(@) {
		742	my $timeout = ref $_[-1] ? undef : pop;
		743	my $cb = pop;
		744
		745	my $port = port {
		746	undef $timeout;
		747	kil $SELF;
		748	&$cb;
		749	};
		750
		751	if (defined $timeout) {
		752	$timeout = AE::timer $timeout, 0, sub {
		753	undef $timeout;
		754	kil $port;
		755	$cb->();
		756	};
		757	} else {
		758	mon $_[0], sub {
		759	kil $port;
		760	$cb->();
		761	};
		762	}
		763
		764	push @_, $port;
		765	&snd;
		766
		767	$port
		768	}
668		769
669	=back	770	=back
670		771
671	=head1 AnyEvent::MP vs. Distributed Erlang	772	=head1 AnyEvent::MP vs. Distributed Erlang
672		773
…		…
682		783
683	Despite the similarities, there are also some important differences:	784	Despite the similarities, there are also some important differences:
684		785
685	=over 4	786	=over 4
686		787
687	=item * Node references contain the recipe on how to contact them.	788	=item * Node IDs are arbitrary strings in AEMP.
688		789
689	Erlang relies on special naming and DNS to work everywhere in the	790	Erlang relies on special naming and DNS to work everywhere in the same
690	same way. AEMP relies on each node knowing it's own address(es), with	791	way. AEMP relies on each node somehow knowing its own address(es) (e.g. by
691	convenience functionality.	792	configuration or DNS), but will otherwise discover other odes itself.
692		793
693	This means that AEMP requires a less tightly controlled environment at the	794	=item * Erlang has a "remote ports are like local ports" philosophy, AEMP
694	cost of longer node references and a slightly higher management overhead.	795	uses "local ports are like remote ports".
		796
		797	The failure modes for local ports are quite different (runtime errors
		798	only) then for remote ports - when a local port dies, you I<know> it dies,
		799	when a connection to another node dies, you know nothing about the other
		800	port.
		801
		802	Erlang pretends remote ports are as reliable as local ports, even when
		803	they are not.
		804
		805	AEMP encourages a "treat remote ports differently" philosophy, with local
		806	ports being the special case/exception, where transport errors cannot
		807	occur.
695		808
696	=item * Erlang uses processes and a mailbox, AEMP does not queue.	809	=item * Erlang uses processes and a mailbox, AEMP does not queue.
697		810
698	Erlang uses processes that selctively receive messages, and therefore	811	Erlang uses processes that selectively receive messages, and therefore
699	needs a queue. AEMP is event based, queuing messages would serve no useful	812	needs a queue. AEMP is event based, queuing messages would serve no
700	purpose.	813	useful purpose. For the same reason the pattern-matching abilities of
		814	AnyEvent::MP are more limited, as there is little need to be able to
		815	filter messages without dequeuing them.
701		816
702	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).	817	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).
703		818
704	=item * Erlang sends are synchronous, AEMP sends are asynchronous.	819	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
705		820
706	Sending messages in Erlang is synchronous and blocks the process. AEMP	821	Sending messages in Erlang is synchronous and blocks the process (and
707	sends are immediate, connection establishment is handled in the	822	so does not need a queue that can overflow). AEMP sends are immediate,
708	background.	823	connection establishment is handled in the background.
709		824
710	=item * Erlang can silently lose messages, AEMP cannot.	825	=item * Erlang suffers from silent message loss, AEMP does not.
711		826
712	Erlang makes few guarantees on messages delivery - messages can get lost	827	Erlang makes few guarantees on messages delivery - messages can get lost
713	without any of the processes realising it (i.e. you send messages a, b,	828	without any of the processes realising it (i.e. you send messages a, b,
714	and c, and the other side only receives messages a and c).	829	and c, and the other side only receives messages a and c).
715		830
716	AEMP guarantees correct ordering, and the guarantee that there are no	831	AEMP guarantees correct ordering, and the guarantee that after one message
717	holes in the message sequence.	832	is lost, all following ones sent to the same port are lost as well, until
718		833	monitoring raises an error, so there are no silent "holes" in the message
719	=item * In Erlang, processes can be declared dead and later be found to be	834	sequence.
720	alive.
721
722	In Erlang it can happen that a monitored process is declared dead and
723	linked processes get killed, but later it turns out that the process is
724	still alive - and can receive messages.
725
726	In AEMP, when port monitoring detects a port as dead, then that port will
727	eventually be killed - it cannot happen that a node detects a port as dead
728	and then later sends messages to it, finding it is still alive.
729		835
730	=item * Erlang can send messages to the wrong port, AEMP does not.	836	=item * Erlang can send messages to the wrong port, AEMP does not.
731		837
732	In Erlang it is quite possible that a node that restarts reuses a process	838	In Erlang it is quite likely that a node that restarts reuses a process ID
733	ID known to other nodes for a completely different process, causing	839	known to other nodes for a completely different process, causing messages
734	messages destined for that process to end up in an unrelated process.	840	destined for that process to end up in an unrelated process.
735		841
736	AEMP never reuses port IDs, so old messages or old port IDs floating	842	AEMP never reuses port IDs, so old messages or old port IDs floating
737	around in the network will not be sent to an unrelated port.	843	around in the network will not be sent to an unrelated port.
738		844
739	=item * Erlang uses unprotected connections, AEMP uses secure	845	=item * Erlang uses unprotected connections, AEMP uses secure
740	authentication and can use TLS.	846	authentication and can use TLS.
741		847
742	AEMP can use a proven protocol - SSL/TLS - to protect connections and	848	AEMP can use a proven protocol - TLS - to protect connections and
743	securely authenticate nodes.	849	securely authenticate nodes.
744		850
745	=item * The AEMP protocol is optimised for both text-based and binary	851	=item * The AEMP protocol is optimised for both text-based and binary
746	communications.	852	communications.
747		853
748	The AEMP protocol, unlike the Erlang protocol, supports both	854	The AEMP protocol, unlike the Erlang protocol, supports both programming
749	language-independent text-only protocols (good for debugging) and binary,	855	language independent text-only protocols (good for debugging) and binary,
750	language-specific serialisers (e.g. Storable).	856	language-specific serialisers (e.g. Storable). By default, unless TLS is
		857	used, the protocol is actually completely text-based.
751		858
752	It has also been carefully designed to be implementable in other languages	859	It has also been carefully designed to be implementable in other languages
753	with a minimum of work while gracefully degrading fucntionality to make the	860	with a minimum of work while gracefully degrading functionality to make the
754	protocol simple.	861	protocol simple.
755		862
756	=item * AEMP has more flexible monitoring options than Erlang.	863	=item * AEMP has more flexible monitoring options than Erlang.
757		864
758	In Erlang, you can chose to receive I<all> exit signals as messages	865	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	866	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	867	difficult to implement. Monitoring in AEMP is more flexible than in
761	Erlang, as one can choose between automatic kill, exit message or callback	868	Erlang, as one can choose between automatic kill, exit message or callback
762	on a per-process basis.	869	on a per-process basis.
763		870
764	=item * Erlang has different semantics for monitoring and linking, AEMP has the same.	871	=item * Erlang tries to hide remote/local connections, AEMP does not.
765		872
766	Monitoring in Erlang is not an indicator of process death/crashes,	873	Monitoring in Erlang is not an indicator of process death/crashes, in the
767	as linking is (except linking is unreliable in Erlang). In AEMP, the	874	same way as linking is (except linking is unreliable in Erlang).
768	semantics of monitoring and linking are identical, linking is simply	875
769	two-way monitoring with automatic kill.	876	In AEMP, you don't "look up" registered port names or send to named ports
		877	that might or might not be persistent. Instead, you normally spawn a port
		878	on the remote node. The init function monitors you, and you monitor the
		879	remote port. Since both monitors are local to the node, they are much more
		880	reliable (no need for C<spawn_link>).
		881
		882	This also saves round-trips and avoids sending messages to the wrong port
		883	(hard to do in Erlang).
770		884
771	=back	885	=back
772		886
		887	=head1 RATIONALE
		888
		889	=over 4
		890
		891	=item Why strings for port and node IDs, why not objects?
		892
		893	We considered "objects", but found that the actual number of methods
		894	that can be called are quite low. Since port and node IDs travel over
		895	the network frequently, the serialising/deserialising would add lots of
		896	overhead, as well as having to keep a proxy object everywhere.
		897
		898	Strings can easily be printed, easily serialised etc. and need no special
		899	procedures to be "valid".
		900
		901	And as a result, a miniport consists of a single closure stored in a
		902	global hash - it can't become much cheaper.
		903
		904	=item Why favour JSON, why not a real serialising format such as Storable?
		905
		906	In fact, any AnyEvent::MP node will happily accept Storable as framing
		907	format, but currently there is no way to make a node use Storable by
		908	default (although all nodes will accept it).
		909
		910	The default framing protocol is JSON because a) JSON::XS is many times
		911	faster for small messages and b) most importantly, after years of
		912	experience we found that object serialisation is causing more problems
		913	than it solves: Just like function calls, objects simply do not travel
		914	easily over the network, mostly because they will always be a copy, so you
		915	always have to re-think your design.
		916
		917	Keeping your messages simple, concentrating on data structures rather than
		918	objects, will keep your messages clean, tidy and efficient.
		919
		920	=back
		921
773	=head1 SEE ALSO	922	=head1 SEE ALSO
		923
		924	L<AnyEvent::MP::Intro> - a gentle introduction.
		925
		926	L<AnyEvent::MP::Kernel> - more, lower-level, stuff.
		927
		928	L<AnyEvent::MP::Global> - network maintainance and port groups, to find
		929	your applications.
		930
		931	L<AnyEvent::MP::LogCatcher> - simple service to display log messages from
		932	all nodes.
774		933
775	L<AnyEvent>.	934	L<AnyEvent>.
776		935
777	=head1 AUTHOR	936	=head1 AUTHOR
778		937

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Revision 1.36 by root, Thu Aug 6 10:46:48 2009 UTC vs.
Revision 1.91 by root, Tue Sep 22 09:54:42 2009 UTC