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

Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.47 by root, Thu Aug 13 01:57:10 2009 UTC vs.
Revision 1.86 by root, Wed Sep 9 01:47:01 2009 UTC

…		…
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
13	$SELF # receiving/own port id in rcv callbacks	12	$SELF # receiving/own port id in rcv callbacks
14		13
		14	# initialise the node so it can send/receive messages
		15	configure;
		16
15	# ports are message endpoints	17	# ports are message destinations
16		18
17	# sending messages	19	# sending messages
18	snd $port, type => data...;	20	snd $port, type => data...;
19	snd $port, @msg;	21	snd $port, @msg;
20	snd @msg_with_first_element_being_a_port;	22	snd @msg_with_first_element_being_a_port;
21		23
22	# miniports	24	# creating/using ports, the simple way
23	my $miniport = port { my @msg = @_; 0 };	25	my $simple_port = port { my @msg = @_ };
24		26
25	# full ports	27	# creating/using ports, tagged message matching
26	my $port = port;	28	my $port = port;
27	rcv $port, smartmatch => $cb->(@msg);
28	rcv $port, ping => sub { snd $_[0], "pong"; 0 };	29	rcv $port, ping => sub { snd $_[0], "pong" };
29	rcv $port, pong => sub { warn "pong received\n"; 0 };	30	rcv $port, pong => sub { warn "pong received\n" };
30		31
31	# remote ports	32	# create a port on another node
32	my $port = spawn $node, $initfunc, @initdata;	33	my $port = spawn $node, $initfunc, @initdata;
33
34	# more, smarter, matches (_any_ is exported by this module)
35	rcv $port, [child_died => $pid] => sub { ...
36	rcv $port, [_any_, _any_, 3] => sub { .. $_[2] is 3
37		34
38	# monitoring	35	# monitoring
39	mon $port, $cb->(@msg) # callback is invoked on death	36	mon $port, $cb->(@msg) # callback is invoked on death
40	mon $port, $otherport # kill otherport on abnormal death	37	mon $port, $otherport # kill otherport on abnormal death
41	mon $port, $otherport, @msg # send message on death	38	mon $port, $otherport, @msg # send message on death
42		39
43	=head1 CURRENT STATUS	40	=head1 CURRENT STATUS
44		41
		42	bin/aemp - stable.
45	AnyEvent::MP - stable API, should work	43	AnyEvent::MP - stable API, should work.
46	AnyEvent::MP::Intro - outdated	44	AnyEvent::MP::Intro - explains most concepts.
47	AnyEvent::MP::Kernel - WIP
48	AnyEvent::MP::Transport - mostly stable	45	AnyEvent::MP::Kernel - mostly stable.
		46	AnyEvent::MP::Global - stable but incomplete, protocol not yet final.
49		47
50	stay tuned.	48	stay tuned.
51		49
52	=head1 DESCRIPTION	50	=head1 DESCRIPTION
53		51
54	This module (-family) implements a simple message passing framework.	52	This module (-family) implements a simple message passing framework.
55		53
56	Despite its simplicity, you can securely message other processes running	54	Despite its simplicity, you can securely message other processes running
57	on the same or other hosts.	55	on the same or other hosts, and you can supervise entities remotely.
58		56
59	For an introduction to this module family, see the L<AnyEvent::MP::Intro>	57	For an introduction to this module family, see the L<AnyEvent::MP::Intro>
60	manual page.	58	manual page and the examples under F<eg/>.
61
62	At the moment, this module family is severly broken and underdocumented,
63	so do not use. This was uploaded mainly to reserve the CPAN namespace -
64	stay tuned!
65		59
66	=head1 CONCEPTS	60	=head1 CONCEPTS
67		61
68	=over 4	62	=over 4
69		63
70	=item port	64	=item port
71		65
72	A port is something you can send messages to (with the C<snd> function).	66	Not to be confused with a TCP port, a "port" is something you can send
		67	messages to (with the C<snd> function).
73		68
74	Some ports allow you to register C<rcv> handlers that can match specific	69	Ports allow you to register C<rcv> handlers that can match all or just
75	messages. All C<rcv> handlers will receive messages they match, messages	70	some messages. Messages send to ports will not be queued, regardless of
76	will not be queued.	71	anything was listening for them or not.
77		72
78	=item port id - C<noderef#portname>	73	=item port ID - C<nodeid#portname>
79		74
80	A port id is normaly the concatenation of a noderef, a hash-mark (C<#>) as	75	A port ID is the concatenation of a node ID, a hash-mark (C<#>) as
81	separator, and a port name (a printable string of unspecified format). An	76	separator, and a port name (a printable string of unspecified format).
82	exception is the the node port, whose ID is identical to its node
83	reference.
84		77
85	=item node	78	=item node
86		79
87	A node is a single process containing at least one port - the node	80	A node is a single process containing at least one port - the node port,
88	port. You can send messages to node ports to find existing ports or to	81	which enables nodes to manage each other remotely, and to create new
89	create new ports, among other things.	82	ports.
90		83
91	Nodes are either private (single-process only), slaves (connected to a	84	Nodes are either public (have one or more listening ports) or private
92	master node only) or public nodes (connectable from unrelated nodes).	85	(no listening ports). Private nodes cannot talk to other private nodes
		86	currently.
93		87
94	=item noderef - C<host:port,host:port...>, C<id@noderef>, C<id>	88	=item node ID - C<[A-Z_][a-zA-Z0-9_\-.:]*>
95		89
96	A node reference is a string that either simply identifies the node (for	90	A node ID is a string that uniquely identifies the node within a
97	private and slave nodes), or contains a recipe on how to reach a given	91	network. Depending on the configuration used, node IDs can look like a
98	node (for public nodes).	92	hostname, a hostname and a port, or a random string. AnyEvent::MP itself
		93	doesn't interpret node IDs in any way.
99		94
100	This recipe is simply a comma-separated list of C<address:port> pairs (for	95	=item binds - C<ip:port>
101	TCP/IP, other protocols might look different).
102		96
103	Node references come in two flavours: resolved (containing only numerical	97	Nodes can only talk to each other by creating some kind of connection to
104	addresses) or unresolved (where hostnames are used instead of addresses).	98	each other. To do this, nodes should listen on one or more local transport
		99	endpoints - binds. Currently, only standard C<ip:port> specifications can
		100	be used, which specify TCP ports to listen on.
105		101
106	Before using an unresolved node reference in a message you first have to	102	=item seed nodes
107	resolve it.	103
		104	When a node starts, it knows nothing about the network. To teach the node
		105	about the network it first has to contact some other node within the
		106	network. This node is called a seed.
		107
		108	Apart from the fact that other nodes know them as seed nodes and they have
		109	to have fixed listening addresses, seed nodes are perfectly normal nodes -
		110	any node can function as a seed node for others.
		111
		112	In addition to discovering the network, seed nodes are also used to
		113	maintain the network and to connect nodes that otherwise would have
		114	trouble connecting. They form the backbone of an AnyEvent::MP network.
		115
		116	Seed nodes are expected to be long-running, and at least one seed node
		117	should always be available. They should also be relatively responsive - a
		118	seed node that blocks for long periods will slow down everybody else.
		119
		120	=item seeds - C<host:port>
		121
		122	Seeds are transport endpoint(s) (usually a hostname/IP address and a
		123	TCP port) of nodes thta should be used as seed nodes.
		124
		125	The nodes listening on those endpoints are expected to be long-running,
		126	and at least one of those should always be available. When nodes run out
		127	of connections (e.g. due to a network error), they try to re-establish
		128	connections to some seednodes again to join the network.
108		129
109	=back	130	=back
110		131
111	=head1 VARIABLES/FUNCTIONS	132	=head1 VARIABLES/FUNCTIONS
112		133
…		…
127	use base "Exporter";	148	use base "Exporter";
128		149
129	our $VERSION = $AnyEvent::MP::Kernel::VERSION;	150	our $VERSION = $AnyEvent::MP::Kernel::VERSION;
130		151
131	our @EXPORT = qw(	152	our @EXPORT = qw(
132	NODE $NODE *SELF node_of _any_	153	NODE $NODE *SELF node_of after
133	resolve_node initialise_node	154	configure
134	snd rcv mon kil reg psub spawn	155	snd rcv mon mon_guard kil reg psub spawn
135	port	156	port
136	);	157	);
137		158
138	our $SELF;	159	our $SELF;
139		160
…		…
143	kil $SELF, die => $msg;	164	kil $SELF, die => $msg;
144	}	165	}
145		166
146	=item $thisnode = NODE / $NODE	167	=item $thisnode = NODE / $NODE
147		168
148	The C<NODE> function returns, and the C<$NODE> variable contains	169	The C<NODE> function returns, and the C<$NODE> variable contains, the node
149	the noderef of the local node. The value is initialised by a call	170	ID of the node running in the current process. This value is initialised by
150	to C<become_public> or C<become_slave>, after which all local port	171	a call to C<configure>.
151	identifiers become invalid.
152		172
153	=item $noderef = node_of $port	173	=item $nodeid = node_of $port
154		174
155	Extracts and returns the noderef from a portid or a noderef.	175	Extracts and returns the node ID from a port ID or a node ID.
156		176
157	=item initialise_node $noderef, $seednode, $seednode...	177	=item configure $profile, key => value...
158		178
159	=item initialise_node "slave/", $master, $master...	179	=item configure key => value...
160		180
161	Before a node can talk to other nodes on the network it has to initialise	181	Before a node can talk to other nodes on the network (i.e. enter
162	itself - the minimum a node needs to know is it's own name, and optionally	182	"distributed mode") it has to configure itself - the minimum a node needs
163	it should know the noderefs of some other nodes in the network.	183	to know is its own name, and optionally it should know the addresses of
		184	some other nodes in the network to discover other nodes.
164		185
165	This function initialises a node - it must be called exactly once (or	186	This function configures a node - it must be called exactly once (or
166	never) before calling other AnyEvent::MP functions.	187	never) before calling other AnyEvent::MP functions.
167		188
168	All arguments are noderefs, which can be either resolved or unresolved.
169
170	There are two types of networked nodes, public nodes and slave nodes:
171
172	=over 4	189	=over 4
173		190
174	=item public nodes	191	=item step 1, gathering configuration from profiles
175		192
176	For public nodes, C<$noderef> must either be a (possibly unresolved)	193	The function first looks up a profile in the aemp configuration (see the
177	noderef, in which case it will be resolved, or C<undef> (or missing), in	194	L<aemp> commandline utility). The profile name can be specified via the
178	which case the noderef will be guessed.	195	named C<profile> parameter or can simply be the first parameter). If it is
		196	missing, then the nodename (F<uname -n>) will be used as profile name.
179		197
180	Afterwards, the node will bind itself on all endpoints and try to connect	198	The profile data is then gathered as follows:
181	to all additional C<$seednodes> that are specified. Seednodes are optional
182	and can be used to quickly bootstrap the node into an existing network.
183		199
184	=item slave nodes	200	First, all remaining key => value pairs (all of which are conveniently
		201	undocumented at the moment) will be interpreted as configuration
		202	data. Then they will be overwritten by any values specified in the global
		203	default configuration (see the F<aemp> utility), then the chain of
		204	profiles chosen by the profile name (and any C<parent> attributes).
185		205
186	When the C<$noderef> is the special string C<slave/>, then the node will	206	That means that the values specified in the profile have highest priority
187	become a slave node. Slave nodes cannot be contacted from outside and will	207	and the values specified directly via C<configure> have lowest priority,
188	route most of their traffic to the master node that they attach to.	208	and can only be used to specify defaults.
189		209
190	At least one additional noderef is required: The node will try to connect	210	If the profile specifies a node ID, then this will become the node ID of
191	to all of them and will become a slave attached to the first node it can	211	this process. If not, then the profile name will be used as node ID. The
192	successfully connect to.	212	special node ID of C<anon/> will be replaced by a random node ID.
		213
		214	=item step 2, bind listener sockets
		215
		216	The next step is to look up the binds in the profile, followed by binding
		217	aemp protocol listeners on all binds specified (it is possible and valid
		218	to have no binds, meaning that the node cannot be contacted form the
		219	outside. This means the node cannot talk to other nodes that also have no
		220	binds, but it can still talk to all "normal" nodes).
		221
		222	If the profile does not specify a binds list, then a default of C<*> is
		223	used, meaning the node will bind on a dynamically-assigned port on every
		224	local IP address it finds.
		225
		226	=item step 3, connect to seed nodes
		227
		228	As the last step, the seeds list from the profile is passed to the
		229	L<AnyEvent::MP::Global> module, which will then use it to keep
		230	connectivity with at least one node at any point in time.
193		231
194	=back	232	=back
195		233
196	This function will block until all nodes have been resolved and, for slave	234	Example: become a distributed node using the locla node name as profile.
197	nodes, until it has successfully established a connection to a master	235	This should be the most common form of invocation for "daemon"-type nodes.
198	server.
199		236
200	Example: become a public node listening on the default node.	237	configure
201		238
202	initialise_node;	239	Example: become an anonymous node. This form is often used for commandline
		240	clients.
203		241
204	Example: become a public node, and try to contact some well-known master	242	configure nodeid => "anon/";
205	servers to become part of the network.
206		243
207	initialise_node undef, "master1", "master2";	244	Example: configure a node using a profile called seed, which si suitable
		245	for a seed node as it binds on all local addresses on a fixed port (4040,
		246	customary for aemp).
208		247
209	Example: become a public node listening on port C<4041>.	248	# use the aemp commandline utility
		249	# aemp profile seed nodeid anon/ binds '*:4040'
210		250
211	initialise_node 4041;	251	# then use it
		252	configure profile => "seed";
212		253
213	Example: become a public node, only visible on localhost port 4044.	254	# or simply use aemp from the shell again:
		255	# aemp run profile seed
214		256
215	initialise_node "locahost:4044";	257	# or provide a nicer-to-remember nodeid
216		258	# aemp run profile seed nodeid "$(hostname)"
217	Example: become a slave node to any of the specified master servers.
218
219	initialise_node "slave/", "master1", "192.168.13.17", "mp.example.net";
220
221	=item $cv = resolve_node $noderef
222
223	Takes an unresolved node reference that may contain hostnames and
224	abbreviated IDs, resolves all of them and returns a resolved node
225	reference.
226
227	In addition to C<address:port> pairs allowed in resolved noderefs, the
228	following forms are supported:
229
230	=over 4
231
232	=item the empty string
233
234	An empty-string component gets resolved as if the default port (4040) was
235	specified.
236
237	=item naked port numbers (e.g. C<1234>)
238
239	These are resolved by prepending the local nodename and a colon, to be
240	further resolved.
241
242	=item hostnames (e.g. C<localhost:1234>, C<localhost>)
243
244	These are resolved by using AnyEvent::DNS to resolve them, optionally
245	looking up SRV records for the C<aemp=4040> port, if no port was
246	specified.
247
248	=back
249		259
250	=item $SELF	260	=item $SELF
251		261
252	Contains the current port id while executing C<rcv> callbacks or C<psub>	262	Contains the current port id while executing C<rcv> callbacks or C<psub>
253	blocks.	263	blocks.
254		264
255	=item SELF, %SELF, @SELF...	265	=item *SELF, SELF, %SELF, @SELF...
256		266
257	Due to some quirks in how perl exports variables, it is impossible to	267	Due to some quirks in how perl exports variables, it is impossible to
258	just export C<$SELF>, all the symbols called C<SELF> are exported by this	268	just export C<$SELF>, all the symbols named C<SELF> are exported by this
259	module, but only C<$SELF> is currently used.	269	module, but only C<$SELF> is currently used.
260		270
261	=item snd $port, type => @data	271	=item snd $port, type => @data
262		272
263	=item snd $port, @msg	273	=item snd $port, @msg
264		274
265	Send the given message to the given port ID, which can identify either	275	Send the given message to the given port, which can identify either a
266	a local or a remote port, and can be either a string or soemthignt hat	276	local or a remote port, and must be a port ID.
267	stringifies a sa port ID (such as a port object :).
268		277
269	While the message can be about anything, it is highly recommended to use a	278	While the message can be almost anything, it is highly recommended to
270	string as first element (a portid, or some word that indicates a request	279	use a string as first element (a port ID, or some word that indicates a
271	type etc.).	280	request type etc.) and to consist if only simple perl values (scalars,
		281	arrays, hashes) - if you think you need to pass an object, think again.
272		282
273	The message data effectively becomes read-only after a call to this	283	The message data logically becomes read-only after a call to this
274	function: modifying any argument is not allowed and can cause many	284	function: modifying any argument (or values referenced by them) is
275	problems.	285	forbidden, as there can be considerable time between the call to C<snd>
		286	and the time the message is actually being serialised - in fact, it might
		287	never be copied as within the same process it is simply handed to the
		288	receiving port.
276		289
277	The type of data you can transfer depends on the transport protocol: when	290	The type of data you can transfer depends on the transport protocol: when
278	JSON is used, then only strings, numbers and arrays and hashes consisting	291	JSON is used, then only strings, numbers and arrays and hashes consisting
279	of those are allowed (no objects). When Storable is used, then anything	292	of those are allowed (no objects). When Storable is used, then anything
280	that Storable can serialise and deserialise is allowed, and for the local	293	that Storable can serialise and deserialise is allowed, and for the local
281	node, anything can be passed.	294	node, anything can be passed. Best rely only on the common denominator of
		295	these.
282		296
283	=item $local_port = port	297	=item $local_port = port
284		298
285	Create a new local port object that can be used either as a pattern	299	Create a new local port object and returns its port ID. Initially it has
286	matching port ("full port") or a single-callback port ("miniport"),	300	no callbacks set and will throw an error when it receives messages.
287	depending on how C<rcv> callbacks are bound to the object.
288		301
289	=item $port = port { my @msg = @_; $finished }	302	=item $local_port = port { my @msg = @_ }
290		303
291	Creates a "miniport", that is, a very lightweight port without any pattern	304	Creates a new local port, and returns its ID. Semantically the same as
292	matching behind it, and returns its ID. Semantically the same as creating
293	a port and calling C<rcv $port, $callback> on it.	305	creating a port and calling C<rcv $port, $callback> on it.
294		306
295	The block will be called for every message received on the port. When the	307	The block will be called for every message received on the port, with the
296	callback returns a true value its job is considered "done" and the port	308	global variable C<$SELF> set to the port ID. Runtime errors will cause the
297	will be destroyed. Otherwise it will stay alive.	309	port to be C<kil>ed. The message will be passed as-is, no extra argument
		310	(i.e. no port ID) will be passed to the callback.
298		311
299	The message will be passed as-is, no extra argument (i.e. no port id) will	312	If you want to stop/destroy the port, simply C<kil> it:
300	be passed to the callback.
301		313
302	If you need the local port id in the callback, this works nicely:	314	my $port = port {
303		315	my @msg = @_;
304	my $port; $port = port {	316	...
305	snd $otherport, reply => $port;	317	kil $SELF;
306	};	318	};
307		319
308	=cut	320	=cut
309		321
310	sub rcv($@);	322	sub rcv($@);
		323
		324	sub _kilme {
		325	die "received message on port without callback";
		326	}
311		327
312	sub port(;&) {	328	sub port(;&) {
313	my $id = "$UNIQ." . $ID++;	329	my $id = "$UNIQ." . $ID++;
314	my $port = "$NODE#$id";	330	my $port = "$NODE#$id";
315		331
316	if (@_) {	332	rcv $port, shift \|\| \&_kilme;
317	rcv $port, shift;
318	} else {
319	$PORT{$id} = sub { }; # nop
320	}
321		333
322	$port	334	$port
323	}	335	}
324		336
325	=item reg $port, $name
326
327	=item reg $name
328
329	Registers the given port (or C<$SELF><<< if missing) under the name
330	C<$name>. If the name already exists it is replaced.
331
332	A port can only be registered under one well known name.
333
334	A port automatically becomes unregistered when it is killed.
335
336	=cut
337
338	sub reg(@) {
339	my $port = @_ > 1 ? shift : $SELF \|\| Carp::croak 'reg: called with one argument only, but $SELF not set,';
340
341	$REG{$_[0]} = $port;
342	}
343
344	=item rcv $port, $callback->(@msg)	337	=item rcv $local_port, $callback->(@msg)
345		338
346	Replaces the callback on the specified miniport (after converting it to	339	Replaces the default callback on the specified port. There is no way to
347	one if required).	340	remove the default callback: use C<sub { }> to disable it, or better
348		341	C<kil> the port when it is no longer needed.
349	=item rcv $port, tagstring => $callback->(@msg), ...
350
351	=item rcv $port, $smartmatch => $callback->(@msg), ...
352
353	=item rcv $port, [$smartmatch...] => $callback->(@msg), ...
354
355	Register callbacks to be called on matching messages on the given full
356	port (after converting it to one if required) and return the port.
357
358	The callback has to return a true value when its work is done, after
359	which is will be removed, or a false value in which case it will stay
360	registered.
361		342
362	The global C<$SELF> (exported by this module) contains C<$port> while	343	The global C<$SELF> (exported by this module) contains C<$port> while
363	executing the callback.	344	executing the callback. Runtime errors during callback execution will
		345	result in the port being C<kil>ed.
364		346
365	Runtime errors during callback execution will result in the port being	347	The default callback received all messages not matched by a more specific
366	C<kil>ed.	348	C<tag> match.
367		349
368	If the match is an array reference, then it will be matched against the	350	=item rcv $local_port, tag => $callback->(@msg_without_tag), ...
369	first elements of the message, otherwise only the first element is being
370	matched.
371		351
372	Any element in the match that is specified as C<_any_> (a function	352	Register (or replace) callbacks to be called on messages starting with the
373	exported by this module) matches any single element of the message.	353	given tag on the given port (and return the port), or unregister it (when
		354	C<$callback> is C<$undef> or missing). There can only be one callback
		355	registered for each tag.
374		356
375	While not required, it is highly recommended that the first matching	357	The original message will be passed to the callback, after the first
376	element is a string identifying the message. The one-string-only match is	358	element (the tag) has been removed. The callback will use the same
377	also the most efficient match (by far).	359	environment as the default callback (see above).
378		360
379	Example: create a port and bind receivers on it in one go.	361	Example: create a port and bind receivers on it in one go.
380		362
381	my $port = rcv port,	363	my $port = rcv port,
382	msg1 => sub { ...; 0 },	364	msg1 => sub { ... },
383	msg2 => sub { ...; 0 },	365	msg2 => sub { ... },
384	;	366	;
385		367
386	Example: create a port, bind receivers and send it in a message elsewhere	368	Example: create a port, bind receivers and send it in a message elsewhere
387	in one go:	369	in one go:
388		370
389	snd $otherport, reply =>	371	snd $otherport, reply =>
390	rcv port,	372	rcv port,
391	msg1 => sub { ...; 0 },	373	msg1 => sub { ... },
392	...	374	...
393	;	375	;
394		376
		377	Example: temporarily register a rcv callback for a tag matching some port
		378	(e.g. for a rpc reply) and unregister it after a message was received.
		379
		380	rcv $port, $otherport => sub {
		381	my @reply = @_;
		382
		383	rcv $SELF, $otherport;
		384	};
		385
395	=cut	386	=cut
396		387
397	sub rcv($@) {	388	sub rcv($@) {
398	my $port = shift;	389	my $port = shift;
399	my ($noderef, $portid) = split /#/, $port, 2;	390	my ($nodeid, $portid) = split /#/, $port, 2;
400		391
401	($NODE{$noderef} \|\| add_node $noderef) == $NODE{""}	392	$NODE{$nodeid} == $NODE{""}
402	or Carp::croak "$port: rcv can only be called on local ports, caught";	393	or Carp::croak "$port: rcv can only be called on local ports, caught";
403		394
404	if (@_ == 1) {	395	while (@_) {
		396	if (ref $_[0]) {
		397	if (my $self = $PORT_DATA{$portid}) {
		398	"AnyEvent::MP::Port" eq ref $self
		399	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
		400
		401	$self->[2] = shift;
		402	} else {
405	my $cb = shift;	403	my $cb = shift;
406	delete $PORT_DATA{$portid};
407	$PORT{$portid} = sub {	404	$PORT{$portid} = sub {
408	local $SELF = $port;	405	local $SELF = $port;
409	eval {	406	eval { &$cb }; _self_die if $@;
410	&$cb	407	};
411	and kil $port;
412	};	408	}
413	_self_die if $@;	409	} elsif (defined $_[0]) {
414	};
415	} else {
416	my $self = $PORT_DATA{$portid} \|\|= do {	410	my $self = $PORT_DATA{$portid} \|\|= do {
417	my $self = bless {	411	my $self = bless [$PORT{$port} \|\| sub { }, { }, $port], "AnyEvent::MP::Port";
418	id => $port,
419	}, "AnyEvent::MP::Port";
420		412
421	$PORT{$portid} = sub {	413	$PORT{$portid} = sub {
422	local $SELF = $port;	414	local $SELF = $port;
423		415
424	eval {
425	for (@{ $self->{rc0}{$_[0]} }) {	416	if (my $cb = $self->[1]{$_[0]}) {
426	$_ && &{$_->[0]}	417	shift;
427	&& undef $_;	418	eval { &$cb }; _self_die if $@;
428	}	419	} else {
429
430	for (@{ $self->{rcv}{$_[0]} }) {
431	$_ && [@_[1 .. @{$_->[1]}]] ~~ $_->[1]
432	&& &{$_->[0]}	420	&{ $self->[0] };
433	&& undef $_;
434	}
435
436	for (@{ $self->{any} }) {
437	$_ && [@_[0 .. $#{$_->[1]}]] ~~ $_->[1]
438	&& &{$_->[0]}
439	&& undef $_;
440	}	421	}
441	};	422	};
442	_self_die if $@;	423
		424	$self
443	};	425	};
444		426
445	$self
446	};
447
448	"AnyEvent::MP::Port" eq ref $self	427	"AnyEvent::MP::Port" eq ref $self
449	or Carp::croak "$port: rcv can only be called on message matching ports, caught";	428	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
450		429
451	while (@_) {
452	my ($match, $cb) = splice @_, 0, 2;	430	my ($tag, $cb) = splice @_, 0, 2;
453		431
454	if (!ref $match) {	432	if (defined $cb) {
455	push @{ $self->{rc0}{$match} }, [$cb];	433	$self->[1]{$tag} = $cb;
456	} elsif (("ARRAY" eq ref $match && !ref $match->[0])) {
457	my ($type, @match) = @$match;
458	@match
459	? push @{ $self->{rcv}{$match->[0]} }, [$cb, \@match]
460	: push @{ $self->{rc0}{$match->[0]} }, [$cb];
461	} else {	434	} else {
462	push @{ $self->{any} }, [$cb, $match];	435	delete $self->[1]{$tag};
463	}	436	}
464	}	437	}
465	}	438	}
466		439
467	$port	440	$port
…		…
503	$res	476	$res
504	}	477	}
505	}	478	}
506	}	479	}
507		480
508	=item $guard = mon $port, $cb->(@reason)	481	=item $guard = mon $port, $cb->(@reason) # call $cb when $port dies
509		482
510	=item $guard = mon $port, $rcvport	483	=item $guard = mon $port, $rcvport # kill $rcvport when $port dies
511		484
512	=item $guard = mon $port	485	=item $guard = mon $port # kill $SELF when $port dies
513		486
514	=item $guard = mon $port, $rcvport, @msg	487	=item $guard = mon $port, $rcvport, @msg # send a message when $port dies
515		488
516	Monitor the given port and do something when the port is killed or	489	Monitor the given port and do something when the port is killed or
517	messages to it were lost, and optionally return a guard that can be used	490	messages to it were lost, and optionally return a guard that can be used
518	to stop monitoring again.	491	to stop monitoring again.
519
520	C<mon> effectively guarantees that, in the absence of hardware failures,
521	that after starting the monitor, either all messages sent to the port
522	will arrive, or the monitoring action will be invoked after possible
523	message loss has been detected. No messages will be lost "in between"
524	(after the first lost message no further messages will be received by the
525	port). After the monitoring action was invoked, further messages might get
526	delivered again.
527		492
528	In the first form (callback), the callback is simply called with any	493	In the first form (callback), the callback is simply called with any
529	number of C<@reason> elements (no @reason means that the port was deleted	494	number of C<@reason> elements (no @reason means that the port was deleted
530	"normally"). Note also that I<< the callback B<must> never die >>, so use	495	"normally"). Note also that I<< the callback B<must> never die >>, so use
531	C<eval> if unsure.	496	C<eval> if unsure.
532		497
533	In the second form (another port given), the other port (C<$rcvport>)	498	In the second form (another port given), the other port (C<$rcvport>)
534	will be C<kil>'ed with C<@reason>, iff a @reason was specified, i.e. on	499	will be C<kil>'ed with C<@reason>, if a @reason was specified, i.e. on
535	"normal" kils nothing happens, while under all other conditions, the other	500	"normal" kils nothing happens, while under all other conditions, the other
536	port is killed with the same reason.	501	port is killed with the same reason.
537		502
538	The third form (kill self) is the same as the second form, except that	503	The third form (kill self) is the same as the second form, except that
539	C<$rvport> defaults to C<$SELF>.	504	C<$rvport> defaults to C<$SELF>.
540		505
541	In the last form (message), a message of the form C<@msg, @reason> will be	506	In the last form (message), a message of the form C<@msg, @reason> will be
542	C<snd>.	507	C<snd>.
		508
		509	Monitoring-actions are one-shot: once messages are lost (and a monitoring
		510	alert was raised), they are removed and will not trigger again.
543		511
544	As a rule of thumb, monitoring requests should always monitor a port from	512	As a rule of thumb, monitoring requests should always monitor a port from
545	a local port (or callback). The reason is that kill messages might get	513	a local port (or callback). The reason is that kill messages might get
546	lost, just like any other message. Another less obvious reason is that	514	lost, just like any other message. Another less obvious reason is that
547	even monitoring requests can get lost (for exmaple, when the connection	515	even monitoring requests can get lost (for example, when the connection
548	to the other node goes down permanently). When monitoring a port locally	516	to the other node goes down permanently). When monitoring a port locally
549	these problems do not exist.	517	these problems do not exist.
550		518
		519	C<mon> effectively guarantees that, in the absence of hardware failures,
		520	after starting the monitor, either all messages sent to the port will
		521	arrive, or the monitoring action will be invoked after possible message
		522	loss has been detected. No messages will be lost "in between" (after
		523	the first lost message no further messages will be received by the
		524	port). After the monitoring action was invoked, further messages might get
		525	delivered again.
		526
		527	Inter-host-connection timeouts and monitoring depend on the transport
		528	used. The only transport currently implemented is TCP, and AnyEvent::MP
		529	relies on TCP to detect node-downs (this can take 10-15 minutes on a
		530	non-idle connection, and usually around two hours for idle conenctions).
		531
		532	This means that monitoring is good for program errors and cleaning up
		533	stuff eventually, but they are no replacement for a timeout when you need
		534	to ensure some maximum latency.
		535
551	Example: call a given callback when C<$port> is killed.	536	Example: call a given callback when C<$port> is killed.
552		537
553	mon $port, sub { warn "port died because of <@_>\n" };	538	mon $port, sub { warn "port died because of <@_>\n" };
554		539
555	Example: kill ourselves when C<$port> is killed abnormally.	540	Example: kill ourselves when C<$port> is killed abnormally.
…		…
561	mon $port, $self => "restart";	546	mon $port, $self => "restart";
562		547
563	=cut	548	=cut
564		549
565	sub mon {	550	sub mon {
566	my ($noderef, $port) = split /#/, shift, 2;	551	my ($nodeid, $port) = split /#/, shift, 2;
567		552
568	my $node = $NODE{$noderef} \|\| add_node $noderef;	553	my $node = $NODE{$nodeid} \|\| add_node $nodeid;
569		554
570	my $cb = @_ ? shift : $SELF \|\| Carp::croak 'mon: called with one argument only, but $SELF not set,';	555	my $cb = @_ ? shift : $SELF \|\| Carp::croak 'mon: called with one argument only, but $SELF not set,';
571		556
572	unless (ref $cb) {	557	unless (ref $cb) {
573	if (@_) {	558	if (@_) {
…		…
593	is killed, the references will be freed.	578	is killed, the references will be freed.
594		579
595	Optionally returns a guard that will stop the monitoring.	580	Optionally returns a guard that will stop the monitoring.
596		581
597	This function is useful when you create e.g. timers or other watchers and	582	This function is useful when you create e.g. timers or other watchers and
598	want to free them when the port gets killed:	583	want to free them when the port gets killed (note the use of C<psub>):
599		584
600	$port->rcv (start => sub {	585	$port->rcv (start => sub {
601	my $timer; $timer = mon_guard $port, AE::timer 1, 1, sub {	586	my $timer; $timer = mon_guard $port, AE::timer 1, 1, psub {
602	undef $timer if 0.9 < rand;	587	undef $timer if 0.9 < rand;
603	});	588	});
604	});	589	});
605		590
606	=cut	591	=cut
…		…
615		600
616	=item kil $port[, @reason]	601	=item kil $port[, @reason]
617		602
618	Kill the specified port with the given C<@reason>.	603	Kill the specified port with the given C<@reason>.
619		604
620	If no C<@reason> is specified, then the port is killed "normally" (linked	605	If no C<@reason> is specified, then the port is killed "normally" (ports
621	ports will not be kileld, or even notified).	606	monitoring other ports will not necessarily die because a port dies
		607	"normally").
622		608
623	Otherwise, linked ports get killed with the same reason (second form of	609	Otherwise, linked ports get killed with the same reason (second form of
624	C<mon>, see below).	610	C<mon>, see above).
625		611
626	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks	612	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks
627	will be reported as reason C<< die => $@ >>.	613	will be reported as reason C<< die => $@ >>.
628		614
629	Transport/communication errors are reported as C<< transport_error =>	615	Transport/communication errors are reported as C<< transport_error =>
…		…
634	=item $port = spawn $node, $initfunc[, @initdata]	620	=item $port = spawn $node, $initfunc[, @initdata]
635		621
636	Creates a port on the node C<$node> (which can also be a port ID, in which	622	Creates a port on the node C<$node> (which can also be a port ID, in which
637	case it's the node where that port resides).	623	case it's the node where that port resides).
638		624
639	The port ID of the newly created port is return immediately, and it is	625	The port ID of the newly created port is returned immediately, and it is
640	permissible to immediately start sending messages or monitor the port.	626	possible to immediately start sending messages or to monitor the port.
641		627
642	After the port has been created, the init function is	628	After the port has been created, the init function is called on the remote
643	called. This function must be a fully-qualified function name	629	node, in the same context as a C<rcv> callback. This function must be a
644	(e.g. C<MyApp::Chat::Server::init>). To specify a function in the main	630	fully-qualified function name (e.g. C<MyApp::Chat::Server::init>). To
645	program, use C<::name>.	631	specify a function in the main program, use C<::name>.
646		632
647	If the function doesn't exist, then the node tries to C<require>	633	If the function doesn't exist, then the node tries to C<require>
648	the package, then the package above the package and so on (e.g.	634	the package, then the package above the package and so on (e.g.
649	C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function	635	C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function
650	exists or it runs out of package names.	636	exists or it runs out of package names.
651		637
652	The init function is then called with the newly-created port as context	638	The init function is then called with the newly-created port as context
653	object (C<$SELF>) and the C<@initdata> values as arguments.	639	object (C<$SELF>) and the C<@initdata> values as arguments. It I<must>
		640	call one of the C<rcv> functions to set callbacks on C<$SELF>, otherwise
		641	the port might not get created.
654		642
655	A common idiom is to pass your own port, monitor the spawned port, and	643	A common idiom is to pass a local port, immediately monitor the spawned
656	in the init function, monitor the original port. This two-way monitoring	644	port, and in the remote init function, immediately monitor the passed
657	ensures that both ports get cleaned up when there is a problem.	645	local port. This two-way monitoring ensures that both ports get cleaned up
		646	when there is a problem.
		647
		648	C<spawn> guarantees that the C<$initfunc> has no visible effects on the
		649	caller before C<spawn> returns (by delaying invocation when spawn is
		650	called for the local node).
658		651
659	Example: spawn a chat server port on C<$othernode>.	652	Example: spawn a chat server port on C<$othernode>.
660		653
661	# this node, executed from within a port context:	654	# this node, executed from within a port context:
662	my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF;	655	my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF;
…		…
677		670
678	sub _spawn {	671	sub _spawn {
679	my $port = shift;	672	my $port = shift;
680	my $init = shift;	673	my $init = shift;
681		674
		675	# rcv will create the actual port
682	local $SELF = "$NODE#$port";	676	local $SELF = "$NODE#$port";
683	eval {	677	eval {
684	&{ load_func $init }	678	&{ load_func $init }
685	};	679	};
686	_self_die if $@;	680	_self_die if $@;
687	}	681	}
688		682
689	sub spawn(@) {	683	sub spawn(@) {
690	my ($noderef, undef) = split /#/, shift, 2;	684	my ($nodeid, undef) = split /#/, shift, 2;
691		685
692	my $id = "$RUNIQ." . $ID++;	686	my $id = "$RUNIQ." . $ID++;
693		687
694	$_[0] =~ /::/	688	$_[0] =~ /::/
695	or Carp::croak "spawn init function must be a fully-qualified name, caught";	689	or Carp::croak "spawn init function must be a fully-qualified name, caught";
696		690
697	($NODE{$noderef} \|\| add_node $noderef)	691	snd_to_func $nodeid, "AnyEvent::MP::_spawn" => $id, @_;
698	->send (["", "AnyEvent::MP::_spawn" => $id, @_]);
699		692
700	"$noderef#$id"	693	"$nodeid#$id"
701	}	694	}
702		695
703	=back	696	=item after $timeout, @msg
704		697
705	=head1 NODE MESSAGES	698	=item after $timeout, $callback
706		699
707	Nodes understand the following messages sent to them. Many of them take	700	Either sends the given message, or call the given callback, after the
708	arguments called C<@reply>, which will simply be used to compose a reply	701	specified number of seconds.
709	message - C<$reply[0]> is the port to reply to, C<$reply[1]> the type and
710	the remaining arguments are simply the message data.
711		702
712	While other messages exist, they are not public and subject to change.	703	This is simply a utility function that comes in handy at times - the
		704	AnyEvent::MP author is not convinced of the wisdom of having it, though,
		705	so it may go away in the future.
713		706
714	=over 4
715
716	=cut	707	=cut
717		708
718	=item lookup => $name, @reply	709	sub after($@) {
		710	my ($timeout, @action) = @_;
719		711
720	Replies with the port ID of the specified well-known port, or C<undef>.	712	my $t; $t = AE::timer $timeout, 0, sub {
721		713	undef $t;
722	=item devnull => ...	714	ref $action[0]
723		715	? $action[0]()
724	Generic data sink/CPU heat conversion.	716	: snd @action;
725		717	};
726	=item relay => $port, @msg	718	}
727
728	Simply forwards the message to the given port.
729
730	=item eval => $string[ @reply]
731
732	Evaluates the given string. If C<@reply> is given, then a message of the
733	form C<@reply, $@, @evalres> is sent.
734
735	Example: crash another node.
736
737	snd $othernode, eval => "exit";
738
739	=item time => @reply
740
741	Replies the the current node time to C<@reply>.
742
743	Example: tell the current node to send the current time to C<$myport> in a
744	C<timereply> message.
745
746	snd $NODE, time => $myport, timereply => 1, 2;
747	# => snd $myport, timereply => 1, 2, <time>
748		719
749	=back	720	=back
750		721
751	=head1 AnyEvent::MP vs. Distributed Erlang	722	=head1 AnyEvent::MP vs. Distributed Erlang
752		723
…		…
762		733
763	Despite the similarities, there are also some important differences:	734	Despite the similarities, there are also some important differences:
764		735
765	=over 4	736	=over 4
766		737
767	=item * Node references contain the recipe on how to contact them.	738	=item * Node IDs are arbitrary strings in AEMP.
768		739
769	Erlang relies on special naming and DNS to work everywhere in the	740	Erlang relies on special naming and DNS to work everywhere in the same
770	same way. AEMP relies on each node knowing it's own address(es), with	741	way. AEMP relies on each node somehow knowing its own address(es) (e.g. by
771	convenience functionality.	742	configuration or DNS), but will otherwise discover other odes itself.
772		743
773	This means that AEMP requires a less tightly controlled environment at the	744	=item * Erlang has a "remote ports are like local ports" philosophy, AEMP
774	cost of longer node references and a slightly higher management overhead.	745	uses "local ports are like remote ports".
		746
		747	The failure modes for local ports are quite different (runtime errors
		748	only) then for remote ports - when a local port dies, you I<know> it dies,
		749	when a connection to another node dies, you know nothing about the other
		750	port.
		751
		752	Erlang pretends remote ports are as reliable as local ports, even when
		753	they are not.
		754
		755	AEMP encourages a "treat remote ports differently" philosophy, with local
		756	ports being the special case/exception, where transport errors cannot
		757	occur.
775		758
776	=item * Erlang uses processes and a mailbox, AEMP does not queue.	759	=item * Erlang uses processes and a mailbox, AEMP does not queue.
777		760
778	Erlang uses processes that selctively receive messages, and therefore	761	Erlang uses processes that selectively receive messages, and therefore
779	needs a queue. AEMP is event based, queuing messages would serve no useful	762	needs a queue. AEMP is event based, queuing messages would serve no
780	purpose.	763	useful purpose. For the same reason the pattern-matching abilities of
		764	AnyEvent::MP are more limited, as there is little need to be able to
		765	filter messages without dequeuing them.
781		766
782	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).	767	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).
783		768
784	=item * Erlang sends are synchronous, AEMP sends are asynchronous.	769	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
785		770
786	Sending messages in Erlang is synchronous and blocks the process. AEMP	771	Sending messages in Erlang is synchronous and blocks the process (and
787	sends are immediate, connection establishment is handled in the	772	so does not need a queue that can overflow). AEMP sends are immediate,
788	background.	773	connection establishment is handled in the background.
789		774
790	=item * Erlang can silently lose messages, AEMP cannot.	775	=item * Erlang suffers from silent message loss, AEMP does not.
791		776
792	Erlang makes few guarantees on messages delivery - messages can get lost	777	Erlang makes few guarantees on messages delivery - messages can get lost
793	without any of the processes realising it (i.e. you send messages a, b,	778	without any of the processes realising it (i.e. you send messages a, b,
794	and c, and the other side only receives messages a and c).	779	and c, and the other side only receives messages a and c).
795		780
796	AEMP guarantees correct ordering, and the guarantee that there are no	781	AEMP guarantees correct ordering, and the guarantee that after one message
797	holes in the message sequence.	782	is lost, all following ones sent to the same port are lost as well, until
798		783	monitoring raises an error, so there are no silent "holes" in the message
799	=item * In Erlang, processes can be declared dead and later be found to be	784	sequence.
800	alive.
801
802	In Erlang it can happen that a monitored process is declared dead and
803	linked processes get killed, but later it turns out that the process is
804	still alive - and can receive messages.
805
806	In AEMP, when port monitoring detects a port as dead, then that port will
807	eventually be killed - it cannot happen that a node detects a port as dead
808	and then later sends messages to it, finding it is still alive.
809		785
810	=item * Erlang can send messages to the wrong port, AEMP does not.	786	=item * Erlang can send messages to the wrong port, AEMP does not.
811		787
812	In Erlang it is quite possible that a node that restarts reuses a process	788	In Erlang it is quite likely that a node that restarts reuses a process ID
813	ID known to other nodes for a completely different process, causing	789	known to other nodes for a completely different process, causing messages
814	messages destined for that process to end up in an unrelated process.	790	destined for that process to end up in an unrelated process.
815		791
816	AEMP never reuses port IDs, so old messages or old port IDs floating	792	AEMP never reuses port IDs, so old messages or old port IDs floating
817	around in the network will not be sent to an unrelated port.	793	around in the network will not be sent to an unrelated port.
818		794
819	=item * Erlang uses unprotected connections, AEMP uses secure	795	=item * Erlang uses unprotected connections, AEMP uses secure
820	authentication and can use TLS.	796	authentication and can use TLS.
821		797
822	AEMP can use a proven protocol - SSL/TLS - to protect connections and	798	AEMP can use a proven protocol - TLS - to protect connections and
823	securely authenticate nodes.	799	securely authenticate nodes.
824		800
825	=item * The AEMP protocol is optimised for both text-based and binary	801	=item * The AEMP protocol is optimised for both text-based and binary
826	communications.	802	communications.
827		803
828	The AEMP protocol, unlike the Erlang protocol, supports both	804	The AEMP protocol, unlike the Erlang protocol, supports both programming
829	language-independent text-only protocols (good for debugging) and binary,	805	language independent text-only protocols (good for debugging) and binary,
830	language-specific serialisers (e.g. Storable).	806	language-specific serialisers (e.g. Storable). By default, unless TLS is
		807	used, the protocol is actually completely text-based.
831		808
832	It has also been carefully designed to be implementable in other languages	809	It has also been carefully designed to be implementable in other languages
833	with a minimum of work while gracefully degrading fucntionality to make the	810	with a minimum of work while gracefully degrading functionality to make the
834	protocol simple.	811	protocol simple.
835		812
836	=item * AEMP has more flexible monitoring options than Erlang.	813	=item * AEMP has more flexible monitoring options than Erlang.
837		814
838	In Erlang, you can chose to receive I<all> exit signals as messages	815	In Erlang, you can chose to receive I<all> exit signals as messages
…		…
841	Erlang, as one can choose between automatic kill, exit message or callback	818	Erlang, as one can choose between automatic kill, exit message or callback
842	on a per-process basis.	819	on a per-process basis.
843		820
844	=item * Erlang tries to hide remote/local connections, AEMP does not.	821	=item * Erlang tries to hide remote/local connections, AEMP does not.
845		822
846	Monitoring in Erlang is not an indicator of process death/crashes,	823	Monitoring in Erlang is not an indicator of process death/crashes, in the
847	as linking is (except linking is unreliable in Erlang).	824	same way as linking is (except linking is unreliable in Erlang).
848		825
849	In AEMP, you don't "look up" registered port names or send to named ports	826	In AEMP, you don't "look up" registered port names or send to named ports
850	that might or might not be persistent. Instead, you normally spawn a port	827	that might or might not be persistent. Instead, you normally spawn a port
851	on the remote node. The init function monitors the you, and you monitor	828	on the remote node. The init function monitors you, and you monitor the
852	the remote port. Since both monitors are local to the node, they are much	829	remote port. Since both monitors are local to the node, they are much more
853	more reliable.	830	reliable (no need for C<spawn_link>).
854		831
855	This also saves round-trips and avoids sending messages to the wrong port	832	This also saves round-trips and avoids sending messages to the wrong port
856	(hard to do in Erlang).	833	(hard to do in Erlang).
857		834
858	=back	835	=back
859		836
860	=head1 RATIONALE	837	=head1 RATIONALE
861		838
862	=over 4	839	=over 4
863		840
864	=item Why strings for ports and noderefs, why not objects?	841	=item Why strings for port and node IDs, why not objects?
865		842
866	We considered "objects", but found that the actual number of methods	843	We considered "objects", but found that the actual number of methods
867	thatc an be called are very low. Since port IDs and noderefs travel over	844	that can be called are quite low. Since port and node IDs travel over
868	the network frequently, the serialising/deserialising would add lots of	845	the network frequently, the serialising/deserialising would add lots of
869	overhead, as well as having to keep a proxy object.	846	overhead, as well as having to keep a proxy object everywhere.
870		847
871	Strings can easily be printed, easily serialised etc. and need no special	848	Strings can easily be printed, easily serialised etc. and need no special
872	procedures to be "valid".	849	procedures to be "valid".
873		850
874	And a a miniport consists of a single closure stored in a global hash - it	851	And as a result, a miniport consists of a single closure stored in a
875	can't become much cheaper.	852	global hash - it can't become much cheaper.
876		853
877	=item Why favour JSON, why not real serialising format such as Storable?	854	=item Why favour JSON, why not a real serialising format such as Storable?
878		855
879	In fact, any AnyEvent::MP node will happily accept Storable as framing	856	In fact, any AnyEvent::MP node will happily accept Storable as framing
880	format, but currently there is no way to make a node use Storable by	857	format, but currently there is no way to make a node use Storable by
881	default.	858	default (although all nodes will accept it).
882		859
883	The default framing protocol is JSON because a) JSON::XS is many times	860	The default framing protocol is JSON because a) JSON::XS is many times
884	faster for small messages and b) most importantly, after years of	861	faster for small messages and b) most importantly, after years of
885	experience we found that object serialisation is causing more problems	862	experience we found that object serialisation is causing more problems
886	than it gains: Just like function calls, objects simply do not travel	863	than it solves: Just like function calls, objects simply do not travel
887	easily over the network, mostly because they will always be a copy, so you	864	easily over the network, mostly because they will always be a copy, so you
888	always have to re-think your design.	865	always have to re-think your design.
889		866
890	Keeping your messages simple, concentrating on data structures rather than	867	Keeping your messages simple, concentrating on data structures rather than
891	objects, will keep your messages clean, tidy and efficient.	868	objects, will keep your messages clean, tidy and efficient.
892		869
893	=back	870	=back
894		871
895	=head1 SEE ALSO	872	=head1 SEE ALSO
896		873
		874	L<AnyEvent::MP::Intro> - a gentle introduction.
		875
		876	L<AnyEvent::MP::Kernel> - more, lower-level, stuff.
		877
		878	L<AnyEvent::MP::Global> - network maintainance and port groups, to find
		879	your applications.
		880
		881	L<AnyEvent::MP::LogCatcher> - simple service to display log messages from
		882	all nodes.
		883
897	L<AnyEvent>.	884	L<AnyEvent>.
898		885
899	=head1 AUTHOR	886	=head1 AUTHOR
900		887
901	Marc Lehmann <schmorp@schmorp.de>	888	Marc Lehmann <schmorp@schmorp.de>

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Revision 1.47 by root, Thu Aug 13 01:57:10 2009 UTC vs.
Revision 1.86 by root, Wed Sep 9 01:47:01 2009 UTC