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

Comparing AnyEvent-MP/MP.pm (file contents):
Revision 1.49 by root, Thu Aug 13 15:29:58 2009 UTC vs.
Revision 1.83 by root, Tue Sep 8 01:38:16 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
15	# initialise the node so it can send/receive messages	14	# initialise the node so it can send/receive messages
16	initialise_node; # -OR-	15	configure;
17	initialise_node "localhost:4040"; # -OR-
18	initialise_node "slave/", "localhost:4040"
19		16
20	# ports are message endpoints	17	# ports are message destinations
21		18
22	# sending messages	19	# sending messages
23	snd $port, type => data...;	20	snd $port, type => data...;
24	snd $port, @msg;	21	snd $port, @msg;
25	snd @msg_with_first_element_being_a_port;	22	snd @msg_with_first_element_being_a_port;
26		23
27	# creating/using miniports	24	# creating/using ports, the simple way
28	my $miniport = port { my @msg = @_; 0 };	25	my $simple_port = port { my @msg = @_ };
29		26
30	# creating/using full ports	27	# creating/using ports, tagged message matching
31	my $port = port;	28	my $port = port;
32	rcv $port, smartmatch => $cb->(@msg);
33	rcv $port, ping => sub { snd $_[0], "pong"; 0 };	29	rcv $port, ping => sub { snd $_[0], "pong" };
34	rcv $port, pong => sub { warn "pong received\n"; 0 };	30	rcv $port, pong => sub { warn "pong received\n" };
35
36	# more, smarter, matches (_any_ is exported by this module)
37	rcv $port, [child_died => $pid] => sub { ...
38	rcv $port, [_any_, _any_, 3] => sub { .. $_[2] is 3
39		31
40	# create a port on another node	32	# create a port on another node
41	my $port = spawn $node, $initfunc, @initdata;	33	my $port = spawn $node, $initfunc, @initdata;
42		34
43	# monitoring	35	# monitoring
…		…
45	mon $port, $otherport # kill otherport on abnormal death	37	mon $port, $otherport # kill otherport on abnormal death
46	mon $port, $otherport, @msg # send message on death	38	mon $port, $otherport, @msg # send message on death
47		39
48	=head1 CURRENT STATUS	40	=head1 CURRENT STATUS
49		41
		42	bin/aemp - stable.
50	AnyEvent::MP - stable API, should work	43	AnyEvent::MP - stable API, should work.
51	AnyEvent::MP::Intro - outdated	44	AnyEvent::MP::Intro - explains most concepts.
52	AnyEvent::MP::Kernel - WIP
53	AnyEvent::MP::Transport - mostly stable	45	AnyEvent::MP::Kernel - mostly stable.
		46	AnyEvent::MP::Global - stable but incomplete, protocol not yet final.
54		47
55	stay tuned.	48	stay tuned.
56		49
57	=head1 DESCRIPTION	50	=head1 DESCRIPTION
58		51
59	This module (-family) implements a simple message passing framework.	52	This module (-family) implements a simple message passing framework.
60		53
61	Despite its simplicity, you can securely message other processes running	54	Despite its simplicity, you can securely message other processes running
62	on the same or other hosts.	55	on the same or other hosts, and you can supervise entities remotely.
63		56
64	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>
65	manual page.	58	manual page and the examples under F<eg/>.
66
67	At the moment, this module family is severly broken and underdocumented,
68	so do not use. This was uploaded mainly to reserve the CPAN namespace -
69	stay tuned!
70		59
71	=head1 CONCEPTS	60	=head1 CONCEPTS
72		61
73	=over 4	62	=over 4
74		63
75	=item port	64	=item port
76		65
77	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).
78		68
79	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
80	messages. All C<rcv> handlers will receive messages they match, messages	70	some messages. Messages send to ports will not be queued, regardless of
81	will not be queued.	71	anything was listening for them or not.
82		72
83	=item port id - C<noderef#portname>	73	=item port ID - C<nodeid#portname>
84		74
85	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
86	separator, and a port name (a printable string of unspecified format). An	76	separator, and a port name (a printable string of unspecified format).
87	exception is the the node port, whose ID is identical to its node
88	reference.
89		77
90	=item node	78	=item node
91		79
92	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,
93	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
94	create new ports, among other things.	82	ports.
95		83
96	Nodes are either private (single-process only), slaves (connected to a	84	Nodes are either public (have one or more listening ports) or private
97	master node only) or public nodes (connectable from unrelated nodes).	85	(no listening ports). Private nodes cannot talk to other private nodes
		86	currently.
98		87
99	=item noderef - C<host:port,host:port...>, C<id@noderef>, C<id>	88	=item node ID - C<[a-za-Z0-9_\-.:]+>
100		89
101	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
102	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
103	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.
104		94
105	This recipe is simply a comma-separated list of C<address:port> pairs (for	95	=item binds - C<ip:port>
106	TCP/IP, other protocols might look different).
107		96
108	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
109	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.
110		101
111	Before using an unresolved node reference in a message you first have to	102	=item seed nodes
112	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 the AnyEvent::MP network.
		115
		116	Seed nodes are expected to be long-running, and at least one seed node
		117	should always be available.
		118
		119	=item seeds - C<host:port>
		120
		121	Seeds are transport endpoint(s) (usually a hostname/IP address and a
		122	TCP port) of nodes thta should be used as seed nodes.
		123
		124	The nodes listening on those endpoints are expected to be long-running,
		125	and at least one of those should always be available. When nodes run out
		126	of connections (e.g. due to a network error), they try to re-establish
		127	connections to some seednodes again to join the network.
113		128
114	=back	129	=back
115		130
116	=head1 VARIABLES/FUNCTIONS	131	=head1 VARIABLES/FUNCTIONS
117		132
…		…
132	use base "Exporter";	147	use base "Exporter";
133		148
134	our $VERSION = $AnyEvent::MP::Kernel::VERSION;	149	our $VERSION = $AnyEvent::MP::Kernel::VERSION;
135		150
136	our @EXPORT = qw(	151	our @EXPORT = qw(
137	NODE $NODE *SELF node_of _any_	152	NODE $NODE *SELF node_of after
138	resolve_node initialise_node	153	configure
139	snd rcv mon kil reg psub spawn	154	snd rcv mon mon_guard kil reg psub spawn
140	port	155	port
141	);	156	);
142		157
143	our $SELF;	158	our $SELF;
144		159
…		…
148	kil $SELF, die => $msg;	163	kil $SELF, die => $msg;
149	}	164	}
150		165
151	=item $thisnode = NODE / $NODE	166	=item $thisnode = NODE / $NODE
152		167
153	The C<NODE> function returns, and the C<$NODE> variable contains	168	The C<NODE> function returns, and the C<$NODE> variable contains, the node
154	the noderef of the local node. The value is initialised by a call	169	ID of the node running in the current process. This value is initialised by
155	to C<become_public> or C<become_slave>, after which all local port	170	a call to C<configure>.
156	identifiers become invalid.
157		171
158	=item $noderef = node_of $port	172	=item $nodeid = node_of $port
159		173
160	Extracts and returns the noderef from a portid or a noderef.	174	Extracts and returns the node ID from a port ID or a node ID.
161		175
162	=item initialise_node $noderef, $seednode, $seednode...	176	=item configure $profile, key => value...
163		177
164	=item initialise_node "slave/", $master, $master...	178	=item configure key => value...
165		179
166	Before a node can talk to other nodes on the network it has to initialise	180	Before a node can talk to other nodes on the network (i.e. enter
167	itself - the minimum a node needs to know is it's own name, and optionally	181	"distributed mode") it has to configure itself - the minimum a node needs
168	it should know the noderefs of some other nodes in the network.	182	to know is its own name, and optionally it should know the addresses of
		183	some other nodes in the network to discover other nodes.
169		184
170	This function initialises a node - it must be called exactly once (or	185	This function configures a node - it must be called exactly once (or
171	never) before calling other AnyEvent::MP functions.	186	never) before calling other AnyEvent::MP functions.
172		187
173	All arguments (optionally except for the first) are noderefs, which can be
174	either resolved or unresolved.
175
176	The first argument will be looked up in the configuration database first
177	(if it is C<undef> then the current nodename will be used instead) to find
178	the relevant configuration profile (see L<aemp>). If none is found then
179	the default configuration is used. The configuration supplies additional
180	seed/master nodes and can override the actual noderef.
181
182	There are two types of networked nodes, public nodes and slave nodes:
183
184	=over 4	188	=over 4
185		189
186	=item public nodes	190	=item step 1, gathering configuration from profiles
187		191
188	For public nodes, C<$noderef> (supplied either directly to	192	The function first looks up a profile in the aemp configuration (see the
189	C<initialise_node> or indirectly via a profile or the nodename) must be a	193	L<aemp> commandline utility). The profile name can be specified via the
190	noderef (possibly unresolved, in which case it will be resolved).	194	named C<profile> parameter or can simply be the first parameter). If it is
		195	missing, then the nodename (F<uname -n>) will be used as profile name.
191		196
192	After resolving, the node will bind itself on all endpoints and try to	197	The profile data is then gathered as follows:
193	connect to all additional C<$seednodes> that are specified. Seednodes are
194	optional and can be used to quickly bootstrap the node into an existing
195	network.
196		198
197	=item slave nodes	199	First, all remaining key => value pairs (all of which are conveniently
		200	undocumented at the moment) will be interpreted as configuration
		201	data. Then they will be overwritten by any values specified in the global
		202	default configuration (see the F<aemp> utility), then the chain of
		203	profiles chosen by the profile name (and any C<parent> attributes).
198		204
199	When the C<$noderef> (either as given or overriden by the config file)	205	That means that the values specified in the profile have highest priority
200	is the special string C<slave/>, then the node will become a slave	206	and the values specified directly via C<configure> have lowest priority,
201	node. Slave nodes cannot be contacted from outside and will route most of	207	and can only be used to specify defaults.
202	their traffic to the master node that they attach to.
203		208
204	At least one additional noderef is required (either by specifying it	209	If the profile specifies a node ID, then this will become the node ID of
205	directly or because it is part of the configuration profile): The node	210	this process. If not, then the profile name will be used as node ID. The
206	will try to connect to all of them and will become a slave attached to the	211	special node ID of C<anon/> will be replaced by a random node ID.
207	first node it can successfully connect to.	212
		213	=item step 2, bind listener sockets
		214
		215	The next step is to look up the binds in the profile, followed by binding
		216	aemp protocol listeners on all binds specified (it is possible and valid
		217	to have no binds, meaning that the node cannot be contacted form the
		218	outside. This means the node cannot talk to other nodes that also have no
		219	binds, but it can still talk to all "normal" nodes).
		220
		221	If the profile does not specify a binds list, then a default of C<*> is
		222	used, meaning the node will bind on a dynamically-assigned port on every
		223	local IP address it finds.
		224
		225	=item step 3, connect to seed nodes
		226
		227	As the last step, the seeds list from the profile is passed to the
		228	L<AnyEvent::MP::Global> module, which will then use it to keep
		229	connectivity with at least one node at any point in time.
208		230
209	=back	231	=back
210		232
211	This function will block until all nodes have been resolved and, for slave	233	Example: become a distributed node using the locla node name as profile.
212	nodes, until it has successfully established a connection to a master	234	This should be the most common form of invocation for "daemon"-type nodes.
213	server.
214		235
215	Example: become a public node listening on the guessed noderef, or the one	236	configure
216	specified via C<aemp> for the current node. This should be the most common
217	form of invocation for "daemon"-type nodes.
218		237
219	initialise_node;	238	Example: become an anonymous node. This form is often used for commandline
		239	clients.
220		240
221	Example: become a slave node to any of the the seednodes specified via	241	configure nodeid => "anon/";
222	C<aemp>. This form is often used for commandline clients.
223		242
224	initialise_node "slave/";	243	Example: configure a node using a profile called seed, which si suitable
		244	for a seed node as it binds on all local addresses on a fixed port (4040,
		245	customary for aemp).
225		246
226	Example: become a slave node to any of the specified master servers. This	247	# use the aemp commandline utility
227	form is also often used for commandline clients.	248	# aemp profile seed nodeid anon/ binds '*:4040'
228		249
229	initialise_node "slave/", "master1", "192.168.13.17", "mp.example.net";	250	# then use it
		251	configure profile => "seed";
230		252
231	Example: become a public node, and try to contact some well-known master	253	# or simply use aemp from the shell again:
232	servers to become part of the network.	254	# aemp run profile seed
233		255
234	initialise_node undef, "master1", "master2";	256	# or provide a nicer-to-remember nodeid
235		257	# aemp run profile seed nodeid "$(hostname)"
236	Example: become a public node listening on port C<4041>.
237
238	initialise_node 4041;
239
240	Example: become a public node, only visible on localhost port 4044.
241
242	initialise_node "localhost:4044";
243
244	=item $cv = resolve_node $noderef
245
246	Takes an unresolved node reference that may contain hostnames and
247	abbreviated IDs, resolves all of them and returns a resolved node
248	reference.
249
250	In addition to C<address:port> pairs allowed in resolved noderefs, the
251	following forms are supported:
252
253	=over 4
254
255	=item the empty string
256
257	An empty-string component gets resolved as if the default port (4040) was
258	specified.
259
260	=item naked port numbers (e.g. C<1234>)
261
262	These are resolved by prepending the local nodename and a colon, to be
263	further resolved.
264
265	=item hostnames (e.g. C<localhost:1234>, C<localhost>)
266
267	These are resolved by using AnyEvent::DNS to resolve them, optionally
268	looking up SRV records for the C<aemp=4040> port, if no port was
269	specified.
270
271	=back
272		258
273	=item $SELF	259	=item $SELF
274		260
275	Contains the current port id while executing C<rcv> callbacks or C<psub>	261	Contains the current port id while executing C<rcv> callbacks or C<psub>
276	blocks.	262	blocks.
277		263
278	=item SELF, %SELF, @SELF...	264	=item *SELF, SELF, %SELF, @SELF...
279		265
280	Due to some quirks in how perl exports variables, it is impossible to	266	Due to some quirks in how perl exports variables, it is impossible to
281	just export C<$SELF>, all the symbols called C<SELF> are exported by this	267	just export C<$SELF>, all the symbols named C<SELF> are exported by this
282	module, but only C<$SELF> is currently used.	268	module, but only C<$SELF> is currently used.
283		269
284	=item snd $port, type => @data	270	=item snd $port, type => @data
285		271
286	=item snd $port, @msg	272	=item snd $port, @msg
287		273
288	Send the given message to the given port ID, which can identify either	274	Send the given message to the given port, which can identify either a
289	a local or a remote port, and can be either a string or soemthignt hat	275	local or a remote port, and must be a port ID.
290	stringifies a sa port ID (such as a port object :).
291		276
292	While the message can be about anything, it is highly recommended to use a	277	While the message can be almost anything, it is highly recommended to
293	string as first element (a portid, or some word that indicates a request	278	use a string as first element (a port ID, or some word that indicates a
294	type etc.).	279	request type etc.) and to consist if only simple perl values (scalars,
		280	arrays, hashes) - if you think you need to pass an object, think again.
295		281
296	The message data effectively becomes read-only after a call to this	282	The message data logically becomes read-only after a call to this
297	function: modifying any argument is not allowed and can cause many	283	function: modifying any argument (or values referenced by them) is
298	problems.	284	forbidden, as there can be considerable time between the call to C<snd>
		285	and the time the message is actually being serialised - in fact, it might
		286	never be copied as within the same process it is simply handed to the
		287	receiving port.
299		288
300	The type of data you can transfer depends on the transport protocol: when	289	The type of data you can transfer depends on the transport protocol: when
301	JSON is used, then only strings, numbers and arrays and hashes consisting	290	JSON is used, then only strings, numbers and arrays and hashes consisting
302	of those are allowed (no objects). When Storable is used, then anything	291	of those are allowed (no objects). When Storable is used, then anything
303	that Storable can serialise and deserialise is allowed, and for the local	292	that Storable can serialise and deserialise is allowed, and for the local
304	node, anything can be passed.	293	node, anything can be passed. Best rely only on the common denominator of
		294	these.
305		295
306	=item $local_port = port	296	=item $local_port = port
307		297
308	Create a new local port object that can be used either as a pattern	298	Create a new local port object and returns its port ID. Initially it has
309	matching port ("full port") or a single-callback port ("miniport"),	299	no callbacks set and will throw an error when it receives messages.
310	depending on how C<rcv> callbacks are bound to the object.
311		300
312	=item $port = port { my @msg = @_; $finished }	301	=item $local_port = port { my @msg = @_ }
313		302
314	Creates a "miniport", that is, a very lightweight port without any pattern	303	Creates a new local port, and returns its ID. Semantically the same as
315	matching behind it, and returns its ID. Semantically the same as creating
316	a port and calling C<rcv $port, $callback> on it.	304	creating a port and calling C<rcv $port, $callback> on it.
317		305
318	The block will be called for every message received on the port. When the	306	The block will be called for every message received on the port, with the
319	callback returns a true value its job is considered "done" and the port	307	global variable C<$SELF> set to the port ID. Runtime errors will cause the
320	will be destroyed. Otherwise it will stay alive.	308	port to be C<kil>ed. The message will be passed as-is, no extra argument
		309	(i.e. no port ID) will be passed to the callback.
321		310
322	The message will be passed as-is, no extra argument (i.e. no port id) will	311	If you want to stop/destroy the port, simply C<kil> it:
323	be passed to the callback.
324		312
325	If you need the local port id in the callback, this works nicely:	313	my $port = port {
326		314	my @msg = @_;
327	my $port; $port = port {	315	...
328	snd $otherport, reply => $port;	316	kil $SELF;
329	};	317	};
330		318
331	=cut	319	=cut
332		320
333	sub rcv($@);	321	sub rcv($@);
		322
		323	sub _kilme {
		324	die "received message on port without callback";
		325	}
334		326
335	sub port(;&) {	327	sub port(;&) {
336	my $id = "$UNIQ." . $ID++;	328	my $id = "$UNIQ." . $ID++;
337	my $port = "$NODE#$id";	329	my $port = "$NODE#$id";
338		330
339	if (@_) {	331	rcv $port, shift \|\| \&_kilme;
340	rcv $port, shift;
341	} else {
342	$PORT{$id} = sub { }; # nop
343	}
344		332
345	$port	333	$port
346	}	334	}
347		335
348	=item reg $port, $name
349
350	=item reg $name
351
352	Registers the given port (or C<$SELF><<< if missing) under the name
353	C<$name>. If the name already exists it is replaced.
354
355	A port can only be registered under one well known name.
356
357	A port automatically becomes unregistered when it is killed.
358
359	=cut
360
361	sub reg(@) {
362	my $port = @_ > 1 ? shift : $SELF \|\| Carp::croak 'reg: called with one argument only, but $SELF not set,';
363
364	$REG{$_[0]} = $port;
365	}
366
367	=item rcv $port, $callback->(@msg)	336	=item rcv $local_port, $callback->(@msg)
368		337
369	Replaces the callback on the specified miniport (after converting it to	338	Replaces the default callback on the specified port. There is no way to
370	one if required).	339	remove the default callback: use C<sub { }> to disable it, or better
371		340	C<kil> the port when it is no longer needed.
372	=item rcv $port, tagstring => $callback->(@msg), ...
373
374	=item rcv $port, $smartmatch => $callback->(@msg), ...
375
376	=item rcv $port, [$smartmatch...] => $callback->(@msg), ...
377
378	Register callbacks to be called on matching messages on the given full
379	port (after converting it to one if required) and return the port.
380
381	The callback has to return a true value when its work is done, after
382	which is will be removed, or a false value in which case it will stay
383	registered.
384		341
385	The global C<$SELF> (exported by this module) contains C<$port> while	342	The global C<$SELF> (exported by this module) contains C<$port> while
386	executing the callback.	343	executing the callback. Runtime errors during callback execution will
		344	result in the port being C<kil>ed.
387		345
388	Runtime errors during callback execution will result in the port being	346	The default callback received all messages not matched by a more specific
389	C<kil>ed.	347	C<tag> match.
390		348
391	If the match is an array reference, then it will be matched against the	349	=item rcv $local_port, tag => $callback->(@msg_without_tag), ...
392	first elements of the message, otherwise only the first element is being
393	matched.
394		350
395	Any element in the match that is specified as C<_any_> (a function	351	Register (or replace) callbacks to be called on messages starting with the
396	exported by this module) matches any single element of the message.	352	given tag on the given port (and return the port), or unregister it (when
		353	C<$callback> is C<$undef> or missing). There can only be one callback
		354	registered for each tag.
397		355
398	While not required, it is highly recommended that the first matching	356	The original message will be passed to the callback, after the first
399	element is a string identifying the message. The one-string-only match is	357	element (the tag) has been removed. The callback will use the same
400	also the most efficient match (by far).	358	environment as the default callback (see above).
401		359
402	Example: create a port and bind receivers on it in one go.	360	Example: create a port and bind receivers on it in one go.
403		361
404	my $port = rcv port,	362	my $port = rcv port,
405	msg1 => sub { ...; 0 },	363	msg1 => sub { ... },
406	msg2 => sub { ...; 0 },	364	msg2 => sub { ... },
407	;	365	;
408		366
409	Example: create a port, bind receivers and send it in a message elsewhere	367	Example: create a port, bind receivers and send it in a message elsewhere
410	in one go:	368	in one go:
411		369
412	snd $otherport, reply =>	370	snd $otherport, reply =>
413	rcv port,	371	rcv port,
414	msg1 => sub { ...; 0 },	372	msg1 => sub { ... },
415	...	373	...
416	;	374	;
417		375
		376	Example: temporarily register a rcv callback for a tag matching some port
		377	(e.g. for a rpc reply) and unregister it after a message was received.
		378
		379	rcv $port, $otherport => sub {
		380	my @reply = @_;
		381
		382	rcv $SELF, $otherport;
		383	};
		384
418	=cut	385	=cut
419		386
420	sub rcv($@) {	387	sub rcv($@) {
421	my $port = shift;	388	my $port = shift;
422	my ($noderef, $portid) = split /#/, $port, 2;	389	my ($nodeid, $portid) = split /#/, $port, 2;
423		390
424	($NODE{$noderef} \|\| add_node $noderef) == $NODE{""}	391	$NODE{$nodeid} == $NODE{""}
425	or Carp::croak "$port: rcv can only be called on local ports, caught";	392	or Carp::croak "$port: rcv can only be called on local ports, caught";
426		393
427	if (@_ == 1) {	394	while (@_) {
		395	if (ref $_[0]) {
		396	if (my $self = $PORT_DATA{$portid}) {
		397	"AnyEvent::MP::Port" eq ref $self
		398	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
		399
		400	$self->[2] = shift;
		401	} else {
428	my $cb = shift;	402	my $cb = shift;
429	delete $PORT_DATA{$portid};
430	$PORT{$portid} = sub {	403	$PORT{$portid} = sub {
431	local $SELF = $port;	404	local $SELF = $port;
432	eval {	405	eval { &$cb }; _self_die if $@;
433	&$cb	406	};
434	and kil $port;
435	};	407	}
436	_self_die if $@;	408	} elsif (defined $_[0]) {
437	};
438	} else {
439	my $self = $PORT_DATA{$portid} \|\|= do {	409	my $self = $PORT_DATA{$portid} \|\|= do {
440	my $self = bless {	410	my $self = bless [$PORT{$port} \|\| sub { }, { }, $port], "AnyEvent::MP::Port";
441	id => $port,
442	}, "AnyEvent::MP::Port";
443		411
444	$PORT{$portid} = sub {	412	$PORT{$portid} = sub {
445	local $SELF = $port;	413	local $SELF = $port;
446		414
447	eval {
448	for (@{ $self->{rc0}{$_[0]} }) {	415	if (my $cb = $self->[1]{$_[0]}) {
449	$_ && &{$_->[0]}	416	shift;
450	&& undef $_;	417	eval { &$cb }; _self_die if $@;
451	}	418	} else {
452
453	for (@{ $self->{rcv}{$_[0]} }) {
454	$_ && [@_[1 .. @{$_->[1]}]] ~~ $_->[1]
455	&& &{$_->[0]}	419	&{ $self->[0] };
456	&& undef $_;
457	}
458
459	for (@{ $self->{any} }) {
460	$_ && [@_[0 .. $#{$_->[1]}]] ~~ $_->[1]
461	&& &{$_->[0]}
462	&& undef $_;
463	}	420	}
464	};	421	};
465	_self_die if $@;	422
		423	$self
466	};	424	};
467		425
468	$self
469	};
470
471	"AnyEvent::MP::Port" eq ref $self	426	"AnyEvent::MP::Port" eq ref $self
472	or Carp::croak "$port: rcv can only be called on message matching ports, caught";	427	or Carp::croak "$port: rcv can only be called on message matching ports, caught";
473		428
474	while (@_) {
475	my ($match, $cb) = splice @_, 0, 2;	429	my ($tag, $cb) = splice @_, 0, 2;
476		430
477	if (!ref $match) {	431	if (defined $cb) {
478	push @{ $self->{rc0}{$match} }, [$cb];	432	$self->[1]{$tag} = $cb;
479	} elsif (("ARRAY" eq ref $match && !ref $match->[0])) {
480	my ($type, @match) = @$match;
481	@match
482	? push @{ $self->{rcv}{$match->[0]} }, [$cb, \@match]
483	: push @{ $self->{rc0}{$match->[0]} }, [$cb];
484	} else {	433	} else {
485	push @{ $self->{any} }, [$cb, $match];	434	delete $self->[1]{$tag};
486	}	435	}
487	}	436	}
488	}	437	}
489		438
490	$port	439	$port
…		…
526	$res	475	$res
527	}	476	}
528	}	477	}
529	}	478	}
530		479
531	=item $guard = mon $port, $cb->(@reason)	480	=item $guard = mon $port, $cb->(@reason) # call $cb when $port dies
532		481
533	=item $guard = mon $port, $rcvport	482	=item $guard = mon $port, $rcvport # kill $rcvport when $port dies
534		483
535	=item $guard = mon $port	484	=item $guard = mon $port # kill $SELF when $port dies
536		485
537	=item $guard = mon $port, $rcvport, @msg	486	=item $guard = mon $port, $rcvport, @msg # send a message when $port dies
538		487
539	Monitor the given port and do something when the port is killed or	488	Monitor the given port and do something when the port is killed or
540	messages to it were lost, and optionally return a guard that can be used	489	messages to it were lost, and optionally return a guard that can be used
541	to stop monitoring again.	490	to stop monitoring again.
542
543	C<mon> effectively guarantees that, in the absence of hardware failures,
544	that after starting the monitor, either all messages sent to the port
545	will arrive, or the monitoring action will be invoked after possible
546	message loss has been detected. No messages will be lost "in between"
547	(after the first lost message no further messages will be received by the
548	port). After the monitoring action was invoked, further messages might get
549	delivered again.
550		491
551	In the first form (callback), the callback is simply called with any	492	In the first form (callback), the callback is simply called with any
552	number of C<@reason> elements (no @reason means that the port was deleted	493	number of C<@reason> elements (no @reason means that the port was deleted
553	"normally"). Note also that I<< the callback B<must> never die >>, so use	494	"normally"). Note also that I<< the callback B<must> never die >>, so use
554	C<eval> if unsure.	495	C<eval> if unsure.
555		496
556	In the second form (another port given), the other port (C<$rcvport>)	497	In the second form (another port given), the other port (C<$rcvport>)
557	will be C<kil>'ed with C<@reason>, iff a @reason was specified, i.e. on	498	will be C<kil>'ed with C<@reason>, if a @reason was specified, i.e. on
558	"normal" kils nothing happens, while under all other conditions, the other	499	"normal" kils nothing happens, while under all other conditions, the other
559	port is killed with the same reason.	500	port is killed with the same reason.
560		501
561	The third form (kill self) is the same as the second form, except that	502	The third form (kill self) is the same as the second form, except that
562	C<$rvport> defaults to C<$SELF>.	503	C<$rvport> defaults to C<$SELF>.
563		504
564	In the last form (message), a message of the form C<@msg, @reason> will be	505	In the last form (message), a message of the form C<@msg, @reason> will be
565	C<snd>.	506	C<snd>.
		507
		508	Monitoring-actions are one-shot: once messages are lost (and a monitoring
		509	alert was raised), they are removed and will not trigger again.
566		510
567	As a rule of thumb, monitoring requests should always monitor a port from	511	As a rule of thumb, monitoring requests should always monitor a port from
568	a local port (or callback). The reason is that kill messages might get	512	a local port (or callback). The reason is that kill messages might get
569	lost, just like any other message. Another less obvious reason is that	513	lost, just like any other message. Another less obvious reason is that
570	even monitoring requests can get lost (for exmaple, when the connection	514	even monitoring requests can get lost (for example, when the connection
571	to the other node goes down permanently). When monitoring a port locally	515	to the other node goes down permanently). When monitoring a port locally
572	these problems do not exist.	516	these problems do not exist.
573		517
		518	C<mon> effectively guarantees that, in the absence of hardware failures,
		519	after starting the monitor, either all messages sent to the port will
		520	arrive, or the monitoring action will be invoked after possible message
		521	loss has been detected. No messages will be lost "in between" (after
		522	the first lost message no further messages will be received by the
		523	port). After the monitoring action was invoked, further messages might get
		524	delivered again.
		525
		526	Inter-host-connection timeouts and monitoring depend on the transport
		527	used. The only transport currently implemented is TCP, and AnyEvent::MP
		528	relies on TCP to detect node-downs (this can take 10-15 minutes on a
		529	non-idle connection, and usually around two hours for idle conenctions).
		530
		531	This means that monitoring is good for program errors and cleaning up
		532	stuff eventually, but they are no replacement for a timeout when you need
		533	to ensure some maximum latency.
		534
574	Example: call a given callback when C<$port> is killed.	535	Example: call a given callback when C<$port> is killed.
575		536
576	mon $port, sub { warn "port died because of <@_>\n" };	537	mon $port, sub { warn "port died because of <@_>\n" };
577		538
578	Example: kill ourselves when C<$port> is killed abnormally.	539	Example: kill ourselves when C<$port> is killed abnormally.
…		…
584	mon $port, $self => "restart";	545	mon $port, $self => "restart";
585		546
586	=cut	547	=cut
587		548
588	sub mon {	549	sub mon {
589	my ($noderef, $port) = split /#/, shift, 2;	550	my ($nodeid, $port) = split /#/, shift, 2;
590		551
591	my $node = $NODE{$noderef} \|\| add_node $noderef;	552	my $node = $NODE{$nodeid} \|\| add_node $nodeid;
592		553
593	my $cb = @_ ? shift : $SELF \|\| Carp::croak 'mon: called with one argument only, but $SELF not set,';	554	my $cb = @_ ? shift : $SELF \|\| Carp::croak 'mon: called with one argument only, but $SELF not set,';
594		555
595	unless (ref $cb) {	556	unless (ref $cb) {
596	if (@_) {	557	if (@_) {
…		…
616	is killed, the references will be freed.	577	is killed, the references will be freed.
617		578
618	Optionally returns a guard that will stop the monitoring.	579	Optionally returns a guard that will stop the monitoring.
619		580
620	This function is useful when you create e.g. timers or other watchers and	581	This function is useful when you create e.g. timers or other watchers and
621	want to free them when the port gets killed:	582	want to free them when the port gets killed (note the use of C<psub>):
622		583
623	$port->rcv (start => sub {	584	$port->rcv (start => sub {
624	my $timer; $timer = mon_guard $port, AE::timer 1, 1, sub {	585	my $timer; $timer = mon_guard $port, AE::timer 1, 1, psub {
625	undef $timer if 0.9 < rand;	586	undef $timer if 0.9 < rand;
626	});	587	});
627	});	588	});
628		589
629	=cut	590	=cut
…		…
638		599
639	=item kil $port[, @reason]	600	=item kil $port[, @reason]
640		601
641	Kill the specified port with the given C<@reason>.	602	Kill the specified port with the given C<@reason>.
642		603
643	If no C<@reason> is specified, then the port is killed "normally" (linked	604	If no C<@reason> is specified, then the port is killed "normally" (ports
644	ports will not be kileld, or even notified).	605	monitoring other ports will not necessarily die because a port dies
		606	"normally").
645		607
646	Otherwise, linked ports get killed with the same reason (second form of	608	Otherwise, linked ports get killed with the same reason (second form of
647	C<mon>, see below).	609	C<mon>, see above).
648		610
649	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks	611	Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks
650	will be reported as reason C<< die => $@ >>.	612	will be reported as reason C<< die => $@ >>.
651		613
652	Transport/communication errors are reported as C<< transport_error =>	614	Transport/communication errors are reported as C<< transport_error =>
…		…
657	=item $port = spawn $node, $initfunc[, @initdata]	619	=item $port = spawn $node, $initfunc[, @initdata]
658		620
659	Creates a port on the node C<$node> (which can also be a port ID, in which	621	Creates a port on the node C<$node> (which can also be a port ID, in which
660	case it's the node where that port resides).	622	case it's the node where that port resides).
661		623
662	The port ID of the newly created port is return immediately, and it is	624	The port ID of the newly created port is returned immediately, and it is
663	permissible to immediately start sending messages or monitor the port.	625	possible to immediately start sending messages or to monitor the port.
664		626
665	After the port has been created, the init function is	627	After the port has been created, the init function is called on the remote
666	called. This function must be a fully-qualified function name	628	node, in the same context as a C<rcv> callback. This function must be a
667	(e.g. C<MyApp::Chat::Server::init>). To specify a function in the main	629	fully-qualified function name (e.g. C<MyApp::Chat::Server::init>). To
668	program, use C<::name>.	630	specify a function in the main program, use C<::name>.
669		631
670	If the function doesn't exist, then the node tries to C<require>	632	If the function doesn't exist, then the node tries to C<require>
671	the package, then the package above the package and so on (e.g.	633	the package, then the package above the package and so on (e.g.
672	C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function	634	C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function
673	exists or it runs out of package names.	635	exists or it runs out of package names.
674		636
675	The init function is then called with the newly-created port as context	637	The init function is then called with the newly-created port as context
676	object (C<$SELF>) and the C<@initdata> values as arguments.	638	object (C<$SELF>) and the C<@initdata> values as arguments. It I<must>
		639	call one of the C<rcv> functions to set callbacks on C<$SELF>, otherwise
		640	the port might not get created.
677		641
678	A common idiom is to pass your own port, monitor the spawned port, and	642	A common idiom is to pass a local port, immediately monitor the spawned
679	in the init function, monitor the original port. This two-way monitoring	643	port, and in the remote init function, immediately monitor the passed
680	ensures that both ports get cleaned up when there is a problem.	644	local port. This two-way monitoring ensures that both ports get cleaned up
		645	when there is a problem.
		646
		647	C<spawn> guarantees that the C<$initfunc> has no visible effects on the
		648	caller before C<spawn> returns (by delaying invocation when spawn is
		649	called for the local node).
681		650
682	Example: spawn a chat server port on C<$othernode>.	651	Example: spawn a chat server port on C<$othernode>.
683		652
684	# this node, executed from within a port context:	653	# this node, executed from within a port context:
685	my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF;	654	my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF;
…		…
700		669
701	sub _spawn {	670	sub _spawn {
702	my $port = shift;	671	my $port = shift;
703	my $init = shift;	672	my $init = shift;
704		673
		674	# rcv will create the actual port
705	local $SELF = "$NODE#$port";	675	local $SELF = "$NODE#$port";
706	eval {	676	eval {
707	&{ load_func $init }	677	&{ load_func $init }
708	};	678	};
709	_self_die if $@;	679	_self_die if $@;
710	}	680	}
711		681
712	sub spawn(@) {	682	sub spawn(@) {
713	my ($noderef, undef) = split /#/, shift, 2;	683	my ($nodeid, undef) = split /#/, shift, 2;
714		684
715	my $id = "$RUNIQ." . $ID++;	685	my $id = "$RUNIQ." . $ID++;
716		686
717	$_[0] =~ /::/	687	$_[0] =~ /::/
718	or Carp::croak "spawn init function must be a fully-qualified name, caught";	688	or Carp::croak "spawn init function must be a fully-qualified name, caught";
719		689
720	($NODE{$noderef} \|\| add_node $noderef)	690	snd_to_func $nodeid, "AnyEvent::MP::_spawn" => $id, @_;
721	->send (["", "AnyEvent::MP::_spawn" => $id, @_]);
722		691
723	"$noderef#$id"	692	"$nodeid#$id"
724	}	693	}
725		694
726	=back	695	=item after $timeout, @msg
727		696
728	=head1 NODE MESSAGES	697	=item after $timeout, $callback
729		698
730	Nodes understand the following messages sent to them. Many of them take	699	Either sends the given message, or call the given callback, after the
731	arguments called C<@reply>, which will simply be used to compose a reply	700	specified number of seconds.
732	message - C<$reply[0]> is the port to reply to, C<$reply[1]> the type and
733	the remaining arguments are simply the message data.
734		701
735	While other messages exist, they are not public and subject to change.	702	This is simply a utility function that comes in handy at times - the
		703	AnyEvent::MP author is not convinced of the wisdom of having it, though,
		704	so it may go away in the future.
736		705
737	=over 4
738
739	=cut	706	=cut
740		707
741	=item lookup => $name, @reply	708	sub after($@) {
		709	my ($timeout, @action) = @_;
742		710
743	Replies with the port ID of the specified well-known port, or C<undef>.	711	my $t; $t = AE::timer $timeout, 0, sub {
744		712	undef $t;
745	=item devnull => ...	713	ref $action[0]
746		714	? $action[0]()
747	Generic data sink/CPU heat conversion.	715	: snd @action;
748		716	};
749	=item relay => $port, @msg	717	}
750
751	Simply forwards the message to the given port.
752
753	=item eval => $string[ @reply]
754
755	Evaluates the given string. If C<@reply> is given, then a message of the
756	form C<@reply, $@, @evalres> is sent.
757
758	Example: crash another node.
759
760	snd $othernode, eval => "exit";
761
762	=item time => @reply
763
764	Replies the the current node time to C<@reply>.
765
766	Example: tell the current node to send the current time to C<$myport> in a
767	C<timereply> message.
768
769	snd $NODE, time => $myport, timereply => 1, 2;
770	# => snd $myport, timereply => 1, 2, <time>
771		718
772	=back	719	=back
773		720
774	=head1 AnyEvent::MP vs. Distributed Erlang	721	=head1 AnyEvent::MP vs. Distributed Erlang
775		722
…		…
785		732
786	Despite the similarities, there are also some important differences:	733	Despite the similarities, there are also some important differences:
787		734
788	=over 4	735	=over 4
789		736
790	=item * Node references contain the recipe on how to contact them.	737	=item * Node IDs are arbitrary strings in AEMP.
791		738
792	Erlang relies on special naming and DNS to work everywhere in the	739	Erlang relies on special naming and DNS to work everywhere in the same
793	same way. AEMP relies on each node knowing it's own address(es), with	740	way. AEMP relies on each node somehow knowing its own address(es) (e.g. by
794	convenience functionality.	741	configuration or DNS), but will otherwise discover other odes itself.
795		742
796	This means that AEMP requires a less tightly controlled environment at the	743	=item * Erlang has a "remote ports are like local ports" philosophy, AEMP
797	cost of longer node references and a slightly higher management overhead.	744	uses "local ports are like remote ports".
		745
		746	The failure modes for local ports are quite different (runtime errors
		747	only) then for remote ports - when a local port dies, you I<know> it dies,
		748	when a connection to another node dies, you know nothing about the other
		749	port.
		750
		751	Erlang pretends remote ports are as reliable as local ports, even when
		752	they are not.
		753
		754	AEMP encourages a "treat remote ports differently" philosophy, with local
		755	ports being the special case/exception, where transport errors cannot
		756	occur.
798		757
799	=item * Erlang uses processes and a mailbox, AEMP does not queue.	758	=item * Erlang uses processes and a mailbox, AEMP does not queue.
800		759
801	Erlang uses processes that selctively receive messages, and therefore	760	Erlang uses processes that selectively receive messages, and therefore
802	needs a queue. AEMP is event based, queuing messages would serve no useful	761	needs a queue. AEMP is event based, queuing messages would serve no
803	purpose.	762	useful purpose. For the same reason the pattern-matching abilities of
		763	AnyEvent::MP are more limited, as there is little need to be able to
		764	filter messages without dequeuing them.
804		765
805	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).	766	(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).
806		767
807	=item * Erlang sends are synchronous, AEMP sends are asynchronous.	768	=item * Erlang sends are synchronous, AEMP sends are asynchronous.
808		769
809	Sending messages in Erlang is synchronous and blocks the process. AEMP	770	Sending messages in Erlang is synchronous and blocks the process (and
810	sends are immediate, connection establishment is handled in the	771	so does not need a queue that can overflow). AEMP sends are immediate,
811	background.	772	connection establishment is handled in the background.
812		773
813	=item * Erlang can silently lose messages, AEMP cannot.	774	=item * Erlang suffers from silent message loss, AEMP does not.
814		775
815	Erlang makes few guarantees on messages delivery - messages can get lost	776	Erlang makes few guarantees on messages delivery - messages can get lost
816	without any of the processes realising it (i.e. you send messages a, b,	777	without any of the processes realising it (i.e. you send messages a, b,
817	and c, and the other side only receives messages a and c).	778	and c, and the other side only receives messages a and c).
818		779
819	AEMP guarantees correct ordering, and the guarantee that there are no	780	AEMP guarantees correct ordering, and the guarantee that after one message
820	holes in the message sequence.	781	is lost, all following ones sent to the same port are lost as well, until
821		782	monitoring raises an error, so there are no silent "holes" in the message
822	=item * In Erlang, processes can be declared dead and later be found to be	783	sequence.
823	alive.
824
825	In Erlang it can happen that a monitored process is declared dead and
826	linked processes get killed, but later it turns out that the process is
827	still alive - and can receive messages.
828
829	In AEMP, when port monitoring detects a port as dead, then that port will
830	eventually be killed - it cannot happen that a node detects a port as dead
831	and then later sends messages to it, finding it is still alive.
832		784
833	=item * Erlang can send messages to the wrong port, AEMP does not.	785	=item * Erlang can send messages to the wrong port, AEMP does not.
834		786
835	In Erlang it is quite possible that a node that restarts reuses a process	787	In Erlang it is quite likely that a node that restarts reuses a process ID
836	ID known to other nodes for a completely different process, causing	788	known to other nodes for a completely different process, causing messages
837	messages destined for that process to end up in an unrelated process.	789	destined for that process to end up in an unrelated process.
838		790
839	AEMP never reuses port IDs, so old messages or old port IDs floating	791	AEMP never reuses port IDs, so old messages or old port IDs floating
840	around in the network will not be sent to an unrelated port.	792	around in the network will not be sent to an unrelated port.
841		793
842	=item * Erlang uses unprotected connections, AEMP uses secure	794	=item * Erlang uses unprotected connections, AEMP uses secure
843	authentication and can use TLS.	795	authentication and can use TLS.
844		796
845	AEMP can use a proven protocol - SSL/TLS - to protect connections and	797	AEMP can use a proven protocol - TLS - to protect connections and
846	securely authenticate nodes.	798	securely authenticate nodes.
847		799
848	=item * The AEMP protocol is optimised for both text-based and binary	800	=item * The AEMP protocol is optimised for both text-based and binary
849	communications.	801	communications.
850		802
851	The AEMP protocol, unlike the Erlang protocol, supports both	803	The AEMP protocol, unlike the Erlang protocol, supports both programming
852	language-independent text-only protocols (good for debugging) and binary,	804	language independent text-only protocols (good for debugging) and binary,
853	language-specific serialisers (e.g. Storable).	805	language-specific serialisers (e.g. Storable). By default, unless TLS is
		806	used, the protocol is actually completely text-based.
854		807
855	It has also been carefully designed to be implementable in other languages	808	It has also been carefully designed to be implementable in other languages
856	with a minimum of work while gracefully degrading fucntionality to make the	809	with a minimum of work while gracefully degrading functionality to make the
857	protocol simple.	810	protocol simple.
858		811
859	=item * AEMP has more flexible monitoring options than Erlang.	812	=item * AEMP has more flexible monitoring options than Erlang.
860		813
861	In Erlang, you can chose to receive I<all> exit signals as messages	814	In Erlang, you can chose to receive I<all> exit signals as messages
…		…
864	Erlang, as one can choose between automatic kill, exit message or callback	817	Erlang, as one can choose between automatic kill, exit message or callback
865	on a per-process basis.	818	on a per-process basis.
866		819
867	=item * Erlang tries to hide remote/local connections, AEMP does not.	820	=item * Erlang tries to hide remote/local connections, AEMP does not.
868		821
869	Monitoring in Erlang is not an indicator of process death/crashes,	822	Monitoring in Erlang is not an indicator of process death/crashes, in the
870	as linking is (except linking is unreliable in Erlang).	823	same way as linking is (except linking is unreliable in Erlang).
871		824
872	In AEMP, you don't "look up" registered port names or send to named ports	825	In AEMP, you don't "look up" registered port names or send to named ports
873	that might or might not be persistent. Instead, you normally spawn a port	826	that might or might not be persistent. Instead, you normally spawn a port
874	on the remote node. The init function monitors the you, and you monitor	827	on the remote node. The init function monitors you, and you monitor the
875	the remote port. Since both monitors are local to the node, they are much	828	remote port. Since both monitors are local to the node, they are much more
876	more reliable.	829	reliable (no need for C<spawn_link>).
877		830
878	This also saves round-trips and avoids sending messages to the wrong port	831	This also saves round-trips and avoids sending messages to the wrong port
879	(hard to do in Erlang).	832	(hard to do in Erlang).
880		833
881	=back	834	=back
882		835
883	=head1 RATIONALE	836	=head1 RATIONALE
884		837
885	=over 4	838	=over 4
886		839
887	=item Why strings for ports and noderefs, why not objects?	840	=item Why strings for port and node IDs, why not objects?
888		841
889	We considered "objects", but found that the actual number of methods	842	We considered "objects", but found that the actual number of methods
890	thatc an be called are very low. Since port IDs and noderefs travel over	843	that can be called are quite low. Since port and node IDs travel over
891	the network frequently, the serialising/deserialising would add lots of	844	the network frequently, the serialising/deserialising would add lots of
892	overhead, as well as having to keep a proxy object.	845	overhead, as well as having to keep a proxy object everywhere.
893		846
894	Strings can easily be printed, easily serialised etc. and need no special	847	Strings can easily be printed, easily serialised etc. and need no special
895	procedures to be "valid".	848	procedures to be "valid".
896		849
897	And a a miniport consists of a single closure stored in a global hash - it	850	And as a result, a miniport consists of a single closure stored in a
898	can't become much cheaper.	851	global hash - it can't become much cheaper.
899		852
900	=item Why favour JSON, why not real serialising format such as Storable?	853	=item Why favour JSON, why not a real serialising format such as Storable?
901		854
902	In fact, any AnyEvent::MP node will happily accept Storable as framing	855	In fact, any AnyEvent::MP node will happily accept Storable as framing
903	format, but currently there is no way to make a node use Storable by	856	format, but currently there is no way to make a node use Storable by
904	default.	857	default (although all nodes will accept it).
905		858
906	The default framing protocol is JSON because a) JSON::XS is many times	859	The default framing protocol is JSON because a) JSON::XS is many times
907	faster for small messages and b) most importantly, after years of	860	faster for small messages and b) most importantly, after years of
908	experience we found that object serialisation is causing more problems	861	experience we found that object serialisation is causing more problems
909	than it gains: Just like function calls, objects simply do not travel	862	than it solves: Just like function calls, objects simply do not travel
910	easily over the network, mostly because they will always be a copy, so you	863	easily over the network, mostly because they will always be a copy, so you
911	always have to re-think your design.	864	always have to re-think your design.
912		865
913	Keeping your messages simple, concentrating on data structures rather than	866	Keeping your messages simple, concentrating on data structures rather than
914	objects, will keep your messages clean, tidy and efficient.	867	objects, will keep your messages clean, tidy and efficient.
915		868
916	=back	869	=back
917		870
918	=head1 SEE ALSO	871	=head1 SEE ALSO
919		872
		873	L<AnyEvent::MP::Intro> - a gentle introduction.
		874
		875	L<AnyEvent::MP::Kernel> - more, lower-level, stuff.
		876
		877	L<AnyEvent::MP::Global> - network maintainance and port groups, to find
		878	your applications.
		879
		880	L<AnyEvent::MP::LogCatcher> - simple service to display log messages from
		881	all nodes.
		882
920	L<AnyEvent>.	883	L<AnyEvent>.
921		884
922	=head1 AUTHOR	885	=head1 AUTHOR
923		886
924	Marc Lehmann <schmorp@schmorp.de>	887	Marc Lehmann <schmorp@schmorp.de>

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Revision 1.83 by root, Tue Sep 8 01:38:16 2009 UTC