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Revision 1.93 by root, Tue Sep 22 14:14:29 2009 UTC

1=head1 NAME 1=head1 NAME
2 2
3AnyEvent::MP - multi-processing/message-passing framework 3AnyEvent::MP - erlang-style multi-processing/message-passing framework
4 4
5=head1 SYNOPSIS 5=head1 SYNOPSIS
6 6
7 use AnyEvent::MP; 7 use AnyEvent::MP;
8 8
9 $NODE # contains this node's noderef 9 $NODE # contains this node's node ID
10 NODE # returns this node's noderef 10 NODE # returns this node's node ID
11 NODE $port # returns the noderef of the port
12 11
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; 15 configure;
17 16
18 # ports are message endpoints 17 # ports are message destinations
19 18
20 # sending messages 19 # sending messages
21 snd $port, type => data...; 20 snd $port, type => data...;
22 snd $port, @msg; 21 snd $port, @msg;
23 snd @msg_with_first_element_being_a_port; 22 snd @msg_with_first_element_being_a_port;
24 23
25 # creating/using ports, the simple way 24 # creating/using ports, the simple way
26 my $simple_port = port { my @msg = @_; 0 }; 25 my $simple_port = port { my @msg = @_ };
27 26
28 # creating/using ports, tagged message matching 27 # creating/using ports, tagged message matching
29 my $port = port; 28 my $port = port;
30 rcv $port, ping => sub { snd $_[0], "pong"; 0 }; 29 rcv $port, ping => sub { snd $_[0], "pong" };
31 rcv $port, pong => sub { warn "pong received\n"; 0 }; 30 rcv $port, pong => sub { warn "pong received\n" };
32 31
33 # create a port on another node 32 # create a port on another node
34 my $port = spawn $node, $initfunc, @initdata; 33 my $port = spawn $node, $initfunc, @initdata;
35 34
36 # monitoring 35 # monitoring
37 mon $port, $cb->(@msg) # callback is invoked on death 36 mon $localport, $cb->(@msg) # callback is invoked on death
38 mon $port, $otherport # kill otherport on abnormal death 37 mon $localport, $otherport # kill otherport on abnormal death
39 mon $port, $otherport, @msg # send message on death 38 mon $localport, $otherport, @msg # send message on death
40 39
41=head1 CURRENT STATUS 40=head1 CURRENT STATUS
42 41
42 bin/aemp - stable.
43 AnyEvent::MP - stable API, should work 43 AnyEvent::MP - stable API, should work.
44 AnyEvent::MP::Intro - outdated 44 AnyEvent::MP::Intro - explains most concepts.
45 AnyEvent::MP::Kernel - mostly stable 45 AnyEvent::MP::Kernel - mostly stable API.
46 AnyEvent::MP::Global - mostly stable 46 AnyEvent::MP::Global - stable API.
47 AnyEvent::MP::Node - mostly stable, but internal anyways
48 AnyEvent::MP::Transport - mostly stable, but internal anyways
49
50 stay tuned.
51 47
52=head1 DESCRIPTION 48=head1 DESCRIPTION
53 49
54This module (-family) implements a simple message passing framework. 50This module (-family) implements a simple message passing framework.
55 51
57on the same or other hosts, and you can supervise entities remotely. 53on the same or other hosts, and you can supervise entities remotely.
58 54
59For an introduction to this module family, see the L<AnyEvent::MP::Intro> 55For an introduction to this module family, see the L<AnyEvent::MP::Intro>
60manual page and the examples under F<eg/>. 56manual page and the examples under F<eg/>.
61 57
62At the moment, this module family is a bit underdocumented.
63
64=head1 CONCEPTS 58=head1 CONCEPTS
65 59
66=over 4 60=over 4
67 61
68=item port 62=item port
69 63
70A port is something you can send messages to (with the C<snd> function). 64Not to be confused with a TCP port, a "port" is something you can send
65messages to (with the C<snd> function).
71 66
72Ports allow you to register C<rcv> handlers that can match all or just 67Ports allow you to register C<rcv> handlers that can match all or just
73some messages. Messages send to ports will not be queued, regardless of 68some messages. Messages send to ports will not be queued, regardless of
74anything was listening for them or not. 69anything was listening for them or not.
75 70
86 81
87Nodes are either public (have one or more listening ports) or private 82Nodes are either public (have one or more listening ports) or private
88(no listening ports). Private nodes cannot talk to other private nodes 83(no listening ports). Private nodes cannot talk to other private nodes
89currently. 84currently.
90 85
91=item node ID - C<[a-za-Z0-9_\-.:]+> 86=item node ID - C<[A-Z_][a-zA-Z0-9_\-.:]*>
92 87
93A node ID is a string that uniquely identifies the node within a 88A node ID is a string that uniquely identifies the node within a
94network. Depending on the configuration used, node IDs can look like a 89network. Depending on the configuration used, node IDs can look like a
95hostname, a hostname and a port, or a random string. AnyEvent::MP itself 90hostname, a hostname and a port, or a random string. AnyEvent::MP itself
96doesn't interpret node IDs in any way. 91doesn't interpret node IDs in any way.
100Nodes can only talk to each other by creating some kind of connection to 95Nodes can only talk to each other by creating some kind of connection to
101each other. To do this, nodes should listen on one or more local transport 96each other. To do this, nodes should listen on one or more local transport
102endpoints - binds. Currently, only standard C<ip:port> specifications can 97endpoints - binds. Currently, only standard C<ip:port> specifications can
103be used, which specify TCP ports to listen on. 98be used, which specify TCP ports to listen on.
104 99
105=item seeds - C<host:port> 100=item seed nodes
106 101
107When a node starts, it knows nothing about the network. To teach the node 102When a node starts, it knows nothing about the network. To teach the node
108about the network it first has to contact some other node within the 103about the network it first has to contact some other node within the
109network. This node is called a seed. 104network. This node is called a seed.
110 105
111Seeds are transport endpoint(s) of as many nodes as one wants. Those nodes 106Apart from the fact that other nodes know them as seed nodes and they have
107to have fixed listening addresses, seed nodes are perfectly normal nodes -
108any node can function as a seed node for others.
109
110In addition to discovering the network, seed nodes are also used to
111maintain the network and to connect nodes that otherwise would have
112trouble connecting. They form the backbone of an AnyEvent::MP network.
113
112are expected to be long-running, and at least one of those should always 114Seed nodes are expected to be long-running, and at least one seed node
113be available. When nodes run out of connections (e.g. due to a network 115should always be available. They should also be relatively responsive - a
114error), they try to re-establish connections to some seednodes again to 116seed node that blocks for long periods will slow down everybody else.
115join the network.
116 117
117Apart from being sued for seeding, seednodes are not special in any way - 118=item seeds - C<host:port>
118every public node can be a seednode. 119
120Seeds are transport endpoint(s) (usually a hostname/IP address and a
121TCP port) of nodes thta should be used as seed nodes.
122
123The nodes listening on those endpoints are expected to be long-running,
124and at least one of those should always be available. When nodes run out
125of connections (e.g. due to a network error), they try to re-establish
126connections to some seednodes again to join the network.
119 127
120=back 128=back
121 129
122=head1 VARIABLES/FUNCTIONS 130=head1 VARIABLES/FUNCTIONS
123 131
139 147
140our $VERSION = $AnyEvent::MP::Kernel::VERSION; 148our $VERSION = $AnyEvent::MP::Kernel::VERSION;
141 149
142our @EXPORT = qw( 150our @EXPORT = qw(
143 NODE $NODE *SELF node_of after 151 NODE $NODE *SELF node_of after
144 initialise_node 152 configure
145 snd rcv mon mon_guard kil reg psub spawn 153 snd rcv mon mon_guard kil psub spawn cal
146 port 154 port
147); 155);
148 156
149our $SELF; 157our $SELF;
150 158
156 164
157=item $thisnode = NODE / $NODE 165=item $thisnode = NODE / $NODE
158 166
159The C<NODE> function returns, and the C<$NODE> variable contains, the node 167The C<NODE> function returns, and the C<$NODE> variable contains, the node
160ID of the node running in the current process. This value is initialised by 168ID of the node running in the current process. This value is initialised by
161a call to C<initialise_node>. 169a call to C<configure>.
162 170
163=item $nodeid = node_of $port 171=item $nodeid = node_of $port
164 172
165Extracts and returns the node ID from a port ID or a node ID. 173Extracts and returns the node ID from a port ID or a node ID.
166 174
167=item initialise_node $profile_name, key => value... 175=item configure $profile, key => value...
176
177=item configure key => value...
168 178
169Before a node can talk to other nodes on the network (i.e. enter 179Before a node can talk to other nodes on the network (i.e. enter
170"distributed mode") it has to initialise itself - the minimum a node needs 180"distributed mode") it has to configure itself - the minimum a node needs
171to know is its own name, and optionally it should know the addresses of 181to know is its own name, and optionally it should know the addresses of
172some other nodes in the network to discover other nodes. 182some other nodes in the network to discover other nodes.
173 183
174This function initialises a node - it must be called exactly once (or 184This function configures a node - it must be called exactly once (or
175never) before calling other AnyEvent::MP functions. 185never) before calling other AnyEvent::MP functions.
176 186
177The first argument is a profile name. If it is C<undef> or missing, then 187=over 4
178the current nodename will be used instead (i.e. F<uname -n>).
179 188
189=item step 1, gathering configuration from profiles
190
180The function first looks up the profile in the aemp configuration (see the 191The function first looks up a profile in the aemp configuration (see the
181L<aemp> commandline utility). the profile is calculated as follows: 192L<aemp> commandline utility). The profile name can be specified via the
193named C<profile> parameter or can simply be the first parameter). If it is
194missing, then the nodename (F<uname -n>) will be used as profile name.
182 195
183First, all remaining key => value pairs will be used. Then they will be 196The profile data is then gathered as follows:
184overwritten by any values specified in the global default configuration 197
185(see the F<aemp> utility), then the chain of profiles selected, if 198First, all remaining key => value pairs (all of which are conveniently
199undocumented at the moment) will be interpreted as configuration
200data. Then they will be overwritten by any values specified in the global
201default configuration (see the F<aemp> utility), then the chain of
202profiles chosen by the profile name (and any C<parent> attributes).
203
186any. That means that the values specified in the profile have highest 204That means that the values specified in the profile have highest priority
187priority and the values specified via C<initialise_node> have lowest 205and the values specified directly via C<configure> have lowest priority,
188priority. 206and can only be used to specify defaults.
189 207
190If the profile specifies a node ID, then this will become the node ID of 208If the profile specifies a node ID, then this will become the node ID of
191this process. If not, then the profile name will be used as node ID. The 209this process. If not, then the profile name will be used as node ID. The
192special node ID of C<anon/> will be replaced by a random node ID. 210special node ID of C<anon/> will be replaced by a random node ID.
211
212=item step 2, bind listener sockets
193 213
194The next step is to look up the binds in the profile, followed by binding 214The next step is to look up the binds in the profile, followed by binding
195aemp protocol listeners on all binds specified (it is possible and valid 215aemp protocol listeners on all binds specified (it is possible and valid
196to have no binds, meaning that the node cannot be contacted form the 216to have no binds, meaning that the node cannot be contacted form the
197outside. This means the node cannot talk to other nodes that also have no 217outside. This means the node cannot talk to other nodes that also have no
198binds, but it can still talk to all "normal" nodes). 218binds, but it can still talk to all "normal" nodes).
199 219
200If the profile does not specify a binds list, then the node ID will be 220If the profile does not specify a binds list, then a default of C<*> is
201treated as if it were of the form C<host:port>, which will be resolved and 221used, meaning the node will bind on a dynamically-assigned port on every
202used as binds list. 222local IP address it finds.
203 223
224=item step 3, connect to seed nodes
225
204Lastly, the seeds list from the profile is passed to the 226As the last step, the seeds list from the profile is passed to the
205L<AnyEvent::MP::Global> module, which will then use it to keep 227L<AnyEvent::MP::Global> module, which will then use it to keep
206connectivity with at least on of those seed nodes at any point in time. 228connectivity with at least one node at any point in time.
207 229
208Example: become a distributed node listening on the guessed noderef, or 230=back
209the one specified via C<aemp> for the current node. This should be the 231
232Example: become a distributed node using the local node name as profile.
210most common form of invocation for "daemon"-type nodes. 233This should be the most common form of invocation for "daemon"-type nodes.
211 234
212 initialise_node; 235 configure
213 236
214Example: become an anonymous node. This form is often used for commandline 237Example: become an anonymous node. This form is often used for commandline
215clients. 238clients.
216 239
217 initialise_node "anon/"; 240 configure nodeid => "anon/";
218 241
219Example: become a distributed node. If there is no profile of the given 242Example: configure a node using a profile called seed, which si suitable
220name, or no binds list was specified, resolve C<localhost:4044> and bind 243for a seed node as it binds on all local addresses on a fixed port (4040,
221on the resulting addresses. 244customary for aemp).
222 245
223 initialise_node "localhost:4044"; 246 # use the aemp commandline utility
247 # aemp profile seed nodeid anon/ binds '*:4040'
248
249 # then use it
250 configure profile => "seed";
251
252 # or simply use aemp from the shell again:
253 # aemp run profile seed
254
255 # or provide a nicer-to-remember nodeid
256 # aemp run profile seed nodeid "$(hostname)"
224 257
225=item $SELF 258=item $SELF
226 259
227Contains the current port id while executing C<rcv> callbacks or C<psub> 260Contains the current port id while executing C<rcv> callbacks or C<psub>
228blocks. 261blocks.
350 383
351=cut 384=cut
352 385
353sub rcv($@) { 386sub rcv($@) {
354 my $port = shift; 387 my $port = shift;
355 my ($noderef, $portid) = split /#/, $port, 2; 388 my ($nodeid, $portid) = split /#/, $port, 2;
356 389
357 $NODE{$noderef} == $NODE{""} 390 $NODE{$nodeid} == $NODE{""}
358 or Carp::croak "$port: rcv can only be called on local ports, caught"; 391 or Carp::croak "$port: rcv can only be called on local ports, caught";
359 392
360 while (@_) { 393 while (@_) {
361 if (ref $_[0]) { 394 if (ref $_[0]) {
362 if (my $self = $PORT_DATA{$portid}) { 395 if (my $self = $PORT_DATA{$portid}) {
453 486
454Monitor the given port and do something when the port is killed or 487Monitor the given port and do something when the port is killed or
455messages to it were lost, and optionally return a guard that can be used 488messages to it were lost, and optionally return a guard that can be used
456to stop monitoring again. 489to stop monitoring again.
457 490
491In the first form (callback), the callback is simply called with any
492number of C<@reason> elements (no @reason means that the port was deleted
493"normally"). Note also that I<< the callback B<must> never die >>, so use
494C<eval> if unsure.
495
496In the second form (another port given), the other port (C<$rcvport>)
497will be C<kil>'ed with C<@reason>, if a @reason was specified, i.e. on
498"normal" kils nothing happens, while under all other conditions, the other
499port is killed with the same reason.
500
501The third form (kill self) is the same as the second form, except that
502C<$rvport> defaults to C<$SELF>.
503
504In the last form (message), a message of the form C<@msg, @reason> will be
505C<snd>.
506
507Monitoring-actions are one-shot: once messages are lost (and a monitoring
508alert was raised), they are removed and will not trigger again.
509
510As a rule of thumb, monitoring requests should always monitor a port from
511a local port (or callback). The reason is that kill messages might get
512lost, just like any other message. Another less obvious reason is that
513even monitoring requests can get lost (for example, when the connection
514to the other node goes down permanently). When monitoring a port locally
515these problems do not exist.
516
458C<mon> effectively guarantees that, in the absence of hardware failures, 517C<mon> effectively guarantees that, in the absence of hardware failures,
459after starting the monitor, either all messages sent to the port will 518after starting the monitor, either all messages sent to the port will
460arrive, or the monitoring action will be invoked after possible message 519arrive, or the monitoring action will be invoked after possible message
461loss has been detected. No messages will be lost "in between" (after 520loss has been detected. No messages will be lost "in between" (after
462the first lost message no further messages will be received by the 521the first lost message no further messages will be received by the
463port). After the monitoring action was invoked, further messages might get 522port). After the monitoring action was invoked, further messages might get
464delivered again. 523delivered again.
465 524
466Note that monitoring-actions are one-shot: once messages are lost (and a 525Inter-host-connection timeouts and monitoring depend on the transport
467monitoring alert was raised), they are removed and will not trigger again. 526used. The only transport currently implemented is TCP, and AnyEvent::MP
527relies on TCP to detect node-downs (this can take 10-15 minutes on a
528non-idle connection, and usually around two hours for idle conenctions).
468 529
469In the first form (callback), the callback is simply called with any 530This means that monitoring is good for program errors and cleaning up
470number of C<@reason> elements (no @reason means that the port was deleted 531stuff eventually, but they are no replacement for a timeout when you need
471"normally"). Note also that I<< the callback B<must> never die >>, so use 532to ensure some maximum latency.
472C<eval> if unsure.
473
474In the second form (another port given), the other port (C<$rcvport>)
475will be C<kil>'ed with C<@reason>, iff a @reason was specified, i.e. on
476"normal" kils nothing happens, while under all other conditions, the other
477port is killed with the same reason.
478
479The third form (kill self) is the same as the second form, except that
480C<$rvport> defaults to C<$SELF>.
481
482In the last form (message), a message of the form C<@msg, @reason> will be
483C<snd>.
484
485As a rule of thumb, monitoring requests should always monitor a port from
486a local port (or callback). The reason is that kill messages might get
487lost, just like any other message. Another less obvious reason is that
488even monitoring requests can get lost (for exmaple, when the connection
489to the other node goes down permanently). When monitoring a port locally
490these problems do not exist.
491 533
492Example: call a given callback when C<$port> is killed. 534Example: call a given callback when C<$port> is killed.
493 535
494 mon $port, sub { warn "port died because of <@_>\n" }; 536 mon $port, sub { warn "port died because of <@_>\n" };
495 537
502 mon $port, $self => "restart"; 544 mon $port, $self => "restart";
503 545
504=cut 546=cut
505 547
506sub mon { 548sub mon {
507 my ($noderef, $port) = split /#/, shift, 2; 549 my ($nodeid, $port) = split /#/, shift, 2;
508 550
509 my $node = $NODE{$noderef} || add_node $noderef; 551 my $node = $NODE{$nodeid} || add_node $nodeid;
510 552
511 my $cb = @_ ? shift : $SELF || Carp::croak 'mon: called with one argument only, but $SELF not set,'; 553 my $cb = @_ ? shift : $SELF || Carp::croak 'mon: called with one argument only, but $SELF not set,';
512 554
513 unless (ref $cb) { 555 unless (ref $cb) {
514 if (@_) { 556 if (@_) {
523 } 565 }
524 566
525 $node->monitor ($port, $cb); 567 $node->monitor ($port, $cb);
526 568
527 defined wantarray 569 defined wantarray
570 and $cb += 0
528 and AnyEvent::Util::guard { $node->unmonitor ($port, $cb) } 571 and AnyEvent::Util::guard { $node->unmonitor ($port, $cb) }
529} 572}
530 573
531=item $guard = mon_guard $port, $ref, $ref... 574=item $guard = mon_guard $port, $ref, $ref...
532 575
590the package, then the package above the package and so on (e.g. 633the package, then the package above the package and so on (e.g.
591C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function 634C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function
592exists or it runs out of package names. 635exists or it runs out of package names.
593 636
594The init function is then called with the newly-created port as context 637The init function is then called with the newly-created port as context
595object (C<$SELF>) and the C<@initdata> values as arguments. 638object (C<$SELF>) and the C<@initdata> values as arguments. It I<must>
639call one of the C<rcv> functions to set callbacks on C<$SELF>, otherwise
640the port might not get created.
596 641
597A common idiom is to pass a local port, immediately monitor the spawned 642A common idiom is to pass a local port, immediately monitor the spawned
598port, and in the remote init function, immediately monitor the passed 643port, and in the remote init function, immediately monitor the passed
599local port. This two-way monitoring ensures that both ports get cleaned up 644local port. This two-way monitoring ensures that both ports get cleaned up
600when there is a problem. 645when there is a problem.
601 646
647C<spawn> guarantees that the C<$initfunc> has no visible effects on the
648caller before C<spawn> returns (by delaying invocation when spawn is
649called for the local node).
650
602Example: spawn a chat server port on C<$othernode>. 651Example: spawn a chat server port on C<$othernode>.
603 652
604 # this node, executed from within a port context: 653 # this node, executed from within a port context:
605 my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF; 654 my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF;
606 mon $server; 655 mon $server;
620 669
621sub _spawn { 670sub _spawn {
622 my $port = shift; 671 my $port = shift;
623 my $init = shift; 672 my $init = shift;
624 673
674 # rcv will create the actual port
625 local $SELF = "$NODE#$port"; 675 local $SELF = "$NODE#$port";
626 eval { 676 eval {
627 &{ load_func $init } 677 &{ load_func $init }
628 }; 678 };
629 _self_die if $@; 679 _self_die if $@;
630} 680}
631 681
632sub spawn(@) { 682sub spawn(@) {
633 my ($noderef, undef) = split /#/, shift, 2; 683 my ($nodeid, undef) = split /#/, shift, 2;
634 684
635 my $id = "$RUNIQ." . $ID++; 685 my $id = "$RUNIQ." . $ID++;
636 686
637 $_[0] =~ /::/ 687 $_[0] =~ /::/
638 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";
639 689
640 snd_to_func $noderef, "AnyEvent::MP::_spawn" => $id, @_; 690 snd_to_func $nodeid, "AnyEvent::MP::_spawn" => $id, @_;
641 691
642 "$noderef#$id" 692 "$nodeid#$id"
643} 693}
644 694
645=item after $timeout, @msg 695=item after $timeout, @msg
646 696
647=item after $timeout, $callback 697=item after $timeout, $callback
664 ? $action[0]() 714 ? $action[0]()
665 : snd @action; 715 : snd @action;
666 }; 716 };
667} 717}
668 718
719=item cal $port, @msg, $callback[, $timeout]
720
721A simple form of RPC - sends a message to the given C<$port> with the
722given contents (C<@msg>), but adds a reply port to the message.
723
724The reply port is created temporarily just for the purpose of receiving
725the reply, and will be C<kil>ed when no longer needed.
726
727A reply message sent to the port is passed to the C<$callback> as-is.
728
729If an optional time-out (in seconds) is given and it is not C<undef>,
730then the callback will be called without any arguments after the time-out
731elapsed and the port is C<kil>ed.
732
733If no time-out is given, then the local port will monitor the remote port
734instead, so it eventually gets cleaned-up.
735
736Currently this function returns the temporary port, but this "feature"
737might go in future versions unless you can make a convincing case that
738this is indeed useful for something.
739
740=cut
741
742sub cal(@) {
743 my $timeout = ref $_[-1] ? undef : pop;
744 my $cb = pop;
745
746 my $port = port {
747 undef $timeout;
748 kil $SELF;
749 &$cb;
750 };
751
752 if (defined $timeout) {
753 $timeout = AE::timer $timeout, 0, sub {
754 undef $timeout;
755 kil $port;
756 $cb->();
757 };
758 } else {
759 mon $_[0], sub {
760 kil $port;
761 $cb->();
762 };
763 }
764
765 push @_, $port;
766 &snd;
767
768 $port
769}
770
669=back 771=back
670 772
671=head1 AnyEvent::MP vs. Distributed Erlang 773=head1 AnyEvent::MP vs. Distributed Erlang
672 774
673AnyEvent::MP got lots of its ideas from distributed Erlang (Erlang node 775AnyEvent::MP got lots of its ideas from distributed Erlang (Erlang node
686 788
687=item * Node IDs are arbitrary strings in AEMP. 789=item * Node IDs are arbitrary strings in AEMP.
688 790
689Erlang relies on special naming and DNS to work everywhere in the same 791Erlang relies on special naming and DNS to work everywhere in the same
690way. AEMP relies on each node somehow knowing its own address(es) (e.g. by 792way. AEMP relies on each node somehow knowing its own address(es) (e.g. by
691configuraiton or DNS), but will otherwise discover other odes itself. 793configuration or DNS), but will otherwise discover other odes itself.
692 794
693=item * Erlang has a "remote ports are like local ports" philosophy, AEMP 795=item * Erlang has a "remote ports are like local ports" philosophy, AEMP
694uses "local ports are like remote ports". 796uses "local ports are like remote ports".
695 797
696The failure modes for local ports are quite different (runtime errors 798The failure modes for local ports are quite different (runtime errors
709 811
710Erlang uses processes that selectively receive messages, and therefore 812Erlang uses processes that selectively receive messages, and therefore
711needs a queue. AEMP is event based, queuing messages would serve no 813needs a queue. AEMP is event based, queuing messages would serve no
712useful purpose. For the same reason the pattern-matching abilities of 814useful purpose. For the same reason the pattern-matching abilities of
713AnyEvent::MP are more limited, as there is little need to be able to 815AnyEvent::MP are more limited, as there is little need to be able to
714filter messages without dequeing them. 816filter messages without dequeuing them.
715 817
716(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP). 818(But see L<Coro::MP> for a more Erlang-like process model on top of AEMP).
717 819
718=item * Erlang sends are synchronous, AEMP sends are asynchronous. 820=item * Erlang sends are synchronous, AEMP sends are asynchronous.
719 821
825L<AnyEvent::MP::Kernel> - more, lower-level, stuff. 927L<AnyEvent::MP::Kernel> - more, lower-level, stuff.
826 928
827L<AnyEvent::MP::Global> - network maintainance and port groups, to find 929L<AnyEvent::MP::Global> - network maintainance and port groups, to find
828your applications. 930your applications.
829 931
932L<AnyEvent::MP::LogCatcher> - simple service to display log messages from
933all nodes.
934
830L<AnyEvent>. 935L<AnyEvent>.
831 936
832=head1 AUTHOR 937=head1 AUTHOR
833 938
834 Marc Lehmann <schmorp@schmorp.de> 939 Marc Lehmann <schmorp@schmorp.de>

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