… | |
… | |
43 | |
43 | |
44 | =over 4 |
44 | =over 4 |
45 | |
45 | |
46 | =item port |
46 | =item port |
47 | |
47 | |
48 | A port is something you can send messages to with the C<snd> function, and |
48 | A port is something you can send messages to (with the C<snd> function). |
49 | you can register C<rcv> handlers with. All C<rcv> handlers will receive |
49 | |
50 | messages they match, messages will not be queued. |
50 | Some ports allow you to register C<rcv> handlers that can match specific |
|
|
51 | messages. All C<rcv> handlers will receive messages they match, messages |
|
|
52 | will not be queued. |
51 | |
53 | |
52 | =item port id - C<noderef#portname> |
54 | =item port id - C<noderef#portname> |
53 | |
55 | |
54 | A port id is always the noderef, a hash-mark (C<#>) as separator, followed |
56 | A port id is normaly the concatenation of a noderef, a hash-mark (C<#>) as |
55 | by a port name (a printable string of unspecified format). |
57 | separator, and a port name (a printable string of unspecified format). An |
|
|
58 | exception is the the node port, whose ID is identical to its node |
|
|
59 | reference. |
56 | |
60 | |
57 | =item node |
61 | =item node |
58 | |
62 | |
59 | A node is a single process containing at least one port - the node |
63 | A node is a single process containing at least one port - the node |
60 | port. You can send messages to node ports to let them create new ports, |
64 | port. You can send messages to node ports to find existing ports or to |
61 | among other things. |
65 | create new ports, among other things. |
62 | |
66 | |
63 | Initially, nodes are either private (single-process only) or hidden |
67 | Nodes are either private (single-process only), slaves (connected to a |
64 | (connected to a master node only). Only when they epxlicitly "become |
68 | master node only) or public nodes (connectable from unrelated nodes). |
65 | public" can you send them messages from unrelated other nodes. |
|
|
66 | |
69 | |
67 | =item noderef - C<host:port,host:port...>, C<id@noderef>, C<id> |
70 | =item noderef - C<host:port,host:port...>, C<id@noderef>, C<id> |
68 | |
71 | |
69 | A noderef is a string that either uniquely identifies a given node (for |
72 | A node reference is a string that either simply identifies the node (for |
70 | private and hidden nodes), or contains a recipe on how to reach a given |
73 | private and slave nodes), or contains a recipe on how to reach a given |
71 | node (for public nodes). |
74 | node (for public nodes). |
|
|
75 | |
|
|
76 | This recipe is simply a comma-separated list of C<address:port> pairs (for |
|
|
77 | TCP/IP, other protocols might look different). |
|
|
78 | |
|
|
79 | Node references come in two flavours: resolved (containing only numerical |
|
|
80 | addresses) or unresolved (where hostnames are used instead of addresses). |
|
|
81 | |
|
|
82 | Before using an unresolved node reference in a message you first have to |
|
|
83 | resolve it. |
72 | |
84 | |
73 | =back |
85 | =back |
74 | |
86 | |
75 | =head1 VARIABLES/FUNCTIONS |
87 | =head1 VARIABLES/FUNCTIONS |
76 | |
88 | |
… | |
… | |
91 | use base "Exporter"; |
103 | use base "Exporter"; |
92 | |
104 | |
93 | our $VERSION = '0.1'; |
105 | our $VERSION = '0.1'; |
94 | our @EXPORT = qw( |
106 | our @EXPORT = qw( |
95 | NODE $NODE *SELF node_of _any_ |
107 | NODE $NODE *SELF node_of _any_ |
96 | become_slave become_public |
108 | resolve_node initialise_node |
97 | snd rcv mon kil reg psub |
109 | snd rcv mon kil reg psub |
98 | port |
110 | port |
99 | ); |
111 | ); |
100 | |
112 | |
101 | our $SELF; |
113 | our $SELF; |
… | |
… | |
115 | |
127 | |
116 | =item $noderef = node_of $portid |
128 | =item $noderef = node_of $portid |
117 | |
129 | |
118 | Extracts and returns the noderef from a portid or a noderef. |
130 | Extracts and returns the noderef from a portid or a noderef. |
119 | |
131 | |
|
|
132 | =item $cv = resolve_node $noderef |
|
|
133 | |
|
|
134 | Takes an unresolved node reference that may contain hostnames and |
|
|
135 | abbreviated IDs, resolves all of them and returns a resolved node |
|
|
136 | reference. |
|
|
137 | |
|
|
138 | In addition to C<address:port> pairs allowed in resolved noderefs, the |
|
|
139 | following forms are supported: |
|
|
140 | |
|
|
141 | =over 4 |
|
|
142 | |
|
|
143 | =item the empty string |
|
|
144 | |
|
|
145 | An empty-string component gets resolved as if the default port (4040) was |
|
|
146 | specified. |
|
|
147 | |
|
|
148 | =item naked port numbers (e.g. C<1234>) |
|
|
149 | |
|
|
150 | These are resolved by prepending the local nodename and a colon, to be |
|
|
151 | further resolved. |
|
|
152 | |
|
|
153 | =item hostnames (e.g. C<localhost:1234>, C<localhost>) |
|
|
154 | |
|
|
155 | These are resolved by using AnyEvent::DNS to resolve them, optionally |
|
|
156 | looking up SRV records for the C<aemp=4040> port, if no port was |
|
|
157 | specified. |
|
|
158 | |
|
|
159 | =back |
|
|
160 | |
120 | =item $SELF |
161 | =item $SELF |
121 | |
162 | |
122 | Contains the current port id while executing C<rcv> callbacks or C<psub> |
163 | Contains the current port id while executing C<rcv> callbacks or C<psub> |
123 | blocks. |
164 | blocks. |
124 | |
165 | |
… | |
… | |
148 | JSON is used, then only strings, numbers and arrays and hashes consisting |
189 | JSON is used, then only strings, numbers and arrays and hashes consisting |
149 | of those are allowed (no objects). When Storable is used, then anything |
190 | of those are allowed (no objects). When Storable is used, then anything |
150 | that Storable can serialise and deserialise is allowed, and for the local |
191 | that Storable can serialise and deserialise is allowed, and for the local |
151 | node, anything can be passed. |
192 | node, anything can be passed. |
152 | |
193 | |
153 | =item kil $portid[, @reason] |
|
|
154 | |
|
|
155 | Kill the specified port with the given C<@reason>. |
|
|
156 | |
|
|
157 | If no C<@reason> is specified, then the port is killed "normally" (linked |
|
|
158 | ports will not be kileld, or even notified). |
|
|
159 | |
|
|
160 | Otherwise, linked ports get killed with the same reason (second form of |
|
|
161 | C<mon>, see below). |
|
|
162 | |
|
|
163 | Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks |
|
|
164 | will be reported as reason C<< die => $@ >>. |
|
|
165 | |
|
|
166 | Transport/communication errors are reported as C<< transport_error => |
|
|
167 | $message >>. |
|
|
168 | |
|
|
169 | =item $guard = mon $portid, $cb->(@reason) |
|
|
170 | |
|
|
171 | =item $guard = mon $portid, $otherport |
|
|
172 | |
|
|
173 | =item $guard = mon $portid, $otherport, @msg |
|
|
174 | |
|
|
175 | Monitor the given port and do something when the port is killed. |
|
|
176 | |
|
|
177 | In the first form, the callback is simply called with any number |
|
|
178 | of C<@reason> elements (no @reason means that the port was deleted |
|
|
179 | "normally"). Note also that I<< the callback B<must> never die >>, so use |
|
|
180 | C<eval> if unsure. |
|
|
181 | |
|
|
182 | In the second form, the other port will be C<kil>'ed with C<@reason>, iff |
|
|
183 | a @reason was specified, i.e. on "normal" kils nothing happens, while |
|
|
184 | under all other conditions, the other port is killed with the same reason. |
|
|
185 | |
|
|
186 | In the last form, a message of the form C<@msg, @reason> will be C<snd>. |
|
|
187 | |
|
|
188 | Example: call a given callback when C<$port> is killed. |
|
|
189 | |
|
|
190 | mon $port, sub { warn "port died because of <@_>\n" }; |
|
|
191 | |
|
|
192 | Example: kill ourselves when C<$port> is killed abnormally. |
|
|
193 | |
|
|
194 | mon $port, $self; |
|
|
195 | |
|
|
196 | Example: send us a restart message another C<$port> is killed. |
|
|
197 | |
|
|
198 | mon $port, $self => "restart"; |
|
|
199 | |
|
|
200 | =cut |
|
|
201 | |
|
|
202 | sub mon { |
|
|
203 | my ($noderef, $port, $cb) = ((split /#/, shift, 2), shift); |
|
|
204 | |
|
|
205 | my $node = $NODE{$noderef} || add_node $noderef; |
|
|
206 | |
|
|
207 | #TODO: ports must not be references |
|
|
208 | if (!ref $cb or "AnyEvent::MP::Port" eq ref $cb) { |
|
|
209 | if (@_) { |
|
|
210 | # send a kill info message |
|
|
211 | my (@msg) = ($cb, @_); |
|
|
212 | $cb = sub { snd @msg, @_ }; |
|
|
213 | } else { |
|
|
214 | # simply kill other port |
|
|
215 | my $port = $cb; |
|
|
216 | $cb = sub { kil $port, @_ if @_ }; |
|
|
217 | } |
|
|
218 | } |
|
|
219 | |
|
|
220 | $node->monitor ($port, $cb); |
|
|
221 | |
|
|
222 | defined wantarray |
|
|
223 | and AnyEvent::Util::guard { $node->unmonitor ($port, $cb) } |
|
|
224 | } |
|
|
225 | |
|
|
226 | =item $guard = mon_guard $port, $ref, $ref... |
|
|
227 | |
|
|
228 | Monitors the given C<$port> and keeps the passed references. When the port |
|
|
229 | is killed, the references will be freed. |
|
|
230 | |
|
|
231 | Optionally returns a guard that will stop the monitoring. |
|
|
232 | |
|
|
233 | This function is useful when you create e.g. timers or other watchers and |
|
|
234 | want to free them when the port gets killed: |
|
|
235 | |
|
|
236 | $port->rcv (start => sub { |
|
|
237 | my $timer; $timer = mon_guard $port, AE::timer 1, 1, sub { |
|
|
238 | undef $timer if 0.9 < rand; |
|
|
239 | }); |
|
|
240 | }); |
|
|
241 | |
|
|
242 | =cut |
|
|
243 | |
|
|
244 | sub mon_guard { |
|
|
245 | my ($port, @refs) = @_; |
|
|
246 | |
|
|
247 | mon $port, sub { 0 && @refs } |
|
|
248 | } |
|
|
249 | |
|
|
250 | =item lnk $port1, $port2 |
|
|
251 | |
|
|
252 | Link two ports. This is simply a shorthand for: |
|
|
253 | |
|
|
254 | mon $port1, $port2; |
|
|
255 | mon $port2, $port1; |
|
|
256 | |
|
|
257 | It means that if either one is killed abnormally, the other one gets |
|
|
258 | killed as well. |
|
|
259 | |
|
|
260 | =item $local_port = port |
194 | =item $local_port = port |
261 | |
195 | |
262 | Create a new local port object that supports message matching. |
196 | Create a new local port object that can be used either as a pattern |
|
|
197 | matching port ("full port") or a single-callback port ("miniport"), |
|
|
198 | depending on how C<rcv> callbacks are bound to the object. |
263 | |
199 | |
264 | =item $portid = port { my @msg = @_; $finished } |
200 | =item $portid = port { my @msg = @_; $finished } |
265 | |
201 | |
266 | Creates a "mini port", that is, a very lightweight port without any |
202 | Creates a "mini port", that is, a very lightweight port without any |
267 | pattern matching behind it, and returns its ID. |
203 | pattern matching behind it, and returns its ID. |
… | |
… | |
273 | The message will be passed as-is, no extra argument (i.e. no port id) will |
209 | The message will be passed as-is, no extra argument (i.e. no port id) will |
274 | be passed to the callback. |
210 | be passed to the callback. |
275 | |
211 | |
276 | If you need the local port id in the callback, this works nicely: |
212 | If you need the local port id in the callback, this works nicely: |
277 | |
213 | |
278 | my $port; $port = miniport { |
214 | my $port; $port = port { |
279 | snd $otherport, reply => $port; |
215 | snd $otherport, reply => $port; |
280 | }; |
216 | }; |
281 | |
217 | |
282 | =cut |
218 | =cut |
283 | |
219 | |
… | |
… | |
344 | my ($portid, $name) = @_; |
280 | my ($portid, $name) = @_; |
345 | |
281 | |
346 | $REG{$name} = $portid; |
282 | $REG{$name} = $portid; |
347 | } |
283 | } |
348 | |
284 | |
|
|
285 | =item rcv $portid, $callback->(@msg) |
|
|
286 | |
|
|
287 | Replaces the callback on the specified miniport (or newly created port |
|
|
288 | object, see C<port>). Full ports are configured with the following calls: |
|
|
289 | |
349 | =item rcv $portid, tagstring => $callback->(@msg), ... |
290 | =item rcv $portid, tagstring => $callback->(@msg), ... |
350 | |
291 | |
351 | =item rcv $portid, $smartmatch => $callback->(@msg), ... |
292 | =item rcv $portid, $smartmatch => $callback->(@msg), ... |
352 | |
293 | |
353 | =item rcv $portid, [$smartmatch...] => $callback->(@msg), ... |
294 | =item rcv $portid, [$smartmatch...] => $callback->(@msg), ... |
354 | |
295 | |
355 | Register callbacks to be called on matching messages on the given port. |
296 | Register callbacks to be called on matching messages on the given full |
|
|
297 | port (or newly created port). |
356 | |
298 | |
357 | The callback has to return a true value when its work is done, after |
299 | The callback has to return a true value when its work is done, after |
358 | which is will be removed, or a false value in which case it will stay |
300 | which is will be removed, or a false value in which case it will stay |
359 | registered. |
301 | registered. |
360 | |
302 | |
… | |
… | |
376 | also the most efficient match (by far). |
318 | also the most efficient match (by far). |
377 | |
319 | |
378 | =cut |
320 | =cut |
379 | |
321 | |
380 | sub rcv($@) { |
322 | sub rcv($@) { |
|
|
323 | my $portid = shift; |
381 | my ($noderef, $port) = split /#/, shift, 2; |
324 | my ($noderef, $port) = split /#/, $port, 2; |
382 | |
325 | |
383 | ($NODE{$noderef} || add_node $noderef) == $NODE{""} |
326 | ($NODE{$noderef} || add_node $noderef) == $NODE{""} |
384 | or Carp::croak "$noderef#$port: rcv can only be called on local ports, caught"; |
327 | or Carp::croak "$noderef#$port: rcv can only be called on local ports, caught"; |
385 | |
328 | |
386 | my $self = $PORT_DATA{$port} |
329 | my $self = $PORT_DATA{$port} |
… | |
… | |
401 | : push @{ $self->{rc0}{$match->[0]} }, [$cb]; |
344 | : push @{ $self->{rc0}{$match->[0]} }, [$cb]; |
402 | } else { |
345 | } else { |
403 | push @{ $self->{any} }, [$cb, $match]; |
346 | push @{ $self->{any} }, [$cb, $match]; |
404 | } |
347 | } |
405 | } |
348 | } |
|
|
349 | |
|
|
350 | $portid |
406 | } |
351 | } |
407 | |
352 | |
408 | =item $closure = psub { BLOCK } |
353 | =item $closure = psub { BLOCK } |
409 | |
354 | |
410 | Remembers C<$SELF> and creates a closure out of the BLOCK. When the |
355 | Remembers C<$SELF> and creates a closure out of the BLOCK. When the |
… | |
… | |
441 | $res |
386 | $res |
442 | } |
387 | } |
443 | } |
388 | } |
444 | } |
389 | } |
445 | |
390 | |
|
|
391 | =item $guard = mon $portid, $cb->(@reason) |
|
|
392 | |
|
|
393 | =item $guard = mon $portid, $otherport |
|
|
394 | |
|
|
395 | =item $guard = mon $portid, $otherport, @msg |
|
|
396 | |
|
|
397 | Monitor the given port and do something when the port is killed. |
|
|
398 | |
|
|
399 | In the first form, the callback is simply called with any number |
|
|
400 | of C<@reason> elements (no @reason means that the port was deleted |
|
|
401 | "normally"). Note also that I<< the callback B<must> never die >>, so use |
|
|
402 | C<eval> if unsure. |
|
|
403 | |
|
|
404 | In the second form, the other port will be C<kil>'ed with C<@reason>, iff |
|
|
405 | a @reason was specified, i.e. on "normal" kils nothing happens, while |
|
|
406 | under all other conditions, the other port is killed with the same reason. |
|
|
407 | |
|
|
408 | In the last form, a message of the form C<@msg, @reason> will be C<snd>. |
|
|
409 | |
|
|
410 | Example: call a given callback when C<$port> is killed. |
|
|
411 | |
|
|
412 | mon $port, sub { warn "port died because of <@_>\n" }; |
|
|
413 | |
|
|
414 | Example: kill ourselves when C<$port> is killed abnormally. |
|
|
415 | |
|
|
416 | mon $port, $self; |
|
|
417 | |
|
|
418 | Example: send us a restart message another C<$port> is killed. |
|
|
419 | |
|
|
420 | mon $port, $self => "restart"; |
|
|
421 | |
|
|
422 | =cut |
|
|
423 | |
|
|
424 | sub mon { |
|
|
425 | my ($noderef, $port) = split /#/, shift, 2; |
|
|
426 | |
|
|
427 | my $node = $NODE{$noderef} || add_node $noderef; |
|
|
428 | |
|
|
429 | my $cb = shift; |
|
|
430 | |
|
|
431 | unless (ref $cb) { |
|
|
432 | if (@_) { |
|
|
433 | # send a kill info message |
|
|
434 | my (@msg) = ($cb, @_); |
|
|
435 | $cb = sub { snd @msg, @_ }; |
|
|
436 | } else { |
|
|
437 | # simply kill other port |
|
|
438 | my $port = $cb; |
|
|
439 | $cb = sub { kil $port, @_ if @_ }; |
|
|
440 | } |
|
|
441 | } |
|
|
442 | |
|
|
443 | $node->monitor ($port, $cb); |
|
|
444 | |
|
|
445 | defined wantarray |
|
|
446 | and AnyEvent::Util::guard { $node->unmonitor ($port, $cb) } |
|
|
447 | } |
|
|
448 | |
|
|
449 | =item $guard = mon_guard $port, $ref, $ref... |
|
|
450 | |
|
|
451 | Monitors the given C<$port> and keeps the passed references. When the port |
|
|
452 | is killed, the references will be freed. |
|
|
453 | |
|
|
454 | Optionally returns a guard that will stop the monitoring. |
|
|
455 | |
|
|
456 | This function is useful when you create e.g. timers or other watchers and |
|
|
457 | want to free them when the port gets killed: |
|
|
458 | |
|
|
459 | $port->rcv (start => sub { |
|
|
460 | my $timer; $timer = mon_guard $port, AE::timer 1, 1, sub { |
|
|
461 | undef $timer if 0.9 < rand; |
|
|
462 | }); |
|
|
463 | }); |
|
|
464 | |
|
|
465 | =cut |
|
|
466 | |
|
|
467 | sub mon_guard { |
|
|
468 | my ($port, @refs) = @_; |
|
|
469 | |
|
|
470 | mon $port, sub { 0 && @refs } |
|
|
471 | } |
|
|
472 | |
|
|
473 | =item lnk $port1, $port2 |
|
|
474 | |
|
|
475 | Link two ports. This is simply a shorthand for: |
|
|
476 | |
|
|
477 | mon $port1, $port2; |
|
|
478 | mon $port2, $port1; |
|
|
479 | |
|
|
480 | It means that if either one is killed abnormally, the other one gets |
|
|
481 | killed as well. |
|
|
482 | |
|
|
483 | =item kil $portid[, @reason] |
|
|
484 | |
|
|
485 | Kill the specified port with the given C<@reason>. |
|
|
486 | |
|
|
487 | If no C<@reason> is specified, then the port is killed "normally" (linked |
|
|
488 | ports will not be kileld, or even notified). |
|
|
489 | |
|
|
490 | Otherwise, linked ports get killed with the same reason (second form of |
|
|
491 | C<mon>, see below). |
|
|
492 | |
|
|
493 | Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks |
|
|
494 | will be reported as reason C<< die => $@ >>. |
|
|
495 | |
|
|
496 | Transport/communication errors are reported as C<< transport_error => |
|
|
497 | $message >>. |
|
|
498 | |
446 | =back |
499 | =back |
447 | |
500 | |
448 | =head1 FUNCTIONS FOR NODES |
501 | =head1 FUNCTIONS FOR NODES |
449 | |
502 | |
450 | =over 4 |
503 | =over 4 |
451 | |
504 | |
452 | =item become_public endpoint... |
505 | =item become_public $noderef |
453 | |
506 | |
454 | Tells the node to become a public node, i.e. reachable from other nodes. |
507 | Tells the node to become a public node, i.e. reachable from other nodes. |
455 | |
508 | |
456 | If no arguments are given, or the first argument is C<undef>, then |
509 | The first argument is the (unresolved) node reference of the local node |
457 | AnyEvent::MP tries to bind on port C<4040> on all IP addresses that the |
510 | (if missing then the empty string is used). |
458 | local nodename resolves to. |
|
|
459 | |
511 | |
460 | Otherwise the first argument must be an array-reference with transport |
512 | It is quite common to not specify anything, in which case the local node |
461 | endpoints ("ip:port", "hostname:port") or port numbers (in which case the |
513 | tries to listen on the default port, or to only specify a port number, in |
462 | local nodename is used as hostname). The endpoints are all resolved and |
514 | which case AnyEvent::MP tries to guess the local addresses. |
463 | will become the node reference. |
|
|
464 | |
515 | |
465 | =cut |
516 | =cut |
466 | |
517 | |
467 | =back |
518 | =back |
468 | |
519 | |
… | |
… | |
471 | Nodes understand the following messages sent to them. Many of them take |
522 | Nodes understand the following messages sent to them. Many of them take |
472 | arguments called C<@reply>, which will simply be used to compose a reply |
523 | arguments called C<@reply>, which will simply be used to compose a reply |
473 | message - C<$reply[0]> is the port to reply to, C<$reply[1]> the type and |
524 | message - C<$reply[0]> is the port to reply to, C<$reply[1]> the type and |
474 | the remaining arguments are simply the message data. |
525 | the remaining arguments are simply the message data. |
475 | |
526 | |
|
|
527 | While other messages exist, they are not public and subject to change. |
|
|
528 | |
476 | =over 4 |
529 | =over 4 |
477 | |
530 | |
478 | =cut |
531 | =cut |
479 | |
532 | |
480 | =item lookup => $name, @reply |
533 | =item lookup => $name, @reply |
… | |
… | |
508 | snd $NODE, time => $myport, timereply => 1, 2; |
561 | snd $NODE, time => $myport, timereply => 1, 2; |
509 | # => snd $myport, timereply => 1, 2, <time> |
562 | # => snd $myport, timereply => 1, 2, <time> |
510 | |
563 | |
511 | =back |
564 | =back |
512 | |
565 | |
|
|
566 | =head1 AnyEvent::MP vs. Distributed Erlang |
|
|
567 | |
|
|
568 | AnyEvent::MP got lots of its ideas from distributed erlang (erlang node |
|
|
569 | == aemp node, erlang process == aemp port), so many of the documents and |
|
|
570 | programming techniques employed by erlang apply to AnyEvent::MP. Here is a |
|
|
571 | sample: |
|
|
572 | |
|
|
573 | http://www.erlang.se/doc/programming_rules.shtml |
|
|
574 | http://erlang.org/doc/getting_started/part_frame.html # chapters 3 and 4 |
|
|
575 | http://erlang.org/download/erlang-book-part1.pdf # chapters 5 and 6 |
|
|
576 | http://erlang.org/download/armstrong_thesis_2003.pdf # chapters 4 and 5 |
|
|
577 | |
|
|
578 | Despite the similarities, there are also some important differences: |
|
|
579 | |
|
|
580 | =over 4 |
|
|
581 | |
|
|
582 | =item * Node references contain the recipe on how to contact them. |
|
|
583 | |
|
|
584 | Erlang relies on special naming and DNS to work everywhere in the |
|
|
585 | same way. AEMP relies on each node knowing it's own address(es), with |
|
|
586 | convenience functionality. |
|
|
587 | |
|
|
588 | This means that AEMP requires a less tightly controlled environment at the |
|
|
589 | cost of longer node references and a slightly higher management overhead. |
|
|
590 | |
|
|
591 | =item * Erlang uses processes and a mailbox, AEMP does not queue. |
|
|
592 | |
|
|
593 | Erlang uses processes that selctively receive messages, and therefore |
|
|
594 | needs a queue. AEMP is event based, queuing messages would serve no useful |
|
|
595 | purpose. |
|
|
596 | |
|
|
597 | (But see L<Coro::MP> for a more erlang-like process model on top of AEMP). |
|
|
598 | |
|
|
599 | =item * Erlang sends are synchronous, AEMP sends are asynchronous. |
|
|
600 | |
|
|
601 | Sending messages in erlang is synchronous and blocks the process. AEMP |
|
|
602 | sends are immediate, connection establishment is handled in the |
|
|
603 | background. |
|
|
604 | |
|
|
605 | =item * Erlang can silently lose messages, AEMP cannot. |
|
|
606 | |
|
|
607 | Erlang makes few guarantees on messages delivery - messages can get lost |
|
|
608 | without any of the processes realising it (i.e. you send messages a, b, |
|
|
609 | and c, and the other side only receives messages a and c). |
|
|
610 | |
|
|
611 | AEMP guarantees correct ordering, and the guarantee that there are no |
|
|
612 | holes in the message sequence. |
|
|
613 | |
|
|
614 | =item * In erlang, processes can be declared dead and later be found to be |
|
|
615 | alive. |
|
|
616 | |
|
|
617 | In erlang it can happen that a monitored process is declared dead and |
|
|
618 | linked processes get killed, but later it turns out that the process is |
|
|
619 | still alive - and can receive messages. |
|
|
620 | |
|
|
621 | In AEMP, when port monitoring detects a port as dead, then that port will |
|
|
622 | eventually be killed - it cannot happen that a node detects a port as dead |
|
|
623 | and then later sends messages to it, finding it is still alive. |
|
|
624 | |
|
|
625 | =item * Erlang can send messages to the wrong port, AEMP does not. |
|
|
626 | |
|
|
627 | In erlang it is quite possible that a node that restarts reuses a process |
|
|
628 | ID known to other nodes for a completely different process, causing |
|
|
629 | messages destined for that process to end up in an unrelated process. |
|
|
630 | |
|
|
631 | AEMP never reuses port IDs, so old messages or old port IDs floating |
|
|
632 | around in the network will not be sent to an unrelated port. |
|
|
633 | |
|
|
634 | =item * Erlang uses unprotected connections, AEMP uses secure |
|
|
635 | authentication and can use TLS. |
|
|
636 | |
|
|
637 | AEMP can use a proven protocol - SSL/TLS - to protect connections and |
|
|
638 | securely authenticate nodes. |
|
|
639 | |
|
|
640 | =item * The AEMP protocol is optimised for both text-based and binary |
|
|
641 | communications. |
|
|
642 | |
|
|
643 | The AEMP protocol, unlike the erlang protocol, supports both |
|
|
644 | language-independent text-only protocols (good for debugging) and binary, |
|
|
645 | language-specific serialisers (e.g. Storable). |
|
|
646 | |
|
|
647 | It has also been carefully designed to be implementable in other languages |
|
|
648 | with a minimum of work while gracefully degrading fucntionality to make the |
|
|
649 | protocol simple. |
|
|
650 | |
|
|
651 | =back |
|
|
652 | |
513 | =head1 SEE ALSO |
653 | =head1 SEE ALSO |
514 | |
654 | |
515 | L<AnyEvent>. |
655 | L<AnyEvent>. |
516 | |
656 | |
517 | =head1 AUTHOR |
657 | =head1 AUTHOR |