… | |
… | |
11 | NODE $port # returns the noderef of the port |
11 | NODE $port # returns the noderef of the port |
12 | |
12 | |
13 | $SELF # receiving/own port id in rcv callbacks |
13 | $SELF # receiving/own port id in rcv callbacks |
14 | |
14 | |
15 | # initialise the node so it can send/receive messages |
15 | # initialise the node so it can send/receive messages |
16 | initialise_node; # -OR- |
16 | configure; |
17 | initialise_node "localhost:4040"; # -OR- |
|
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18 | initialise_node "slave/", "localhost:4040" |
|
|
19 | |
17 | |
20 | # ports are message endpoints |
18 | # ports are message endpoints |
21 | |
19 | |
22 | # sending messages |
20 | # sending messages |
23 | snd $port, type => data...; |
21 | snd $port, type => data...; |
24 | snd $port, @msg; |
22 | snd $port, @msg; |
25 | snd @msg_with_first_element_being_a_port; |
23 | snd @msg_with_first_element_being_a_port; |
26 | |
24 | |
27 | # creating/using ports, the simple way |
25 | # creating/using ports, the simple way |
28 | my $somple_port = port { my @msg = @_; 0 }; |
26 | my $simple_port = port { my @msg = @_; 0 }; |
29 | |
27 | |
30 | # creating/using ports, type matching |
28 | # creating/using ports, tagged message matching |
31 | my $port = port; |
29 | my $port = port; |
32 | rcv $port, ping => sub { snd $_[0], "pong"; 0 }; |
30 | rcv $port, ping => sub { snd $_[0], "pong"; 0 }; |
33 | rcv $port, pong => sub { warn "pong received\n"; 0 }; |
31 | rcv $port, pong => sub { warn "pong received\n"; 0 }; |
34 | |
32 | |
35 | # create a port on another node |
33 | # create a port on another node |
… | |
… | |
40 | mon $port, $otherport # kill otherport on abnormal death |
38 | mon $port, $otherport # kill otherport on abnormal death |
41 | mon $port, $otherport, @msg # send message on death |
39 | mon $port, $otherport, @msg # send message on death |
42 | |
40 | |
43 | =head1 CURRENT STATUS |
41 | =head1 CURRENT STATUS |
44 | |
42 | |
|
|
43 | bin/aemp - stable. |
45 | AnyEvent::MP - stable API, should work |
44 | AnyEvent::MP - stable API, should work. |
46 | AnyEvent::MP::Intro - outdated |
45 | AnyEvent::MP::Intro - uptodate, but incomplete. |
47 | AnyEvent::MP::Kernel - WIP |
|
|
48 | AnyEvent::MP::Transport - mostly stable |
46 | AnyEvent::MP::Kernel - mostly stable. |
|
|
47 | AnyEvent::MP::Global - stable API, protocol not yet final. |
49 | |
48 | |
50 | stay tuned. |
49 | stay tuned. |
51 | |
50 | |
52 | =head1 DESCRIPTION |
51 | =head1 DESCRIPTION |
53 | |
52 | |
54 | This module (-family) implements a simple message passing framework. |
53 | This module (-family) implements a simple message passing framework. |
55 | |
54 | |
56 | Despite its simplicity, you can securely message other processes running |
55 | Despite its simplicity, you can securely message other processes running |
57 | on the same or other hosts. |
56 | on the same or other hosts, and you can supervise entities remotely. |
58 | |
57 | |
59 | For an introduction to this module family, see the L<AnyEvent::MP::Intro> |
58 | For an introduction to this module family, see the L<AnyEvent::MP::Intro> |
60 | manual page. |
59 | manual page and the examples under F<eg/>. |
61 | |
60 | |
62 | At the moment, this module family is severly broken and underdocumented, |
61 | At the moment, this module family is a bit underdocumented. |
63 | so do not use. This was uploaded mainly to reserve the CPAN namespace - |
|
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64 | stay tuned! |
|
|
65 | |
62 | |
66 | =head1 CONCEPTS |
63 | =head1 CONCEPTS |
67 | |
64 | |
68 | =over 4 |
65 | =over 4 |
69 | |
66 | |
70 | =item port |
67 | =item port |
71 | |
68 | |
72 | A port is something you can send messages to (with the C<snd> function). |
69 | A port is something you can send messages to (with the C<snd> function). |
73 | |
70 | |
74 | Some ports allow you to register C<rcv> handlers that can match specific |
71 | Ports allow you to register C<rcv> handlers that can match all or just |
75 | messages. All C<rcv> handlers will receive messages they match, messages |
72 | some messages. Messages send to ports will not be queued, regardless of |
76 | will not be queued. |
73 | anything was listening for them or not. |
77 | |
74 | |
78 | =item port id - C<noderef#portname> |
75 | =item port ID - C<nodeid#portname> |
79 | |
76 | |
80 | A port id is normaly the concatenation of a noderef, a hash-mark (C<#>) as |
77 | A port ID is the concatenation of a node ID, a hash-mark (C<#>) as |
81 | separator, and a port name (a printable string of unspecified format). An |
78 | separator, and a port name (a printable string of unspecified format). |
82 | exception is the the node port, whose ID is identical to its node |
|
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83 | reference. |
|
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84 | |
79 | |
85 | =item node |
80 | =item node |
86 | |
81 | |
87 | A node is a single process containing at least one port - the node |
82 | A node is a single process containing at least one port - the node port, |
88 | port. You can send messages to node ports to find existing ports or to |
83 | which enables nodes to manage each other remotely, and to create new |
89 | create new ports, among other things. |
84 | ports. |
90 | |
85 | |
91 | Nodes are either private (single-process only), slaves (connected to a |
86 | Nodes are either public (have one or more listening ports) or private |
92 | master node only) or public nodes (connectable from unrelated nodes). |
87 | (no listening ports). Private nodes cannot talk to other private nodes |
|
|
88 | currently. |
93 | |
89 | |
94 | =item noderef - C<host:port,host:port...>, C<id@noderef>, C<id> |
90 | =item node ID - C<[a-za-Z0-9_\-.:]+> |
95 | |
91 | |
96 | A node reference is a string that either simply identifies the node (for |
92 | A node ID is a string that uniquely identifies the node within a |
97 | private and slave nodes), or contains a recipe on how to reach a given |
93 | network. Depending on the configuration used, node IDs can look like a |
98 | node (for public nodes). |
94 | hostname, a hostname and a port, or a random string. AnyEvent::MP itself |
|
|
95 | doesn't interpret node IDs in any way. |
99 | |
96 | |
100 | This recipe is simply a comma-separated list of C<address:port> pairs (for |
97 | =item binds - C<ip:port> |
101 | TCP/IP, other protocols might look different). |
|
|
102 | |
98 | |
103 | Node references come in two flavours: resolved (containing only numerical |
99 | Nodes can only talk to each other by creating some kind of connection to |
104 | addresses) or unresolved (where hostnames are used instead of addresses). |
100 | each other. To do this, nodes should listen on one or more local transport |
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101 | endpoints - binds. Currently, only standard C<ip:port> specifications can |
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102 | be used, which specify TCP ports to listen on. |
105 | |
103 | |
106 | Before using an unresolved node reference in a message you first have to |
104 | =item seeds - C<host:port> |
107 | resolve it. |
105 | |
|
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106 | When a node starts, it knows nothing about the network. To teach the node |
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107 | about the network it first has to contact some other node within the |
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108 | network. This node is called a seed. |
|
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109 | |
|
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110 | Seeds are transport endpoint(s) of as many nodes as one wants. Those nodes |
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111 | are expected to be long-running, and at least one of those should always |
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112 | be available. When nodes run out of connections (e.g. due to a network |
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113 | error), they try to re-establish connections to some seednodes again to |
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114 | join the network. |
|
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115 | |
|
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116 | Apart from being sued for seeding, seednodes are not special in any way - |
|
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117 | every public node can be a seednode. |
108 | |
118 | |
109 | =back |
119 | =back |
110 | |
120 | |
111 | =head1 VARIABLES/FUNCTIONS |
121 | =head1 VARIABLES/FUNCTIONS |
112 | |
122 | |
… | |
… | |
127 | use base "Exporter"; |
137 | use base "Exporter"; |
128 | |
138 | |
129 | our $VERSION = $AnyEvent::MP::Kernel::VERSION; |
139 | our $VERSION = $AnyEvent::MP::Kernel::VERSION; |
130 | |
140 | |
131 | our @EXPORT = qw( |
141 | our @EXPORT = qw( |
132 | NODE $NODE *SELF node_of _any_ |
142 | NODE $NODE *SELF node_of after |
133 | resolve_node initialise_node |
143 | configure |
134 | snd rcv mon kil reg psub spawn |
144 | snd rcv mon mon_guard kil reg psub spawn |
135 | port |
145 | port |
136 | ); |
146 | ); |
137 | |
147 | |
138 | our $SELF; |
148 | our $SELF; |
139 | |
149 | |
… | |
… | |
143 | kil $SELF, die => $msg; |
153 | kil $SELF, die => $msg; |
144 | } |
154 | } |
145 | |
155 | |
146 | =item $thisnode = NODE / $NODE |
156 | =item $thisnode = NODE / $NODE |
147 | |
157 | |
148 | The C<NODE> function returns, and the C<$NODE> variable contains |
158 | The C<NODE> function returns, and the C<$NODE> variable contains, the node |
149 | the noderef of the local node. The value is initialised by a call |
159 | ID of the node running in the current process. This value is initialised by |
150 | to C<become_public> or C<become_slave>, after which all local port |
160 | a call to C<configure>. |
151 | identifiers become invalid. |
|
|
152 | |
161 | |
153 | =item $noderef = node_of $port |
162 | =item $nodeid = node_of $port |
154 | |
163 | |
155 | Extracts and returns the noderef from a portid or a noderef. |
164 | Extracts and returns the node ID from a port ID or a node ID. |
156 | |
165 | |
157 | =item initialise_node $noderef, $seednode, $seednode... |
166 | =item configure key => value... |
158 | |
167 | |
159 | =item initialise_node "slave/", $master, $master... |
|
|
160 | |
|
|
161 | Before a node can talk to other nodes on the network it has to initialise |
168 | Before a node can talk to other nodes on the network (i.e. enter |
162 | itself - the minimum a node needs to know is it's own name, and optionally |
169 | "distributed mode") it has to configure itself - the minimum a node needs |
163 | it should know the noderefs of some other nodes in the network. |
170 | to know is its own name, and optionally it should know the addresses of |
|
|
171 | some other nodes in the network to discover other nodes. |
164 | |
172 | |
165 | This function initialises a node - it must be called exactly once (or |
173 | This function configures a node - it must be called exactly once (or |
166 | never) before calling other AnyEvent::MP functions. |
174 | never) before calling other AnyEvent::MP functions. |
167 | |
175 | |
168 | All arguments (optionally except for the first) are noderefs, which can be |
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169 | either resolved or unresolved. |
|
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170 | |
|
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171 | The first argument will be looked up in the configuration database first |
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172 | (if it is C<undef> then the current nodename will be used instead) to find |
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173 | the relevant configuration profile (see L<aemp>). If none is found then |
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174 | the default configuration is used. The configuration supplies additional |
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175 | seed/master nodes and can override the actual noderef. |
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176 | |
|
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177 | There are two types of networked nodes, public nodes and slave nodes: |
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178 | |
|
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179 | =over 4 |
176 | =over 4 |
180 | |
177 | |
181 | =item public nodes |
178 | =item step 1, gathering configuration from profiles |
182 | |
179 | |
183 | For public nodes, C<$noderef> (supplied either directly to |
180 | The function first looks up a profile in the aemp configuration (see the |
184 | C<initialise_node> or indirectly via a profile or the nodename) must be a |
181 | L<aemp> commandline utility). The profile name can be specified via the |
185 | noderef (possibly unresolved, in which case it will be resolved). |
182 | named C<profile> parameter. If it is missing, then the nodename (F<uname |
|
|
183 | -n>) will be used as profile name. |
186 | |
184 | |
187 | After resolving, the node will bind itself on all endpoints and try to |
185 | The profile data is then gathered as follows: |
188 | connect to all additional C<$seednodes> that are specified. Seednodes are |
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189 | optional and can be used to quickly bootstrap the node into an existing |
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190 | network. |
|
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191 | |
186 | |
192 | =item slave nodes |
187 | First, all remaining key => value pairs (all of which are conviniently |
|
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188 | undocumented at the moment) will be interpreted as configuration |
|
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189 | data. Then they will be overwritten by any values specified in the global |
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190 | default configuration (see the F<aemp> utility), then the chain of |
|
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191 | profiles chosen by the profile name (and any C<parent> attributes). |
193 | |
192 | |
194 | When the C<$noderef> (either as given or overriden by the config file) |
193 | That means that the values specified in the profile have highest priority |
195 | is the special string C<slave/>, then the node will become a slave |
194 | and the values specified directly via C<configure> have lowest priority, |
196 | node. Slave nodes cannot be contacted from outside and will route most of |
195 | and can only be used to specify defaults. |
197 | their traffic to the master node that they attach to. |
|
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198 | |
196 | |
199 | At least one additional noderef is required (either by specifying it |
197 | If the profile specifies a node ID, then this will become the node ID of |
200 | directly or because it is part of the configuration profile): The node |
198 | this process. If not, then the profile name will be used as node ID. The |
201 | will try to connect to all of them and will become a slave attached to the |
199 | special node ID of C<anon/> will be replaced by a random node ID. |
202 | first node it can successfully connect to. |
200 | |
|
|
201 | =item step 2, bind listener sockets |
|
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202 | |
|
|
203 | The next step is to look up the binds in the profile, followed by binding |
|
|
204 | aemp protocol listeners on all binds specified (it is possible and valid |
|
|
205 | to have no binds, meaning that the node cannot be contacted form the |
|
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206 | outside. This means the node cannot talk to other nodes that also have no |
|
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207 | binds, but it can still talk to all "normal" nodes). |
|
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208 | |
|
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209 | If the profile does not specify a binds list, then a default of C<*> is |
|
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210 | used, meaning the node will bind on a dynamically-assigned port on every |
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211 | local IP address it finds. |
|
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212 | |
|
|
213 | =item step 3, connect to seed nodes |
|
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214 | |
|
|
215 | As the last step, the seeds list from the profile is passed to the |
|
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216 | L<AnyEvent::MP::Global> module, which will then use it to keep |
|
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217 | connectivity with at least one node at any point in time. |
203 | |
218 | |
204 | =back |
219 | =back |
205 | |
220 | |
206 | This function will block until all nodes have been resolved and, for slave |
221 | Example: become a distributed node using the locla node name as profile. |
207 | nodes, until it has successfully established a connection to a master |
222 | This should be the most common form of invocation for "daemon"-type nodes. |
208 | server. |
|
|
209 | |
223 | |
210 | Example: become a public node listening on the guessed noderef, or the one |
224 | configure |
211 | specified via C<aemp> for the current node. This should be the most common |
|
|
212 | form of invocation for "daemon"-type nodes. |
|
|
213 | |
225 | |
214 | initialise_node; |
226 | Example: become an anonymous node. This form is often used for commandline |
|
|
227 | clients. |
215 | |
228 | |
216 | Example: become a slave node to any of the the seednodes specified via |
229 | configure nodeid => "anon/"; |
217 | C<aemp>. This form is often used for commandline clients. |
|
|
218 | |
230 | |
219 | initialise_node "slave/"; |
231 | Example: configure a node using a profile called seed, which si suitable |
|
|
232 | for a seed node as it binds on all local addresses on a fixed port (4040, |
|
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233 | customary for aemp). |
220 | |
234 | |
221 | Example: become a slave node to any of the specified master servers. This |
235 | # use the aemp commandline utility |
222 | form is also often used for commandline clients. |
236 | # aemp profile seed setnodeid anon/ setbinds '*:4040' |
223 | |
237 | |
224 | initialise_node "slave/", "master1", "192.168.13.17", "mp.example.net"; |
238 | # then use it |
|
|
239 | configure profile => "seed"; |
225 | |
240 | |
226 | Example: become a public node, and try to contact some well-known master |
241 | # or simply use aemp from the shell again: |
227 | servers to become part of the network. |
242 | # aemp run profile seed |
228 | |
243 | |
229 | initialise_node undef, "master1", "master2"; |
244 | # or provide a nicer-to-remember nodeid |
230 | |
245 | # aemp run profile seed nodeid "$(hostname)" |
231 | Example: become a public node listening on port C<4041>. |
|
|
232 | |
|
|
233 | initialise_node 4041; |
|
|
234 | |
|
|
235 | Example: become a public node, only visible on localhost port 4044. |
|
|
236 | |
|
|
237 | initialise_node "localhost:4044"; |
|
|
238 | |
|
|
239 | =item $cv = resolve_node $noderef |
|
|
240 | |
|
|
241 | Takes an unresolved node reference that may contain hostnames and |
|
|
242 | abbreviated IDs, resolves all of them and returns a resolved node |
|
|
243 | reference. |
|
|
244 | |
|
|
245 | In addition to C<address:port> pairs allowed in resolved noderefs, the |
|
|
246 | following forms are supported: |
|
|
247 | |
|
|
248 | =over 4 |
|
|
249 | |
|
|
250 | =item the empty string |
|
|
251 | |
|
|
252 | An empty-string component gets resolved as if the default port (4040) was |
|
|
253 | specified. |
|
|
254 | |
|
|
255 | =item naked port numbers (e.g. C<1234>) |
|
|
256 | |
|
|
257 | These are resolved by prepending the local nodename and a colon, to be |
|
|
258 | further resolved. |
|
|
259 | |
|
|
260 | =item hostnames (e.g. C<localhost:1234>, C<localhost>) |
|
|
261 | |
|
|
262 | These are resolved by using AnyEvent::DNS to resolve them, optionally |
|
|
263 | looking up SRV records for the C<aemp=4040> port, if no port was |
|
|
264 | specified. |
|
|
265 | |
|
|
266 | =back |
|
|
267 | |
246 | |
268 | =item $SELF |
247 | =item $SELF |
269 | |
248 | |
270 | Contains the current port id while executing C<rcv> callbacks or C<psub> |
249 | Contains the current port id while executing C<rcv> callbacks or C<psub> |
271 | blocks. |
250 | blocks. |
272 | |
251 | |
273 | =item SELF, %SELF, @SELF... |
252 | =item *SELF, SELF, %SELF, @SELF... |
274 | |
253 | |
275 | Due to some quirks in how perl exports variables, it is impossible to |
254 | Due to some quirks in how perl exports variables, it is impossible to |
276 | just export C<$SELF>, all the symbols called C<SELF> are exported by this |
255 | just export C<$SELF>, all the symbols named C<SELF> are exported by this |
277 | module, but only C<$SELF> is currently used. |
256 | module, but only C<$SELF> is currently used. |
278 | |
257 | |
279 | =item snd $port, type => @data |
258 | =item snd $port, type => @data |
280 | |
259 | |
281 | =item snd $port, @msg |
260 | =item snd $port, @msg |
282 | |
261 | |
283 | Send the given message to the given port ID, which can identify either |
262 | Send the given message to the given port, which can identify either a |
284 | a local or a remote port, and can be either a string or soemthignt hat |
263 | local or a remote port, and must be a port ID. |
285 | stringifies a sa port ID (such as a port object :). |
|
|
286 | |
264 | |
287 | While the message can be about anything, it is highly recommended to use a |
265 | While the message can be almost anything, it is highly recommended to |
288 | string as first element (a portid, or some word that indicates a request |
266 | use a string as first element (a port ID, or some word that indicates a |
289 | type etc.). |
267 | request type etc.) and to consist if only simple perl values (scalars, |
|
|
268 | arrays, hashes) - if you think you need to pass an object, think again. |
290 | |
269 | |
291 | The message data effectively becomes read-only after a call to this |
270 | The message data logically becomes read-only after a call to this |
292 | function: modifying any argument is not allowed and can cause many |
271 | function: modifying any argument (or values referenced by them) is |
293 | problems. |
272 | forbidden, as there can be considerable time between the call to C<snd> |
|
|
273 | and the time the message is actually being serialised - in fact, it might |
|
|
274 | never be copied as within the same process it is simply handed to the |
|
|
275 | receiving port. |
294 | |
276 | |
295 | The type of data you can transfer depends on the transport protocol: when |
277 | The type of data you can transfer depends on the transport protocol: when |
296 | JSON is used, then only strings, numbers and arrays and hashes consisting |
278 | JSON is used, then only strings, numbers and arrays and hashes consisting |
297 | of those are allowed (no objects). When Storable is used, then anything |
279 | of those are allowed (no objects). When Storable is used, then anything |
298 | that Storable can serialise and deserialise is allowed, and for the local |
280 | that Storable can serialise and deserialise is allowed, and for the local |
299 | node, anything can be passed. |
281 | node, anything can be passed. Best rely only on the common denominator of |
|
|
282 | these. |
300 | |
283 | |
301 | =item $local_port = port |
284 | =item $local_port = port |
302 | |
285 | |
303 | Create a new local port object and returns its port ID. Initially it has |
286 | Create a new local port object and returns its port ID. Initially it has |
304 | no callbacks set and will throw an error when it receives messages. |
287 | no callbacks set and will throw an error when it receives messages. |
… | |
… | |
351 | The default callback received all messages not matched by a more specific |
334 | The default callback received all messages not matched by a more specific |
352 | C<tag> match. |
335 | C<tag> match. |
353 | |
336 | |
354 | =item rcv $local_port, tag => $callback->(@msg_without_tag), ... |
337 | =item rcv $local_port, tag => $callback->(@msg_without_tag), ... |
355 | |
338 | |
356 | Register callbacks to be called on messages starting with the given tag on |
339 | Register (or replace) callbacks to be called on messages starting with the |
357 | the given port (and return the port), or unregister it (when C<$callback> |
340 | given tag on the given port (and return the port), or unregister it (when |
358 | is C<$undef>). |
341 | C<$callback> is C<$undef> or missing). There can only be one callback |
|
|
342 | registered for each tag. |
359 | |
343 | |
360 | The original message will be passed to the callback, after the first |
344 | The original message will be passed to the callback, after the first |
361 | element (the tag) has been removed. The callback will use the same |
345 | element (the tag) has been removed. The callback will use the same |
362 | environment as the default callback (see above). |
346 | environment as the default callback (see above). |
363 | |
347 | |
… | |
… | |
375 | rcv port, |
359 | rcv port, |
376 | msg1 => sub { ... }, |
360 | msg1 => sub { ... }, |
377 | ... |
361 | ... |
378 | ; |
362 | ; |
379 | |
363 | |
|
|
364 | Example: temporarily register a rcv callback for a tag matching some port |
|
|
365 | (e.g. for a rpc reply) and unregister it after a message was received. |
|
|
366 | |
|
|
367 | rcv $port, $otherport => sub { |
|
|
368 | my @reply = @_; |
|
|
369 | |
|
|
370 | rcv $SELF, $otherport; |
|
|
371 | }; |
|
|
372 | |
380 | =cut |
373 | =cut |
381 | |
374 | |
382 | sub rcv($@) { |
375 | sub rcv($@) { |
383 | my $port = shift; |
376 | my $port = shift; |
384 | my ($noderef, $portid) = split /#/, $port, 2; |
377 | my ($noderef, $portid) = split /#/, $port, 2; |
385 | |
378 | |
386 | ($NODE{$noderef} || add_node $noderef) == $NODE{""} |
379 | $NODE{$noderef} == $NODE{""} |
387 | or Carp::croak "$port: rcv can only be called on local ports, caught"; |
380 | or Carp::croak "$port: rcv can only be called on local ports, caught"; |
388 | |
381 | |
389 | while (@_) { |
382 | while (@_) { |
390 | if (ref $_[0]) { |
383 | if (ref $_[0]) { |
391 | if (my $self = $PORT_DATA{$portid}) { |
384 | if (my $self = $PORT_DATA{$portid}) { |
… | |
… | |
470 | $res |
463 | $res |
471 | } |
464 | } |
472 | } |
465 | } |
473 | } |
466 | } |
474 | |
467 | |
475 | =item $guard = mon $port, $cb->(@reason) |
468 | =item $guard = mon $port, $cb->(@reason) # call $cb when $port dies |
476 | |
469 | |
477 | =item $guard = mon $port, $rcvport |
470 | =item $guard = mon $port, $rcvport # kill $rcvport when $port dies |
478 | |
471 | |
479 | =item $guard = mon $port |
472 | =item $guard = mon $port # kill $SELF when $port dies |
480 | |
473 | |
481 | =item $guard = mon $port, $rcvport, @msg |
474 | =item $guard = mon $port, $rcvport, @msg # send a message when $port dies |
482 | |
475 | |
483 | Monitor the given port and do something when the port is killed or |
476 | Monitor the given port and do something when the port is killed or |
484 | messages to it were lost, and optionally return a guard that can be used |
477 | messages to it were lost, and optionally return a guard that can be used |
485 | to stop monitoring again. |
478 | to stop monitoring again. |
486 | |
479 | |
487 | C<mon> effectively guarantees that, in the absence of hardware failures, |
480 | C<mon> effectively guarantees that, in the absence of hardware failures, |
488 | that after starting the monitor, either all messages sent to the port |
481 | after starting the monitor, either all messages sent to the port will |
489 | will arrive, or the monitoring action will be invoked after possible |
482 | arrive, or the monitoring action will be invoked after possible message |
490 | message loss has been detected. No messages will be lost "in between" |
483 | loss has been detected. No messages will be lost "in between" (after |
491 | (after the first lost message no further messages will be received by the |
484 | the first lost message no further messages will be received by the |
492 | port). After the monitoring action was invoked, further messages might get |
485 | port). After the monitoring action was invoked, further messages might get |
493 | delivered again. |
486 | delivered again. |
|
|
487 | |
|
|
488 | Note that monitoring-actions are one-shot: once messages are lost (and a |
|
|
489 | monitoring alert was raised), they are removed and will not trigger again. |
494 | |
490 | |
495 | In the first form (callback), the callback is simply called with any |
491 | In the first form (callback), the callback is simply called with any |
496 | number of C<@reason> elements (no @reason means that the port was deleted |
492 | number of C<@reason> elements (no @reason means that the port was deleted |
497 | "normally"). Note also that I<< the callback B<must> never die >>, so use |
493 | "normally"). Note also that I<< the callback B<must> never die >>, so use |
498 | C<eval> if unsure. |
494 | C<eval> if unsure. |
… | |
… | |
560 | is killed, the references will be freed. |
556 | is killed, the references will be freed. |
561 | |
557 | |
562 | Optionally returns a guard that will stop the monitoring. |
558 | Optionally returns a guard that will stop the monitoring. |
563 | |
559 | |
564 | This function is useful when you create e.g. timers or other watchers and |
560 | This function is useful when you create e.g. timers or other watchers and |
565 | want to free them when the port gets killed: |
561 | want to free them when the port gets killed (note the use of C<psub>): |
566 | |
562 | |
567 | $port->rcv (start => sub { |
563 | $port->rcv (start => sub { |
568 | my $timer; $timer = mon_guard $port, AE::timer 1, 1, sub { |
564 | my $timer; $timer = mon_guard $port, AE::timer 1, 1, psub { |
569 | undef $timer if 0.9 < rand; |
565 | undef $timer if 0.9 < rand; |
570 | }); |
566 | }); |
571 | }); |
567 | }); |
572 | |
568 | |
573 | =cut |
569 | =cut |
… | |
… | |
582 | |
578 | |
583 | =item kil $port[, @reason] |
579 | =item kil $port[, @reason] |
584 | |
580 | |
585 | Kill the specified port with the given C<@reason>. |
581 | Kill the specified port with the given C<@reason>. |
586 | |
582 | |
587 | If no C<@reason> is specified, then the port is killed "normally" (linked |
583 | If no C<@reason> is specified, then the port is killed "normally" (ports |
588 | ports will not be kileld, or even notified). |
584 | monitoring other ports will not necessarily die because a port dies |
|
|
585 | "normally"). |
589 | |
586 | |
590 | Otherwise, linked ports get killed with the same reason (second form of |
587 | Otherwise, linked ports get killed with the same reason (second form of |
591 | C<mon>, see below). |
588 | C<mon>, see above). |
592 | |
589 | |
593 | Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks |
590 | Runtime errors while evaluating C<rcv> callbacks or inside C<psub> blocks |
594 | will be reported as reason C<< die => $@ >>. |
591 | will be reported as reason C<< die => $@ >>. |
595 | |
592 | |
596 | Transport/communication errors are reported as C<< transport_error => |
593 | Transport/communication errors are reported as C<< transport_error => |
… | |
… | |
601 | =item $port = spawn $node, $initfunc[, @initdata] |
598 | =item $port = spawn $node, $initfunc[, @initdata] |
602 | |
599 | |
603 | Creates a port on the node C<$node> (which can also be a port ID, in which |
600 | Creates a port on the node C<$node> (which can also be a port ID, in which |
604 | case it's the node where that port resides). |
601 | case it's the node where that port resides). |
605 | |
602 | |
606 | The port ID of the newly created port is return immediately, and it is |
603 | The port ID of the newly created port is returned immediately, and it is |
607 | permissible to immediately start sending messages or monitor the port. |
604 | possible to immediately start sending messages or to monitor the port. |
608 | |
605 | |
609 | After the port has been created, the init function is |
606 | After the port has been created, the init function is called on the remote |
610 | called. This function must be a fully-qualified function name |
607 | node, in the same context as a C<rcv> callback. This function must be a |
611 | (e.g. C<MyApp::Chat::Server::init>). To specify a function in the main |
608 | fully-qualified function name (e.g. C<MyApp::Chat::Server::init>). To |
612 | program, use C<::name>. |
609 | specify a function in the main program, use C<::name>. |
613 | |
610 | |
614 | If the function doesn't exist, then the node tries to C<require> |
611 | If the function doesn't exist, then the node tries to C<require> |
615 | the package, then the package above the package and so on (e.g. |
612 | the package, then the package above the package and so on (e.g. |
616 | C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function |
613 | C<MyApp::Chat::Server>, C<MyApp::Chat>, C<MyApp>) until the function |
617 | exists or it runs out of package names. |
614 | exists or it runs out of package names. |
618 | |
615 | |
619 | The init function is then called with the newly-created port as context |
616 | The init function is then called with the newly-created port as context |
620 | object (C<$SELF>) and the C<@initdata> values as arguments. |
617 | object (C<$SELF>) and the C<@initdata> values as arguments. |
621 | |
618 | |
622 | A common idiom is to pass your own port, monitor the spawned port, and |
619 | A common idiom is to pass a local port, immediately monitor the spawned |
623 | in the init function, monitor the original port. This two-way monitoring |
620 | port, and in the remote init function, immediately monitor the passed |
624 | ensures that both ports get cleaned up when there is a problem. |
621 | local port. This two-way monitoring ensures that both ports get cleaned up |
|
|
622 | when there is a problem. |
625 | |
623 | |
626 | Example: spawn a chat server port on C<$othernode>. |
624 | Example: spawn a chat server port on C<$othernode>. |
627 | |
625 | |
628 | # this node, executed from within a port context: |
626 | # this node, executed from within a port context: |
629 | my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF; |
627 | my $server = spawn $othernode, "MyApp::Chat::Server::connect", $SELF; |
… | |
… | |
659 | my $id = "$RUNIQ." . $ID++; |
657 | my $id = "$RUNIQ." . $ID++; |
660 | |
658 | |
661 | $_[0] =~ /::/ |
659 | $_[0] =~ /::/ |
662 | or Carp::croak "spawn init function must be a fully-qualified name, caught"; |
660 | or Carp::croak "spawn init function must be a fully-qualified name, caught"; |
663 | |
661 | |
664 | ($NODE{$noderef} || add_node $noderef) |
662 | snd_to_func $noderef, "AnyEvent::MP::_spawn" => $id, @_; |
665 | ->send (["", "AnyEvent::MP::_spawn" => $id, @_]); |
|
|
666 | |
663 | |
667 | "$noderef#$id" |
664 | "$noderef#$id" |
668 | } |
665 | } |
669 | |
666 | |
670 | =back |
667 | =item after $timeout, @msg |
671 | |
668 | |
672 | =head1 NODE MESSAGES |
669 | =item after $timeout, $callback |
673 | |
670 | |
674 | Nodes understand the following messages sent to them. Many of them take |
671 | Either sends the given message, or call the given callback, after the |
675 | arguments called C<@reply>, which will simply be used to compose a reply |
672 | specified number of seconds. |
676 | message - C<$reply[0]> is the port to reply to, C<$reply[1]> the type and |
|
|
677 | the remaining arguments are simply the message data. |
|
|
678 | |
673 | |
679 | While other messages exist, they are not public and subject to change. |
674 | This is simply a utility function that comes in handy at times - the |
|
|
675 | AnyEvent::MP author is not convinced of the wisdom of having it, though, |
|
|
676 | so it may go away in the future. |
680 | |
677 | |
681 | =over 4 |
|
|
682 | |
|
|
683 | =cut |
678 | =cut |
684 | |
679 | |
685 | =item lookup => $name, @reply |
680 | sub after($@) { |
|
|
681 | my ($timeout, @action) = @_; |
686 | |
682 | |
687 | Replies with the port ID of the specified well-known port, or C<undef>. |
683 | my $t; $t = AE::timer $timeout, 0, sub { |
688 | |
684 | undef $t; |
689 | =item devnull => ... |
685 | ref $action[0] |
690 | |
686 | ? $action[0]() |
691 | Generic data sink/CPU heat conversion. |
687 | : snd @action; |
692 | |
688 | }; |
693 | =item relay => $port, @msg |
689 | } |
694 | |
|
|
695 | Simply forwards the message to the given port. |
|
|
696 | |
|
|
697 | =item eval => $string[ @reply] |
|
|
698 | |
|
|
699 | Evaluates the given string. If C<@reply> is given, then a message of the |
|
|
700 | form C<@reply, $@, @evalres> is sent. |
|
|
701 | |
|
|
702 | Example: crash another node. |
|
|
703 | |
|
|
704 | snd $othernode, eval => "exit"; |
|
|
705 | |
|
|
706 | =item time => @reply |
|
|
707 | |
|
|
708 | Replies the the current node time to C<@reply>. |
|
|
709 | |
|
|
710 | Example: tell the current node to send the current time to C<$myport> in a |
|
|
711 | C<timereply> message. |
|
|
712 | |
|
|
713 | snd $NODE, time => $myport, timereply => 1, 2; |
|
|
714 | # => snd $myport, timereply => 1, 2, <time> |
|
|
715 | |
690 | |
716 | =back |
691 | =back |
717 | |
692 | |
718 | =head1 AnyEvent::MP vs. Distributed Erlang |
693 | =head1 AnyEvent::MP vs. Distributed Erlang |
719 | |
694 | |
… | |
… | |
729 | |
704 | |
730 | Despite the similarities, there are also some important differences: |
705 | Despite the similarities, there are also some important differences: |
731 | |
706 | |
732 | =over 4 |
707 | =over 4 |
733 | |
708 | |
734 | =item * Node references contain the recipe on how to contact them. |
709 | =item * Node IDs are arbitrary strings in AEMP. |
735 | |
710 | |
736 | Erlang relies on special naming and DNS to work everywhere in the |
711 | Erlang relies on special naming and DNS to work everywhere in the same |
737 | same way. AEMP relies on each node knowing it's own address(es), with |
712 | way. AEMP relies on each node somehow knowing its own address(es) (e.g. by |
738 | convenience functionality. |
713 | configuraiton or DNS), but will otherwise discover other odes itself. |
739 | |
714 | |
740 | This means that AEMP requires a less tightly controlled environment at the |
715 | =item * Erlang has a "remote ports are like local ports" philosophy, AEMP |
741 | cost of longer node references and a slightly higher management overhead. |
716 | uses "local ports are like remote ports". |
|
|
717 | |
|
|
718 | The failure modes for local ports are quite different (runtime errors |
|
|
719 | only) then for remote ports - when a local port dies, you I<know> it dies, |
|
|
720 | when a connection to another node dies, you know nothing about the other |
|
|
721 | port. |
|
|
722 | |
|
|
723 | Erlang pretends remote ports are as reliable as local ports, even when |
|
|
724 | they are not. |
|
|
725 | |
|
|
726 | AEMP encourages a "treat remote ports differently" philosophy, with local |
|
|
727 | ports being the special case/exception, where transport errors cannot |
|
|
728 | occur. |
742 | |
729 | |
743 | =item * Erlang uses processes and a mailbox, AEMP does not queue. |
730 | =item * Erlang uses processes and a mailbox, AEMP does not queue. |
744 | |
731 | |
745 | Erlang uses processes that selctively receive messages, and therefore |
732 | Erlang uses processes that selectively receive messages, and therefore |
746 | needs a queue. AEMP is event based, queuing messages would serve no useful |
733 | needs a queue. AEMP is event based, queuing messages would serve no |
747 | purpose. |
734 | useful purpose. For the same reason the pattern-matching abilities of |
|
|
735 | AnyEvent::MP are more limited, as there is little need to be able to |
|
|
736 | filter messages without dequeing them. |
748 | |
737 | |
749 | (But see L<Coro::MP> for a more Erlang-like process model on top of AEMP). |
738 | (But see L<Coro::MP> for a more Erlang-like process model on top of AEMP). |
750 | |
739 | |
751 | =item * Erlang sends are synchronous, AEMP sends are asynchronous. |
740 | =item * Erlang sends are synchronous, AEMP sends are asynchronous. |
752 | |
741 | |
753 | Sending messages in Erlang is synchronous and blocks the process. AEMP |
742 | Sending messages in Erlang is synchronous and blocks the process (and |
754 | sends are immediate, connection establishment is handled in the |
743 | so does not need a queue that can overflow). AEMP sends are immediate, |
755 | background. |
744 | connection establishment is handled in the background. |
756 | |
745 | |
757 | =item * Erlang can silently lose messages, AEMP cannot. |
746 | =item * Erlang suffers from silent message loss, AEMP does not. |
758 | |
747 | |
759 | Erlang makes few guarantees on messages delivery - messages can get lost |
748 | Erlang makes few guarantees on messages delivery - messages can get lost |
760 | without any of the processes realising it (i.e. you send messages a, b, |
749 | without any of the processes realising it (i.e. you send messages a, b, |
761 | and c, and the other side only receives messages a and c). |
750 | and c, and the other side only receives messages a and c). |
762 | |
751 | |
763 | AEMP guarantees correct ordering, and the guarantee that there are no |
752 | AEMP guarantees correct ordering, and the guarantee that after one message |
764 | holes in the message sequence. |
753 | is lost, all following ones sent to the same port are lost as well, until |
765 | |
754 | monitoring raises an error, so there are no silent "holes" in the message |
766 | =item * In Erlang, processes can be declared dead and later be found to be |
755 | sequence. |
767 | alive. |
|
|
768 | |
|
|
769 | In Erlang it can happen that a monitored process is declared dead and |
|
|
770 | linked processes get killed, but later it turns out that the process is |
|
|
771 | still alive - and can receive messages. |
|
|
772 | |
|
|
773 | In AEMP, when port monitoring detects a port as dead, then that port will |
|
|
774 | eventually be killed - it cannot happen that a node detects a port as dead |
|
|
775 | and then later sends messages to it, finding it is still alive. |
|
|
776 | |
756 | |
777 | =item * Erlang can send messages to the wrong port, AEMP does not. |
757 | =item * Erlang can send messages to the wrong port, AEMP does not. |
778 | |
758 | |
779 | In Erlang it is quite possible that a node that restarts reuses a process |
759 | In Erlang it is quite likely that a node that restarts reuses a process ID |
780 | ID known to other nodes for a completely different process, causing |
760 | known to other nodes for a completely different process, causing messages |
781 | messages destined for that process to end up in an unrelated process. |
761 | destined for that process to end up in an unrelated process. |
782 | |
762 | |
783 | AEMP never reuses port IDs, so old messages or old port IDs floating |
763 | AEMP never reuses port IDs, so old messages or old port IDs floating |
784 | around in the network will not be sent to an unrelated port. |
764 | around in the network will not be sent to an unrelated port. |
785 | |
765 | |
786 | =item * Erlang uses unprotected connections, AEMP uses secure |
766 | =item * Erlang uses unprotected connections, AEMP uses secure |
787 | authentication and can use TLS. |
767 | authentication and can use TLS. |
788 | |
768 | |
789 | AEMP can use a proven protocol - SSL/TLS - to protect connections and |
769 | AEMP can use a proven protocol - TLS - to protect connections and |
790 | securely authenticate nodes. |
770 | securely authenticate nodes. |
791 | |
771 | |
792 | =item * The AEMP protocol is optimised for both text-based and binary |
772 | =item * The AEMP protocol is optimised for both text-based and binary |
793 | communications. |
773 | communications. |
794 | |
774 | |
795 | The AEMP protocol, unlike the Erlang protocol, supports both |
775 | The AEMP protocol, unlike the Erlang protocol, supports both programming |
796 | language-independent text-only protocols (good for debugging) and binary, |
776 | language independent text-only protocols (good for debugging) and binary, |
797 | language-specific serialisers (e.g. Storable). |
777 | language-specific serialisers (e.g. Storable). By default, unless TLS is |
|
|
778 | used, the protocol is actually completely text-based. |
798 | |
779 | |
799 | It has also been carefully designed to be implementable in other languages |
780 | It has also been carefully designed to be implementable in other languages |
800 | with a minimum of work while gracefully degrading fucntionality to make the |
781 | with a minimum of work while gracefully degrading functionality to make the |
801 | protocol simple. |
782 | protocol simple. |
802 | |
783 | |
803 | =item * AEMP has more flexible monitoring options than Erlang. |
784 | =item * AEMP has more flexible monitoring options than Erlang. |
804 | |
785 | |
805 | In Erlang, you can chose to receive I<all> exit signals as messages |
786 | In Erlang, you can chose to receive I<all> exit signals as messages |
… | |
… | |
808 | Erlang, as one can choose between automatic kill, exit message or callback |
789 | Erlang, as one can choose between automatic kill, exit message or callback |
809 | on a per-process basis. |
790 | on a per-process basis. |
810 | |
791 | |
811 | =item * Erlang tries to hide remote/local connections, AEMP does not. |
792 | =item * Erlang tries to hide remote/local connections, AEMP does not. |
812 | |
793 | |
813 | Monitoring in Erlang is not an indicator of process death/crashes, |
794 | Monitoring in Erlang is not an indicator of process death/crashes, in the |
814 | as linking is (except linking is unreliable in Erlang). |
795 | same way as linking is (except linking is unreliable in Erlang). |
815 | |
796 | |
816 | In AEMP, you don't "look up" registered port names or send to named ports |
797 | In AEMP, you don't "look up" registered port names or send to named ports |
817 | that might or might not be persistent. Instead, you normally spawn a port |
798 | that might or might not be persistent. Instead, you normally spawn a port |
818 | on the remote node. The init function monitors the you, and you monitor |
799 | on the remote node. The init function monitors you, and you monitor the |
819 | the remote port. Since both monitors are local to the node, they are much |
800 | remote port. Since both monitors are local to the node, they are much more |
820 | more reliable. |
801 | reliable (no need for C<spawn_link>). |
821 | |
802 | |
822 | This also saves round-trips and avoids sending messages to the wrong port |
803 | This also saves round-trips and avoids sending messages to the wrong port |
823 | (hard to do in Erlang). |
804 | (hard to do in Erlang). |
824 | |
805 | |
825 | =back |
806 | =back |
826 | |
807 | |
827 | =head1 RATIONALE |
808 | =head1 RATIONALE |
828 | |
809 | |
829 | =over 4 |
810 | =over 4 |
830 | |
811 | |
831 | =item Why strings for ports and noderefs, why not objects? |
812 | =item Why strings for port and node IDs, why not objects? |
832 | |
813 | |
833 | We considered "objects", but found that the actual number of methods |
814 | We considered "objects", but found that the actual number of methods |
834 | thatc an be called are very low. Since port IDs and noderefs travel over |
815 | that can be called are quite low. Since port and node IDs travel over |
835 | the network frequently, the serialising/deserialising would add lots of |
816 | the network frequently, the serialising/deserialising would add lots of |
836 | overhead, as well as having to keep a proxy object. |
817 | overhead, as well as having to keep a proxy object everywhere. |
837 | |
818 | |
838 | Strings can easily be printed, easily serialised etc. and need no special |
819 | Strings can easily be printed, easily serialised etc. and need no special |
839 | procedures to be "valid". |
820 | procedures to be "valid". |
840 | |
821 | |
841 | And a a miniport consists of a single closure stored in a global hash - it |
822 | And as a result, a miniport consists of a single closure stored in a |
842 | can't become much cheaper. |
823 | global hash - it can't become much cheaper. |
843 | |
824 | |
844 | =item Why favour JSON, why not real serialising format such as Storable? |
825 | =item Why favour JSON, why not a real serialising format such as Storable? |
845 | |
826 | |
846 | In fact, any AnyEvent::MP node will happily accept Storable as framing |
827 | In fact, any AnyEvent::MP node will happily accept Storable as framing |
847 | format, but currently there is no way to make a node use Storable by |
828 | format, but currently there is no way to make a node use Storable by |
848 | default. |
829 | default (although all nodes will accept it). |
849 | |
830 | |
850 | The default framing protocol is JSON because a) JSON::XS is many times |
831 | The default framing protocol is JSON because a) JSON::XS is many times |
851 | faster for small messages and b) most importantly, after years of |
832 | faster for small messages and b) most importantly, after years of |
852 | experience we found that object serialisation is causing more problems |
833 | experience we found that object serialisation is causing more problems |
853 | than it gains: Just like function calls, objects simply do not travel |
834 | than it solves: Just like function calls, objects simply do not travel |
854 | easily over the network, mostly because they will always be a copy, so you |
835 | easily over the network, mostly because they will always be a copy, so you |
855 | always have to re-think your design. |
836 | always have to re-think your design. |
856 | |
837 | |
857 | Keeping your messages simple, concentrating on data structures rather than |
838 | Keeping your messages simple, concentrating on data structures rather than |
858 | objects, will keep your messages clean, tidy and efficient. |
839 | objects, will keep your messages clean, tidy and efficient. |
859 | |
840 | |
860 | =back |
841 | =back |
861 | |
842 | |
862 | =head1 SEE ALSO |
843 | =head1 SEE ALSO |
863 | |
844 | |
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845 | L<AnyEvent::MP::Intro> - a gentle introduction. |
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846 | |
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847 | L<AnyEvent::MP::Kernel> - more, lower-level, stuff. |
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848 | |
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849 | L<AnyEvent::MP::Global> - network maintainance and port groups, to find |
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850 | your applications. |
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851 | |
864 | L<AnyEvent>. |
852 | L<AnyEvent>. |
865 | |
853 | |
866 | =head1 AUTHOR |
854 | =head1 AUTHOR |
867 | |
855 | |
868 | Marc Lehmann <schmorp@schmorp.de> |
856 | Marc Lehmann <schmorp@schmorp.de> |