1POE::Component::Client:U:sPeirngC(o3n)tributed Perl DocuPmOeEn:t:aCtoimopnonent::Client::Ping(3)
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NAME

6       POE::Component::Client::Ping - a non-blocking ICMP ping client
7

SYNOPSIS

9         use POE qw(Component::Client::Ping);
10
11         POE::Component::Client::Ping->spawn(
12           Alias               => "pingthing",  # defaults to "pinger"
13           Timeout             => 10,           # defaults to 1 second
14           Retry               => 3,            # defaults to 1 attempt
15           OneReply            => 1,            # defaults to disabled
16           Parallelism         => 64,           # defaults to autodetect
17           BufferSize          => 65536,        # defaults to undef
18           AlwaysDecodeAddress => 1,            # defaults to 0
19         );
20
21         sub some_event_handler {
22           $kernel->post(
23             "pingthing", # Post the request to the "pingthing" component.
24             "ping",      # Ask it to "ping" an address.
25             "pong",      # Have it post an answer as a "pong" event.
26             $address,    # This is the address we want to ping.
27             $timeout,    # Optional timeout.  It overrides the default.
28             $retry,      # Optional retries. It overrides the default.
29           );
30         }
31
32         # This is the sub which is called when the session receives a "pong"
33         # event.  It handles responses from the Ping component.
34         sub got_pong {
35           my ($request, $response) = @_[ARG0, ARG1];
36
37           my ($req_address, $req_timeout, $req_time)      = @$request;
38           my ($resp_address, $roundtrip_time, $resp_time, $resp_ttl) = @$response;
39
40           # The response address is defined if this is a response.
41           if (defined $resp_address) {
42             printf(
43               "ping to %-15.15s at %10d. pong from %-15.15s in %6.3f s\n",
44               $req_address, $req_time,
45               $resp_address, $roundtrip_time,
46             );
47             return;
48           }
49
50           # Otherwise the timeout period has ended.
51           printf(
52             "ping to %-15.15s is done.\n", $req_address,
53           );
54         }
55
56         or
57
58         use POE::Component::Client::Ping ":const";
59
60         # Post an array ref as the callback to get data back to you
61         $kernel->post("pinger", "ping", [ "pong", $user_data ]);
62
63         # use the REQ_USER_ARGS constant to get to your data
64         sub got_pong {
65             my ($request, $response) = @_[ARG0, ARG1];
66             my $user_data = $request->[REQ_USER_ARGS];
67             ...;
68         }
69

DESCRIPTION

71       POE::Component::Client::Ping is non-blocking ICMP ping client.  It lets
72       several other sessions ping through it in parallel, and it lets them
73       continue doing other things while they wait for responses.
74
75       Ping client components are not proper objects.  Instead of being
76       created, as most objects are, they are "spawned" as separate sessions.
77       To avoid confusion (and hopefully not cause other confusion), they must
78       be spawned with a "spawn" method, not created anew with a "new" one.
79
80       PoCo::Client::Ping's "spawn" method takes a few named parameters:
81
82       Alias => $session_alias
83         "Alias" sets the component's alias.  It is the target of post()
84         calls.  See the synopsis.  The alias defaults to "pinger".
85
86       Socket => $raw_socket
87         "Socket" allows developers to open an existing raw socket rather than
88         letting the component attempt opening one itself.  If omitted, the
89         component will create its own raw socket.
90
91         This is useful for people who would rather not perform a security
92         audit on POE, since it allows them to create a raw socket in their
93         own code and then run POE at reduced privileges.
94
95       Timeout => $ping_timeout
96         "Timeout" sets the default amount of time (in seconds) a Ping
97         component will wait for a single ICMP echo reply before retrying.  It
98         is 1 by default.  It is possible and meaningful to set the timeout to
99         a fractional number of seconds.
100
101         This default timeout is only used for ping requests that don't
102         include their own timeouts.
103
104       Retry => $ping_attempts
105         "Retry" sets the default number of attempts a ping will be sent
106         before it should be considered failed. It is 1 by default.
107
108       OneReply => 0|1
109         Set "OneReply" to prevent the Ping component from waiting the full
110         timeout period for replies.  Normally the ICMP protocol allows for
111         multiple replies to a single request, so it's proper to wait for late
112         responses.  This option disables the wait, ending the ping
113         transaction at the first response.  Any subsequent responses will be
114         silently ignored.
115
116         "OneReply" is disabled by default, and a single successful request
117         will generate at least two responses.  The first response is a
118         successful ICMP ECHO REPLY event.  The second is an undefined
119         response event, signifying that the timeout period has ended.
120
121         A ping request will generate exactly one reply when "OneReply" is
122         enabled.  This reply will represent either the first ICMP ECHO REPLY
123         to arrive or that the timeout period has ended.
124
125       Parallelism => $limit
126         Parallelism sets POE::Component::Client::Ping's maximum number of
127         simultaneous ICMP requests.  Higher numbers speed up the processing
128         of large host lists, up to the point where the operating system or
129         network becomes oversaturated and begin to drop packets.
130
131         The difference can be dramatic.  A tuned Parallelism can enable
132         responses down to 1ms, depending on the network, although it will
133         take longer to get through the hosts list.
134
135           Pinging 762 hosts at Parallelism=64
136           Starting to ping hosts.
137           Pinged 10.0.0.25       - Response from 10.0.0.25       in  0.002s
138           Pinged 10.0.0.200      - Response from 10.0.0.200      in  0.003s
139           Pinged 10.0.0.201      - Response from 10.0.0.201      in  0.001s
140
141           real  1m1.923s
142           user  0m2.584s
143           sys   0m0.207s
144
145         Responses will take significantly longer with an untuned Parallelism,
146         but the total run time will be quicker.
147
148           Pinging 762 hosts at Parallelism=500
149           Starting to ping hosts.
150           Pinged 10.0.0.25       - Response from 10.0.0.25       in  3.375s
151           Pinged 10.0.0.200      - Response from 10.0.0.200      in  1.258s
152           Pinged 10.0.0.201      - Response from 10.0.0.201      in  2.040s
153
154           real  0m13.410s
155           user  0m6.390s
156           sys   0m0.290s
157
158         Excessively high parallelism values may saturate the OS or network,
159         resulting in few or no responses.
160
161           Pinging 762 hosts at Parallelism=1000
162           Starting to ping hosts.
163
164           real  0m20.520s
165           user  0m7.896s
166           sys   0m0.297s
167
168         By default, POE::Component::Client::Ping will guess at an optimal
169         Parallelism value based on the raw socket receive buffer size and the
170         operating system's nominal ICMP packet size.  The latter figure is
171         3000 octets for Linux and 100 octets for other systems.  ICMP packets
172         are generally under 90 bytes, but operating systems may use
173         alternative numbers when calculating buffer capacities.  The
174         component tries to mimic calculations observed in the wild.
175
176         When in doubt, experiment with different Parallelism values and use
177         the one that works best.
178
179       BufferSize => $bytes
180         If set, then the size of the receive buffer of the raw socket will be
181         modified to the given value. The default size of the receive buffer
182         is operating system dependent. If the buffer cannot be set to the
183         given value, a warning will be generated but the system will continue
184         working. Note that if the buffer is set too small and too many ping
185         replies arrive at the same time, then the operating system may
186         discard the ping replies and mistakenly cause this component to
187         believe the ping to have timed out. In this case, you will typically
188         see discards being noted in the counters displayed by 'netstat -s'.
189
190         Increased BufferSize values can expand the practical limit for
191         Parallelism.
192
193       AlwaysDecodeAddress => 0|1
194         If set, then any input addresses will always be looked up, even if
195         the hostname happens to be only 4 characters in size.  Ideally, you
196         should be passing addresses in to the system to avoid slow hostname
197         lookups, but if you must use hostnames and there is a possibility
198         that you might have short hostnames, then you should set this.
199
200       Payload => $bytes
201         Sets the ICMP payload (data bytes).  Otherwise the component
202         generates 56 data bytes internally.  Note that some firewalls will
203         discard ICMP packets with nonstandard payload sizes.
204
205       Sessions communicate asynchronously with the Client::Ping component.
206       They post ping requests to it, and they receive pong events back.
207
208       Requests are posted to the component's "ping" handler.  They include
209       the name of an event to post back, an address to ping, and an optional
210       amount of time to wait for responses.  The address may be a numeric
211       dotted quad, a packed inet_aton address, or a host name.  Host names
212       are not recommended: they must be looked up for every ping request, and
213       DNS lookups can be very slow.  The optional timeout overrides the one
214       set when "spawn" is called.
215
216       Ping responses come with two array references:
217
218         my ($request, $response) = @_[ARG0, ARG1];
219
220       $request contains information about the original request:
221
222         my (
223           $req_address, $req_timeout, $req_time, $req_user_args,
224         ) = @$request;
225
226       $req_address
227         This is the original request address.  It matches the address posted
228         along with the original "ping" request.
229
230         It is useful along with $req_user_args for pairing requests with
231         their corresponding responses.
232
233       $req_timeout
234         This is the original request timeout.  It's either the one passed
235         with the "ping" request or the default timeout set with "spawn".
236
237       $req_time
238         This is the time that the "ping" event was received by the Ping
239         component.  It is a real number based on the current system's time()
240         epoch.
241
242       $req_user_args
243         This is a scalar containing arbitrary data that can be sent along
244         with a request.  It's often used to provide continuity between
245         requests and their responses.  $req_user_args may contain a reference
246         to some larger data structure.
247
248         To use it, replace the response event with an array reference in the
249         original request.  The array reference should contain two items: the
250         actual response event and a scalar with the context data the program
251         needs back.  See the SYNOPSIS for an example.
252
253       $response contains information about the ICMP ping response.  There may
254       be multiple responses for a single request.
255
256         my ($response_address, $roundtrip_time, $reply_time, $reply_ttl) =
257         @$response;
258
259       $response_address
260         This is the address that responded to the ICMP echo request.  It may
261         be different than $request_address, especially if the request was
262         sent to a broadcast address.
263
264         $response_address will be undefined if $request_timeout seconds have
265         elapsed.  This marks the end of responses for a given request.
266         Programs can assume that no more responses will be sent for the
267         request address.  They may use this marker to initiate another ping
268         request.
269
270       $roundtrip_time
271         This is the number of seconds that elapsed between the ICMP echo
272         request's transmission and its corresponding response's receipt.
273         It's a real number. This is purely the trip time and does *not*
274         include any time spent queueing if the system's parallelism limit
275         caused the ping transmission to be delayed.
276
277       $reply_time
278         This is the time when the ICMP echo response was received.  It is a
279         real number based on the current system's time() epoch.
280
281       $reply_ttl
282         This is the ttl for the echo response packet we received.
283
284       If the ":const" tagset is imported the following constants will be
285       exported:
286
287       REQ_ADDRESS, REQ_TIMEOUT, REQ_TIME REQ_USER_ARGS, RES_ADDRESS,
288       RES_ROUNDTRIP, RES_TIME, RES_TTL
289

SEE ALSO

291       This component's ICMP ping code was lifted from Net::Ping, which is an
292       excellent module when you only need to ping one host at a time.
293
294       See POE, of course, which includes a lot of documentation about how POE
295       works.
296
297       Also see the test program, t/01_ping.t, in the component's
298       distribution.
299

BUG TRACKER

301       https://rt.cpan.org/Dist/Display.html?Queue=POE-Component-Client-Ping
302

REPOSITORY

304       http://github.com/rcaputo/poe-component-client-ping/
305

OTHER RESOURCES

307       http://search.cpan.org/dist/POE-Component-Client-Ping/
308

AUTHOR & COPYRIGHTS

310       POE::Component::Client::Ping is Copyright 1999-2009 by Rocco Caputo.
311       All rights are reserved.  POE::Component::Client::Ping is free
312       software; you may redistribute it and/or modify it under the same terms
313       as Perl itself.
314
315       You can learn more about POE at http://poe.perl.org/
316
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318
319perl v5.30.1                      2020-01-30   POE::Component::Client::Ping(3)
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