1Hijk(3pm)             User Contributed Perl Documentation            Hijk(3pm)
2
3
4

NAME

6       Hijk - Fast & minimal low-level HTTP client
7

SYNOPSIS

9       A simple GET request:
10
11           use Hijk ();
12           my $res = Hijk::request({
13               method       => "GET",
14               host         => "example.com",
15               port         => "80",
16               path         => "/flower",
17               query_string => "color=red"
18           });
19
20           if (exists $res->{error} and $res->{error} & Hijk::Error::TIMEOUT) {
21               die "Oh noes we had some sort of timeout";
22           }
23
24           die "Expecting an 'OK' response" unless $res->{status} == 200;
25
26           say $res->{body};
27
28       A POST request, you have to manually set the appropriate headers, URI
29       escape your values etc.
30
31           use Hijk ();
32           use URI::Escape qw(uri_escape);
33
34           my $res = Hijk::request({
35               method       => "POST",
36               host         => "example.com",
37               port         => "80",
38               path         => "/new",
39               head         => [ "Content-Type" => "application/x-www-form-urlencoded" ],
40               query_string => "type=flower&bucket=the%20one%20out%20back",
41               body         => "description=" . uri_escape("Another flower, let's hope it's exciting"),
42           });
43
44           die "Expecting an 'OK' response" unless $res->{status} == 200;
45

DESCRIPTION

47       Hijk is a fast & minimal low-level HTTP client intended to be used
48       where you control both the client and the server, e.g. for talking to
49       some internal service from a frontend user-facing web application.
50
51       It is "NOT" a general HTTP user agent, it doesn't support redirects,
52       proxies, SSL and any number of other advanced HTTP features like (in
53       roughly descending order of feature completeness) LWP::UserAgent,
54       WWW::Curl, HTTP::Tiny, HTTP::Lite or Furl. This library is basically
55       one step above manually talking HTTP over sockets.
56
57       Having said that it's lightning fast and extensively used in production
58       at Booking.com <https://www.booking.com> where it's used as the go-to
59       transport layer for talking to internal services. It uses non-blocking
60       sockets and correctly handles all combinations of connect/read timeouts
61       and other issues you might encounter from various combinations of parts
62       of your system going down or becoming otherwise unavailable.
63

FUNCTION: Hijk::request( $args :HashRef ) :HashRef

65       "Hijk::request" is the only function you should use. It (or anything
66       else in this package for that matter) is not exported, so you have to
67       use the fully qualified name.
68
69       It takes a "HashRef" of arguments and either dies or returns a
70       "HashRef" as a response.
71
72       The "HashRef" argument to it must contain some of the key-value pairs
73       from the following list. The value for "host" and "port" are mandatory,
74       but others are optional with default values listed below.
75
76           protocol               => "HTTP/1.1", # (or "HTTP/1.0")
77           host                   => ...,
78           port                   => ...,
79           connect_timeout        => undef,
80           read_timeout           => undef,
81           read_length            => 10240,
82           method                 => "GET",
83           path                   => "/",
84           query_string           => "",
85           head                   => [],
86           body                   => "",
87           socket_cache           => \%Hijk::SOCKET_CACHE, # (undef to disable, or \my %your_socket_cache)
88           on_connect             => undef, # (or sub { ... })
89           parse_chunked          => 0,
90           head_as_array          => 0,
91           no_default_host_header => 1,
92
93       Notice how Hijk does not take a full URI string as input, you have to
94       specify the individual parts of the URL. Users who need to parse an
95       existing URI string to produce a request should use the URI module to
96       do so.
97
98       The value of "head" is an "ArrayRef" of key-value pairs instead of a
99       "HashRef", this way you can decide in which order the headers are sent,
100       and you can send the same header name multiple times. For example:
101
102           head => [
103               "Content-Type" => "application/json",
104               "X-Requested-With" => "Hijk",
105           ]
106
107       Will produce these request headers:
108
109           Content-Type: application/json
110           X-Requested-With: Hijk
111
112       In addition Hijk will provide a "Host" header for you by default with
113       the "host" value you pass to "request()". To suppress this (e.g. to
114       send custom "Host" requests) pass a true value to the
115       "no_default_host_header" option and provide your own "Host" header in
116       the "head" "ArrayRef" (or don't, if you want to construct a "Host"-less
117       request knock yourself out...).
118
119       Hijk doesn't escape any values for you, it just passes them through as-
120       is. You can easily produce invalid requests if e.g. any of these
121       strings contain a newline, or aren't otherwise properly escaped.
122
123       The value of "connect_timeout" or "read_timeout" is in floating point
124       seconds, and is used as the time limit for connecting to the host, and
125       reading the response back from it, respectively. The default value for
126       both is "undef", meaning no timeout limit. If you don't supply these
127       timeouts and the host really is unreachable or slow, we'll reach the
128       TCP timeout limit before returning some other error to you.
129
130       The default "protocol" is "HTTP/1.1", but you can also specify
131       "HTTP/1.0". The advantage of using "HTTP/1.1" is support for keep-
132       alive, which matters a lot in environments where the connection setup
133       represents non-trivial overhead. Sometimes that overhead is negligible
134       (e.g. on Linux talking to an nginx on the local network), and keeping
135       open connections down and reducing complexity is more important, in
136       those cases you can either use "HTTP/1.0", or specify "Connection:
137       close" in the request, but just using "HTTP/1.0" is an easy way to
138       accomplish the same thing.
139
140       By default we will provide a "socket_cache" for you which is a global
141       singleton that we maintain keyed on "join($;, $$, $host, $port)".
142       Alternatively you can pass in "socket_cache" hash of your own which
143       we'll use as the cache. To completely disable the cache pass in
144       "undef".
145
146       The optional "on_connect" callback is intended to be used for you to
147       figure out from production traffic what you should set the
148       "connect_timeout". I.e. you can start a timer when you call
149       "Hijk::request()" that you end when "on_connect" is called, that's how
150       long it took us to get a connection. If you start another timer in that
151       callback that you end when "Hijk::request()" returns to you that'll
152       give you how long it took to send/receive data after we constructed the
153       socket, i.e. it'll help you to tweak your "read_timeout". The
154       "on_connect" callback is provided with no arguments, and is called in
155       void context.
156
157       We have experimental support for parsing chunked responses encoding.
158       historically Hijk didn't support this at all and if you wanted to use
159       it with e.g. nginx you had to add "chunked_transfer_encoding off" to
160       the nginx config file.
161
162       Since you may just want to do that instead of having Hijk do more work
163       to parse this out with a more complex and experimental codepath you
164       have to explicitly enable it with "parse_chunked". Otherwise Hijk will
165       die when it encounters chunked responses. The "parse_chunked" option
166       may be turned on by default in the future.
167
168       The return value is a "HashRef" representing a response. It contains
169       the following key-value pairs.
170
171           proto         => :Str
172           status        => :StatusCode
173           body          => :Str
174           head          => :HashRef (or :ArrayRef with "head_as_array")
175           error         => :PositiveInt
176           error_message => :Str
177           errno_number  => :Int
178           errno_string  => :Str
179
180       For example, to send a request to
181       "http://example.com/flower?color=red", pass the following parameters:
182
183           my $res = Hijk::request({
184               host         => "example.com",
185               port         => "80",
186               path         => "/flower",
187               query_string => "color=red"
188           });
189           die "Response is not 'OK'" unless $res->{status} == 200;
190
191       Notice that you do not need to put the leading "?" character in the
192       "query_string". You do, however, need to properly "uri_escape" the
193       content of "query_string".
194
195       Again, Hijk doesn't escape any values for you, so these values MUST be
196       properly escaped before being passed in, unless you want to issue
197       invalid requests.
198
199       By default the "head" in the response is a "HashRef" rather then an
200       "ArrayRef". This makes it easier to retrieve specific header fields,
201       but it means that we'll clobber any duplicated header names with the
202       most recently seen header value. To get the returned headers as an
203       "ArrayRef" instead specify "head_as_array".
204
205       If you want to fiddle with the "read_length" value it controls how much
206       we "POSIX::read($fd, $buf, $read_length)" at a time.
207
208       We currently don't support servers returning a http body without an
209       accompanying "Content-Length" header; bodies MUST have a
210       "Content-Length" or we won't pick them up.
211

ERROR CODES

213       If we had a recoverable error we'll include an "error" key whose value
214       is a bitfield that you can check against Hijk::Error::* constants.
215       Those are:
216
217           Hijk::Error::CONNECT_TIMEOUT
218           Hijk::Error::READ_TIMEOUT
219           Hijk::Error::TIMEOUT
220           Hijk::Error::CANNOT_RESOLVE
221           Hijk::Error::REQUEST_SELECT_ERROR
222           Hijk::Error::REQUEST_WRITE_ERROR
223           Hijk::Error::REQUEST_ERROR
224           Hijk::Error::RESPONSE_READ_ERROR
225           Hijk::Error::RESPONSE_BAD_READ_VALUE
226           Hijk::Error::RESPONSE_ERROR
227
228       In addition we might return "error_message", "errno_number" and
229       "errno_string" keys, see the discussion of "Hijk::Error::REQUEST_*" and
230       "Hijk::Error::RESPONSE_*" errors below.
231
232       The "Hijk::Error::TIMEOUT" constant is the same as
233       "Hijk::Error::CONNECT_TIMEOUT | Hijk::Error::READ_TIMEOUT". It's there
234       for convenience so you can do:
235
236           .. if exists $res->{error} and $res->{error} & Hijk::Error::TIMEOUT;
237
238       Instead of the more verbose:
239
240           .. if exists $res->{error} and $res->{error} & (Hijk::Error::CONNECT_TIMEOUT | Hijk::Error::READ_TIMEOUT)
241
242       We'll return "Hijk::Error::CANNOT_RESOLVE" if we can't
243       "gethostbyname()" the host you've provided.
244
245       If we fail to do a "select()" or "write()" during when sending the
246       response we'll return "Hijk::Error::REQUEST_SELECT_ERROR" or
247       "Hijk::Error::REQUEST_WRITE_ERROR", respectively. Similarly to
248       "Hijk::Error::TIMEOUT" the "Hijk::Error::REQUEST_ERROR" constant is a
249       union of these two, and any other request errors we might add in the
250       future.
251
252       When we're getting the response back we'll return
253       "Hijk::Error::RESPONSE_READ_ERROR" when we can't "read()" the response,
254       and "Hijk::Error::RESPONSE_BAD_READ_VALUE" when the value we got from
255       "read()" is 0. The "Hijk::Error::RESPONSE_ERROR" constant is a union of
256       these two and any other response errors we might add in the future.
257
258       Some of these "Hijk::Error::REQUEST_*" and "Hijk::Error::RESPONSE_*"
259       errors are re-thrown errors from system calls. In that case we'll also
260       pass along "error_message" which is a short human readable error
261       message about the error, as well as "errno_number" & "errno_string",
262       which are "$!+0" and "$!" at the time we had the error.
263
264       Hijk might encounter other errors during the course of the request and
265       WILL call "die" if that happens, so if you don't want your program to
266       stop when a request like that fails wrap it in "eval".
267
268       Having said that the point of the "Hijk::Error::*" interface is that
269       all errors that happen during normal operation, i.e. making valid
270       requests against servers where you can have issues like timeouts,
271       network blips or the server thread on the other end being suddenly kill
272       -9'd should be caught, categorized and returned in a structural way by
273       Hijk.
274
275       We're not currently aware of any issues that occur in such normal
276       operations that aren't classified as a "Hijk::Error::*", and if we find
277       new issues that fit the criteria above we'll likely just make a new
278       "Hijk::Error::*" for it.
279
280       We're just not trying to guarantee that the library can never "die",
281       and aren't trying to catch truly exceptional issues like e.g. "fcntl()"
282       failing on a valid socket.
283

AUTHORS

285       Kang-min Liu <gugod@gugod.org>
286
287       AEvar Arnfjoerd` Bjarmason <avar@cpan.org>
288
289       Borislav Nikolov <jack@sofialondonmoskva.com>
290
291       Damian Gryski <damian@gryski.com>
292
294       Copyright (c) 2013- Kang-min Liu "<gugod@gugod.org>".
295

LICENCE

297       The MIT License
298

DISCLAIMER OF WARRANTY

300       BECAUSE THIS SOFTWARE IS LICENSED FREE OF CHARGE, THERE IS NO WARRANTY
301       FOR THE SOFTWARE, TO THE EXTENT PERMITTED BY APPLICABLE LAW. EXCEPT
302       WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER
303       PARTIES PROVIDE THE SOFTWARE "AS IS" WITHOUT WARRANTY OF ANY KIND,
304       EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
305       WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE
306       ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE SOFTWARE IS WITH
307       YOU. SHOULD THE SOFTWARE PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL
308       NECESSARY SERVICING, REPAIR, OR CORRECTION.
309
310       IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING
311       WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY MODIFY AND/OR
312       REDISTRIBUTE THE SOFTWARE AS PERMITTED BY THE ABOVE LICENCE, BE LIABLE
313       TO YOU FOR DAMAGES, INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL, OR
314       CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OR INABILITY TO USE THE
315       SOFTWARE (INCLUDING BUT NOT LIMITED TO LOSS OF DATA OR DATA BEING
316       RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD PARTIES OR A
317       FAILURE OF THE SOFTWARE TO OPERATE WITH ANY OTHER SOFTWARE), EVEN IF
318       SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
319       DAMAGES.
320
321
322
323perl v5.32.0                      2020-07-28                         Hijk(3pm)
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