[ViewVC] Annotation of: cvs/AnyEvent-HTTP/README

NAME
    AnyEvent::HTTP - simple but non-blocking HTTP/HTTPS client

SYNOPSIS
       use AnyEvent::HTTP;

       http_get "http://www.nethype.de/", sub { print $_[1] };

       # ... do something else here

DESCRIPTION
    This module is an AnyEvent user, you need to make sure that you use and
    run a supported event loop.

    This module implements a simple, stateless and non-blocking HTTP client.
    It supports GET, POST and other request methods, cookies and more, all
    on a very low level. It can follow redirects supports proxies and
    automatically limits the number of connections to the values specified
    in the RFC.

    It should generally be a "good client" that is enough for most HTTP
    tasks. Simple tasks should be simple, but complex tasks should still be
    possible as the user retains control over request and response headers.

    The caller is responsible for authentication management, cookies (if the
    simplistic implementation in this module doesn't suffice), referer and
    other high-level protocol details for which this module offers only
    limited support.

  METHODS
    http_get $url, key => value..., $cb->($data, $headers)
        Executes an HTTP-GET request. See the http_request function for
        details on additional parameters and the return value.

    http_head $url, key => value..., $cb->($data, $headers)
        Executes an HTTP-HEAD request. See the http_request function for
        details on additional parameters and the return value.

    http_post $url, $body, key => value..., $cb->($data, $headers)
        Executes an HTTP-POST request with a request body of $body. See the
        http_request function for details on additional parameters and the
        return value.

    http_request $method => $url, key => value..., $cb->($data, $headers)
        Executes a HTTP request of type $method (e.g. "GET", "POST"). The
        URL must be an absolute http or https URL.

        When called in void context, nothing is returned. In other contexts,
        "http_request" returns a "cancellation guard" - you have to keep the
        object at least alive until the callback get called. If the object
        gets destroyed before the callbakc is called, the request will be
        cancelled.

        The callback will be called with the response body data as first
        argument (or "undef" if an error occured), and a hash-ref with
        response headers as second argument.

        All the headers in that hash are lowercased. In addition to the
        response headers, the "pseudo-headers" "HTTPVersion", "Status" and
        "Reason" contain the three parts of the HTTP Status-Line of the same
        name. The pseudo-header "URL" contains the original URL (which can
        differ from the requested URL when following redirects).

        If the server sends a header multiple times, then their contents
        will be joined together with a comma (","), as per the HTTP spec.

        If an internal error occurs, such as not being able to resolve a
        hostname, then $data will be "undef", "$headers->{Status}" will be
        "59x" (usually 599) and the "Reason" pseudo-header will contain an
        error message.

        A typical callback might look like this:

           sub {
              my ($body, $hdr) = @_;

              if ($hdr->{Status} =~ /^2/) {
                 ... everything should be ok
              } else {
                 print "error, $hdr->{Status} $hdr->{Reason}\n";
              }
           }

        Additional parameters are key-value pairs, and are fully optional.
        They include:

        recurse => $count (default: $MAX_RECURSE)
            Whether to recurse requests or not, e.g. on redirects,
            authentication retries and so on, and how often to do so.

        headers => hashref
            The request headers to use. Currently, "http_request" may
            provide its own "Host:", "Content-Length:", "Connection:" and
            "Cookie:" headers and will provide defaults for "User-Agent:"
            and "Referer:".

        timeout => $seconds
            The time-out to use for various stages - each connect attempt
            will reset the timeout, as will read or write activity. Default
            timeout is 5 minutes.

        proxy => [$host, $port[, $scheme]] or undef
            Use the given http proxy for all requests. If not specified,
            then the default proxy (as specified by $ENV{http_proxy}) is
            used.

            $scheme must be either missing or "http" for HTTP, or "https"
            for HTTPS.

        body => $string
            The request body, usually empty. Will be-sent as-is (future
            versions of this module might offer more options).

        cookie_jar => $hash_ref
            Passing this parameter enables (simplified) cookie-processing,
            loosely based on the original netscape specification.

            The $hash_ref must be an (initially empty) hash reference which
            will get updated automatically. It is possible to save the
            cookie_jar to persistent storage with something like JSON or
            Storable, but this is not recommended, as expiry times are
            currently being ignored.

            Note that this cookie implementation is not of very high
            quality, nor meant to be complete. If you want complete cookie
            management you have to do that on your own. "cookie_jar" is
            meant as a quick fix to get some cookie-using sites working.
            Cookies are a privacy disaster, do not use them unless required
            to.

        tls_ctx => $scheme | $tls_ctx
            Specifies the AnyEvent::TLS context to be used for https
            connections. This parameter follows the same rules as the
            "tls_ctx" parameter to AnyEvent::Handle, but additionally, the
            two strings "low" or "high" can be specified, which give you a
            predefined low-security (no verification, highest compatibility)
            and high-security (CA and common-name verification) TLS context.

            The default for this option is "low", which could be interpreted
            as "give me the page, no matter what".

        on_header => $callback->($headers)
            When specified, this callback will be called with the header
            hash as soon as headers have been successfully received from the
            remote server (not on locally-generated errors).

            It has to return either true (in which case AnyEvent::HTTP will
            continue), or false, in which case AnyEvent::HTTP will cancel
            the download (and call the finish callback with an error code of
            598).

            This callback is useful, among other things, to quickly reject
            unwanted content, which, if it is supposed to be rare, can be
            faster than first doing a "HEAD" request.

            Example: cancel the request unless the content-type is
            "text/html".

               on_header => sub {
                  $_[0]{"content-type"} =~ /^text\/html\s*(?:;|$)/
               },

        on_body => $callback->($partial_body, $headers)
            When specified, all body data will be passed to this callback
            instead of to the completion callback. The completion callback
            will get the empty string instead of the body data.

            It has to return either true (in which case AnyEvent::HTTP will
            continue), or false, in which case AnyEvent::HTTP will cancel
            the download (and call the completion callback with an error
            code of 598).

            This callback is useful when the data is too large to be held in
            memory (so the callback writes it to a file) or when only some
            information should be extracted, or when the body should be
            processed incrementally.

            It is usually preferred over doing your own body handling via
            "want_body_handle", but in case of streaming APIs, where HTTP is
            only used to create a connection, "want_body_handle" is the
            better alternative, as it allows you to install your own event
            handler, reducing resource usage.

        want_body_handle => $enable
            When enabled (default is disabled), the behaviour of
            AnyEvent::HTTP changes considerably: after parsing the headers,
            and instead of downloading the body (if any), the completion
            callback will be called. Instead of the $body argument
            containing the body data, the callback will receive the
            AnyEvent::Handle object associated with the connection. In error
            cases, "undef" will be passed. When there is no body (e.g.
            status 304), the empty string will be passed.

            The handle object might or might not be in TLS mode, might be
            connected to a proxy, be a persistent connection etc., and
            configured in unspecified ways. The user is responsible for this
            handle (it will not be used by this module anymore).

            This is useful with some push-type services, where, after the
            initial headers, an interactive protocol is used (typical
            example would be the push-style twitter API which starts a
            JSON/XML stream).

            If you think you need this, first have a look at "on_body", to
            see if that doesn't solve your problem in a better way.

        Example: make a simple HTTP GET request for http://www.nethype.de/

           http_request GET => "http://www.nethype.de/", sub {
              my ($body, $hdr) = @_;
              print "$body\n";
           };

        Example: make a HTTP HEAD request on https://www.google.com/, use a
        timeout of 30 seconds.

           http_request
              GET     => "https://www.google.com",
              timeout => 30,
              sub {
                 my ($body, $hdr) = @_;
                 use Data::Dumper;
                 print Dumper $hdr;
              }
           ;

        Example: make another simple HTTP GET request, but immediately try
        to cancel it.

           my $request = http_request GET => "http://www.nethype.de/", sub {
              my ($body, $hdr) = @_;
              print "$body\n";
           };

           undef $request;

  GLOBAL FUNCTIONS AND VARIABLES
    AnyEvent::HTTP::set_proxy "proxy-url"
        Sets the default proxy server to use. The proxy-url must begin with
        a string of the form "http://host:port" (optionally "https:...").

    $AnyEvent::HTTP::MAX_RECURSE
        The default value for the "recurse" request parameter (default: 10).

    $AnyEvent::HTTP::USERAGENT
        The default value for the "User-Agent" header (the default is
        "Mozilla/5.0 (compatible; U; AnyEvent-HTTP/$VERSION;
        +http://software.schmorp.de/pkg/AnyEvent)").

    $AnyEvent::HTTP::MAX_PER_HOST
        The maximum number of concurrent conenctions to the same host
        (identified by the hostname). If the limit is exceeded, then the
        additional requests are queued until previous connections are
        closed.

        The default value for this is 4, and it is highly advisable to not
        increase it.

    $AnyEvent::HTTP::ACTIVE
        The number of active connections. This is not the number of
        currently running requests, but the number of currently open and
        non-idle TCP connections. This number of can be useful for
        load-leveling.

SEE ALSO
    AnyEvent.

AUTHOR
       Marc Lehmann <schmorp@schmorp.de>
       http://home.schmorp.de/

    With many thanks to Дмитрий Шалашов, who provided
    countless testcases and bugreports.

Revision:	1.9
Committed:	Sat Jul 25 01:29:09 2009 UTC (14 years, 9 months ago) by root
Branch:	MAIN
CVS Tags:	rel-1_41
Changes since 1.8:	+5 -2 lines
Log Message:	1.41
#	User	Rev	Content
1	root	1.1	NAME
2	root	1.2	AnyEvent::HTTP - simple but non-blocking HTTP/HTTPS client
3	root	1.1
4			SYNOPSIS
5	root	1.2	use AnyEvent::HTTP;
6	root	1.1
7	root	1.3	http_get "http://www.nethype.de/", sub { print $_[1] };
8
9			# ... do something else here
10
11	root	1.1	DESCRIPTION
12			This module is an AnyEvent user, you need to make sure that you use and
13			run a supported event loop.
14
15	root	1.2	This module implements a simple, stateless and non-blocking HTTP client.
16			It supports GET, POST and other request methods, cookies and more, all
17			on a very low level. It can follow redirects supports proxies and
18			automatically limits the number of connections to the values specified
19			in the RFC.
20
21			It should generally be a "good client" that is enough for most HTTP
22			tasks. Simple tasks should be simple, but complex tasks should still be
23			possible as the user retains control over request and response headers.
24
25			The caller is responsible for authentication management, cookies (if the
26			simplistic implementation in this module doesn't suffice), referer and
27			other high-level protocol details for which this module offers only
28			limited support.
29
30			METHODS
31			http_get $url, key => value..., $cb->($data, $headers)
32			Executes an HTTP-GET request. See the http_request function for
33	root	1.5	details on additional parameters and the return value.
34	root	1.2
35			http_head $url, key => value..., $cb->($data, $headers)
36			Executes an HTTP-HEAD request. See the http_request function for
37	root	1.5	details on additional parameters and the return value.
38	root	1.2
39			http_post $url, $body, key => value..., $cb->($data, $headers)
40	root	1.4	Executes an HTTP-POST request with a request body of $body. See the
41	root	1.5	http_request function for details on additional parameters and the
42			return value.
43	root	1.2
44			http_request $method => $url, key => value..., $cb->($data, $headers)
45			Executes a HTTP request of type $method (e.g. "GET", "POST"). The
46			URL must be an absolute http or https URL.
47
48	root	1.5	When called in void context, nothing is returned. In other contexts,
49			"http_request" returns a "cancellation guard" - you have to keep the
50			object at least alive until the callback get called. If the object
51			gets destroyed before the callbakc is called, the request will be
52			cancelled.
53
54	root	1.8	The callback will be called with the response body data as first
55			argument (or "undef" if an error occured), and a hash-ref with
56			response headers as second argument.
57	root	1.2
58			All the headers in that hash are lowercased. In addition to the
59	root	1.3	response headers, the "pseudo-headers" "HTTPVersion", "Status" and
60			"Reason" contain the three parts of the HTTP Status-Line of the same
61			name. The pseudo-header "URL" contains the original URL (which can
62			differ from the requested URL when following redirects).
63
64	root	1.6	If the server sends a header multiple times, then their contents
65			will be joined together with a comma (","), as per the HTTP spec.
66	root	1.2
67			If an internal error occurs, such as not being able to resolve a
68			hostname, then $data will be "undef", "$headers->{Status}" will be
69	root	1.8	"59x" (usually 599) and the "Reason" pseudo-header will contain an
70			error message.
71	root	1.2
72			A typical callback might look like this:
73
74			sub {
75			my ($body, $hdr) = @_;
76
77			if ($hdr->{Status} =~ /^2/) {
78			... everything should be ok
79			} else {
80			print "error, $hdr->{Status} $hdr->{Reason}\n";
81			}
82			}
83
84			Additional parameters are key-value pairs, and are fully optional.
85			They include:
86
87			recurse => $count (default: $MAX_RECURSE)
88			Whether to recurse requests or not, e.g. on redirects,
89			authentication retries and so on, and how often to do so.
90
91			headers => hashref
92			The request headers to use. Currently, "http_request" may
93			provide its own "Host:", "Content-Length:", "Connection:" and
94			"Cookie:" headers and will provide defaults for "User-Agent:"
95			and "Referer:".
96
97			timeout => $seconds
98			The time-out to use for various stages - each connect attempt
99			will reset the timeout, as will read or write activity. Default
100			timeout is 5 minutes.
101
102			proxy => [$host, $port[, $scheme]] or undef
103			Use the given http proxy for all requests. If not specified,
104			then the default proxy (as specified by $ENV{http_proxy}) is
105			used.
106
107			$scheme must be either missing or "http" for HTTP, or "https"
108			for HTTPS.
109
110			body => $string
111			The request body, usually empty. Will be-sent as-is (future
112			versions of this module might offer more options).
113
114			cookie_jar => $hash_ref
115			Passing this parameter enables (simplified) cookie-processing,
116			loosely based on the original netscape specification.
117
118			The $hash_ref must be an (initially empty) hash reference which
119			will get updated automatically. It is possible to save the
120			cookie_jar to persistent storage with something like JSON or
121	root	1.8	Storable, but this is not recommended, as expiry times are
122	root	1.2	currently being ignored.
123
124			Note that this cookie implementation is not of very high
125			quality, nor meant to be complete. If you want complete cookie
126			management you have to do that on your own. "cookie_jar" is
127			meant as a quick fix to get some cookie-using sites working.
128			Cookies are a privacy disaster, do not use them unless required
129			to.
130
131	root	1.8	tls_ctx => $scheme \| $tls_ctx
132			Specifies the AnyEvent::TLS context to be used for https
133			connections. This parameter follows the same rules as the
134			"tls_ctx" parameter to AnyEvent::Handle, but additionally, the
135			two strings "low" or "high" can be specified, which give you a
136			predefined low-security (no verification, highest compatibility)
137			and high-security (CA and common-name verification) TLS context.
138
139			The default for this option is "low", which could be interpreted
140			as "give me the page, no matter what".
141
142			on_header => $callback->($headers)
143			When specified, this callback will be called with the header
144			hash as soon as headers have been successfully received from the
145			remote server (not on locally-generated errors).
146
147			It has to return either true (in which case AnyEvent::HTTP will
148			continue), or false, in which case AnyEvent::HTTP will cancel
149			the download (and call the finish callback with an error code of
150			598).
151
152			This callback is useful, among other things, to quickly reject
153			unwanted content, which, if it is supposed to be rare, can be
154			faster than first doing a "HEAD" request.
155
156			Example: cancel the request unless the content-type is
157			"text/html".
158
159			on_header => sub {
160			$_[0]{"content-type"} =~ /^text\/html\s*(?:;\|$)/
161			},
162
163			on_body => $callback->($partial_body, $headers)
164			When specified, all body data will be passed to this callback
165			instead of to the completion callback. The completion callback
166			will get the empty string instead of the body data.
167
168			It has to return either true (in which case AnyEvent::HTTP will
169			continue), or false, in which case AnyEvent::HTTP will cancel
170			the download (and call the completion callback with an error
171			code of 598).
172
173			This callback is useful when the data is too large to be held in
174			memory (so the callback writes it to a file) or when only some
175			information should be extracted, or when the body should be
176			processed incrementally.
177
178			It is usually preferred over doing your own body handling via
179	root	1.9	"want_body_handle", but in case of streaming APIs, where HTTP is
180			only used to create a connection, "want_body_handle" is the
181			better alternative, as it allows you to install your own event
182			handler, reducing resource usage.
183	root	1.8
184			want_body_handle => $enable
185			When enabled (default is disabled), the behaviour of
186			AnyEvent::HTTP changes considerably: after parsing the headers,
187			and instead of downloading the body (if any), the completion
188			callback will be called. Instead of the $body argument
189			containing the body data, the callback will receive the
190			AnyEvent::Handle object associated with the connection. In error
191			cases, "undef" will be passed. When there is no body (e.g.
192			status 304), the empty string will be passed.
193
194			The handle object might or might not be in TLS mode, might be
195			connected to a proxy, be a persistent connection etc., and
196			configured in unspecified ways. The user is responsible for this
197			handle (it will not be used by this module anymore).
198
199			This is useful with some push-type services, where, after the
200			initial headers, an interactive protocol is used (typical
201			example would be the push-style twitter API which starts a
202			JSON/XML stream).
203
204			If you think you need this, first have a look at "on_body", to
205	root	1.9	see if that doesn't solve your problem in a better way.
206	root	1.8
207	root	1.2	Example: make a simple HTTP GET request for http://www.nethype.de/
208
209			http_request GET => "http://www.nethype.de/", sub {
210			my ($body, $hdr) = @_;
211			print "$body\n";
212			};
213
214			Example: make a HTTP HEAD request on https://www.google.com/, use a
215			timeout of 30 seconds.
216
217			http_request
218			GET => "https://www.google.com",
219			timeout => 30,
220			sub {
221			my ($body, $hdr) = @_;
222			use Data::Dumper;
223			print Dumper $hdr;
224			}
225			;
226
227	root	1.5	Example: make another simple HTTP GET request, but immediately try
228			to cancel it.
229
230			my $request = http_request GET => "http://www.nethype.de/", sub {
231			my ($body, $hdr) = @_;
232			print "$body\n";
233			};
234
235			undef $request;
236
237	root	1.2	GLOBAL FUNCTIONS AND VARIABLES
238			AnyEvent::HTTP::set_proxy "proxy-url"
239			Sets the default proxy server to use. The proxy-url must begin with
240			a string of the form "http://host:port" (optionally "https:...").
241
242			$AnyEvent::HTTP::MAX_RECURSE
243			The default value for the "recurse" request parameter (default: 10).
244
245			$AnyEvent::HTTP::USERAGENT
246			The default value for the "User-Agent" header (the default is
247	root	1.8	"Mozilla/5.0 (compatible; U; AnyEvent-HTTP/$VERSION;
248	root	1.2	+http://software.schmorp.de/pkg/AnyEvent)").
249
250	root	1.8	$AnyEvent::HTTP::MAX_PER_HOST
251			The maximum number of concurrent conenctions to the same host
252			(identified by the hostname). If the limit is exceeded, then the
253			additional requests are queued until previous connections are
254			closed.
255	root	1.2
256	root	1.8	The default value for this is 4, and it is highly advisable to not
257			increase it.
258	root	1.2
259			$AnyEvent::HTTP::ACTIVE
260			The number of active connections. This is not the number of
261			currently running requests, but the number of currently open and
262			non-idle TCP connections. This number of can be useful for
263			load-leveling.
264	root	1.1
265			SEE ALSO
266	root	1.2	AnyEvent.
267	root	1.1
268			AUTHOR
269	root	1.3	Marc Lehmann <schmorp@schmorp.de>
270			http://home.schmorp.de/
271	root	1.1
272	root	1.7	With many thanks to Дмитрий Шалашов, who provided
273			countless testcases and bugreports.
274