[ViewVC] Contents 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:" (this can be suppressed by using "undef" for
            these headers in which case they won't be sent at all).

        timeout => $seconds
            The time-out to use for various stages - each connect attempt
            will reset the timeout, as will read or write activity, i.e.
            this is not an overall timeout.

            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, "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_prepare => $callback->($fh)
            In rare cases you need to "tune" the socket before it is used to
            connect (for exmaple, to bind it on a given IP address). This
            parameter overrides the prepare callback passed to
            "AnyEvent::Socket::tcp_connect" and behaves exactly the same way
            (e.g. it has to provide a timeout). See the description for the
            $prepare_cb argument of "AnyEvent::Socket::tcp_connect" for
            details.

        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:..."),
        croaks otherwise.

        To clear an already-set proxy, use "undef".

    $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 connections 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:	1.12
Committed:	Sat Dec 5 15:37:07 2009 UTC (14 years, 5 months ago) by root
Branch:	MAIN
CVS Tags:	rel-1_44
Changes since 1.11:	+4 -1 lines
Log Message:	1.44
#	Content
1	NAME
2	AnyEvent::HTTP - simple but non-blocking HTTP/HTTPS client
3
4	SYNOPSIS
5	use AnyEvent::HTTP;
6
7	http_get "http://www.nethype.de/", sub { print $_[1] };
8
9	# ... do something else here
10
11	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	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	details on additional parameters and the return value.
34
35	http_head $url, key => value..., $cb->($data, $headers)
36	Executes an HTTP-HEAD request. See the http_request function for
37	details on additional parameters and the return value.
38
39	http_post $url, $body, key => value..., $cb->($data, $headers)
40	Executes an HTTP-POST request with a request body of $body. See the
41	http_request function for details on additional parameters and the
42	return value.
43
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	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	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
58	All the headers in that hash are lowercased. In addition to the
59	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	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
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	"59x" (usually 599) and the "Reason" pseudo-header will contain an
70	error message.
71
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:" (this can be suppressed by using "undef" for
96	these headers in which case they won't be sent at all).
97
98	timeout => $seconds
99	The time-out to use for various stages - each connect attempt
100	will reset the timeout, as will read or write activity, i.e.
101	this is not an overall timeout.
102
103	Default timeout is 5 minutes.
104
105	proxy => [$host, $port[, $scheme]] or undef
106	Use the given http proxy for all requests. If not specified,
107	then the default proxy (as specified by $ENV{http_proxy}) is
108	used.
109
110	$scheme must be either missing, "http" for HTTP or "https" for
111	HTTPS.
112
113	body => $string
114	The request body, usually empty. Will be-sent as-is (future
115	versions of this module might offer more options).
116
117	cookie_jar => $hash_ref
118	Passing this parameter enables (simplified) cookie-processing,
119	loosely based on the original netscape specification.
120
121	The $hash_ref must be an (initially empty) hash reference which
122	will get updated automatically. It is possible to save the
123	cookie_jar to persistent storage with something like JSON or
124	Storable, but this is not recommended, as expiry times are
125	currently being ignored.
126
127	Note that this cookie implementation is not of very high
128	quality, nor meant to be complete. If you want complete cookie
129	management you have to do that on your own. "cookie_jar" is
130	meant as a quick fix to get some cookie-using sites working.
131	Cookies are a privacy disaster, do not use them unless required
132	to.
133
134	tls_ctx => $scheme \| $tls_ctx
135	Specifies the AnyEvent::TLS context to be used for https
136	connections. This parameter follows the same rules as the
137	"tls_ctx" parameter to AnyEvent::Handle, but additionally, the
138	two strings "low" or "high" can be specified, which give you a
139	predefined low-security (no verification, highest compatibility)
140	and high-security (CA and common-name verification) TLS context.
141
142	The default for this option is "low", which could be interpreted
143	as "give me the page, no matter what".
144
145	on_prepare => $callback->($fh)
146	In rare cases you need to "tune" the socket before it is used to
147	connect (for exmaple, to bind it on a given IP address). This
148	parameter overrides the prepare callback passed to
149	"AnyEvent::Socket::tcp_connect" and behaves exactly the same way
150	(e.g. it has to provide a timeout). See the description for the
151	$prepare_cb argument of "AnyEvent::Socket::tcp_connect" for
152	details.
153
154	on_header => $callback->($headers)
155	When specified, this callback will be called with the header
156	hash as soon as headers have been successfully received from the
157	remote server (not on locally-generated errors).
158
159	It has to return either true (in which case AnyEvent::HTTP will
160	continue), or false, in which case AnyEvent::HTTP will cancel
161	the download (and call the finish callback with an error code of
162	598).
163
164	This callback is useful, among other things, to quickly reject
165	unwanted content, which, if it is supposed to be rare, can be
166	faster than first doing a "HEAD" request.
167
168	Example: cancel the request unless the content-type is
169	"text/html".
170
171	on_header => sub {
172	$_[0]{"content-type"} =~ /^text\/html\s*(?:;\|$)/
173	},
174
175	on_body => $callback->($partial_body, $headers)
176	When specified, all body data will be passed to this callback
177	instead of to the completion callback. The completion callback
178	will get the empty string instead of the body data.
179
180	It has to return either true (in which case AnyEvent::HTTP will
181	continue), or false, in which case AnyEvent::HTTP will cancel
182	the download (and call the completion callback with an error
183	code of 598).
184
185	This callback is useful when the data is too large to be held in
186	memory (so the callback writes it to a file) or when only some
187	information should be extracted, or when the body should be
188	processed incrementally.
189
190	It is usually preferred over doing your own body handling via
191	"want_body_handle", but in case of streaming APIs, where HTTP is
192	only used to create a connection, "want_body_handle" is the
193	better alternative, as it allows you to install your own event
194	handler, reducing resource usage.
195
196	want_body_handle => $enable
197	When enabled (default is disabled), the behaviour of
198	AnyEvent::HTTP changes considerably: after parsing the headers,
199	and instead of downloading the body (if any), the completion
200	callback will be called. Instead of the $body argument
201	containing the body data, the callback will receive the
202	AnyEvent::Handle object associated with the connection. In error
203	cases, "undef" will be passed. When there is no body (e.g.
204	status 304), the empty string will be passed.
205
206	The handle object might or might not be in TLS mode, might be
207	connected to a proxy, be a persistent connection etc., and
208	configured in unspecified ways. The user is responsible for this
209	handle (it will not be used by this module anymore).
210
211	This is useful with some push-type services, where, after the
212	initial headers, an interactive protocol is used (typical
213	example would be the push-style twitter API which starts a
214	JSON/XML stream).
215
216	If you think you need this, first have a look at "on_body", to
217	see if that doesn't solve your problem in a better way.
218
219	Example: make a simple HTTP GET request for http://www.nethype.de/
220
221	http_request GET => "http://www.nethype.de/", sub {
222	my ($body, $hdr) = @_;
223	print "$body\n";
224	};
225
226	Example: make a HTTP HEAD request on https://www.google.com/, use a
227	timeout of 30 seconds.
228
229	http_request
230	GET => "https://www.google.com",
231	timeout => 30,
232	sub {
233	my ($body, $hdr) = @_;
234	use Data::Dumper;
235	print Dumper $hdr;
236	}
237	;
238
239	Example: make another simple HTTP GET request, but immediately try
240	to cancel it.
241
242	my $request = http_request GET => "http://www.nethype.de/", sub {
243	my ($body, $hdr) = @_;
244	print "$body\n";
245	};
246
247	undef $request;
248
249	GLOBAL FUNCTIONS AND VARIABLES
250	AnyEvent::HTTP::set_proxy "proxy-url"
251	Sets the default proxy server to use. The proxy-url must begin with
252	a string of the form "http://host:port" (optionally "https:..."),
253	croaks otherwise.
254
255	To clear an already-set proxy, use "undef".
256
257	$AnyEvent::HTTP::MAX_RECURSE
258	The default value for the "recurse" request parameter (default: 10).
259
260	$AnyEvent::HTTP::USERAGENT
261	The default value for the "User-Agent" header (the default is
262	"Mozilla/5.0 (compatible; U; AnyEvent-HTTP/$VERSION;
263	+http://software.schmorp.de/pkg/AnyEvent)").
264
265	$AnyEvent::HTTP::MAX_PER_HOST
266	The maximum number of concurrent connections to the same host
267	(identified by the hostname). If the limit is exceeded, then the
268	additional requests are queued until previous connections are
269	closed.
270
271	The default value for this is 4, and it is highly advisable to not
272	increase it.
273
274	$AnyEvent::HTTP::ACTIVE
275	The number of active connections. This is not the number of
276	currently running requests, but the number of currently open and
277	non-idle TCP connections. This number of can be useful for
278	load-leveling.
279
280	SEE ALSO
281	AnyEvent.
282
283	AUTHOR
284	Marc Lehmann <schmorp@schmorp.de>
285	http://home.schmorp.de/
286
287	With many thanks to Дмитрий Шалашов, who provided
288	countless testcases and bugreports.
289