[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 callback 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" (uppercase to avoid clashing
        with possible response headers) "HTTPVersion", "Status" and "Reason"
        contain the three parts of the HTTP Status-Line of the same name. If
        an error occurs during the body phase of a request, then the
        original "Status" and "Reason" values from the header are available
        as "OrigStatus" and "OrigReason".

        The pseudo-header "URL" contains the actual URL (which can differ
        from the requested URL when following redirects - for example, you
        might get an error that your URL scheme is not supported even though
        your URL is a valid http URL because it redirected to an ftp URL, in
        which case you can look at the URL pseudo header).

        The pseudo-header "Redirect" only exists when the request was a
        result of an internal redirect. In that case it is an array
        reference with the "($data, $headers)" from the redirect response.
        Note that this response could in turn be the result of a redirect
        itself, and "$headers->{Redirect}[1]{Redirect}" will then contain
        the original response, and so on.

        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.

        tcp_connect => $callback->($host, $service, $connect_cb,
        $prepare_cb)
            In even rarer cases you want total control over how
            AnyEvent::HTTP establishes connections. Normally it uses
            AnyEvent::Socket::tcp_connect to do this, but you can provide
            your own "tcp_connect" function - obviously, it has to follow
            the same calling conventions, except that it may always return a
            connection guard object.

            There are probably lots of weird uses for this function,
            starting from tracing the hosts "http_request" actually tries to
            connect, to (inexact but fast) host => IP address caching or
            even socks protocol support.

        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;

  DNS CACHING
    AnyEvent::HTTP uses the AnyEvent::Socket::tcp_connect function for the
    actual connection, which in turn uses AnyEvent::DNS to resolve
    hostnames. The latter is a simple stub resolver and does no caching on
    its own. If you want DNS caching, you currently have to provide your own
    default resolver (by storing a suitable resolver object in
    $AnyEvent::DNS::RESOLVER).

  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".

    $date = AnyEvent::HTTP::format_date $timestamp
        Takes a POSIX timestamp (seconds since the epoch) and formats it as
        a HTTP Date (RFC 2616).

    $timestamp = AnyEvent::HTTP::parse_date $date
        Takes a HTTP Date (RFC 2616) and returns the corresponding POSIX
        timestamp, or "undef" if the date cannot be parsed.

    $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.

  SOCKS PROXIES
    Socks proxies are not directly supported by AnyEvent::HTTP. You can
    compile your perl to support socks, or use an external program such as
    socksify (dante) or tsocks to make your program use a socks proxy
    transparently.

    Alternatively, for AnyEvent::HTTP only, you can use your own
    "tcp_connect" function that does the proxy handshake - here is an
    example that works with socks4a proxies:

       use Errno;
       use AnyEvent::Util;
       use AnyEvent::Socket;
       use AnyEvent::Handle;

       # host, port and username of/for your socks4a proxy
       my $socks_host = "10.0.0.23";
       my $socks_port = 9050;
       my $socks_user = "";

       sub socks4a_connect {
          my ($host, $port, $connect_cb, $prepare_cb) = @_;

          my $hdl = new AnyEvent::Handle
             connect    => [$socks_host, $socks_port],
             on_prepare => sub { $prepare_cb->($_[0]{fh}) },
             on_error   => sub { $connect_cb->() },
          ;

          $hdl->push_write (pack "CCnNZ*Z*", 4, 1, $port, 1, $socks_user, $host);

          $hdl->push_read (chunk => 8, sub {
             my ($hdl, $chunk) = @_;
             my ($status, $port, $ipn) = unpack "xCna4", $chunk;

             if ($status == 0x5a) {
                $connect_cb->($hdl->{fh}, (format_address $ipn) . ":$port");
             } else {
                $! = Errno::ENXIO; $connect_cb->();
             }
          });

          $hdl
       }

    Use "socks4a_connect" instead of "tcp_connect" when doing
    "http_request"s, possibly after switching off other proxy types:

       AnyEvent::HTTP::set_proxy undef; # usually you do not want other proxies

       http_get 'http://www.google.com', tcp_connect => \&socks4a_connect, sub {
          my ($data, $headers) = @_;
          ...
       };

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:	1.14
Committed:	Fri Dec 31 03:47:32 2010 UTC (13 years, 4 months ago) by root
Branch:	MAIN
CVS Tags:	rel-1_5
Changes since 1.13:	+82 -2 lines
Log Message:	1.5
#	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 $method (e.g. "GET", "POST"). The
46			URL must be an absolute http or https URL.
47
48	root	1.5	When called in void context, nothing is returned. In other contexts,
49			"http_request" returns a "cancellation guard" - you have to keep the
50			object at least alive until the callback get called. If the object
51	root	1.14	gets destroyed before the callback is called, the request will be
52	root	1.5	cancelled.
53
54	root	1.8	The callback will be called with the response body data as first
55			argument (or "undef" if an error occured), and a hash-ref with
56			response headers as second argument.
57	root	1.2
58			All the headers in that hash are lowercased. In addition to the
59	root	1.13	response headers, the "pseudo-headers" (uppercase to avoid clashing
60			with possible response headers) "HTTPVersion", "Status" and "Reason"
61	root	1.14	contain the three parts of the HTTP Status-Line of the same name. If
62			an error occurs during the body phase of a request, then the
63			original "Status" and "Reason" values from the header are available
64			as "OrigStatus" and "OrigReason".
65	root	1.13
66			The pseudo-header "URL" contains the actual URL (which can differ
67			from the requested URL when following redirects - for example, you
68			might get an error that your URL scheme is not supported even though
69			your URL is a valid http URL because it redirected to an ftp URL, in
70			which case you can look at the URL pseudo header).
71
72			The pseudo-header "Redirect" only exists when the request was a
73			result of an internal redirect. In that case it is an array
74			reference with the "($data, $headers)" from the redirect response.
75			Note that this response could in turn be the result of a redirect
76			itself, and "$headers->{Redirect}[1]{Redirect}" will then contain
77			the original response, and so on.
78	root	1.3
79	root	1.6	If the server sends a header multiple times, then their contents
80			will be joined together with a comma (","), as per the HTTP spec.
81	root	1.2
82			If an internal error occurs, such as not being able to resolve a
83			hostname, then $data will be "undef", "$headers->{Status}" will be
84	root	1.8	"59x" (usually 599) and the "Reason" pseudo-header will contain an
85			error message.
86	root	1.2
87			A typical callback might look like this:
88
89			sub {
90			my ($body, $hdr) = @_;
91
92			if ($hdr->{Status} =~ /^2/) {
93			... everything should be ok
94			} else {
95			print "error, $hdr->{Status} $hdr->{Reason}\n";
96			}
97			}
98
99			Additional parameters are key-value pairs, and are fully optional.
100			They include:
101
102			recurse => $count (default: $MAX_RECURSE)
103			Whether to recurse requests or not, e.g. on redirects,
104			authentication retries and so on, and how often to do so.
105
106			headers => hashref
107			The request headers to use. Currently, "http_request" may
108			provide its own "Host:", "Content-Length:", "Connection:" and
109			"Cookie:" headers and will provide defaults for "User-Agent:"
110	root	1.10	and "Referer:" (this can be suppressed by using "undef" for
111			these headers in which case they won't be sent at all).
112	root	1.2
113			timeout => $seconds
114			The time-out to use for various stages - each connect attempt
115	root	1.11	will reset the timeout, as will read or write activity, i.e.
116			this is not an overall timeout.
117
118			Default timeout is 5 minutes.
119	root	1.2
120			proxy => [$host, $port[, $scheme]] or undef
121			Use the given http proxy for all requests. If not specified,
122			then the default proxy (as specified by $ENV{http_proxy}) is
123			used.
124
125	root	1.10	$scheme must be either missing, "http" for HTTP or "https" for
126			HTTPS.
127	root	1.2
128			body => $string
129			The request body, usually empty. Will be-sent as-is (future
130			versions of this module might offer more options).
131
132			cookie_jar => $hash_ref
133			Passing this parameter enables (simplified) cookie-processing,
134			loosely based on the original netscape specification.
135
136			The $hash_ref must be an (initially empty) hash reference which
137			will get updated automatically. It is possible to save the
138			cookie_jar to persistent storage with something like JSON or
139	root	1.8	Storable, but this is not recommended, as expiry times are
140	root	1.2	currently being ignored.
141
142			Note that this cookie implementation is not of very high
143			quality, nor meant to be complete. If you want complete cookie
144			management you have to do that on your own. "cookie_jar" is
145			meant as a quick fix to get some cookie-using sites working.
146			Cookies are a privacy disaster, do not use them unless required
147			to.
148
149	root	1.8	tls_ctx => $scheme \| $tls_ctx
150			Specifies the AnyEvent::TLS context to be used for https
151			connections. This parameter follows the same rules as the
152			"tls_ctx" parameter to AnyEvent::Handle, but additionally, the
153			two strings "low" or "high" can be specified, which give you a
154			predefined low-security (no verification, highest compatibility)
155			and high-security (CA and common-name verification) TLS context.
156
157			The default for this option is "low", which could be interpreted
158			as "give me the page, no matter what".
159
160	root	1.11	on_prepare => $callback->($fh)
161			In rare cases you need to "tune" the socket before it is used to
162			connect (for exmaple, to bind it on a given IP address). This
163			parameter overrides the prepare callback passed to
164			"AnyEvent::Socket::tcp_connect" and behaves exactly the same way
165			(e.g. it has to provide a timeout). See the description for the
166			$prepare_cb argument of "AnyEvent::Socket::tcp_connect" for
167			details.
168
169	root	1.14	tcp_connect => $callback->($host, $service, $connect_cb,
170			$prepare_cb)
171			In even rarer cases you want total control over how
172			AnyEvent::HTTP establishes connections. Normally it uses
173			AnyEvent::Socket::tcp_connect to do this, but you can provide
174			your own "tcp_connect" function - obviously, it has to follow
175			the same calling conventions, except that it may always return a
176			connection guard object.
177
178			There are probably lots of weird uses for this function,
179			starting from tracing the hosts "http_request" actually tries to
180			connect, to (inexact but fast) host => IP address caching or
181			even socks protocol support.
182
183	root	1.8	on_header => $callback->($headers)
184			When specified, this callback will be called with the header
185			hash as soon as headers have been successfully received from the
186			remote server (not on locally-generated errors).
187
188			It has to return either true (in which case AnyEvent::HTTP will
189			continue), or false, in which case AnyEvent::HTTP will cancel
190			the download (and call the finish callback with an error code of
191			598).
192
193			This callback is useful, among other things, to quickly reject
194			unwanted content, which, if it is supposed to be rare, can be
195			faster than first doing a "HEAD" request.
196
197			Example: cancel the request unless the content-type is
198			"text/html".
199
200			on_header => sub {
201			$_[0]{"content-type"} =~ /^text\/html\s*(?:;\|$)/
202			},
203
204			on_body => $callback->($partial_body, $headers)
205			When specified, all body data will be passed to this callback
206			instead of to the completion callback. The completion callback
207			will get the empty string instead of the body data.
208
209			It has to return either true (in which case AnyEvent::HTTP will
210			continue), or false, in which case AnyEvent::HTTP will cancel
211			the download (and call the completion callback with an error
212			code of 598).
213
214			This callback is useful when the data is too large to be held in
215			memory (so the callback writes it to a file) or when only some
216			information should be extracted, or when the body should be
217			processed incrementally.
218
219			It is usually preferred over doing your own body handling via
220	root	1.9	"want_body_handle", but in case of streaming APIs, where HTTP is
221			only used to create a connection, "want_body_handle" is the
222			better alternative, as it allows you to install your own event
223			handler, reducing resource usage.
224	root	1.8
225			want_body_handle => $enable
226			When enabled (default is disabled), the behaviour of
227			AnyEvent::HTTP changes considerably: after parsing the headers,
228			and instead of downloading the body (if any), the completion
229			callback will be called. Instead of the $body argument
230			containing the body data, the callback will receive the
231			AnyEvent::Handle object associated with the connection. In error
232			cases, "undef" will be passed. When there is no body (e.g.
233			status 304), the empty string will be passed.
234
235			The handle object might or might not be in TLS mode, might be
236			connected to a proxy, be a persistent connection etc., and
237			configured in unspecified ways. The user is responsible for this
238			handle (it will not be used by this module anymore).
239
240			This is useful with some push-type services, where, after the
241			initial headers, an interactive protocol is used (typical
242			example would be the push-style twitter API which starts a
243			JSON/XML stream).
244
245			If you think you need this, first have a look at "on_body", to
246	root	1.9	see if that doesn't solve your problem in a better way.
247	root	1.8
248	root	1.2	Example: make a simple HTTP GET request for http://www.nethype.de/
249
250			http_request GET => "http://www.nethype.de/", sub {
251			my ($body, $hdr) = @_;
252			print "$body\n";
253			};
254
255			Example: make a HTTP HEAD request on https://www.google.com/, use a
256			timeout of 30 seconds.
257
258			http_request
259			GET => "https://www.google.com",
260			timeout => 30,
261			sub {
262			my ($body, $hdr) = @_;
263			use Data::Dumper;
264			print Dumper $hdr;
265			}
266			;
267
268	root	1.5	Example: make another simple HTTP GET request, but immediately try
269			to cancel it.
270
271			my $request = http_request GET => "http://www.nethype.de/", sub {
272			my ($body, $hdr) = @_;
273			print "$body\n";
274			};
275
276			undef $request;
277
278	root	1.13	DNS CACHING
279			AnyEvent::HTTP uses the AnyEvent::Socket::tcp_connect function for the
280			actual connection, which in turn uses AnyEvent::DNS to resolve
281			hostnames. The latter is a simple stub resolver and does no caching on
282			its own. If you want DNS caching, you currently have to provide your own
283			default resolver (by storing a suitable resolver object in
284			$AnyEvent::DNS::RESOLVER).
285
286	root	1.2	GLOBAL FUNCTIONS AND VARIABLES
287			AnyEvent::HTTP::set_proxy "proxy-url"
288			Sets the default proxy server to use. The proxy-url must begin with
289	root	1.12	a string of the form "http://host:port" (optionally "https:..."),
290			croaks otherwise.
291
292			To clear an already-set proxy, use "undef".
293	root	1.2
294	root	1.14	$date = AnyEvent::HTTP::format_date $timestamp
295			Takes a POSIX timestamp (seconds since the epoch) and formats it as
296			a HTTP Date (RFC 2616).
297
298			$timestamp = AnyEvent::HTTP::parse_date $date
299			Takes a HTTP Date (RFC 2616) and returns the corresponding POSIX
300			timestamp, or "undef" if the date cannot be parsed.
301
302	root	1.2	$AnyEvent::HTTP::MAX_RECURSE
303			The default value for the "recurse" request parameter (default: 10).
304
305			$AnyEvent::HTTP::USERAGENT
306			The default value for the "User-Agent" header (the default is
307	root	1.8	"Mozilla/5.0 (compatible; U; AnyEvent-HTTP/$VERSION;
308	root	1.2	+http://software.schmorp.de/pkg/AnyEvent)").
309
310	root	1.8	$AnyEvent::HTTP::MAX_PER_HOST
311	root	1.10	The maximum number of concurrent connections to the same host
312	root	1.8	(identified by the hostname). If the limit is exceeded, then the
313			additional requests are queued until previous connections are
314			closed.
315	root	1.2
316	root	1.8	The default value for this is 4, and it is highly advisable to not
317			increase it.
318	root	1.2
319			$AnyEvent::HTTP::ACTIVE
320			The number of active connections. This is not the number of
321			currently running requests, but the number of currently open and
322			non-idle TCP connections. This number of can be useful for
323			load-leveling.
324	root	1.1
325	root	1.14	SOCKS PROXIES
326			Socks proxies are not directly supported by AnyEvent::HTTP. You can
327			compile your perl to support socks, or use an external program such as
328			socksify (dante) or tsocks to make your program use a socks proxy
329			transparently.
330
331			Alternatively, for AnyEvent::HTTP only, you can use your own
332			"tcp_connect" function that does the proxy handshake - here is an
333			example that works with socks4a proxies:
334
335			use Errno;
336			use AnyEvent::Util;
337			use AnyEvent::Socket;
338			use AnyEvent::Handle;
339
340			# host, port and username of/for your socks4a proxy
341			my $socks_host = "10.0.0.23";
342			my $socks_port = 9050;
343			my $socks_user = "";
344
345			sub socks4a_connect {
346			my ($host, $port, $connect_cb, $prepare_cb) = @_;
347
348			my $hdl = new AnyEvent::Handle
349			connect => [$socks_host, $socks_port],
350			on_prepare => sub { $prepare_cb->($_[0]{fh}) },
351			on_error => sub { $connect_cb->() },
352			;
353
354			$hdl->push_write (pack "CCnNZZ", 4, 1, $port, 1, $socks_user, $host);
355
356			$hdl->push_read (chunk => 8, sub {
357			my ($hdl, $chunk) = @_;
358			my ($status, $port, $ipn) = unpack "xCna4", $chunk;
359
360			if ($status == 0x5a) {
361			$connect_cb->($hdl->{fh}, (format_address $ipn) . ":$port");
362			} else {
363			$! = Errno::ENXIO; $connect_cb->();
364			}
365			});
366
367			$hdl
368			}
369
370			Use "socks4a_connect" instead of "tcp_connect" when doing
371			"http_request"s, possibly after switching off other proxy types:
372
373			AnyEvent::HTTP::set_proxy undef; # usually you do not want other proxies
374
375			http_get 'http://www.google.com', tcp_connect => \&socks4a_connect, sub {
376			my ($data, $headers) = @_;
377			...
378			};
379
380	root	1.1	SEE ALSO
381	root	1.2	AnyEvent.
382	root	1.1
383			AUTHOR
384	root	1.3	Marc Lehmann <schmorp@schmorp.de>
385			http://home.schmorp.de/
386	root	1.1
387	root	1.7	With many thanks to Дмитрий Шалашов, who provided
388			countless testcases and bugreports.
389