view release on metacpan or  search on metacpan

HTTP.pm  view on Meta::CPAN

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 C<598>).

The downside to cancelling the request is that it makes it impossible to
re-use the connection.

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
C<want_body_handle>, but in case of streaming APIs, where HTTP is
only used to create a connection, C<want_body_handle> is the better
alternative, as it allows you to install your own event handler, reducing
resource usage.

=item 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 C<$body> argument containing the body data, the
callback will receive the L<AnyEvent::Handle> object associated with the
connection. In error cases, C<undef> will be passed. When there is no body
(e.g. status C<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, use chunked transfer encoding
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 C<on_body>, to see if
that doesn't solve your problem in a better way.

=item persistent => $boolean

Try to create/reuse a persistent connection. When this flag is set
(default: true for idempotent requests, false for all others), then
C<http_request> tries to re-use an existing (previously-created)
persistent connection to same host (i.e. identical URL scheme, hostname,
port and sessionid) and, failing that, tries to create a new one.

Requests failing in certain ways will be automatically retried once, which
is dangerous for non-idempotent requests, which is why it defaults to off
for them. The reason for this is because the bozos who designed HTTP/1.1
made it impossible to distinguish between a fatal error and a normal
connection timeout, so you never know whether there was a problem with
your request or not.

When reusing an existent connection, many parameters (such as TLS context)
will be ignored. See the C<sessionid> parameter for a workaround.

=item keepalive => $boolean

Only used when C<persistent> is also true. This parameter decides whether
C<http_request> tries to handshake a HTTP/1.0-style keep-alive connection
(as opposed to only a HTTP/1.1 persistent connection).

The default is true, except when using a proxy, in which case it defaults
to false, as HTTP/1.0 proxies cannot support this in a meaningful way.

=item handle_params => { key => value ... }

The key-value pairs in this hash will be passed to any L<AnyEvent::Handle>
constructor that is called - not all requests will create a handle, and
sometimes more than one is created, so this parameter is only good for
setting hints.

Example: set the maximum read size to 4096, to potentially conserve memory
at the cost of speed.

   handle_params => {
      max_read_size => 4096,
   },

=back

Example: do a simple HTTP GET request for http://www.nethype.de/ and print
the response body.

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

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

   http_request
      HEAD    => "https://www.google.com",
      headers => { "user-agent" => "MySearchClient 1.0" },
      timeout => 30,
      sub {
         my ($body, $hdr) = @_;
         use Data::Dumper;
         print Dumper $hdr;
      }
   ;

Example: do 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;

=cut

#############################################################################
# wait queue/slots

sub _slot_schedule;