POE-Component-Client-HTTP
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NAME
POE::Component::Client::HTTP - a HTTP user-agent component
VERSION
version 0.949
SYNOPSIS
use POE qw(Component::Client::HTTP);
POE::Component::Client::HTTP->spawn(
Agent => 'SpiffCrawler/0.90', # defaults to something long
Alias => 'ua', # defaults to 'weeble'
From => 'spiffster@perl.org', # defaults to undef (no header)
Protocol => 'HTTP/0.9', # defaults to 'HTTP/1.1'
Timeout => 60, # defaults to 180 seconds
MaxSize => 16384, # defaults to entire response
Streaming => 4096, # defaults to 0 (off)
FollowRedirects => 2, # defaults to 0 (off)
Proxy => "http://localhost:80", # defaults to HTTP_PROXY env. variable
NoProxy => [ "localhost", "127.0.0.1" ], # defs to NO_PROXY env. variable
BindAddr => "12.34.56.78", # defaults to INADDR_ANY
);
$kernel->post(
'ua', # posts to the 'ua' alias
'request', # posts to ua's 'request' state
'response', # which of our states will receive the response
$request, # an HTTP::Request object
);
# This is the sub which is called when the session receives a
# 'response' event.
sub response_handler {
my ($request_packet, $response_packet) = @_[ARG0, ARG1];
# HTTP::Request
my $request_object = $request_packet->[0];
# HTTP::Response
my $response_object = $response_packet->[0];
my $stream_chunk;
if (! defined($response_object->content)) {
$stream_chunk = $response_packet->[1];
}
print(
"*" x 78, "\n",
"*** my request:\n",
"-" x 78, "\n",
$request_object->as_string(),
"*" x 78, "\n",
"*** their response:\n",
"-" x 78, "\n",
$response_object->as_string(),
);
if (defined $stream_chunk) {
print "-" x 40, "\n", $stream_chunk, "\n";
}
print "*" x 78, "\n";
}
DESCRIPTION
POE::Component::Client::HTTP is an HTTP user-agent for POE. It lets
other sessions run while HTTP transactions are being processed, and it
lets several HTTP transactions be processed in parallel.
It supports keep-alive through POE::Component::Client::Keepalive, which
in turn uses POE::Component::Resolver for asynchronous IPv4 and IPv6
name resolution.
HTTP client components are not proper objects. Instead of being created,
as most objects are, they are "spawned" as separate sessions. To avoid
confusion (and hopefully not cause other confusion), they must be
spawned with a "spawn" method, not created anew with a "new" one.
CONSTRUCTOR
keep_alive => 10, # seconds to keep connections alive
max_open => 100, # max concurrent connections - total
max_per_host => 20, # max concurrent connections - per host
timeout => 30, # max time (seconds) to establish a new connection
);
POE::Component::Client::HTTP->spawn(
# ...
ConnectionManager => $pool,
# ...
);
See POE::Component::Client::Keepalive for more information, including
how to alter the connection manager's resolver configuration (for
example, to force IPv6 or prefer it before IPv4).
CookieJar => $cookie_jar
"CookieJar" sets the component's cookie jar. It expects the cookie jar
to be a reference to a HTTP::Cookies object.
From => $admin_address
"From" holds an e-mail address where the client's administrator and/or
maintainer may be reached. It defaults to undef, which means no From
header will be included in requests.
MaxSize => OCTETS
"MaxSize" specifies the largest response to accept from a server. The
content of larger responses will be truncated to OCTET octets. This
has been used to return the <head></head> section of web pages without
the need to wade through <body></body>.
NoProxy => [ $host_1, $host_2, ..., $host_N ]
NoProxy => "host1,host2,hostN"
"NoProxy" specifies a list of server hosts that will not be proxied.
It is useful for local hosts and hosts that do not properly support
proxying. If NoProxy is not specified, a list will be taken from the
NO_PROXY environment variable.
NoProxy => [ "localhost", "127.0.0.1" ],
NoProxy => "localhost,127.0.0.1",
BindAddr => $local_ip
Specify "BindAddr" to bind all client sockets to a particular local
address. The value of BindAddr will be passed through
POE::Component::Client::Keepalive to POE::Wheel::SocketFactory (as
"bind_address"). See that module's documentation for implementation
details.
BindAddr => "12.34.56.78"
Protocol => $http_protocol_string
"Protocol" advertises the protocol that the client wishes to see.
Under normal circumstances, it should be left to its default value:
"HTTP/1.1".
Proxy => [ $proxy_host, $proxy_port ]
Proxy => $proxy_url
Proxy => $proxy_url,$proxy_url,...
"Proxy" specifies one or more proxy hosts that requests will be passed
through. If not specified, proxy servers will be taken from the
HTTP_PROXY (or http_proxy) environment variable. No proxying will
occur unless Proxy is set or one of the environment variables exists.
The proxy can be specified either as a host and port, or as one or
more URLs. Proxy URLs must specify the proxy port, even if it is 80.
Proxy => [ "127.0.0.1", 80 ],
Proxy => "http://127.0.0.1:80/",
"Proxy" may specify multiple proxies separated by commas.
PoCo::Client::HTTP will choose proxies from this list at random. This
is useful for load balancing requests through multiple gateways.
Proxy => "http://127.0.0.1:80/,http://127.0.0.1:81/",
Streaming => OCTETS
"Streaming" changes allows Client::HTTP to return large content in
chunks (of OCTETS octets each) rather than combine the entire content
into a single HTTP::Response object.
By default, Client::HTTP reads the entire content for a response into
memory before returning an HTTP::Response object. This is obviously
bad for applications like streaming MP3 clients, because they often
fetch songs that never end. Yes, they go on and on, my friend.
When "Streaming" is set to nonzero, however, the response handler
receives chunks of up to OCTETS octets apiece. The response handler
accepts slightly different parameters in this case. ARG0 is also an
HTTP::Response object but it does not contain response content, and
ARG1 contains a a chunk of raw response content, or undef if the
stream has ended.
sub streaming_response_handler {
my $response_packet = $_[ARG1];
my ($response, $data) = @$response_packet;
print SAVED_STREAM $data if defined $data;
}
FollowRedirects => $number_of_hops_to_follow
"FollowRedirects" specifies how many redirects (e.g. 302 Moved) to
follow. If not specified defaults to 0, and thus no redirection is
followed. This maintains compatibility with the previous behavior,
which was not to follow redirects at all.
If redirects are followed, a response chain should be built, and can
be accessed through $response_object->previous(). See HTTP::Response
for details here.
Timeout => $query_timeout
"Timeout" sets how long POE::Component::Client::HTTP has to process an
application's request, in seconds. "Timeout" defaults to 180 (three
minutes) if not specified.
It's important to note that the timeout begins when the component
receives an application's request, not when it attempts to connect to
the web server.
Timeouts may result from sending the component too many requests at
once. Each request would need to be received and tracked in order.
Consider this:
$request->content_length( -s $file );
$request->content( $upload_cb );
$kernel->post( ua => request, 'response', $request );
CONTENT ENCODING AND COMPRESSION
Transparent content decoding has been disabled as of version 0.84. This
also removes support for transparent gzip requesting and decompression.
To re-enable gzip compression, specify the gzip Content-Encoding and use
HTTP::Response's decoded_content() method rather than content():
my $request = HTTP::Request->new(
GET => "http://www.yahoo.com/", [
'Accept-Encoding' => 'gzip'
]
);
# ... time passes ...
my $content = $response->decoded_content();
The change in POE::Component::Client::HTTP behavior was prompted by
changes in HTTP::Response that surfaced a bug in the component's
transparent gzip handling.
Allowing the application to specify and handle content encodings seems
to be the most reliable and flexible resolution.
For more information about the problem and discussions regarding the
solution, see: <http://www.perlmonks.org/?node_id=683833> and
<http://rt.cpan.org/Ticket/Display.html?id=35538>
CLIENT HEADERS
POE::Component::Client::HTTP sets its own response headers with
additional information. All of its headers begin with "X-PCCH".
X-PCCH-Errmsg
POE::Component::Client::HTTP may fail because of an internal client
error rather than an HTTP protocol error. X-PCCH-Errmsg will contain a
human readable reason for client failures, should they occur.
The text of X-PCCH-Errmsg may also be repeated in the response's
content.
X-PCCH-Peer
X-PCCH-Peer contains the remote IPv4 address and port, separated by a
period. For example, "127.0.0.1.8675" represents port 8675 on localhost.
Proxying will render X-PCCH-Peer nearly useless, since the socket will
be connected to a proxy rather than the server itself.
This feature was added at Doreen Grey's request. Doreen wanted a means
to find the remote server's address without having to make an additional
request.
ENVIRONMENT
POE::Component::Client::HTTP uses two standard environment variables:
HTTP_PROXY and NO_PROXY.
HTTP_PROXY sets the proxy server that Client::HTTP will forward requests
through. NO_PROXY sets a list of hosts that will not be forwarded
through a proxy.
See the Proxy and NoProxy constructor parameters for more information
about these variables.
SEE ALSO
This component is built upon HTTP::Request, HTTP::Response, and POE.
Please see its source code and the documentation for its foundation
modules to learn more. If you want to use cookies, you'll need to read
about HTTP::Cookies as well.
Also see the test program, t/01_request.t, in the PoCo::Client::HTTP
distribution.
BUGS
There is no support for CGI_PROXY or CgiProxy.
Secure HTTP (https) proxying is not supported at this time.
There is no object oriented interface. See
POE::Component::Client::Keepalive and POE::Component::Resolver for
examples of a decent OO interface.
AUTHOR, COPYRIGHT, & LICENSE
POE::Component::Client::HTTP is
* Copyright 1999-2009 Rocco Caputo
* Copyright 2004 Rob Bloodgood
* Copyright 2004-2005 Martijn van Beers
All rights are reserved. POE::Component::Client::HTTP is free software;
you may redistribute it and/or modify it under the same terms as Perl
itself.
CONTRIBUTORS
Joel Bernstein solved some nasty race conditions. Portugal Telecom
<http://www.sapo.pt/> was kind enough to support his contributions.
Jeff Bisbee added POD tests and documentation to pass several of them to
version 0.79. He's a kwalitee-increasing machine!
BUG TRACKER
https://rt.cpan.org/Dist/Display.html?Queue=POE-Component-Client-HTTP
REPOSITORY
Github: <http://github.com/rcaputo/poe-component-client-http> .
Gitorious: <http://gitorious.org/poe-component-client-http> .
OTHER RESOURCES
<http://search.cpan.org/dist/POE-Component-Client-HTTP/>
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