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Net::HTTP(3) |
User Contributed Perl Documentation |
Net::HTTP(3) |
Net::HTTP - Low-level HTTP connection (client)
use Net::HTTP;
my $s = Net::HTTP->new(Host => "www.perl.com") || die $@;
$s->write_request(GET => "/", 'User-Agent' => "Mozilla/5.0");
my($code, $mess, %h) = $s->read_response_headers;
while (1) {
my $buf;
my $n = $s->read_entity_body($buf, 1024);
die "read failed: $!" unless defined $n;
last unless $n;
print $buf;
}
The "Net::HTTP" class is a low-level HTTP
client. An instance of the "Net::HTTP" class
represents a connection to an HTTP server. The HTTP protocol is described in
RFC 2616. The "Net::HTTP" class supports
"HTTP/1.0" and
"HTTP/1.1".
"Net::HTTP" is a sub-class of
one of "IO::Socket::IP" (IPv6+IPv4),
"IO::Socket::INET6" (IPv6+IPv4), or
"IO::Socket::INET" (IPv4 only). You can
mix the methods described below with reading and writing from the socket
directly. This is not necessary a good idea, unless you know what you are
doing.
The following methods are provided (in addition to those of
"IO::Socket::INET"):
- "$s = Net::HTTP->new( %options )"
- The "Net::HTTP" constructor method takes
the same options as "IO::Socket::INET"'s
as well as these:
Host: Initial host attribute value
KeepAlive: Initial keep_alive attribute value
SendTE: Initial send_te attribute_value
HTTPVersion: Initial http_version attribute value
PeerHTTPVersion: Initial peer_http_version attribute value
MaxLineLength: Initial max_line_length attribute value
MaxHeaderLines: Initial max_header_lines attribute value
The "Host" option is also
the default for "IO::Socket::INET"'s
"PeerAddr". The
"PeerPort" defaults to 80 if not
provided. The "PeerPort" specification
can also be embedded in the "PeerAddr"
by preceding it with a ":", and closing the IPv6 address on
brackets "[]" if necessary:
"192.0.2.1:80","[2001:db8::1]:80","any.example.com:80".
The "Listen" option provided
by "IO::Socket::INET"'s constructor
method is not allowed.
If unable to connect to the given HTTP server then the
constructor returns "undef" and $@
contains the reason. After a successful connect, a
"Net:HTTP" object is returned.
- "$s->host"
- Get/set the default value of the "Host"
header to send. The $host must not be set to an
empty string (or "undef") for
HTTP/1.1.
- "$s->keep_alive"
- Get/set the keep-alive value. If this value is TRUE then the
request will be sent with headers indicating that the server should try to
keep the connection open so that multiple requests can be sent.
The actual headers set will depend on the value of the
"http_version" and
"peer_http_version" attributes.
- "$s->send_te"
- Get/set the a value indicating if the request will be sent with a
"TE" header to indicate the transfer encodings that the server
can choose to use. The list of encodings announced as accepted by this
client depends on availability of the following modules:
"Compress::Raw::Zlib" for
deflate, and
"IO::Compress::Gunzip" for
gzip.
- "$s->http_version"
- Get/set the HTTP version number that this client should announce. This
value can only be set to "1.0" or "1.1". The default
is "1.1".
- "$s->peer_http_version"
- Get/set the protocol version number of our peer. This value will initially
be "1.0", but will be updated by a successful
read_response_headers() method call.
- "$s->max_line_length"
- Get/set a limit on the length of response line and response header lines.
The default is 8192. A value of 0 means no limit.
- "$s->max_header_length"
- Get/set a limit on the number of header lines that a response can have.
The default is 128. A value of 0 means no limit.
- "$s->format_request($method, $uri, %headers,
[$content])"
- Format a request message and return it as a string. If the headers do not
include a "Host" header, then a header
is inserted with the value of the "host"
attribute. Headers like "Connection" and
"Keep-Alive" might also be added
depending on the status of the
"keep_alive" attribute.
If $content is given (and it is
non-empty), then a "Content-Length"
header is automatically added unless it was already present.
- "$s->write_request($method, $uri, %headers, [$content])"
- Format and send a request message. Arguments are the same as for
format_request(). Returns true if successful.
- "$s->format_chunk( $data )"
- Returns the string to be written for the given chunk of data.
- "$s->write_chunk($data)"
- Will write a new chunk of request entity body data. This method should
only be used if the "Transfer-Encoding"
header with a value of "chunked" was
sent in the request. Note, writing zero-length data is a no-op. Use the
write_chunk_eof() method to signal end of entity body data.
Returns true if successful.
- "$s->format_chunk_eof( %trailers )"
- Returns the string to be written for signaling EOF when a
"Transfer-Encoding" of
"chunked" is used.
- "$s->write_chunk_eof( %trailers )"
- Will write eof marker for chunked data and optional trailers. Note that
trailers should not really be used unless is was signaled with a
"Trailer" header.
Returns true if successful.
- "($code, $mess, %headers) = $s->read_response_headers( %opts
)"
- Read response headers from server and return it. The
$code is the 3 digit HTTP status code (see
HTTP::Status) and $mess is the textual message
that came with it. Headers are then returned as key/value pairs. Since key
letter casing is not normalized and the same key can even occur multiple
times, assigning these values directly to a hash is not wise. Only the
$code is returned if this method is called in
scalar context.
As a side effect this method updates the 'peer_http_version'
attribute.
Options might be passed in as key/value pairs. There are
currently only two options supported;
"laxed" and
"junk_out".
The "laxed" option will make
read_response_headers() more forgiving towards servers that have
not learned how to speak HTTP properly. The
"laxed" option is a boolean flag, and
is enabled by passing in a TRUE value. The
"junk_out" option can be used to
capture bad header lines when "laxed"
is enabled. The value should be an array reference. Bad header lines
will be pushed onto the array.
The "laxed" option must be
specified in order to communicate with pre-HTTP/1.0 servers that don't
describe the response outcome or the data they send back with a header
block. For these servers peer_http_version is set to "0.9" and
this method returns (200, "Assumed OK").
The method will raise an exception (die) if the server does
not speak proper HTTP or if the
"max_line_length" or
"max_header_length" limits are
reached. If the "laxed" option is
turned on and "max_line_length" and
"max_header_length" checks are turned
off, then no exception will be raised and this method will always return
a response code.
- "$n = $s->read_entity_body($buf, $size);"
- Reads chunks of the entity body content. Basically the same interface as
for read() and sysread(), but the buffer offset argument is
not supported yet. This method should only be called after a successful
read_response_headers() call.
The return value will be
"undef" on read errors, 0 on EOF, -1
if no data could be returned this time, otherwise the number of bytes
assigned to $buf. The
$buf is set to "" when the return
value is -1.
You normally want to retry this call if this function returns
either -1 or "undef" with
$! as EINTR or EAGAIN (see Errno). EINTR can
happen if the application catches signals and EAGAIN can happen if you
made the socket non-blocking.
This method will raise exceptions (die) if the server does not
speak proper HTTP. This can only happen when reading chunked data.
- "%headers = $s->get_trailers"
- After read_entity_body() has returned 0 to indicate end of the
entity body, you might call this method to pick up any trailers.
- "$s->_rbuf"
- Get/set the read buffer content. The read_response_headers() and
read_entity_body() methods use an internal buffer which they will
look for data before they actually sysread more from the socket itself. If
they read too much, the remaining data will be left in this buffer.
- "$s->_rbuf_length"
- Returns the number of bytes in the read buffer. This should always be the
same as:
length($s->_rbuf)
but might be more efficient.
The read_response_headers() and read_entity_body() will invoke the
sysread() method when they need more data. Subclasses might want to
override this method to control how reading takes place.
The object itself is a glob. Subclasses should avoid using hash
key names prefixed with "http_" and
"io_".
LWP, IO::Socket::INET, Net::HTTP::NB
Gisle Aas <gisle@activestate.com>
This software is copyright (c) 2001 by Gisle Aas.
This is free software; you can redistribute it and/or modify it
under the same terms as the Perl 5 programming language system itself.
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