/proc/2714585/root/usr/share/doc/perl-Net-HTTP/ Current File: //proc/2714585/root/usr/share/doc/perl-Net-HTTP/README.md
# NAME

Net::HTTP - Low-level HTTP connection (client)

# VERSION

version 6.17

# SYNOPSIS

    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;
    }

# DESCRIPTION

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](https://metacpan.org/pod/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](https://metacpan.org/pod/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.

# SUBCLASSING

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_`.

# SEE ALSO

[LWP](https://metacpan.org/pod/LWP), [IO::Socket::INET](https://metacpan.org/pod/IO::Socket::INET), [Net::HTTP::NB](https://metacpan.org/pod/Net::HTTP::NB)

# AUTHOR

Gisle Aas <gisle@activestate.com>

# COPYRIGHT AND LICENSE

This software is copyright (c) 2001-2017 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.