NAME¶
HTTP::Response - HTTP style response message
SYNOPSIS¶
Response objects are returned by the
request() method of the
"LWP::UserAgent":
# ...
$response = $ua->request($request)
if ($response->is_success) {
print $response->decoded_content;
}
else {
print STDERR $response->status_line, "\n";
}
DESCRIPTION¶
The "HTTP::Response" class encapsulates HTTP style responses. A
response consists of a response line, some headers, and a content body. Note
that the LWP library uses HTTP style responses even for non-HTTP protocol
schemes. Instances of this class are usually created and returned by the
request() method of an "LWP::UserAgent" object.
"HTTP::Response" is a subclass of "HTTP::Message" and
therefore inherits its methods. The following additional methods are
available:
- $r = HTTP::Response->new( $code )
- $r = HTTP::Response->new( $code, $msg )
- $r = HTTP::Response->new( $code, $msg, $header )
- $r = HTTP::Response->new( $code, $msg, $header, $content
)
- Constructs a new "HTTP::Response" object
describing a response with response code $code and optional message $msg.
The optional $header argument should be a reference to an
"HTTP::Headers" object or a plain array reference of key/value
pairs. The optional $content argument should be a string of bytes. The
meaning these arguments are described below.
- $r = HTTP::Response->parse( $str )
- This constructs a new response object by parsing the given
string.
- $r->code
- $r->code( $code )
- This is used to get/set the code attribute. The code is a 3
digit number that encode the overall outcome of an HTTP response. The
"HTTP::Status" module provide constants that provide mnemonic
names for the code attribute.
- $r->message
- $r->message( $message )
- This is used to get/set the message attribute. The message
is a short human readable single line string that explains the response
code.
- $r->header( $field )
- $r->header( $field => $value )
- This is used to get/set header values and it is inherited
from "HTTP::Headers" via "HTTP::Message". See
HTTP::Headers for details and other similar methods that can be used to
access the headers.
- $r->content
- $r->content( $bytes )
- This is used to get/set the raw content and it is inherited
from the "HTTP::Message" base class. See HTTP::Message for
details and other methods that can be used to access the content.
- $r->decoded_content( %options )
- This will return the content after any
"Content-Encoding" and charsets have been decoded. See
HTTP::Message for details.
- $r->request
- $r->request( $request )
- This is used to get/set the request attribute. The request
attribute is a reference to the the request that caused this response. It
does not have to be the same request passed to the $ua->
request() method, because there might have been redirects and
authorization retries in between.
- $r->previous
- $r->previous( $response )
- This is used to get/set the previous attribute. The
previous attribute is used to link together chains of responses. You get
chains of responses if the first response is redirect or unauthorized. The
value is "undef" if this is the first response in a chain.
Note that the method $r->redirects is provided as a more convenient way
to access the response chain.
- $r->status_line
- Returns the string "<code>
<message>". If the message attribute is not set then the
official name of <code> (see HTTP::Status) is substituted.
- $r->base
- Returns the base URI for this response. The return value
will be a reference to a URI object.
The base URI is obtained from one the following sources (in priority
order):
- 1.
- Embedded in the document content, for instance <BASE
HREF="..."> in HTML documents.
- 2.
- A "Content-Base:" or a
"Content-Location:" header in the response.
For backwards compatibility with older HTTP implementations we will also
look for the "Base:" header.
- 3.
- The URI used to request this response. This might not be
the original URI that was passed to $ua-> request() method,
because we might have received some redirect responses first.
If none of these sources provide an absolute URI, undef is returned.
When the LWP protocol modules produce the HTTP::Response object, then any base
URI embedded in the document (step 1) will already have initialized the
"Content-Base:" header. This means that this method only performs
the last 2 steps (the content is not always available either).
- $r->filename
- Returns a filename for this response. Note that doing
sanity checks on the returned filename (eg. removing characters that
cannot be used on the target filesystem where the filename would be used,
and laundering it for security purposes) are the caller's responsibility;
the only related thing done by this method is that it makes a simple
attempt to return a plain filename with no preceding path segments.
The filename is obtained from one the following sources (in priority
order):
- 1.
- A "Content-Disposition:" header in the response.
Proper decoding of RFC 2047 encoded filenames requires the
"MIME::QuotedPrint" (for "Q" encoding),
"MIME::Base64" (for "B" encoding), and
"Encode" modules.
- 2.
- A "Content-Location:" header in the
response.
- 3.
- The URI used to request this response. This might not be
the original URI that was passed to $ua-> request() method,
because we might have received some redirect responses first.
If a filename cannot be derived from any of these sources, undef is
returned.
- $r->as_string
- $r->as_string( $eol )
- Returns a textual representation of the response.
- $r->is_info
- $r->is_success
- $r->is_redirect
- $r->is_error
- These methods indicate if the response was informational,
successful, a redirection, or an error. See HTTP::Status for the meaning
of these.
- $r->error_as_HTML
- Returns a string containing a complete HTML document
indicating what error occurred. This method should only be called when
$r->is_error is TRUE.
- $r->redirects
- Returns the list of redirect responses that lead up to this
response by following the $r->previous chain. The list order is oldest
first.
In scalar context return the number of redirect responses leading up to this
one.
- $r->current_age
- Calculates the "current age" of the response as
specified by RFC 2616 section 13.2.3. The age of a response is the time
since it was sent by the origin server. The returned value is a number
representing the age in seconds.
- $r->freshness_lifetime( %opt )
- Calculates the "freshness lifetime" of the
response as specified by RFC 2616 section 13.2.4. The "freshness
lifetime" is the length of time between the generation of a response
and its expiration time. The returned value is the number of seconds until
expiry.
If the response does not contain an "Expires" or a
"Cache-Control" header, then this function will apply some
simple heuristic based on the "Last-Modified" header to
determine a suitable lifetime. The following options might be passed to
control the heuristics:
- heuristic_expiry => $bool
- If passed as a FALSE value, don't apply heuristics and just
return "undef" when "Expires" or
"Cache-Control" is lacking.
- h_lastmod_fraction => $num
- This number represent the fraction of the difference since
the "Last-Modified" timestamp to make the expiry time. The
default is 0.10, the suggested typical setting of 10% in RFC 2616.
- h_min => $sec
- This is the lower limit of the heuristic expiry age to use.
The default is 60 (1 minute).
- h_max => $sec
- This is the upper limit of the heuristic expiry age to use.
The default is 86400 (24 hours).
- h_default => $sec
- This is the expiry age to use when nothing else applies.
The default is 3600 (1 hour) or "h_min" if greater.
- $r->is_fresh( %opt )
- Returns TRUE if the response is fresh, based on the values
of freshness_lifetime() and current_age(). If the response
is no longer fresh, then it has to be re-fetched or re-validated by the
origin server.
Options might be passed to control expiry heuristics, see the description of
freshness_lifetime().
- $r->fresh_until( %opt )
- Returns the time (seconds since epoch) when this entity is
no longer fresh.
Options might be passed to control expiry heuristics, see the description of
freshness_lifetime().
SEE ALSO¶
HTTP::Headers, HTTP::Message, HTTP::Status, HTTP::Request
COPYRIGHT¶
Copyright 1995-2004 Gisle Aas.
This library is free software; you can redistribute it and/or modify it under
the same terms as Perl itself.
