HTTP::Headers

LIB::HTTP::HEADERS(1) User Contributed Perl DocumentationLIB::HTTP::HEADERS(1)



NAME
       HTTP::Headers - Class encapsulating HTTP Message headers

SYNOPSIS
        require HTTP::Headers;
        $request = new HTTP::Headers;


DESCRIPTION
       The HTTP::Headers class encapsulates HTTP-style message headers.  The
       headers consist of attribute-value pairs, which may be repeated, and
       which are printed in a particular order.

       Instances of this class are usually created as member variables of the
       HTTP::Request and HTTP::Response classes, internal to the library.

METHODS
       $h = new HTTP::Headers

       Constructs a new HTTP::Headers object.  You might pass some initial
       attribute-value pairs as parameters to the constructor.  E.g.:

        $h = new HTTP::Headers
            Date         => 'Thu, 03 Feb 1994 00:00:00 GMT',
            Content_Type => 'text/html; version=3.2',
            Content_Base => 'http://www.sn.no/';


       $h->header($field [=> $val],...)

       Get or set the value of a header.  The header field name is not case
       sensitive.  To make the life easier for perl users who wants to avoid
       quoting before the => operator, you can use '_' as a synonym for '-' in
       header names.

       The value argument may be a scalar or a reference to a list of scalars.
       If the value argument is not defined, then the header is not modified.

       The header() method accepts multiple ($field => $value) pairs.

       The list of previous values for the last $field is returned.  Only the
       first header value is returned in scalar context.

        $header->header(MIME_Version => '1.0',
                        User_Agent   => 'My-Web-Client/0.01');
        $header->header(Accept => "text/html, text/plain, image/*");
        $header->header(Accept => [qw(text/html text/plain image/*)]);
        @accepts = $header->header('Accept');


       $h->scan(\&doit)

       Apply a subroutine to each header in turn.  The callback routine is
       called with two parameters; the name of the field and a single value.
       If the header has more than one value, then the routine is called once
       for each value.  The field name passed to the callback routine has case
       as suggested by HTTP Spec, and the headers will be visited in the
       recommended "Good Practice" order.

       $h->as_string([$endl])

       Return the header fields as a formatted MIME header.  Since it
       internally uses the scan() method to build the string, the result will
       use case as suggested by HTTP Spec, and it will follow recommended
       "Good Practice" of ordering the header fieds.  Long header values are
       not folded.

       The optional parameter specifies the line ending sequence to use.  The
       default is "\n".  Embedded "\n" characters in the header will be
       substitued with this line ending sequence.

       $h->push_header($field, $val)

       Add a new field value of the specified header.  The header field name
       is not case sensitive.  The field need not already have a value.
       Previous values for the same field are retained.  The argument may be a
       scalar or a reference to a list of scalars.

        $header->push_header(Accept => 'image/jpeg');


       $h->remove_header($field,...)

       This function removes the headers with the specified names.

       $h->clone

       Returns a copy of this HTTP::Headers object.

CONVENIENCE METHODS
       The most frequently used headers can also be accessed through the
       following convenience methods.  These methods can both be used to read
       and to set the value of a header.  The header value is set if you pass
       an argument to the method.  The old header value is always returned.

       Methods that deal with dates/times always convert their value to system
       time (seconds since Jan 1, 1970) and they also expect this kind of
       value when the header value is set.

       $h->date

       This header represents the date and time at which the message was
       originated. E.g.:

         $h->date(time);  # set current date


       $h->expires

       This header gives the date and time after which the entity should be
       considered stale.

       $h->if_modified_since

       This header is used to make a request conditional.  If the requested
       resource has not been modified since the time specified in this field,
       then the server will return a "304 Not Modified" response instead of
       the document itself.

       $h->last_modified

       This header indicates the date and time at which the resource was last
       modified. E.g.:

         # check if document is more than 1 hour old
         if ($h->last_modified < time - 60*60) {
               ...
         }


       $h->content_type

       The Content-Type header field indicates the media type of the message
       content. E.g.:

         $h->content_type('text/html');

       The value returned will be converted to lower case, and potential
       parameters will be chopped off and returned as a separate value if in
       an array context.  This makes it safe to do the following:

         if ($h->content_type eq 'text/html') {
            # we enter this place even if the real header value happens to
            # be 'TEXT/HTML; version=3.0'
            ...
         }


       $h->content_encoding

       The Content-Encoding header field is used as a modifier to the media
       type.  When present, its value indicates what additional encoding
       mechanism has been applied to the resource.

       $h->content_length

       A decimal number indicating the size in bytes of the message content.

       $h->title

       The title of the document.  In libwww-perl this header will be
       initialized automatically from the <TITLE>...</TITLE> element of HTML
       documents.  This header is no longer part of the HTTP standard.

       $h->user_agent

       This header field is used in request messages and contains information
       about the user agent originating the request.  E.g.:

         $h->user_agent('Mozilla/1.2');


       $h->server

       The server header field contains information about the software being
       used by the originating server program handling the request.

       $h->from

       This header should contain an Internet e-mail address for the human
       user who controls the requesting user agent.  The address should be
       machine-usable, as defined by RFC822.  E.g.:

         $h->from('Gisle Aas <aas@sn.no>');


       $h->referer

       Used to specify the address (URI) of the document from which the
       requested resouce address was obtained.

       $h->www_authenticate

       This header must be included as part of a "401 Unauthorized" response.
       The field value consist of a challenge that indicates the
       authentication scheme and parameters applicable to the requested URI.

       $h->authorization

       A user agent that wishes to authenticate itself with a server, may do
       so by including this header.

       $h->authorization_basic

       This method is used to get or set an authorization header that use the
       "Basic Authentication Scheme".  In array context it will return two
       values; the user name and the password.  In scalar context it will
       return "uname:password" as a single string value.

       When used to set the header value, it expects two arguments.  E.g.:

         $h->authorization_basic($uname, $password);





3rd Berkeley Distribution    perl 5.003, patch 07        LIB::HTTP::HEADERS(1)