The B<content> is an arbitrary amount of data.

=back

Since we don't want to handle all possible I<code> values directly in
our programs, a libwww-perl response object has methods that can be
used to query what kind of response this is.  The most commonly used
response classification methods are:

=over 3

=item is_success()

The request was was successfully received, understood or accepted.

=item is_error()

The request failed.  The server or the resource might not be
available, access to the resource might be denied or other things might
have failed for some reason.

=back

=head2 The User Agent

Let us assume that we have created a I<request> object. What do we
actually do with it in order to receive a I<response>?

The answer is that you pass it to a I<user agent> object and this
object takes care of all the things that need to be done
(like low-level communication and error handling) and returns
a I<response> object. The user agent represents your
application on the network and provides you with an interface that
can accept I<requests> and return I<responses>.

The user agent is an interface layer between
your application code and the network.  Through this interface you are
able to access the various servers on the network.

The class name for the user agent is C<LWP::UserAgent>.  Every
libwww-perl application that wants to communicate should create at
least one object of this class. The main method provided by this
object is request(). This method takes an C<HTTP::Request> object as
argument and (eventually) returns a C<HTTP::Response> object.

The user agent has many other attributes that let you
configure how it will interact with the network and with your
application.

=over 3

=item *

The B<timeout> specifies how much time we give remote servers to
respond before the library disconnects and creates an
internal I<timeout> response.

=item *

The B<agent> specifies the name that your application should use when it
presents itself on the network.

=item *

The B<from> attribute can be set to the e-mail address of the person
responsible for running the application.  If this is set, then the
address will be sent to the servers with every request.

=item *

The B<parse_head> specifies whether we should initialize response
headers from the E<lt>head> section of HTML documents.

=item *

The B<proxy> and B<no_proxy> attributes specify if and when to go through
a proxy server. <URL:http://www.w3.org/pub/WWW/Proxies/>

=item *

The B<credentials> provide a way to set up user names and
passwords needed to access certain services.

=back

Many applications want even more control over how they interact
with the network and they get this by sub-classing
C<LWP::UserAgent>.  The library includes a
sub-class, C<LWP::RobotUA>, for robot applications.

=head2 An Example

This example shows how the user agent, a request and a response are
represented in actual perl code:

  # Create a user agent object
  use LWP::UserAgent;
  $ua = LWP::UserAgent->new;
  $ua->agent("MyApp/0.1 ");