<erl>
out(A) ->
       {ssi, "TAB.inc", "%%",[{"cookies", "choosen"}]}.
</erl>

<div id="entry">



  <h1>Yaws and Cookies</h1>
  <p>
    Cookies are the means in HTTP to assign data to a session. A HTTP session
    typically consists of many (and sometimes concurrent) TCP connections from the
    client to the web server. The first time a client arrives to our webserver, we
    issue the HTTP header <tt>Set-Cookie: var=someval</tt>. The browser will then in
    subsequent connections to the same server pass this cookie "var=someval" in its
    client side <tt>Cookie: var=someval</tt> header. We can thereby assign state to a
    session, either through data actualy encoded into the cookie value itself, or by
    associating server side session data to the cookie.</p>
  <p>

    Let's do an example where we set a simple cookie, and create a specific erlang process
    which is then responsible for that session.
    The cookie value will be a string encoding of the pid handling the session.
  </p>
  <p>
    The yaws code in
    <a href="setcookie.yaws">setcookie.yaws</a> sets the cookie in the browser. Note that
    the call to <code>yaws_api:set_cookie/3</code> in the example returns a header setting
    (like <code>{header, HeaderNameAndValue}</code>) from the <code>out/1</code> function,
    which directs Yaws to set the specified header in the response to the browser.
  </p>

  <p>And the yaws code in <a href="readcookie.yaws">readcookie.yaws</a>
    will read the cookie
    and report some uninteresting session data.
  </p>

  <p>
    A correct definition of cookies can be found in
    <a href="http://tools.ietf.org/html/rfc6265">RFC 6265</a></p>


<h2>Set Cookie</h2>

  <p>The code to set the cookie looks like:</p>

<erl>
out(A) ->
       {ok, B} = file:read_file(A#arg.docroot ++ "/setcookie.yaws"),
       {ehtml,
        {'div', [{class, "box"}],
        {pre,[], B}}}.

</erl>

<p>This is the page that set the cookie in the browser.
<a href="readcookie.yaws">readcookie.yaws</a> will
read the cookie and report persistent information as
long as the browser session exists.

<p> it will set the cookie
<tt>foobar = &lt;x,y,z&gt;; </tt> where the
x,y,z  string is the textual representation of an
actual erlang pid which will be responsible for
this session.

</div>


<erl>
out(A) -> {ssi, "END2",[],[]}.
</erl>

