<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>