Wednesday, December 17, 2008

Agilefant : Is it SPRING or what?

Suppose you have a web page.
Suppose the web page is a SCRUM management web application.
Suppose it's called Agilefant, made by the guys over at TKK, Helsinki's Technical Highschool / University. Here is the project page

Now suppose we would like to integrate the most important information of this very usefull application into our Information Radiator. How would we do it?
We would have to handle a few minor issues first, like access for an example. We don't want to just "remind" the host that would connect to our Agilefant server with the available option. We want to create a new session every time we need to access it.
Agilefant is based on Spring( Spring is an application framework. Google it if you want more information, I am surely not crazy enough to dive into it's deepness - and trust me, it's HUGE.
But anyway. Back on track.
Spring, in return, bases its authentication mechanism on Acegi (, Spring's standard authentication sub-framework. Now, Acegi supports various methods of authentication (Form, BASIC, NTLM being the most important ones, but it offers WAY more), but Agilefant provides you only with form-based access, which in cases like ours where you need to leave the door open for automated crawling can be a bit restrictive.

How do we overcome this restriction? Well, Spring handles the authentication through the use of filters, which basically redirect you depending if you supply correct or incorrect credentials. In case the authentication is successfull, the response will contain a JSESSION id in form of a cookie, which hast to be used for later accesses. Which means that we first need to perform a login, fetch the cookie and then fetch our Agilefant informative pages (by providing the cookie) - for example a burndown graph. Since (as mentioned) Agilefant supports only form-based authentication, we have to handle the whole issue at HTTP level.
And here is where the php_http extension for php proofs to be extremely handy. In fact, this library gives you full control on HTTP requests / responses, providing functionality for HTTP requesting / receiving / marshalling and unmarshalling. Wow. You could build a browser in PHP with those functions (has anyone ever been crazy enough to think of that anyway?).

So now the steps to perform (at HTTP level through PHP) are as follows :

a) Supply to the authentication target of Agilefant a valid username/password pair
b) fetch the cookie from the response
c) fetch our desired Agilefant data with the previously obtained cookie
Which, translated to PHP, comes down to a very simple script that looks like this:

header('Content-type: image/png');
$params = array ("j_username" => "yourusername", "j_password" => "yourpassword");
$response = http_post_fields("http://agilefant/agilefant/j_spring_security_check", $params);
$rHeader = http_parse_headers ($response);
$cookies = http_parse_cookie ($rHeader['Set-Cookie']);
$options = Array ('cookies' => $cookies->cookies);
$response = http_get("http://agilefant/agilefant/drawChart.action?iterationId=38", $options);
$rBody = http_parse_message ($response);
echo $rBody->body;

No comments: