Joind.in's API
==============

.. articleMetaData::
   :Where: London, UK
   :Date: 2010-02-12 22:27 Europe/London
   :Tags: blog, php, conference

I speak at many conferences_ and more and more of those conferences are using a
service called `joind.in`_. The joind.in website allows attendees of
conferences to leave feedback for the speakers, organisers and sponsors. For me
as a speaker_ this feedback by attendees is very important (as long as the
comments are constructive). I use those comments to tweak and improve my
presentations if I give them at a later moment.

The joind.in website also provides an API_ that allows you to talk to the
service from other applications and sites. I've now integrated this in my site
(at the talks_ page). It uses `JQuery's ajax`_ functionality to talk to the
backend which queries (and caches) the joind.in API requests. In order to make
API calls, you need to make POST requests to a specific URL. The URL depends on
what type of object you want to use. For example, there is
``http://joind.in/api/talk`` for requesting information about talks, and
``http://joind.in/api/user`` for fetching information about users.

Requests can be either made in XML, or with JSON. A simple example to request
all comments for a specific talk can be done with something like::

	<?php
	$id = 1240;

	$requestData = <<<ENDD
	{"request":{
	    "action":{
	        "type":"getcomments",
	        "data":{"talk_id":$id}
	    }
	}}

	ENDD;

	$data = do_post_request(
		'http://joind.in/api/talk',
		$requestData,
		'Content-type: application/json'
	);
	foreach( json_decode( $data ) as $comment )
	{
		/* ... */
	}
	?>


The ``do_post_request()`` code I lifted from `Wez'`_ page, and looks like::

	<?php
	function do_post_request($url, $data, $optional_headers = null)
	{
		$params = array(
			'http' => array(
				'method' => 'POST',
				'content' => $data
			)
		);
		if ( $optional_headers !== null) {
			$params['http']['header'] = $optional_headers;
		}
		$ctx = stream_context_create( $params );
		$fp = fopen( $url, 'rb', false, $ctx );
		$response = stream_get_contents( $fp );
		return $response;
	}
	?>

I am also fetching the full name for each user. Because this could mean that I
have to do a lot of requests I am caching them with eZ Components' Cache_
component.

You can see the code operational on the talks_ page, by clicking on
the little joind.in logo after each talk that is on the site. If JavaScript is
disabled, the logo turns into a link that takes you to the joind.in site
with all the comments.

.. _conferences: http://derickrethans.nl/talks.html
.. _`joind.in`: http://joind.in
.. _speaker: http://joind.in/user/view/30
.. _API: http://joind.in/api
.. _talks: http://derickrethans.nl/talks.html
.. _`JQuery's ajax`: http://api.jquery.com/category/ajax/
.. _`Wez'`: http://netevil.org/blog/2006/nov/http-post-from-php-without-curl
.. _Cache: http://ezcomponents.org/s/Cache