Data: Flickr API

Data visualization can be rendered in multiple levels or phases. Each of these phases carry forward the values derived from previous phase according to user’s choice and final phase renders the data in a visual manner. These combinations of visual data objects could be derived from various sources, either from an application or external library. In data visualization, to select the data-object from external source, there must be mechanism to access the stored library. Application Program Interface (API) is one of the common mechanisms to access the data.

Flickr is an image hosting and video hosting website, web services suite, and online community. In addition to being a popular website for users to share and embed personal photographs, the service is widely used by bloggers to host images that they embed in blogs and social media. In August 2011, it reported that it was hosting more than 6 billion images.

Some of the key features of Flickr are tag, marking photos as favorites, group photo pools and interestingness.Flickr asks photo submitters to organize images using tags(a form of metadata), which enable searchers to find images related to particular topics, such as place names or subject matter. Flickr was also an early website to implement tag clouds, which provide access to images tagged with the most popular keywords.
Since 2005, developers have collaborated on top of Flickr's APIs to build fun, creative, and gorgeous experiences around photos that extend beyond Flickr.
The Flickr API is divided into various groups of methods. Few of them are listed below:
• activity
• auth
• auth.oauth
• blogs
• collections
• commons
• contacts
• favorites
• galleries
• groups
• groups.members
• groups.pools
• interestingness
• machinetags
• panda
• people
• photos
The complete list can be found here.

flickr.photos.search Method:

The site taggalaxy uses the flickr data to give a galaxial representation of images having the tags mentioned as the search keyword(s) . It uses the flickr.photos.search API method to retrieve data from the flicker site.To quote from frickr’s site, this  API Method
“Return a list of photos matching some criteria. Only photos visible to the calling user will be returned. To return private or semi-private photos, the caller must be authenticated with 'read' permissions ,and have permission to view the photos. Unauthenticated calls will only return public photos.” (http://www.flickr.com/services/api/flickr.photos.search.html).
The Sample Response to this method is as follows:

Flickr API Access:
Flickr API access needs (a) Registration and (b) Application Key
Registration:

• Create a mail id in Yahoo
• Name your Flickr Screen   
• Create Account

Application Key:

• This is available for commercial and non-commercial purpose.
• Following details are to be provided:
• Application Name
• Purpose
• Key returned comprises of two parts:
• Key
• Secret

Based on the above prerequisites application can be built.
Link to the Flickr API : http://www.flickr.com/services/api/