Everything is becoming user-centric these days. Signing on, the usual prerequisite to access additional features of a website is not as prescriptive as it used to be. Sites are now less disposed to demand user registration prior to signing on - a typical usability barrier. Instead, users can opt to log in by designating an existing identity provided by another site. Getting rid of the potentially disruptive registration process makes sense and in tune with creating flowing user experience. For example, users are more likely to comment on blog posts if their actions (and thoughts!) are not punctuated with lengthy form filling and authentication processes. Indeed, better 'flow' is a key goal in many emerging interaction design patterns, e.g. 'stay on the page'.
Federated identity represents the cutting edge of this user-centric trend which also coincides with Web 2.0 in many ways. First, digital content and services from heterogeneous and autonomous websites are increasingly intertwined and federated, in what could be described as diffusion user experience. Second, the plethora of APIs made available by services or sites such as Google, Yahoo!, Twitter and Facebook have really fostered the developments of federated use scenarios in which user identities and data are becoming interoperable.
The following provides a technical account of integrating Twitter sign on into a social networking platform, as a prerequisite for the UX2.0 project work in developing Twitter services for digital library use scenarios.