Skype is known for P2P but today runs its third calling architecture, fourth contacts service, and is about to deploy its fourth chat architecture.

Client changes have been as dramatic as service changes. Bruce addresses why Skype moved away from P2P and the strategies used to make the migrations successful.  Key to safe migrations was robust online experimentation, used to evaluate the impact of both client and service migrations. 

The initial P2P architecture allowed Skype to launch in 2003 and become the de facto standard for Internet voice and video calling.  Over time, however, servers became cheaper, clients began running on phones, and Skype began a gradual evolution from P2P to service-based architecture. But the story isn't as simple as a transition from P2P to services. The P2P architecture always had crucial services, but those services weren't designed for the demands of supporting lightweight clients.   

Experimentation to support the transition from P2P to service-based architecture required addressing the nature of Skype’s client population. With thousands of combinations of client releases and hardware platforms in use, robust scorecards and support for the entire client lifecycle is essential. Building clients based on configuration by focusing on “what” instead of “why” allows clients to continue to work as the overall service evolves to support scenarios unanticipated when the client was designed.

Bruce will discuss the evolution of Skype's architecture and tradeoffs in design made along the way. He will discuss lessons learned and the improvements that are still in process as Skype continues to evolve.

Join Karen Casella of Netflix as she explores architectural issues with a panel of experts from some of the world's largest architectures.