Programmatic Interfaces for Web Applications

e Bay’s launch of its API in November 2000 marked the beginning of an era in which Web applications offer services for third-party application integration. The rapid growth of programmatic interfaces for Web applications has recently revolutionized online content integration and created new opportunities for vendors to build developer ecosystems. According to ProgrammableWeb, a leading service and mashup directory (www. programmableweb.com), the number of open Web APIs has steadily increased since 2008 (see Figure 1). Although it took eight years to reach 1,000 APIs in 2008, and two years to reach 3,000 in 2010, it took only 10 months to reach 5,000 by the end of 2011 (http:// vitvar.com/events/aaai-ss12/slides/ jmusser-keynote.pdf). Today, programmatic Web interfaces have become a core feature that developers expect from any Web application. Services let application vendors track who is using applications, as well as how and why, allowing them to more effectively foster affiliates and drive traffic back to applications. By offering services, vendors provide application functionality and start charging for it. A small fee per service call is acceptable for many subscribers, while big opportunities exist for profiting from usage volume. The volume of API calls Google and Facebook report exceeds 5 billion daily. Twitter, meanwhile, reports more than 13 billion API calls per day, with 75 percent of all Twitter traffic coming from third-par ty applicat ions v ia the Twit ter API (www.slideshare.net/raff ikrikorian/ twitter-by-the-numbers).