APIs have existed for a long time. Since the first¬†computer programs were written, APIs have been providing ‚Äúcontracts‚ÄĚ for¬†information exchange between programs. Early non-web APIs were structured¬†and rigid, requiring strict programming models and structural adherence.
The APIs emerged on the web around 2000, with Salesforce.com producing the¬†first web-based API. That same year, Ebay released its API. Two years later,¬†Amazon started Amazon Web Services.¬†APIs are now coming of age with the advent of cloud computing, where the ability¬†to host external APIs has matured to a point where cloud service providers have¬†scalable capacity to handle transaction loads and spikes in traffic. Mobile¬†platforms now put application reach on millions of devices, all having access to
back-end APIs across the Internet.¬†Serious API focus started around the year 2000, with a dramatic rise starting¬†around 2008.
Over the years, APIs have evolved based on advances in technology (such as¬†network speed, security, and dynamic integration), and also maturation in¬†business that allows for thinking of business functions as discreet, consumable¬†entities. Competition is now possible for business functions based on business¬†value as opposed to technology foundations.
API architecture has also evolved over the years, most recently with the advent of¬†service-oriented architecture (SOA). SOA provides for an architectural model to¬†manage consumer and provider relationships in a dynamic environment. This¬†paved the way for producing and exposing APIs with better business enablement¬†capabilities including request access, entitlement, identification, authorization,¬†management, monitoring, and analytics.
The largest repository of API information and mashups can now be found at¬†Programmable Web.¬†This website provides catalog information, usage statistics, and access¬†information on tens of thousands of APIs.
To learn more please read the Redbook¬†here.