APIs have existed for a long time. Since the first computer programs were written, APIs have been providing “contracts” 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.
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