Application interfaces are as old as the origins of distributed computing and can be traced back to the late 1960's when the first request-response style protocols were conceived. For example, according to this research, it wasn't until the late 1980's when the first popular release of RPC (described below) was introduced by SUN Microsystems (later acquired by Oracle), that internet-based interface protocols gained wide popularity and adoption.
This is perhaps why the term Application Programming Interface (API) even today can often result in ambiguity depending on who you ask and in what context. This is probably because of the fact that historically the term API has been used to (and to a degree continues to) describe all sorts of interfaces well beyond just web APIs (e.g. REST).
This article therefore attempts to demystify (to an extend) the origins of modern web-based APIs. This is done by listing and describing in chronological order (as illustrated below) the different interface protocols and standards that in my view have had major influence to modern web-based APIs as we know them today (e.g. SOAP/WSDL based web services, REST, GraphQL, gRPC to name a few). Read the complete article here.
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