What is the Oracle API platform?

The Oracle API Platform Cloud Service is a 3^rd generation API management platform (refer to the Preface for further context) built almost entirely from the ground up to satisfy modern integration requirements such as real-time access to information via REST APIs.

As its name suggests, the platform is a cloud-based Platform as a Service (PaaS), meaning that it can be purchased in a subscription-based model, metered or non-metered.

The platform supports the full life cycle of API management, from API design (using Apiary, which is described later in the chapter) to continuous integration, implementation, promotion, operations, and decommissioning/retirement.

Please refer to the Oracle API Platform Cloud Service home page for further information https://cloud.oracle.com/en_US/api-platform.

3^rd generation API management platforms

The platform is fully hybrid meaning that it can be deployed in cloud computing but also on-premises. It's lightweight and equally well suited for Microservices Architecture, in other words, 3^rd generation.

A recommended read would be 3rd Generation API platforms: from proxies to micro gateways http://www.oracle.com/technetwork/articles/soa/weir-3rd-gen-api-mgmt-3787102.html.

But what exactly is a 3^rd generation API Platform in the context of Oracle product offering?

This concept is better understood by understanding the chronological evolution of Oracle's API offering throughout time.

In the following section it is described how Oracle's offering evolved from an Enterprise Service Bus centric architecture, to then becoming a SOA/SCA feature-rich (monolithic) platform, and then evolving into an architecture that is distributed, lighter weight, and therefore, suitable for hybrid and microservices architectures.

The following presentation is recommended as it provides a good overview as to how SOA is related to Microservices, and what Microservices actually are: 
https://www.slideshare.net/capgemini/microservices-and-soa