In computing, an open platform describes a software system which is based on open standards, such as published and fully documented external application programming interfaces (API) that allow using the software to function in other ways than the original programmer intended, without requiring modification of the source code.
A service-oriented architecture allows applications, running as services, to be accessed in a distributed computing environment, such as between multiple systems or across the Internet.
A major focus of Web services is to make functional building blocks accessible over standard Internet protocols that are independent from platforms and programming languages.
An open SOA platform would allow anyone to access and interact with these building blocks.
A 2008 Harvard Business School working paper, titled "Opening Platforms: How, When and Why?