Office 365 Unified API Set

[Oct. 12, 2015 note: A more recent version of this report can be found at www.directionsonmicrosoft.com/research/secured/2015/10/office-365-unified-api-set.]

Office 365 is moving to a unified API set that will be simpler to develop for than its current disparate set of APIs. However, the unified API set is also changing rapidly, so developers who use it should plan for frequent changes to their applications.

Office 365 services such as Exchange Online and SharePoint Online already provide APIs for both server-side applications (which run on Office 365 servers) and client-side applications (which run on client devices or on servers outside of Office 365). In May 2015, Microsoft announced plans for a single set of client-side APIs for Office 365 that conforms to Representational State Transfer (REST) conventions. REST-style APIs are commonly used for Web services and simplify access from client-side browser scripts and mobile applications.

Currently in preview, the unified Office 365 API set enables access to files, mail, calendars, directory, and Office 365 Groups information, and queries of the Office 365 Graph service. All APIs in the set use a common security framework for authorizing application access to user information in Office 365, and the API set provides a single Web endpoint for access to all Office 365 services.