Orleans

Project Orleans is an open source framework for distributed applications that is included with .NET. Although Orleans can run on-premises, it is mostly used in Azure for massively scalable real-time applications such as collaborative applications, IoT, and gaming back ends.

Service Overview 

Orleans is an implementation of the “actor model,” which is an architectural style supporting large numbers of (usually small) distributed objects. An object can represent a real-world entity such as a user or device, or a simple abstract entity such as a game. In Orleans parlance, a “grain” is an object class, such as “user”; a “grain instance” represents a particular instance, such as a particular user. Typically, a grain is implemented as a single object in a .NET language, such as C#.

An application may have thousands of grain instances, each of which has a unique identifier. Collections of grain instances are distributed across “silos,” each of which represents a host environment, such as a VM or physical server. Any grain instance can communicate with any other by referencing its identifier; no knowledge of what host either participant is running on is necessary because Orleans maintains this information and handles all communication.