1. A method for managing metadata associated with entities and entity types in a computing system, the method comprising: initializing a global static metadata cache containing global static metadata at the computing system, wherein the global static metadata comprises definitions for core entities and entity types for the computing system; initializing a global dynamic metadata cache containing global dynamic metadata at the computing system, wherein the global dynamic metadata comprises definitions for entities and entity types for the computing system that can be changed without requiring a reboot; receiving a command to initialize a session at the computing system; determining a realm for the session, wherein the realm is a virtual private partition of the computing system; initializing a realm-scoped dynamic metadata cache containing realm-scoped dynamic metadata associated with the realm at the computing system, wherein the realm-scoped dynamic metadata comprises definitions for entities and entity types for the realm; and executing operations on the computing system in compliance with the global static metadata, the global dynamic metadata, and the realm-scoped dynamic metadata.