Most cache products use map-based APIs to store data as key-value pairs. The ObjectMap API and the dynamic cache in WebSphere® Application Server, among others, use this approach. However, map-based APIs have limitations. The EntityManager API simplifies the interaction with the data grid by providing an easy way to declare and interact with a complex graph of related objects.
If you are using a map-based API, such as the dynamic cache in WebSphere Application Server or the ObjectMap API, take the following limitations into consideration:
The EntityManager API uses the existing map-based infrastructure, but it converts entity objects to and from tuples before storing or reading them from the map. An entity object is transformed into a key tuple and a value tuple, which are then stored as key-value pairs. A tuple is an array of primitive attributes.
This set of APIs follows the Plain Old Java™ Object (POJO) style of programming that is adopted by most frameworks.