1. A method for managing a cache service layer of an online solution including a database, at least one client, a cache service layer having a plurality of nodes which are interconnected to each other and provide processing and caching power for the cache service layer, and a cache manager, the database and the at least one client are connected to the cache service layer using a network, the method comprising: reading in a business object from the database; assigning, using the cache manager, the business object to a business object group on a first node of the cache service layer; determining, by the cache manager, the effective probability of cache expiration of the business object group; and setting an expiration time for the business object group based on the determination of the effective probability of cache expiration of the business object group.