Caffeine - Version 1.1 Caffeine is an API for Java which allows any software application to implements a network feature. Caffeine is 10 Kb large in your application and supports multi-users, filters... Caffeine can use filters to make your app being able to send directly objects to server. Thus, Caffeine will turn them into strings, avoiding to slowing down your app. The receive of strings from network is made by an event system... Easy, free (GPL), fast and flexible !