Share static singletons through EJB's

-CacheService
-CacheServiceBean
  -getMyObject()
  -insertMyObject(MyObject)
  -size()

-SomeOtherBean
 cache = jndiLookup(CacheService)
 cache.insertMyObject(x)
 cache.size() -> 1

@Stateless
public class CacheSessionBean implements CacheSessionLocal {
    private static Map<String, Object> cacheMap = new HashMap<String, Object>();

    public Object getCache(String key) {
        return cacheMap.get(key);
    }

    public void putCache(String key, Object o) {
        cacheMap.put(key, o);
    }
}