public interface InstanceCache 
						extends ContainerPlugin
						{
						/**
						* Gets a bean instance from this cache given the identity.
						* This method may involve activation if the instance is not
						* in the cache.
						* Implementation should have O(1) complexity.
						* This method is never called for stateless session beans.
						*
						* @param id the primary key of the bean
						* @return the EnterpriseContext related to the given id
						* @exception RemoteException in case of illegal calls
						* (concurrent / reentrant), NoSuchObjectException if
						* the bean cannot be found.
						* @see #release
						*/
						public EnterpriseContext get(Object id)
						throws RemoteException, NoSuchObjectException;
						
						/**
						* Inserts an active bean instance after creation or activation.
						* Implementation should guarantee proper locking and O(1) complexity.
						*
						* @param ctx the EnterpriseContext to insert in the cache
						* @see #remove
						*/
						public void insert(EnterpriseContext ctx);
						
						/**
						* Releases the given bean instance from this cache.
						* This method may passivate the bean to get it out of the cache.
						* Implementation should return almost immediately leaving the
						* passivation to be executed by another thread.
						*
						* @param ctx the EnterpriseContext to release
						* @see #get
						*/
						public void release(EnterpriseContext ctx);
						
						/**
						* Removes a bean instance from this cache given the identity.
						* Implementation should have O(1) complexity and guarantee
						* proper locking.
						*
						* @param id the primary key of the bean
						* @see #insert
						*/
						public void remove(Object id);
						
						/**
						* Checks whether an instance corresponding to a particular
						* id is active
						*
						* @param id the primary key of the bean
						* @see #insert
						*/
						public boolean isActive(Object id);    
						}