com.sap.tc.cmi.util

Interface ICMIModificationCount

public interface ICMIModificationCount

Interface for classes which support tracking of modifications.

Classes that implement this interface can take part in a more elaborated delta handling. So for model classes for instance the Web Dynpro framework uses this interface to determine, which data has changed and must therefore be sent to the client. In order to support this, a class must provide a counter, which is incremented upon each change. Usually this should be done in a framework that implements this interface in a super class.

Frameworks evaluating this interface can maintain a last counter state and compare it with the current counter state to determine, whether the object has been modified. Since overflows are possible and the access to the a long as returned by the modCount() is not atomic, the frameworks using this interface must test for (in)equality and NOT if the new counter state is greater than the old one.

This interface is not meant for use by application developers. However this type can be called, extended or implemented by frameworks using CMI.

Type Classification:

This interface is part of the Common Model Interface and is intended to be implemented by applications.

Method Summary

long	modCount() Returns the current state of the modification counter.

Method Detail

modCount

public long modCount()

Returns the current state of the modification counter.

The counter is incremented upon each change of state of the current object (e.g. when a set, add or remove method is called on the object). The counter value MUST not be negative ( modCount>=0 ). If the counter overflows then it must be reset to 0. This allows users to maintain an unitialized count by holding an initially negative value.

This concept assumes that the possibility to get the same counter value although the object has changed is neoverflow is neglectible.