SAP Mobile WorkSpace - Mobile Business Object Development contains details about configuring MBOs to enable DCN to refresh cached MBO data.
While an MBO belongs to a single cache group, MBOs in the same project are not necessarily in the same cache group. The cache group policy determines the data refresh behavior of all MBOs within the group. DCN can be used as the sole mechanism of refreshing cached data in SAP Mobile Server by specifying the DCN cache refresh policy. See Best Practices for Loading Data from the EIS to the CDB in Mobile Data Models: Using Mobile Business Objects.