A reflection on my SourceView’s architecture from Li showing it is awkward to add a 
new node in TopoResource.I accepted it with an open mind(modestly).
 I modified the base class NodeLoader.class,defines three abstract methods:
 addNode(DtoInterface dto):adds the node’s information into DB table,at the same time,
 add this node into topo map(a xml file).This method is used during polling period.
 loadAll():loads all table records onto memory,in other words,transforms persistence 
data to memory objectsThis methods is invoked while starting Tomcat.
 loadOne(DtoInterface dto): transforms a table record to a memory object. This method 
is used during polling period too.