Difference between Lead Selection, Supply Function and Singleton Node

Lead selection

Lead selection means in output table selected row number.in context node declaration select lead selection check box by default in output table first row is selected automatically.In that case leade selection automatically takes SY-TABIX value one.For example i displaying sales document header information in my output table.Whenever user selects any row of the sales document header details and click on my custom button then display particular sales document item information.

Supply Function

Supply function is one of the property of context node.If maintain supply function when the context node declaration in methods tab supply function is created automatically. In that method code is generated automatically.this code belongs to fill the context node with data.Supply function is triggers in two cases: First whenever the context node is initial and second one whenever the lead selection is changes.

Singleton Node

Singleton is one of the property of context node.Singleton is used for a context node contains multiple child nodes.If a context node contains singleton property must declare supply function property. Singleton means if the instantiate of child node of the parent node only once.Must use supply function property if a context node contains singleton property.