Difference of ViewObjectScope,RowSetScope and Row Scope

Question

I am reading The uix help online and get a understanding problem(Business Components for Java Integration):
What is the Difference between ViewObjectScope,RowSetScope and Row Scope? And how to use RowSetScope and RowScope
<bc4j:appModuleScope name="alpha" >
<contents>
<bc4j:viewObjectScope name="beta" > <contents>
<!-- indexed children scoped by View Object "beta", in Application Module "alpha". --> ... <bc4j:rowSetScope name="gamma" > <contents>
... <!-- indexed children scoped by Row Set "gamma", of View Object "beta", in Application Module "alpha". --> ... <bc4j:rowScope name="delta" > <contents>
... <!-- indexed children scoped by Row "delta" of Row Set "gamma", of View Object "beta", in Application Module "alpha". --> ... </contents>
</bc4j:rowScope>
</contents>
</bc4j:rowSetScope>
</contents>
</bc4j:viewObjectScope> </contents></bc4j:appModuleScope>

Answer 1

Hi Yong,
I think the best way to understand the different scopes is by example. Run the uiXML for Business Components "Complete uiXML Application" wizard to automatically generate uiXML pages bound to one or more ViewObjects. For example, you could generate Business Components for the EMP and DEPT sample tables, and then generate a uiXML Application for those Business Components.
At the top of each uiXML for Business Component's page you will see a registryDef section that defines what application module and view objects the page uses.
The UIX BC4J elements like textInput, choice, column, etc, all have an attrName attribute. Specifying this attribute will tell UIX to retrieve the data for this element from BC4J. However, an attribute name is not enough to uniquely identify where the data should come from. This is where the scopes come in. UIX figures out what application module, and view object, to look for the attrName by the heirarchy of scope elements surrounding the element on which attrName was used.
For example:
<bc4j:rootAppModuleScope name="EmpAppModule">
<contents>
<form name="TextInputform">
<contents>
<bc4j:viewObjectScope name="EmpView">
<contents>
<ui:stackLayout>
<contents>
<bc4j:textInput name="txt1"
attrName="Ename" />
</contents>
</ui:stackLayout>
</contents>
</bc4j:viewObjectScope>
</contents>
</form>
</contents>
</bc4j:rootAppModuleScope>
This code binds a text input to the value of the EName attribute of the current row of the EmpView view object in the EmpAppModule application module (where EmpView and EmpAppModule are defined in the registryDef section of the page).
The rowScope element defines the scope to be the row with the given name (if no such row is available, it is created with the default values given for each attribute).
The rowSetScope allows you to specify the name of a BC4J rowSet and a child "rowStamp" UIX element that will be rendered (stamped out) for each row in the rowSet.