External mapping in WD for ABAP

Question

Hello,
I am trying to understand how the concept of external context mapping works in Webdynpro.
In system BIZ/000 I created a main WD component ZTEST_WD and another subcomponent WD component ZTEST_MWD.
Then I didthe following:
1. set the component controller context node TEST_FLIGHT_NO of ZTEST_MWD as Input Element (Ext),
2. performed an external mapping between the interface controller context and the main component controller context
3. Created a method GET_FLIGHT_DETAIL to perform some processing with the flight number in the TEST_FLIGHT_NO and display the flight details on the view. It was successful.
As a negative test, I tried to display the value of the subcomponent context with external mapping in the main view, and I expected that it would give an error, but it worked.
I assigned a value to the context in the interface controller method, and the same was displayed in the view. This means that the data flows from the interface controller context to the view context.
In subcomponent ZTEST_MWD, there is a method GET_FLIGHT_DETAIL, where I assigned value to the context.
data_node = wd_context->get_child_node( name = 'TEST_FLIGHT_NO' ).
data_node->set_attribute( exporting name = 'CARRID' value = 'AA' ).
data_node = wd_context->get_child_node( name = 'TEST_FLIGHT_NO' ).
data_node->get_attribute( exporting name = 'CARRID' importing value = lv_carrid ).
And later when the action was processed, the value "AA" displayed on the textbox in the main view.
Now I am a bit confused abt the concept which I understood earlier. I do not see any difference between external mapping and normal mapping.
It would be very very nice if you could throw light on this.
Awaiting responses,
Thanks and Regards,
Maya

Answer 1

Hello,
here's the link to the documentation about external context mapping: http://help.sap.com/saphelp_nw04s/helpdata/en/67/cc744176cb127de10000000a155106/frameset.htm
Regards, Heidi