Comparison of the Two Variants

The two available view elements for presenting selected text via dropdownlists raise the following question: When will which of the two view elementsbe active, that is, in which situations? If the default values from the Data Dictionarywere to be provided, DropDownByKey would be an effective means ofestablishing a connection between the Data Dictionary and the user interface.

For freely definable dropdown lists, however, you should consider variousfactors that can affect performance.For example, the use of the Drop-DownByIndex view element requires the creation of a context node, the instantiation of context node elements, and the manipulation of the leadselection. These steps can adversely affect runtime when the number ofselection list entries is high.However, DropDownByIndex is easier to handle than DropDownByKey. If you use DropDownByKey, the change of the attribute info affects all elements of acontext node with cardinalities of 0..n or 1..n. You should therefore have asound knowledge of the dependencies involved. Changes to the contextnode info are also very complicated and should only be made if you fullyunderstand the potential of their affects. Furthermore, because the changesalways affect all attributes of all elements of a context node, you should onlyuse the view element DropDownByKey if the number of values in the selectionlist is very high, changes frequently, and will be influenced dynamically.Note that you can begin with a DropDownByIndex view element and switch toDropDownByKey, but only if the system performance noticeably deteriorates.

When using dropdown lists in table columns, using the DropDownByIndexview element is inevitable if selection lists with different values are to be displayedfor different rows. The DropDownByKey view element cannot be used here, because the value set is always valid for all elements of a context node.For a table, this characteristic applies to every row and would thereforeresult in the same contents being displayed in every row.