Introduction › Concepts and Facilities › Common Application Services (CAS) › Lists

Lists

A list displays a series of items from which the user can make a selection of, or perform an action against, one or more items.

A list definition contains identifying information, the name of a service procedure that retrieves the list's entries, the identifier of an (optional) criteria definition that filters items for inclusion in the list, the name of an (optional) exit procedure that performs installation specific processing at various points, and the display format for the list.

The format of a list specifies the placement of list items and static text on the list panel. A list format can cover up to ten screens. That is, if the information you want to display for each item does not fit on a single screen, you can add a second screen, third screen, and so on. The user can scroll between these screens by entering the RIGHT and LEFT commands (or using the appropriate function keys).

The list service procedure retrieves list items and processes requests to perform actions against list items.

The list service procedure checks the list's data source (if it is defined) in order to determine how to retrieve list entries for different sources of data. For example, the data source could be an CA SOLVE:InfoMaster category or a file name. This lets multiple list definitions share the same service procedure. A data source need not be specified—in this case the service procedure retrieves entries from a source defined within the procedure.

A list can contain the identifier of an exit that is an NCL procedure used to perform installation specific processing. The exit procedure is called at various processing points; for example, during list initialization, or after an entry is retrieved.

The same list definition can be used to build four types of lists:

• Action lists—let the user apply actions (for example, Browse, Update, Delete, Copy) to one or more items on the list.
• Single Select lists—let the user select one item from the list. The selected item is passed back to the calling procedure.
• Multiple Select lists—let the user select one or more items from the list. All items selected by the user are passed back to the calling procedure.
• Numbered lists (Pick lists)—let the user select one item from the list by entering the appropriate number in the Select Entry field. The item corresponding to the number that the user selected is then returned to the calling procedure.

You specify the type of list that is to be built from a given list definition in the call to the CAS API.

The CAS list maintenance facilities enable you to define list definitions for use by your applications as well as modifying supplied list definitions.

CAS handles the selection of items for the list and the display of lists to the user, providing: full scrolling functions, the FIND and LOCATE commands, and confirmation of the user's selection.