This application contains program coding/logic specifically developed as a prototype to demonstrate the use of the Visual PRO/5 grid control as an integral part of a business application, using the GML "attached file" feature.
Application - Grid Control:
The grid control is an extremely flexible control that provides many features required by business applications running in a Graphical User Interface (GUI) environment. There are two basic types of grid control configurations. In the DATA-AWARE configuration the grid displays data from files and handles file I/O automatically, while in the STANDARD configuration, the grid is populated and maintained by the application program.
Each type of configuration provides specific benefits for use, with corresponding limitations. As an example, DATA-AWARE grids require less Visual PRO/5 coding than STANDARD grids, but are not as flexible due to limitations relating to data validation. Conversely, STANDARD grids provide unlimited access to the data since the data is actually stored in an array once it has been read, a record at a time, from the file. However, as the quantity of records to be read increases, the time required to load the grid with the data increases, and is governed by the level of file system I/O performance.
Application - Grid Prototype:
The core of the prototype uses the Grid Management Library (GML) to interface with the grid control in a STANDARD grid configuration utilizing the GML ATTACHED FILE feature. GML concepts and other items are explained under prototype topics: GML Concepts, Attached File.
Application - Prototype Database:
The database used by the prototype was created by modifying files that were part of the ChileDD demo originally contained in the path \BASIS\Tools\ChileDD\data\. In particular, the ORD_LIN file was changed by increasing the amount of line items per order from less than 20 to orders with line item counts exceeding 1000. This change was necessary to demonstrate the use of the grid with a realistic size database. Since the amount of orderable items is 40, the line items in the new order file (file named O_LINE) are repeated several times within each order. It is recognized that allowing the repeating of the same item ID is not the normal practice, however, in this application this departure from the norm has no effect on the features that are demonstrated in the prototype.
In addition, the order header, file ORD_HED, was modified to include the total order line counts for all orders in the order line (O_LINE) file. Other files in the database include the customer (CUSTOMER) information file, and item (ITEM) file that have not been modified.
Through the use the grid control utilizing the GML in the ATTACHED File mode, database file O_LINE file can be changed by adding new line items, modifying existing line items, and or deleting existing line items. In addition, the grid control can be used to explore (view) the entire contents of the O_LINE file.