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Visual Basic DataFlex (VDF)
VDF main advantage is speed of development. In a system that deals with large amounts of data, Visual Basic will probably require twice the encoding time.
An example of this is in error handling. VB error handling must be coded by hand.
Another example of benefits out of the box "is the pursuit of VDF messages. Coding "find first or last" is fully supported and coded by VDF on methods to increase availableboth the object data dictionary class levels.
Overview: VDF is designed to raise awareness of data in a completely VB script, and is not intended as a given outside know the answer box.
Secondly, VDF is completely in harmony with your code base and data.
A conversion of DOS DataFlex to VDF can take the tried and true code and move it into a system largely intact OOPS VDF reliable without reinventing the wheel.
AConversion of DOS DataFlex to VDF also has the advantage of being run simultaneously with DOS. You can phase the system gradually, Visual Basic rather than being an all out conversion. You can also use the data tables themselves DOS until the conversion is complete, and then move on to the client-server when VDF validation and act as full from DOS.
VDF is a front-end ideal for many databases: DataFlex, Pervasive, MySQL, DB2, Oracle and MS SQL Server, for example. The same programcode will work no matter which database you choose (or switch to).
VDF has a history of 30 years as a development language Visual Basic designed to work with data. VB has this feature as an add-on. The first two versions of VB were not even aware of the database!
VDF has a light footprint. Complex systems can be performed reasonably well 5 years + old computers. VB.net requires "power users" like computers for all users to obtain reasonable performance.
VDF is really Object Oriented. Thistype of programming makes development faster, cleaner and easier to change down the road. Visual Basic is "Object Based" - implementing the concept of a partway Oops. OOPS is a part of "classes". These allow flexible extension of controls that are used to display data.
· For example, suppose you want to color all the fields that are indexed (and thus can be used to find). Add code to do this in class, rebuild, and now every instance of each fieldis indexed will be colored. In VB, this change could take weeks - finding each control and adding code to it.
· Another great advantage of this process is centralized coding. If, for example, you wanted to change the color assigned to the indexed fields VDF can edit a centralized location, providing both the power base for your code, and also doing maintenance work per month rather than a huge one click conversion jobs.
VDF is data dictionaries. DDare perhaps the most powerful of the VDF. All business rules and most of the custom code go here.
• The advantage? How very basic example, say you always want the client's name in uppercase. Set this to the client DD. Since then, every view, dialogue, etc. using the DD client will always capitalize the name of the customer.
• Two years later, he decides to allow sensitive. Go to the DD, change there and then recompile the application. Everyplace using the client's name (no matter whether it is a place or 100) will now allow lowercase.
VDF Data Base Rule interconnected Dictionary:
In a VDF, the database table rules are codified [as] above, with advanced business rules and basic. Example: The customer table is a rule applied worldwide saying that the customer can not go beyond the their credit limit. When you combine the client DD along with the sales order and lineitem DD, this is whatgives:
Customer
Sales orders
LineItem
Now when you save a new LineItem, the rescue operation cascades upwards to the customer table and any attempt to save a lineitem that puts them over the credit limit is denied!
VDF interface has features that make it much easier for the user:
Search: this is pop-up lists (the click of a button or pressing a button) are established to make searching easier. For example, to seek an order, we could showOrder #, Date, Customer, Ship To, Total and Status. You can really see what they need to perform their work efficiently.
Indexing: Position the cursor in the field # & Order, you can move back and forth across the table in order Order #. Put in order of date and you can navigate with the order date, etc. - without programming (except for index creation).
VDF interface is designed for data entry:
The standard VDF application is MDI (Multiple DocumentInterface). This allows the user to have two, three or more data views open at once, but the whole application can be minimized by a click of a button. Also offers menus and toolbars at the top of the application so that should not be added to each view.
If users prefer to move from field to field with the Enter key (instead of Tab) - add a line of code, recompile and you're done.
Any action that can be done with a mouse, you can also do with a key or a keycombination. This means faster and easier access for users, while allowing the use of the mouse by users who prefer it.
VDF has backward and forward compatibility. Application written in version 9.1 to compile and run in 12.0 (5 later) with little or no code modification.
VDF pioneer teaming Windows applications with web applications. A VDF WebApp can easily work with the same data (including data dictionaries!) Let yourWindows system uses.
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