VDB

VDB stands for Virtual Database, because it is an abstract layer that shields your application code from depending on BDE (or any other "real" database access library). Delphi ships with four database libraries (BDE, IBX, dbGo, and dbExpress). There are also numerous third-party options, and choosing one library can be difficult -- impossible for code that is intended to be used in several applications. VDB solves this dilemma by giving Delphi developers an object-oriented, abstract library for developing database applications and reusable modules. You can switch database libraries without even recompiling (for example, by keeping the profile string in an INI file)!

VDB is especially important for building reusable code. Consider your options when attempting to design a module that implements some reusable business logic. Assuming you need to perform some database access, you have to pick a specific database library (such as BDE, for example). Your "reusable" module is now tied to this one library, and can't be used in applications that use a different library. On the other hand, if you use VDB to perform the database access, then your module really is reusable, because it can be used by any application, regardless of which database access library it uses.

VDB has numerous other benefits, such as connection pooling and automatic adaptive query preparing and caching. Also, VDB uses interfaces for simpler memory management, and offers a more streamlined interface than the traditional component-based libraries such as BDE.

Resources

For more information on how VDB can help you get the most out of Delphi, see the Top Ten Reasons to use VDB list.

For answers to frequently asked questions about VDB, see the VDB FAQ.

For details on DSUtil (the general-purpose library that comes with VDB), see the Top Ten Reasons to use DSUtil list.

You can print a One-Page Fact Sheet on VDB (in RTF format). For best results, please install the following True-Type Font: Exotic 350 Demi-Bold BT.

The Story of VDB

We started developing VDB back in September of 2000, because we were experimenting with the differences between BDE and IBX. We wanted to switch from one to the other, without changing the application. Quickly, we realized that we needed an abstract layer that would shield us from depending on one library or the other. That was how it all started, and since then we have added many great features, making VDB more than just an abstraction for the other four libraries -- it is more flexible, streamlined, and powerful than the component-based libraries.

VDB has been used to build real-world, production applications for 18 months. In that time, over 30 real applications have been developed with VDB, including 3-tier application servers, web applications, and back-end (console mode) programs. Now, Dimeric Software is proud to offer VDB to the entire Delphi community. We hope you enjoy it as much as we have!

Scalability

VDB is ideal for multi-threaded server applications, because we have addressed scalability from the very beginning. You can read more about the specific aspects of VDB that address scalability in our Scalability Discussion.