The following topics introduce Zen Direct Access Components (PDAC) for Delphi and C++Builder:

For details on implementing this feature, see Direct Access Components Reference.

Zen Direct Access Components are a set of Visual Component Library (VCL) components that allow direct transactional and relational access to Zen database engines from within the Borland Delphi and C++ Builder Environments. This SDK was formerly known as Pervasive Direct Access Components (PDAC), and the short name PDAC is still found in use in the SDK. Before the Zen v15 release, these runtime components were integrated and installed as .bpl files in the 32- and 64-bit \bin directories of Zen databases. Beginning with Zen v15, Zen installations removed them, but they continue to be available in the downloaded SDK, which also includes design-time components for use in RAD Studio.

See the PDAC release notes for supported development environments.

All versions of PDAC contain the following nonvisual components:

Supporting classes are also provided for these 32-bit components, which duplicate the properties, methods, and binding capabilities of the Embarcadero Data Access components without requiring the presence of the Borland Database Engine (BDE) at run time.

These components are provided in package format, and offer all the design time and runtime functionality of the built-in controls. They bind to the Embarcadero Data Aware controls in the same way as the BDE components, as well as to fully compatible third-party bound controls.

Special components include wwPvTable, wwPvQuery, and wwPvStoredProc and are provided for interoperability with the Woll2Woll InfoPower components.

When opening a query or table, PDAC confirms the database engine version to avoid engine dependency errors. An insufficient engine version returns an exception indicating the required version.

Allows SQL query text to be sent directly to the engine instead of being preparsed.

This property indicates that the database contains characters encoded according to the OEM (DOS) code page, and that these characters should be converted to the ANSI (Windows) code page before use.

Please see the SDK download for PDAC. You can find it at the Actian Zen website.

You install PDAC by extracting the components from a download archive to a directory (installdir). Be sure that any Delphi or C++Builder IDEs on your system can locate the extracted components.

Follow these steps to set C++Builder project options to reflect the INCLUDE and LIBRARY paths for PDAC. These can be added to the default options, so the steps are unnecessary for every project using the Zen components.

After the Include and Library paths are set properly, you can use the Direct Access components in exactly the same way as the corresponding Embarcadero components.

Zen provides support for all Delphi versions starting with Delphi 6. Use the following steps to incorporate Delphi or C++Builder into your IDE.

Once the components for your environment have been selected, a tab for Zen is visible on VCL projects. Applications using PDAC can now be built by adding PvTable or PvQuery.

With a few variations for Embarcadero and other runtime libraries, you can build PDAC applications for deployment to end users in two ways: using runtime packages or statically linking the PDAC libraries in the application executable. C++Builder also offers dynamic or static linking of the Embarcadero library. Either a Zen Client or engine (Enterprise Server, Cloud Server, or Workgroup) must be properly installed on the target computer for a PDAC application to run successfully.

Using runtime packages has several advantages. It provides the smallest executable possible; this can be important where the executable or updates must be downloaded or transferred over slow links. This option allows sharing of the PDAC and Embarcadero runtime binaries and can save considerable disk space and memory in environments with many Embarcadero and PDAC applications.

A disadvantage is that more files must be distributed and kept current, and the shared files can be vulnerable to third party installations that install incorrect versions of them in shared subdirectories. If runtime packages are not used, only the application and drm.dll must be deployed. The PDAC libraries are statically linked into the executable, which will be correspondingly larger.

To use runtime packages, the developer must deploy both the application executable and the PDAC libraries (from the redist subdirectories in the PDAC installation), as well as any Embarcadero or other runtime libraries (borlndmm.dll, found in the compiler bin directory, is often needed) to end users.

Each Embarcadero compiler has a redist directory. This directory contains the .bpl libraries that must be distributed with an application compiled with Build with runtime packages.

In the Delphi IDE, set the appropriate options as follows:

These files may be installed in the same subdirectory as the application executable, but we recommend placing them in the target machine path to be shared by other applications. The Zen installation \bin directory is a good choice on computers where it is the primary Zen executable directory.

In addition, the Delphi PDAC application will require an installation of either a Zen engine (server or workgroup) or a Zen Client and a remote server appropriately installed and configured.

Starting with Delphi 6, we have changed the package naming conventions to be more compatible with Embarcadero standards. Also, the runtime packages have been separated from the design time packages in order to comply with Embarcadero requirements.

The following table shows how to interpret package names if you are coming from a previous version of Delphi and PDAC: