Intro to Microsoft OLE Custom Control Architecture & Tools

The information in this article applies to:

- Professional and Enterprise Editions of Microsoft Visual Basic,

  16-bit only, for Windows, version 4.0

SUMMARY

Microsoft is introducing OLE Custom Controls that combine the benefits of Visual Basic programming system custom controls (.VBX files) with the open standard of Object Linking and Embedding (OLE).

Microsoft also plans to offer a Control Developer's Kit (CDK) to make it easier to add OLE capabilities to existing .VBX custom controls, thus facilitating component-based software development for Windows-based applications. This article describes this new technology and explains the implications for users as well as control developers.

MORE INFORMATION

Microsoft's comprehensive object strategy is built around the OLE object model and is designed to provide developers with a consistent and open standard for defining what an object is and how objects interact with one another.

Benefits Associated with Microsoft OLE Custom Control Architecture

• OLE technology is now an integral part of custom controls, creating a new open standard for component-based software development.
• You will have the ability to create either 16-bit or 32-bit custom controls that have all the power of OLE 2.0 functions and services, including Visual Editing, Drag and Drop, and OLE Automation.
• OLE Custom Controls have a broader base of usability, because they are not limited to being used with Visual Basic as .VBX custom controls are. OLE Custom Controls can be loaded by any container that supports OLE 2.0.
• Both 16-bit and 32-bit components can be developed using the same OLE Custom Control source code under Microsoft Windows, Microsoft Windows NT, and future versions of the Windows operating system and eventually other platforms as well.
• Control wizards in the OLE CDK enable developers to easily build OLE Custom Controls using the Microsoft Foundation Classes (MFC) and allow developers to migrate existing .VBX custom controls to the OLE Custom Control architecture.

Contents and Availability of OLE CDK

The OLE CDK includes:

• 16-bit and 32-bit extensions to MFC version 2.5 to support controls.
• ControlWizard for creating an initial OLE Custom Control project or porting an existing .VBX control to the new architecture.
• ClassWizard extended to support OLE Custom Controls.
• Test Container for verifying OLE Custom Controls.
• Complete online documentation.
• Samples of OLE Custom Controls with source code.

• As an add-on product to Microsoft Visual C++ version 1.5, for creating 16-bit controls.
• As an add-on product to the next version of Microsoft Visual C++ for creating 32-bit controls.

Future of .VBX Custom Controls

To preserve existing customer code bases that use Visual Basic custom controls, Microsoft will continue to support the current .VBX custom control architecture with 16-bit versions of Visual Basic and Visual C++. For 32-bit development, OLE Custom Controls will be the extensibility mechanism of choice.

By merging the benefits of OLE 2.0 with the existing .VBX architecture, Microsoft is offering independent software vendors and customers an open, standard way to realize all the benefits of component-based software development. For example, users will be able to plug different OLE Custom Controls into a database or spreadsheet application to provide a range of custom functions such as specialized financial modules, equation editing, scientific analysis, run-time tutorials and charting. In the past, the primary benefits of object-oriented programming were directed at programmers; OLE brings the benefits of object technology to a broader audience, including end users, developers and system integrators.

Questions & Answers

Q: Can I use OLE controls from other products such as Microsoft Access

   version 2.0 for Windows in my Visual Basic version 4.0 program?

   can be embedded in any OLE 2.0-compliant application, including
   existing released versions of Microsoft Excel for Windows, Visual Basic
   version 4.0 (using the OLE 2.0 container control), and many third-party
   applications as well.

   However, Microsoft Excel developers do not have access to OLE custom
   controls Windows events such as mouse clicks. Microsoft Access version
   2.0 supports OLE custom controls fully, including events.

   The Microsoft Access Developers Kit (ADT) version 2.0 ships with
   several OLE custom controls: the calendar, scroll bar, and the Data View
   control. The calendar and scroll bar can be embedded in any OLE 2.0
   application, including a Visual Basic version 3.0 application, but the
   Data View control cannot be embedded because it is designed to run only
   with Microsoft Access.

A: Most OLE custom controls, like the calendar and scroll bar in the ADT,

   work like .VBX controls. If the Data View custom control is used in a
   Microsoft Access application, the end user must have a copy of
   Microsoft Access installed on their computer. The OLE custom control
   architecture allows for a lot of flexibility, so it is up to the
   control creator to define the licensing restrictions for his or her
   control. We expect most third-party OLE custom controls will have
   licensing restrictions to the same extent as .VBX controls do today.

   version of Visual Basic?

   existing .VBX controls so that no modifications are necessary.
   Third-party OLE controls that replace the .VBX controls will also be
   backwards compatible. Check with the third-party supplier of your
   existing .VBX controls about their plans for releasing OLE custom
   control upgrades.

   the next version of Visual Basic?

   version of both Visual Basic and Visual C++ (16-bit version). However,
   all new 16-bit and 32-bit custom control development in the future will
   be through the OLE Custom Control Development Kit.

   OLE or to create OLE custom controls from scratch?

   tool, and documentation that specifically addresses porting a .VBX
   control to the new architecture. We have found that getting a
   preliminary working OLE custom control up and running can be
   accomplished in a very short period of time. The Control Wizard, which
   is part of the CDK, provides stock properties and events and creates a
   working shell control from which the developer can customize and add
   their own control-specific code and features.

A: We are already working closely with the VBX ISV community, and our

   preliminary experience with porting these controls has shown that a
   porting lab will probably not be necessary because the process is not
   difficult. As we move forward, we will continue to monitor third-party
   porting efforts, and we will assist them in every way we can.

   they can be fast enough for use as components in shipping products?
   How can my controls be as fast via OLE as they are via VBX?

   performance and small footprint. We have done some preliminary tests
   that show that OLE custom controls can, in some cases, be faster than
   .VBX controls.

   .VBX controls.

   next revisions of Visual Basic and Visual C++, concurrent with support
   for the OLE custom control architecture. We will continue to work with
   control vendors to help them evolve from today's VBX standard to the
   new OLE custom control standard for both 16-bit and 32-bit Windows
   platforms. OLE custom controls offer new choices and greater
   flexibility for customers, ultimately resulting in reduced development
   time and decreased costs.

   and support OLE too?

   development. OLE is a standard that is supported widely in the
   software industry. Merging the benefits of OLE with the benefits of
   .VBX custom controls will bring the best of both approaches together
   in one, standard architecture. While .VBX custom controls have helped
   make Visual Basic successful, they use a proprietary technology that
   is tied to the 16-bit Windows architecture.

   and OLE custom controls?

   systems. Much of our future operating system user interface will be
   based on OLE custom controls.

   must ship to build applications that use my OLE custom controls?

   so it is too early to know exactly how big or how small the controls
   will be. The maximum number of files a control developer must ship
   with their application is two files -- one file for the control, the
   second file for a control run-time DLL, which is shared across by
   all OLE custom controls on the system. The standard OLE operating
   system .DLL files must also reside on the computer. The whole concept
   behind OLE and component development is to minimize the amount of
   code on both the developer's and user's desktop, so you can be sure
   that we are working to minimize the size of the files required for
   OLE custom controls, as well as to maximize control performance.

   controls?

   source-tree can be compiled to create a 16-bit or 32-bit OLE custom
   control.

   and the Microsoft Foundation classes to create OLE custom controls?

   custom controls.

   code is burdensome for a simple VBX-like object such as a push-button.

   controls. OLE custom controls even allow you to include multiple OLE
   custom controls in a single file, distributing the already minimal
   overhead across multiple controls. This minimal overhead is a
   worthwhile tradeoff, particularly for developers who want to take full
   advantage of the portability that OLE provides. And developers who
   will be working in 32-bit environments will want to get as much lead
   time as possible to work with OLE custom controls, as it is the
   control model we are supporting in 32-bit mode in all future versions
   of our development tools.

   software around? The VBX model has been such a success. How can I be
   sure of the success of OLE?

   promoting OLE for the past 18 months. OLE is not new. It's no secret
   in the industry that OLE is Microsoft's stated future direction. In
   the past year, Microsoft has sponsored conferences and seminars that
   have focused, in part or in total, on what OLE is, why it is important,
   and how to work with it now and in the future.

   Microsoft is not the only company endorsing and promoting OLE as an
   industry standard for component-based software development. There will
   be over 150 non-Microsoft OLE-compliant applications shipping by
   Spring COMDEX 1994. 25,000 copies of Kraig Brockschmidt's book,
   "Inside OLE 2.0" have been sold. And there are 8,000 developers
   currently doing OLE development work.

   Microsoft and our ISV community have made .VBX controls an industry
   success story. We plan to build on that success by merging the
   benefits of OLE with the benefits of .VBX custom controls to bring the
   best of both approaches together in one, universal custom control
   architecture.

   Naturally, Microsoft will continue to support .VBX controls under 16
   bits in the next revision of Visual Basic, concurrent with support for
   the OLE custom control architecture. We will continue to work with
   control vendors to help them evolve from today's VBX standard to the
   new OLE custom control standard for both 16-bit and 32-bit Window
   platforms.

Trademarks

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