Back in August of 2006, I wrote an article about calling .NET components from PowerBuilder using COM wrappers (i.e., CCW). Since I was basing it on a registry entry approach, the technique demonstrated required the component to be added to the GAC, which in turn required that we create a strong name and sign the assembly (besides having it compiled as a COM-visible assembly).

You don't always have access to the GAC or the registry of the machine that you need to deploy your application to. Well, fortunately we have some options. Beginning with Windows XP and Windows Server 2003, the Microsoft operating systems allowed the use of manifest files rather than registry entries for loading COM components. It not only works for regular COM components, but for .NET components that have been exposed as COM-visible. The only difference is how the manifest file is structured.

If you want further information on the details, I'd recommend the following resources:

This two-part article provides a primer on OLE, some practical examples of its use, and demonstrates some methods for addressing the limitations of PowerBuilder's implementation of OLE.

In Part 1 I provided some background information for OLE and discussed the use of custom controls, in Part 2 I talk about OLE Automation and OLE objects.

OLE Automation
OLE Automation is the interface through which one application (e.g., Microsoft Outlook) makes the methods, properties, and events of its objects (e.g., Folders, Messages, Address Book) available for use within another application. Using OLE Automation, a developer could automate another application (e.g., creating and then printing form letters from Microsoft Word) or they may just use a portion of another application within their own (e.g., using the spell-check capability within Microsoft Word to spell-check text in a control within PowerBuilder).

Using Object Linking and Embedding (OLE) from PowerBuilder - whether in OLE Automation or the use of ActiveX controls - has long been a source of frustration for many PowerBuilder developers.

There are several reasons for this:

• There is a lack of a full understanding of OLE.
• There is little documentation and practical examples of using OLE with PowerBuilder.
• There are some limitations inherent in the method that PowerBuilder implements OLE.

This article is intended to address some of these issues by providing a primer on OLE, providing some practical examples of its use, and demonstrating some methods for addressing the limitations of PowerBuilder's implementation of OLE.

The first thing we need to do is cover some background information, beginning with some definitions of terms and then some explanation of how OLE works.