Book Review :  Dan Appleman's Developing Com/Activex Components With Visual Basic 6

Buy it now at Amazon!

If there is one book you can buy it should be Appleman's other book - the Win32 API guide.  If you can spring for 2 books, the second one should be this one.  This book has the most clarity I've seen in any technical document.  COM is a difficult subject, yet it is handled with such ease that even a VB newbie can master this book.  Appleman starts with an explanation of just what in the world is the difference between OLE controls, OCX, DirectX controls and COM components (absolutely nothing, other than the marketing b.s. Microsoft has unleashed upon us).    He then gets into a discussion on what OOP is.  If you already know it, don't waste your time and skip it.  Finally after that, really interesting subjects such as the life cycle of objects, differences between ActiveX DLLs & EXEs, threading models, Instancing and others are explored.   When I read the 1st edition of this book (VB5-based), it made many things clear to me that the VB documentation should have.  I nearly had a revelation, a religious experience, if you will, and my coding techniques changed overnight.  I felt the uncontrollable urge to port all VB2 code into ActiveX DLLs for modularity.  Thankfully, there is a pill for everything nowadays.  Anyway, back to the book.  My favorite topic of the book is Event handling and OLE Callbacks.  If you master this technique, it will resolve many problems that arise when trying to communicate between objects on multiple computers or between disparate programs on the same computer. 

If you will be designing ActiveX controls (different from ActiveX EXEs and DLLs), Appleman will show you a few tricks (and how to do it right) to get over the bumps you'll encounter while creating controls. 

Appleman talks a bit about Win32 API, but purchase his API guide, if that is what you need.  Further, he points out why ActiveX Documents are a complete waste of time .  Then, he touches lightly on IIS.  Last, but not the least:  if you ever want to make money with selling COM components, do yourself a favor and read the chapter on Licensing and Distribution.

The book is very good overall.  Warning, the book is large - if you are planning to read over the weekend, then don't.  I give it 5 fingers up.