In other words, you want to connect to an XML web service? Yes, Outlook
add-ins can "talk" to web services. The programming language you use is
largely up to what you prefer. There is a small advantage to VB because
Microsoft provides a Web Services toolkit for Office 2002/3 VBA that will
build your proxy classes for you, so you can just copy them to VB. I have
some simple examples in Chapter 23 of my book -- sample (I haven't tested
such code with Outlook 2000, but it should work as long as the user has the
proper SOAP pieces installed.)
What you describe as a "child window of calendar" is an Inspector window.
The combo box would need to already be present as part of a published custom
Outlook form, but your add-in could populate the list with the usual
AddItem, List, or Column method. The key event to use in your add-in is
Inspectors.NewInspector. When that fires, you can examine the Inspector that
it passes as an argument, get its CurrentItem and the MessageClass of that
item to determine if it's an item using your form.
--
Sue Mosher, Outlook MVP
Author of
Microsoft Outlook Programming - Jumpstart for
Administrators, Power Users, and Developers