1. How It All Fits Together
Core Language Implementation
Language / FFI-specific ‘glue’
ActiveX Substrate

2. How an ActiveX Object Looks At Runtime
Language implementation value type
Substrate-provided thread-safe wrapper object
32-bit raw, un-thread-safe object pointer

3. How Event / Notification Queues Work At Runtime
Language
Runtime
Implementation
Non-blocking
(but polling)
Notifications
Events
Obj, Data
Choose event style to fit impl. model
Asynchronous
(languages with
such support)
Win32 Event Handles
(signaled on new entries)

4. Problem? Research Languages Can’t ‘Do Anything’
Substrate provides:
Simple, C-based wrappers for
Raw ActiveX objects creation / manipulation
Event / Notification handlers
Type information
Thread safety
A way to avoid spending months learning to implement IDispatch

5. What do researchers (minimally) write?
VARIANT-to-<langtype> wrapper, and back
Substrate calls this change data types upon function calls and returns
Addition of a storage class or subtype for ‘ActiveX handles’
Simple wrappers for C functions (creation, etc.)

6. What else can researchers wrap?
Asynchronous or non-blocking (polling-based) event handling
Handles both dynamic [source] interfaces and IPropertyNotifySink
Type library information
Coclasses with all interfaces, not just [default]
Interfaces and all of their methods
Constant information

7. Driving IE from Scheme
(define ie (create-object “InternetExplorer.Application”))
(define ie-source-iid "{EAB22AC2-30C1-11CF-A7EB-0000C05BAE0B}")
(invoke ie "Navigate" "
(register-object-event-handler! ie
ie-source-iid
"BeforeNavigate"
(lambda (a b c d e f)
(format #t "The user left lars.com! How *rude*!~%")))
(put ie "Visible" #t)

8. Making the Agent Say Something More Interesting
(define agent-control (create-object "Agent.Control.1"))
(put agent-control "Connected" #t)
(define agent-characters (get agent-control "Characters"))
(invoke agent-characters "Load"
"clippit" "C:/program files/microsoft \
office/office/clippit.acs")
(define clip-it (invoke agent-characters "Character“
"clippit"))
;; Mua-ha-ha!
(invoke clip-it "Show")
(invoke clip-it "Speak" "I'm a twisted, evil piece of metal... but at least I don't have to write C code!")