OLE Automation
Jurgen Postelmans -- Jurgen.Postelmans@ping.be
Thursday, November 16, 1995
I'm trying to learn how to program OLE Automation Clients/Servers in MFC =
but I have some questions that I don't know how to solve:
1) Is there any way to pass a complete class as a parameter of a =
Automation function ? I want to be able to pass an uninitialized class =
to the automation server. The server must then initialize all the data =
members and pass it back to the client. How is this done in OLE ?
2) Is it possible to use optional parameters in Automation function with =
MFC ? I don't know how to set it when adding a function with the =
classwizard. Do I have to edit the ODL file manually ? And what if you =
generate a class from the ODL file ?
Thanks for any help
Jurgen Postelmans
paf Pete Ferreira
Friday, November 17, 1995
>
> 1) Is there any way to pass a complete class as a parameter of a =
> Automation function ? I want to be able to pass an uninitialized class =
> to the automation server. The server must then initialize all the data =
> members and pass it back to the client. How is this done in OLE ?
>
There's several ways to do this. At one extreme, the "COM correct"
way is to make your class a COM object and pass a pointer to its
IUnknown. AT the other end of the spectrum, if you're writing
both the client and the server, and the server is in-proc,
you can cast a pointer to your object to a long, pass it through
a standard IDispatch interface, and cast it back to a pointer on the
other side. These and other methods are covered in the OLE column in
the most recent MSJ.
> 2) Is it possible to use optional parameters in Automation function with =
> MFC ?
I don't think you can have optional parameters a la C varargs, but
you don't have to pass real 'data' as long as the function receiving
the data can tell which parameters are 'real'.
> Do I have to edit the ODL file manually ? And what if you =
> generate a class from the ODL file ?
>
My advice is don't mess with ODL until you're comfortable with the
issues involved in marshalling data.
Hope this helps,
Pete
paf@netcom.com http://www.webcom.com/paf/pete.html
Jim Lavin -- ooptech@Onramp.NET
Friday, November 17, 1995
At 06:03 PM 11/16/95 +-100, you wrote:
>I'm trying to learn how to program OLE Automation Clients/Servers in MFC
but I have some questions that I don't know how to solve:
>
>1) Is there any way to pass a complete class as a parameter of a Automation
function ? I want to be able to pass an uninitialized class to the
automation server. The server must then initialize all the data members and
pass it back to the client. How is this done in OLE ?
>
Sorry, but you can not pass a class to an automation object. You are
sending the class to a different process space, or code segment in WIN16,
therefore you will lose your virtual function table, even if you include the
class's code in the automation server it will not work. What you need to
do, is create a structure that holds the attributes, or data members, of the
class and pass it as a Safe Array to the automation server. Then in the
automation server you will have to decoded the structure and create a class
from it. I do this by having member functions that take a structure as in
input and either reads the structure to initialize the class or fills it out
for passing to the automation server.
>2) Is it possible to use optional parameters in Automation function with
MFC ? I don't know how to set it when adding a function with the
classwizard. Do I have to edit the ODL file manually ? And what if you
generate a class from the ODL file ?
>
I think Microsoft has something about passing optional parameters in OLE
automation on thier Web Site www.microsfot.com in the Visual C++ knowledge
base. I have not done much with optional parameters as far as OLE
automation is concerned so I can't help much.
>Thanks for any help
>
>Jurgen Postelmans
>
>
Good Luck
Jim Lavin
OOP Technologies
http://emporium.turnpike.net/~jlavin
http://rampages.onramp.net/~ooptech
Stephen Keeler -- keelers@igs.net
Saturday, November 18, 1995
> I'm trying to learn how to program OLE Automation Clients/Servers in
> MFC but I have some questions that I don't know how to solve:
>
> 1) Is there any way to pass a complete class as a parameter of a
> Automation function ? I want to be able to pass an uninitialized
> class to the automation server. The server must then initialize all
> the data members and pass it back to the client. How is this done in
> OLE ?
Sorry, don't know the answer to this one.
> 2) Is it possible to use optional parameters in Automation function
> with MFC ? I don't know how to set it when adding a function
> with the classwizard. Do I have to edit the ODL file manually ? And
> what if you generate a class from the ODL file ?
Yes, you need to make sure the parameters are VARIANTS, and I believe
you also need to manually add the 'optional' ODL keyword to the
parameter(s) modifier which is enclosed in the square brackets.
Regards,
Stephen Keeler
On-Line Systems Inc.
Sunil Kumar P -- sunilk@OPTIMASW.COM
Thursday, November 23, 1995
Hi,
I am adding OLE Automation functionality to a server application.
Can anyone suggest a through testing procedure apart from the
controllers developed in DispTest/VisualBasic.
An entry is being made into the Registration Database and the server
application is functioning normally when called from these controllers.
I am using Visual C++ 1.52 and MFC 2.5.
~~~~~~~~~~~~~~~~~~~~~~~~U~T~O~P~I~A~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Sunil Kumar Pothakamoorie Voice : 91-40-290321,292771
Optima Software Services Ltd Fax : 91-40-294810
#503, HUDA COMPLEX Internet : sunilk@optimasw.com
Maitrivanam,
AMEERPET, HYDERABAD 500 038 Home Page: http://www.optimasw.com
ANDHRA PRADESH
INDIA
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
David Dworkin -- ddworkin@wpine.com
Wednesday, November 13, 1996
Environment: VC++ 4.2-flat, Win 95
Hi,
I have an existing MFC app (*not* doc/view based) which I'm trying
to make into an OLE automation server. To get some basic automation
code, I made a generic automation MFC appwizard app, and am grabbing
the stuff from there into my application.
However, it's not quite a direct parallel, as the MFC app is doc/view
based, and my app is not. I yanked the automation stuff out of the Doc
class, and have it in my CWinApp-derived class. [First question: was
that the right thing to do?] At the moment, I just want to launch my
application via OLE automation, then add the properties and methods.
I create a simple VB app which does a CreateObject on my application
object (everything is in the registry correctly I think, and the GUIDS
are all set up properly). When I run the VB app, my application
gets launched appropriately, I detect that it's run via automation
(the m_bRunAutomated flag), everything seems OK. But, control doesn't
come back to the VB app. Shortly (maybe 1 minute), my app goes away,
and VB tells me it could not successfully create the object.
I try the same thing creating an automation clent MFC app (importing the
type library that I created), and same thing -- I call
if (!(m_server.CreateDispatch("MyApp.Document")))
and same thing -- the app launches, but control doesn't come back, then
after 1 minute or so, it goes away, and this call fails.
there must be something that I'm just not doing in my application.
Does anyone have any ideas?
Thanks a lot,
David Dworkin
ddworkin@wpine.com
============================================================================
_________________________________________________________________________
White Pine Software - Nashua, NH has MOVED !
(Please make note of our new NH address)
_________________________________________________________________________
David Dworkin ddworkin@wpine.com
White Pine Software White Pine Software
15 Messenger St. 542 Amherst Street
Plainville MA 02762 Nashua NH 03063
508-699-7051 / 508-695-2378 (Fax) 603-886-9050 ext 402 / 603-886-9051
(Fax)
www.wpine.com (WWW) www.wpine.com (WWW)
============================================================================
Carl Gunther -- cgunther@ix.netcom.com
Monday, November 18, 1996
David,
Although it is true that CWinApp is derived from CCmdTarget, and
therefore inherits the OLE support provided by MFC, I suspect that it is
not an appropriate place to put an OLE server interface. Normally,
you will want to create an instance of your OLE server interface
object when a client requests such a connection, and remove it when
the last reference is gone. This obviously will create problems
if your interface object is also your application object.
My own approach to automating an existing MFC application was to
create a new CCmdTarget-derived class to serve as the OLE interface
object. The constructor of this class should call EnableAutomation()
and AfxOleLockApp(). The destructor should call AfxOleUnlockApp().
Its OnFinalRelease() override should "delete this" to delete itself
when the final reference by a client is released. You also need
an IMPLEMENT_OLECREATE macro call at the top of the implementation file
(and a DECLARE_OLECREATE macro call in the declaration file), with
a unique name and class ID for your interface. All of your
external OLE interface functions can be declared using ClassWizard in
the usual manner (from the OLE Automation tab).
Since it is part of the same compilation unit, you ought to be able to
call any aspect of your application that is required from an
instance of this interface class.
By the way, it has been my experience that if you want to build an OLE
automation server interface into an application that is also
intended to be directly invoked by a user, what MFC's standard
AppWizard-created servers will do is create two separate instances
of the application - one for the server, and one for the end-user
application. Therefore, it is important that your application be
able to run with multiple instances, so you want to be sure
that it's not a large model 16-bit application. If the app is built on
the large model, then you'll have to create a separate server app
using some compiler switches (and a separate .DEF file to rename
the module) if you want to run it as both a server and as an application
(in other words, you're going to need two distinct
applications, compiled for convenience from the same source).
Hope this helps,
Carl Gunther
David Dworkin wrote:
>
> Environment: VC++ 4.2-flat, Win 95
>
> Hi,
>
> I have an existing MFC app (*not* doc/view based) which I'm trying
> to make into an OLE automation server. To get some basic automation
> code, I made a generic automation MFC appwizard app, and am grabbing
> the stuff from there into my application.
>
> However, it's not quite a direct parallel, as the MFC app is doc/view
> based, and my app is not. I yanked the automation stuff out of the Doc
> class, and have it in my CWinApp-derived class. [First question: was
> that the right thing to do?] At the moment, I just want to launch my
> application via OLE automation, then add the properties and methods.
> I create a simple VB app which does a CreateObject on my application
> object (everything is in the registry correctly I think, and the GUIDS
> are all set up properly). When I run the VB app, my application
> gets launched appropriately, I detect that it's run via automation
> (the m_bRunAutomated flag), everything seems OK. But, control doesn't
> come back to the VB app. Shortly (maybe 1 minute), my app goes away,
> and VB tells me it could not successfully create the object.
>
> I try the same thing creating an automation clent MFC app (importing the
> type library that I created), and same thing -- I call
> if (!(m_server.CreateDispatch("MyApp.Document")))
> and same thing -- the app launches, but control doesn't come back, then
> after 1 minute or so, it goes away, and this call fails.
>
> there must be something that I'm just not doing in my application.
> Does anyone have any ideas?
>
> Thanks a lot,
>
> David Dworkin
> ddworkin@wpine.com
> ============================================================================
> _________________________________________________________________________
>
> White Pine Software - Nashua, NH has MOVED !
> (Please make note of our new NH address)
> _________________________________________________________________________
> David Dworkin ddworkin@wpine.com
>
> White Pine Software White Pine Software
> 15 Messenger St. 542 Amherst Street
> Plainville MA 02762 Nashua NH 03063
> 508-699-7051 / 508-695-2378 (Fax) 603-886-9050 ext 402 / 603-886-9051
> (Fax)
> www.wpine.com (WWW) www.wpine.com (WWW)
> ============================================================================
--
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Copyright 1996 Carl E. Gunther. Permission to reproduce this message
in text form for not-for-profit purposes freely granted provided that
the preceeding copyright notice is retained.
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