Advanced FoxPro .NET COM Interop Article Series

December 24, 2005 @ 10:55 am

I've put up a three part article series on advanced FoxPro and .NET Interop topic dealing with handling complex object passing, handling .NET COM events and multi-threading with .NET components. This entry serves as a discussion placeholder for these three articles, so you can leave comments and questions below.

The actual articles can be found here:

   1. Passing objects between FoxPro and .NET COM Components
   2. Handling .NET Events in FoxPro via COM Interop
   3. Creating multi-threaded components .NET for COM Interop with Visual FoxPro

This article is a follow up for the original base article that discussed the basic concepts of COM Interop:

Using .NET Components via COM from Visual FoxPro

Enjoy...

Feedback for this Weblog Entry

re: Advanced FoxPro .NET COM Interop Article Series
by Mukesh January 09, 2006 @ 1:29 am

Sir
I want to know that can i build a VFP DLL that will create a Excel/ Powerpoint document. this DLL will be called from a .NET Web Page on click of a button. This will generate a Excel /Powerpoint Document on web server and available to user as a hyperlink on the web page.

Please reply to my email id muk944@yahoo.com
i will be highly grateful to you

thanks

re: Advanced FoxPro .NET COM Interop Article Series
by Rick Strahl January 23, 2006 @ 5:39 am

There are lots of problems passing arrays over COM. The biggest issue I know of is changing a COM array in VFP, which is a pain and sometimes doesn't work at all. Usually what you have to do is re-write the entire array to make it work.

There are many scenarios here and many don't work as you would expect, but a combination of COMARRAY and copying the elements and re-writining them gets you around most of them.

Finally if you have a choice in the matter use Collections to pass data rather than arrays. Collections are real objects and it's easier for .NET and Fox both to deal with this type of COM data.

re: Advanced FoxPro .NET COM Interop Article Series
by Mikhail Mitiaguin January 23, 2006 @ 5:57 am

Just wondering are there any complications with foxpro arrays.
There seem to be a problem when array is redimensioned or expression for the size is used when declared.

Fox

LOCAL ARRAY col_names[getwordcount(tbl_fields,',')] as String
oBuilder = createobject ( ... )
comarray(( oBuilder, 10 )
oBuilder.Buildindex( @col_names )

Net
public string BuildIndex( string[] columns )

It works OK when array size in Fox is constant.
Using ref C# or changing to passing by value doesn't really help.

re: Advanced FoxPro .NET COM Interop Article Series
by Ralf Dörfel January 31, 2006 @ 4:19 am

Dear Rick,

I am having problems with a COM-Server of a CAD software. A function needs a zero based array, as known FP-arrays always start with index 1, but I have no influence on the server.
Do you have an idea?

Best regards and thank you in advance,
Ralf Dörfel from germany

re: Advanced FoxPro .NET COM Interop Article Series
by Ralf Dörfel February 02, 2006 @ 4:37 am

Hi Rick,
ok I have found your article :-):
http://west-wind.com/weblog/posts/2328.aspx
But I am having the problem with a [m,n] dimensioned array and it still crashes.
Greetings,
Ralf Dörfel from Germany

re: Advanced FoxPro .NET COM Interop Article Series
by Curtis July 17, 2006 @ 10:03 am

Rick,

Thanks for the great article I'm using VFP 7 though and having trouble getting the hardcoded path to the type library in the "Implements IN" parameter changed the the COM progid. Foxpro says it can't find the type library when I change it to the progid any suggestions as to what I am doing wrong?

Thanks,
Curtis

re: Advanced FoxPro .NET COM Interop Article Series
by Rick Strahl July 25, 2006 @ 5:27 pm

Probably not supported in VFP 7...

In 8 and 9 you can use the ProgId of any COM object that's located in the same binary/type library and VFP will find it.

Passing Arrays to a .NET COM object from Visual FoxPro - Rick Strahl's Web Log
by Rick Strahl's Web Log November 12, 2006 @ 6:12 am

Passing arrays from VFP over COM is always a tricky affair because VFP arrays require some special marshalling hints in order to properly translate. This entry shows how to pass VFP arrays to .NET and retrieve array results from .NET COM objects.

DotNetSlackers: Advanced FoxPro COM Interop Article Series
by DotNetSlackers Latest ASP.NET News January 04, 2007 @ 11:15 am

Foxpro
by Geekzone: IT, mobility, wireless and handheld news July 13, 2007 @ 7:19 am

re: Advanced FoxPro .NET COM Interop Article Series
by Paul August 07, 2007 @ 12:47 am

Great job, Rick!
I'm using VFP 9,
Thanks for the great article!

re: Advanced FoxPro .NET COM Interop Article Series
by Allard December 19, 2007 @ 3:22 am

Thanks Rick, this article got me started using vb.net code from our existing fox application. There is one thing I cannot figure out (maybe not possible at all, but maybe you know). If you are launching forms created in .net modeless (using a separate thread), how do you make this form owned by the main foxpro form?

re: Advanced FoxPro .NET COM Interop Article Series
by Viktor May 06, 2008 @ 2:59 am

Dear Rick!

I have this "Type Library Not Foun" too. I'm using VFP9 SP2. Could you help me with some clues? I have none.

Thanks in advance!

Viktor

ps.: simple calls to COM exposed .NET functions work fine, but implementing the interface dies when giving the IMPLEMENTS... part.

re: Advanced FoxPro .NET COM Interop Article Series
by Robert September 24, 2008 @ 1:52 am

Hi Rick
I have a FOX COM using in ASP.NET, and is ok in Windows 2000, but in Windows 2003 when I try return an error : Exception HRESULT: 0x80010105 (RPC_E_SERVERFAULT). There is any special config for FOX COM use in Windows 2003 ? I try with an sample COM with only one Method Hello Word and return error too, but that same code in Windows 2000 work fine .
thanks
Robert