Handling System._ComObject -- using CCW

[Varun Singal]

Hi

I am calling .NET components from my Classical ASPs.
For this I strong named my assemblies, then registered them in the resistry
( using RegAsm), and put them in GAC (using GacUtil) .
Everything worked fine and my ASPs were able to call and use them.

The problem comes when my ASP code assigns an ASP object variable to a
property of a class in the assembly like:
oDotNetObject(" Name") = Request("Name")
( where oDotNetObject is a class in my registered assembly )

The COM Callable Wrapper sends it as System._ComObje ct to .NET Runtime which
then throws exception as nothing is allowed on System._ComObje ct. On the
other hand, passing it as Variant solves the problem.
Dim varName = Request("Name")
oDotNetObject(" Name") = varName

But this would require a significant change in my ASP pages. I want to
modify only my .NET components. Is there any way I can use this
System._ComObje ct in my managed code or any way I can make CCW to handle it.
I was trying to use System.Runtime. InteropServices .Marshal namespace to use
the System._ComObje ct I have not been able to do it.

Thanks in anticipation
Varun

[Varun Singal]

Re: Handling System._ComObje ct -- using CCW

Thanks Oisin

But here my problem is that I am working on a huge application and I cant
change this usage in ASP files.
So I have to find a solution in .Net component -- as you said -- i will have
to marshal a com object
Any ideas about that!

Thanks
Varun

"Oisin Grehan" <oising@nospam. iol.ie.> wrote in message
news:OFHJDiJRDH A.3664@tk2msftn gp13.phx.gbl...[color=blue]
> By assigning Request("Name") to the property, you are using a bad habit[/color]
most[color=blue]
> of us have by relying on default properties. Take a look at this:
>
> <%
> Dim strName
> strName = Request("Name")
> %>
>
> The ASP engine will assigning the default property (which happens to be
> "Item") to the variable and everything will be fine. However, when you[/color]
use:[color=blue]
>
> oDotNetObject(" Name") = Request("Name")
>
> You are relying on the DotNet class to retrieve the default property from
> the COM object "Request". If you use:
>
> oDotNetObject(" Name") = Request("Name") .Item
>
> Everything should be mostl likely be fine as you are not longer[/color]
marshalling[color=blue]
> a COM object, but rather a simple string.
>
> Hope this helps,
>
> - Oisin
>
>
>
>
>
> "Varun Singal" <varun.singal@i nduslogic.com> wrote in message
> news:u$7ErPJRDH A.1624@tk2msftn gp13.phx.gbl...[color=green]
> > Hi
> >
> > I am calling .NET components from my Classical ASPs.
> > For this I strong named my assemblies, then registered them in the[/color]
> resistry[color=green]
> > ( using RegAsm), and put them in GAC (using GacUtil) .
> > Everything worked fine and my ASPs were able to call and use them.
> >
> > The problem comes when my ASP code assigns an ASP object variable to a
> > property of a class in the assembly like:
> > oDotNetObject(" Name") = Request("Name")
> > ( where oDotNetObject is a class in my registered assembly )
> >
> > The COM Callable Wrapper sends it as System._ComObje ct to .NET Runtime[/color]
> which[color=green]
> > then throws exception as nothing is allowed on System._ComObje ct. On the
> > other hand, passing it as Variant solves the problem.
> > Dim varName = Request("Name")
> > oDotNetObject(" Name") = varName
> >
> > But this would require a significant change in my ASP pages. I want to
> > modify only my .NET components. Is there any way I can use this
> > System._ComObje ct in my managed code or any way I can make CCW to handle[/color]
> it.[color=green]
> > I was trying to use System.Runtime. InteropServices .Marshal namespace to[/color]
> use[color=green]
> > the System._ComObje ct I have not been able to do it.
> >
> > Thanks in anticipation
> > Varun
> >
> >[/color]
>
>[/color]

[Oisin Grehan]

Re: Handling System._ComObje ct -- using CCW

Varun, surely it is more work to facilitate this than to spend a while with
global find/replace with regex on those ASP files? Marshalling COM objects
instead of strings is hugely inefficient, incredibly lazy as well as just
plain wrong. But, if you really are a masochist (or an assembly
programmer -- same thing), keep reading:

First of all, I hope you're comfortable with COM interop, IDL, type
libraries and other such nasties. I'm not an interop specialist nor a COM
guru by any means, so I can only try to direct you. Right, since you're
passing in a System._ComObje ct object, I believe you'll need to use the
MarshalAs attribute to tell .NET that you're expecting
UnmanagedType.I Dispatch. "Request" is an IDispatch object. If we inspect the
IDL with OleView (tool included with VS) by pointing it at the ASP type
library available at C:\Program Files\Microsoft Visual
Studio\Common\I DE\IDE98\asp.tl b assuming you've got Vstudio 6.0 installed in
the default location, you can see the following info (trimmed down for
brevity) for IRequest:

[odl, uuid(D97A6DA0-A861-11CF-93AE-00A0C90C2BD8), hidden, dual,
oleautomation]
interface IRequest : IDispatch {
[id(00000000), propget]
HRESULT Item([in] BSTR bstrVar, [out, retval] IDispatch** ppObjReturn);

HRESULT QueryString([out, retval] IRequestDiction ary** ppDictReturn);
HRESULT Form([out, retval] IRequestDiction ary** ppDictReturn);
};

You'll see that Item is the default property (IDL id of 0), it returns an
IDispatch interface, most likely this one in your case:

[odl, uuid(D97A6DA0-A85F-11DF-83AE-00A0C90C2BD8), helpstring("Dic tionary for
Request collections"), hidden, dual, oleautomation]
interface IRequestDiction ary : IDispatch {
[id(00000000), propget]
HRESULT Item([in, optional] VARIANT Var, [out, retval] VARIANT*
pVariantReturn) ;
};

Again, you can see the default property for the IRequestDiction ary is Item
also, which returns a variant. This is the variant you need to get your
grubby hands on. All the information you'll need to imbibe and understand is
on MSDN. A good place to start is to look up the MarshalAs attribute and
pay attention to the UnmanagedType enumeration. There's some good example
code there.

Now, if this hasn't put you off, you plainly have access to the ASP
source -- is it really that huge a task to change it? Open all ASP pages in
VS.NET, use Find/Replace with Regular Expressions. Replace .*
\=\s?Request\(" {.*}\"\) with = Request("\1").I tem. Bingo, assuming that
Regex expression out of my head is correct. If you have the time, sit back
and learn COM interop. If that looks like too steep a hill to climb, change
the ASP pages, or better yet, learn Regular Expressions. It'll be the best
hour you've spend in front of the computer today and it will pay you back
many times over.

Hope this helps,

- Oisin







"Varun Singal" <varun.singal@i nduslogic.com> wrote in message
news:eNzcCRKRDH A.3768@tk2msftn gp13.phx.gbl...[color=blue]
> Thanks Oisin
>
> But here my problem is that I am working on a huge application and I cant
> change this usage in ASP files.
> So I have to find a solution in .Net component -- as you said -- i will[/color]
have[color=blue]
> to marshal a com object
> Any ideas about that!
>
> Thanks
> Varun
>
> "Oisin Grehan" <oising@nospam. iol.ie.> wrote in message
> news:OFHJDiJRDH A.3664@tk2msftn gp13.phx.gbl...[color=green]
> > By assigning Request("Name") to the property, you are using a bad habit[/color]
> most[color=green]
> > of us have by relying on default properties. Take a look at this:
> >
> > <%
> > Dim strName
> > strName = Request("Name")
> > %>
> >
> > The ASP engine will assigning the default property (which happens to be
> > "Item") to the variable and everything will be fine. However, when you[/color]
> use:[color=green]
> >
> > oDotNetObject(" Name") = Request("Name")
> >
> > You are relying on the DotNet class to retrieve the default property[/color][/color]
from[color=blue][color=green]
> > the COM object "Request". If you use:
> >
> > oDotNetObject(" Name") = Request("Name") .Item
> >
> > Everything should be mostl likely be fine as you are not longer[/color]
> marshalling[color=green]
> > a COM object, but rather a simple string.
> >
> > Hope this helps,
> >
> > - Oisin
> >
> >
> >
> >
> >
> > "Varun Singal" <varun.singal@i nduslogic.com> wrote in message
> > news:u$7ErPJRDH A.1624@tk2msftn gp13.phx.gbl...[color=darkred]
> > > Hi
> > >
> > > I am calling .NET components from my Classical ASPs.
> > > For this I strong named my assemblies, then registered them in the[/color]
> > resistry[color=darkred]
> > > ( using RegAsm), and put them in GAC (using GacUtil) .
> > > Everything worked fine and my ASPs were able to call and use them.
> > >
> > > The problem comes when my ASP code assigns an ASP object variable to a
> > > property of a class in the assembly like:
> > > oDotNetObject(" Name") = Request("Name")
> > > ( where oDotNetObject is a class in my registered assembly )
> > >
> > > The COM Callable Wrapper sends it as System._ComObje ct to .NET Runtime[/color]
> > which[color=darkred]
> > > then throws exception as nothing is allowed on System._ComObje ct. On[/color][/color][/color]
the[color=blue][color=green][color=darkred]
> > > other hand, passing it as Variant solves the problem.
> > > Dim varName = Request("Name")
> > > oDotNetObject(" Name") = varName
> > >
> > > But this would require a significant change in my ASP pages. I want to
> > > modify only my .NET components. Is there any way I can use this
> > > System._ComObje ct in my managed code or any way I can make CCW to[/color][/color][/color]
handle[color=blue][color=green]
> > it.[color=darkred]
> > > I was trying to use System.Runtime. InteropServices .Marshal namespace[/color][/color][/color]
to[color=blue][color=green]
> > use[color=darkred]
> > > the System._ComObje ct I have not been able to do it.
> > >
> > > Thanks in anticipation
> > > Varun
> > >
> > >[/color]
> >
> >[/color]
>
>[/color]