Can't invoke DCOM call from ASP.NET

Discussion in 'ASP .Net Web Services' started by Ron Baakkonen, Nov 19, 2003.

  1. I want to wrap a legacy COM dll within an ASP.NET app. The dll
    incorporates a DCOM call to a remote server and will return data,
    which the ASP.NET application will pass through. Changing either the
    dll or the server interface it speaks to will be difficult.

    I built an Interop wrapper for the COM dll and it runs fine from a
    ..NET console application.

    However, when I try use the same wrapper from within an ASP.NET
    application, it fails. The Event Viewer shows me:

    DCOM got error "No such interface supported " from the computer
    DEVSERV when attempting to activate the server:
    {5001A9D4-6FC0-11D4-8B67-0001023E56B0}


    I've set the IIS default web site directory security user name to a
    valid user account (my own) and have put the line

    <identity impersonate="true"></identity>

    in my project's web.config file.

    Can anyone help? Thanks.
     
    Ron Baakkonen, Nov 19, 2003
    #1
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  2. "Ron Baakkonen" <> wrote in message
    news:...
    > I want to wrap a legacy COM dll within an ASP.NET app. The dll
    > incorporates a DCOM call to a remote server and will return data,
    > which the ASP.NET application will pass through. Changing either the
    > dll or the server interface it speaks to will be difficult.
    >
    > I built an Interop wrapper for the COM dll and it runs fine from a
    > .NET console application.
    >
    > However, when I try use the same wrapper from within an ASP.NET
    > application, it fails. The Event Viewer shows me:
    >
    > DCOM got error "No such interface supported " from the computer
    > DEVSERV when attempting to activate the server:
    > {5001A9D4-6FC0-11D4-8B67-0001023E56B0}


    It looks as if the DCOM assembly wrapper GAC registrion has not taken place.
    Create a wrapper using AL.EXE
    and place it inside your ASP.NET code... using GACUTIL you can tell the
    environmnet to trust the assembly... if you're environmnent is very save,
    you'll also need to create and place a strong key inside your new assembly
    wrapper using sn.exe, no easy tasks but using the msdn you'll come very far.
    http://msdn.microsoft.com/library/en-us/dnanchor/html/netfxanchor.asp?frame=true

    besides, using DCOM at a HTTP level server, is not a good choice, because of
    thread blocking it utilizes... A DCOM server is thread affinity tuned while
    ASP and ASP.NET are not.

    >
    > I've set the IIS default web site directory security user name to a
    > valid user account (my own) and have put the line
    >
    > <identity impersonate="true"></identity>
    >
    > in my project's web.config file.
    >
    > Can anyone help? Thanks.
     
    Egbert Nierop \(MVP for IIS\), Nov 24, 2003
    #2
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  3. Thanks for the reply. I'll play around and see if I can get this to
    work.

    However, it sounds like I should try a different approach. I've got a
    substantial in-house application written in unmanaged C++ (COM/ATL/etc.)
    that supports a bunch of VB clients.

    I would like to make this server available via web services. However, I
    don't want to put the server directly in the DMZ. What is the best way
    to communicate between IIS and my server? I've got a legacy DCOM dll
    that does the job just fine for our VB apps and the simplest thing would
    be to reuse it. However, it sounds like this isn't terribly efficient,
    any suggestion?

    Thanks.



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    Ron Baakkonen, Nov 24, 2003
    #3
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