Assembly loaded twice when Assembly.LoadFrom() is used

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fermo111 - 25 Sep 2004 00:39 GMT

The following code results in a strange behavior.

Assembly formAsm = Assembly.LoadFrom ("http://localhost/net/MyAssembly.dll");
Type formType = formAsm.GetType ("MySpace.MyForm");
object formObj = Activator.CreateInstance (formType);

Looking at the HTTP requests that are made, I noticed
that the assembly is requested twice from the server.
The first time the HTTP message is

GET /net/MyAssembly.dll

and the second time is

GET /net/MyAssembly.DLL (DLL is uppercase this time)

The result is that the DLL takes twice the time to download.

Any help on this?

Luca

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Ken Kolda - 25 Sep 2004 01:11 GMT

Although I can't explain that behavior, have you tried using

object frmObj = formAsm.CreateInstance("MySpace.MyForm")

instead?

Ken

> The following code results in a strange behavior.
>
[quoted text clipped - 17 lines]
>
> Luca

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fermo111 - 25 Sep 2004 22:02 GMT

I used a packet analyzer to monitor the communications.
The behavior that I described happens on the call to

Assembly.LoadFrom ("http://localhost/net/MyAssembly.dll")

and before the execution of the following lines.
Hope this may help to delimitate the problem.

Thank you

> Although I can't explain that behavior, have you tried using
>
[quoted text clipped - 26 lines]
> >
> > Luca

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Girish Bharadwaj - 27 Sep 2004 19:18 GMT

What is the HTTP response for the first request. The server might be
responding with a "file not found"?

Signature

Girish Bharadwaj
http://msmvps.com/gbvb

> I used a packet analyzer to monitor the communications.
> The behavior that I described happens on the call to
[quoted text clipped - 36 lines]
> > >
> > > Luca

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fermo111 - 29 Sep 2004 14:03 GMT

Here is the output from the packet analyzer (semplified).
Note that the only difference between the 2 requests is the
capitalization of the extention (dll the first time, DLL the second
time).
Moreover the second request ignores the fact that the DLL has already
been transferred and doesn't send a
    If-Modified-Since: Fri, 24 Sep 2004 11:11:25 GMT
header on the HTTP request as one might have expected

Luca

Trace follows...

First Request
    Version: HTTP/1.1
    Method: GET
    URI: /siarm/dll/RichiesteAttivazione.dll
    Accept: */*
    Accept-Encoding: gzip, deflate
    User-Agent: Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.0; .NET
CLR 1.1.4322; .NET CLR 1
    Host: agrisrv
    Connection: Keep-Alive

First Response
    Version: HTTP/1.1
    Result code: 200
    Result string: OK
    Server: Microsoft-IIS/5.0
    MS-Author-Via: MS-FP/4.0,DAV
    MicrosoftOfficeWebServer: 5.0_Collab
    X-Powered-By: ASP.NET
    Date: Wed, 29 Sep 2004 12:39:59 GMT
    Content-Type: application/x-msdownload
    Accept-Ranges: bytes
    Last-Modified: Fri, 24 Sep 2004 11:11:25 GMT
    ETag: "c5aa883b27a2c41:a69"
    Content-Length: 36864

Second Request
    Version: HTTP/1.1
    Method: GET
    URI: /siarm/dll/RichiesteAttivazione.DLL
    Accept: */*
    Accept-Encoding: gzip, deflate
    User-Agent: Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.0; .NET
CLR 1.1.4322; .NET CLR 1
    Host: agrisrv
    Connection: Keep-Alive

Second response
    Version: HTTP/1.1
    Result code: 200
    Result string: OK
    Server: Microsoft-IIS/5.0
    MS-Author-Via: MS-FP/4.0,DAV
    MicrosoftOfficeWebServer: 5.0_Collab
    X-Powered-By: ASP.NET
    Date: Wed, 29 Sep 2004 12:39:59 GMT
    Content-Type: application/x-msdownload
    Accept-Ranges: bytes
    Last-Modified: Fri, 24 Sep 2004 11:11:25 GMT
    ETag: "c5aa883b27a2c41:a69"
    Content-Length: 36864

> What is the HTTP response for the first request. The server might be
> responding with a "file not found"?
[quoted text clipped - 41 lines]
> > > >
> > > > Luca

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Phil Wilson - 25 Sep 2004 18:22 GMT

I've seen this in similar circumstances, and it's my guess that when .NET
needs the assembly for reflection/metadata purposes it loads it as a
resource, and when it's needed for calling entrypoints, it loads it as an
executable DLL. The result is that the DLL has two occurrences in the
hosting process.

Signature

Phil Wilson
[MVP Windows Installer]
Definitive Guide to Windows Installer
http://www.amazon.com/exec/obidos/tg/detail/-/1590592972/104-7044380-4696760

> The following code results in a strange behavior.
>
[quoted text clipped - 18 lines]
>
> Luca

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Assembly loaded twice when Assembly.LoadFrom() is used

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