ASP.NET and mapscript - unable to load DLL

[Tamas Szekeres]

Mike,

I've tried this code and worked for me:

private void Page_Load(object sender, System.EventArgs e)
{
 // Put user code to initialize the page here
 using (mapObj map = new mapObj(@"C:\Maps\MapFiles\mif1.map"))
 {
  using(imageObj image = map.draw())
  {
   byte[] img = image.getBytes();
   Response.BinaryWrite(img);
  }
 }
}

I suspect you have some kind of security problem in ASP.


Tamas Szekeres

PS: To make image.getBytes work you should apply a patch described in
http://mapserver.gis.umn.edu/bugs/show_bug.cgi?id=1389





On Mon, 22 Aug 2005 10:07:35 -0400, Mike Boos <mboos at AUGSIGNALS.COM> wrote:

>I am certain the error occurs on that line - I even commented out all
>the other lines and ran it again to be sure. It is also the very first
>line in which I use the MapScript interface in the file.
>
>I have also tried invoking the MapScript code from a command line app
>and it runs successfully.
>
>Mike
>
>Tamas Szekeres wrote:
>
>>Are you sure this error happens at the row you have mentioned? It seems
>>that you are using an object instance without calling "new" previously.
>>However Mapserver errors will result in an exception passed back through
>>the SWIG interface.
>>
>>You should try to insantiate mapObj in a Windows test application. The
>>improper security context of aspnet_wp may also be a problem.
>>
>>Tamas
>>
>>
>>On Fri, 19 Aug 2005 16:58:00 -0400, Mike Boos <mboos at AUGSIGNALS.COM>
wrote:
>>
>>
>>
>>>Thank you for that advice! I ran filemon and discovered that it was
>>>trying (unsuccessfully) to find libcurl.dll - which somehow didn't show
>>>up in my dependency tracking tool. It's now in my system path.
>>>
>>>I'm now running into new trouble. When I try to create a mapObj with
>>>"mapObj m_obj = new mapObj(mapfile);" I get the following error:
>>>
>>>
>>>   /Object reference not set to an instance of an object./
>>>
>>>* Description: *An unhandled exception occurred during the execution of
>>>the current web request. Please review the stack trace for more
>>>information about the error and where it originated in the code.
>>>
>>>* Exception Details: *System.NullReferenceException: Object reference
>>>not set to an instance of an object.
>>>
>>>Any suggestions?
>>>Mike
>>>
>>>Tamas Szekeres wrote:
>>>
>>>
>>>
>>>>Have you tried SysInternals's filemon or a similar program to monitor
the
>>>>expected location of theese files?
>>>>
>>>>
>>>>
>>>>On Fri, 19 Aug 2005 13:23:38 -0400, Mike Boos <mboos at AUGSIGNALS.COM>
>>>>
>>>>
>>wrote:
>>
>>
>>>>
>>>>
>>>>
>>>>>mapscript_csharp.dll is present in the bin directory. All the others
are
>>>>>in system32. gdal12.dll is in both as I'm somehow invoking a function
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>from it from elsewhere and not having the slightest bit of trouble
with
>>>>
>>>>
>>>>
>>>>
>>>>>that part (I'm using a direct DllImport attribute). So maybe I will
have
>>>>>to try one of the alternatives. Oh well.
>>>>>
>>>>>Mike
>>>>>
>>>>>Abe Gillespie wrote:
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>>Did you move mapscript.dll to system32 as well?  The only DLL that
>>>>>>should be in your bin dir is mapscript_csharp.dll.
>>>>>>
>>>>>>Suggestions:
>>>>>>1.  Write the mapfile by hand with the file streaming objects?
>>>>>>2.  Wrap the MapServer CGI executable with ASP.NET (I think someone
>>>>>>did just this some time ago).
>>>>>>3.  If this is all you're doing, you *might* be able to get away with
>>>>>>it in ASP.NET.  See if there's a way to protect a section of ASP.NET
>>>>>>code with a semaphore or similar construct.  Is there something that
>>>>>>protects in the virtual thread environment?
>>>>>>
>>>>>>-Abe
>>>>>>
>>>>>>On 8/19/05, Mike Boos <mboos at augsignals.com> wrote:
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>>I tried moving the dlls to the system32 directory, but that doesn't
>>>>>>>
>>>>>>>
>>have
>>
>>
>>>>>>>any effect (am I missing any other dependencies?)
>>>>>>>
>>>>>>>Unfortunately, I'm kind of stuck with ASP.NET, as that's what the
rest
>>>>>>>of the site relies upon. I'm trying to improve the present setup
which
>>>>>>>involves sending a request to a C++ CGI program which writes a map
>>>>>>>
>>>>>>>
>>file
>>
>>
>>>>>>>to the hard disk and forwards the request to mapserv.exe. If you'd
ask
>>>>>>>me, that's a bit of a kluge, and without Mapscript, all I could do
to
>>>>>>>improve on that would be to take out the C++ program and have the
map
>>>>>>>file generated from within the ASP.NET program itself. Can you think
>>>>>>>
>>>>>>>
>>of
>>
>>
>>>>>>>a better way to accomplish the same task?
>>>>>>>
>>>>>>>Mike
>>>>>>>Abe Gillespie wrote:
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>>Placing the depended-on DLLs into the bin dir will do nothing.  I
>>>>>>>>assume you're on a windows box.  Therefore the easiest way to take
>>>>>>>>care of this is by placing all the DLLs (except for map_script)
into
>>>>>>>><windows>\system32 where <windows> is the system windows directory
>>>>>>>>(c:\winnt, c:\windows, etc.).
>>>>>>>>
>>>>>>>>With that said, you're entering a world of pain by using C#
>>>>>>>>
>>>>>>>>
>>map_script
>>
>>
>>>>>>>>in ASP.NET.  Much of the map_script DLL is thread unsafe, that
>>>>>>>>combined with ASP.NET's supremely weird threading model (e.g.
virtual
>>>>>>>>threads), you're going to encounter a plethora of problems.  This
is
>>>>>>>>why you almost never see MapServer + ASP.NET discussion threads.
>>>>>>>>
>>>>>>>>To get more info, search the archives.  You should find ten or so
>>>>>>>>messages about this topic.
>>>>>>>>
>>>>>>>>-Abe
>>>>>>>>
>>>>>>>>On 8/18/05, Mike Boos <mboos at augsignals.com> wrote:
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>>Hello
>>>>>>>>>
>>>>>>>>>I'm trying to run Mapscript using the SWIG C# bindings on an
ASP.NET
>>>>>>>>>server. I compiled the 4.6.0 version of MapServer and have placed
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>what I
>>>>
>>>>
>>>>
>>>>
>>>>>>>>>believe to be the appropriate dependencies (mapscript_csharp.dll,
>>>>>>>>>mapscript.dll, libmap.dll, bgd.dll, gdal12.dll, pdflib.dll) in the
>>>>>>>>>
>>>>>>>>>
>>bin
>>
>>
>>>>>>>>>directory on my server. It is appears to be finding
>>>>>>>>>mapscript_csharp.dll, but is having trouble finding mapscript.dll
or
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>one
>>>>
>>>>
>>>>
>>>>
>>>>>>>>>of its dependencies. I am seeing the following error message:
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>Server Error in '/' Application.
>>>>>>>>>
>>>>>>>>>
>>>>>>>>> /Unable to load DLL (mapscript)./
>>>>>>>>>
>>>>>>>>>* Description: *An unhandled exception occurred during the
execution
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>of
>>>>
>>>>
>>>>
>>>>
>>>>>>>>>the current web request. Please review the stack trace for more
>>>>>>>>>information about the error and where it originated in the code.
>>>>>>>>>
>>>>>>>>>* Exception Details: *System.DllNotFoundException: Unable to load
>>>>>>>>>
>>>>>>>>>
>>DLL
>>
>>
>>>>>>>>>(mapscript).
>>>>>>>>>
>>>>>>>>>Am I missing a dependency? Or do I need to set some configuration
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>option
>>>>
>>>>
>>>>
>>>>
>>>>>>>>>or place the files elsewhere?
>>>>>>>>>
>>>>>>>>>Thanks!
>>>>>>>>>Mike Boos
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>
>>>>
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>>>>
>>>>
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