ASP.NET and mapscript - unable to load DLL

[Mike Boos]

This isn't really a 'fix', but I found it would actually work after I 
restarted IIS. So the problem is no longer reproducable, and I'm not 
sure what is causing it. Thanks for the advice though.

Mike

Mike Boos 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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