Re: [Quickfix-developers] "Cannot pass a GCHandle across AppDomains"

[goncalvm <mar...@pa...>]

Hi Scott,

I am having the same problem as yours. I am creating a VSTO addin and
appdomain problem came up. I don't know anything about c++. Do you have any
sample or any article in c#? 
I tried to build an ActiveX instead and it worked well, but when I press F2
(edit mode in Excel) I lost messages.
Any help will be appreciated!

Best regards,

Marco


Scott Kathrein wrote:
> 
> QuickFIX Documentation:
> http://www.quickfixengine.org/quickfix/doc/html/index.html
> QuickFIX Support: http://www.quickfixengine.org/services.html
> 
> 
> Well, I don't, I think.
> 
> Visual studio was creating the AppDomains for me because I was creating a
> Visual Studio Tools for Office project in visual studio 2008. (I believe
> it
> was creating a "shim"). I've reconfigured my project to create a plain old
> class library, which I then register the same way with regasm, and this
> works, presumably because there is no AppDomain creation.
> 
> I was a little worried I wouldn't have much control over when Excel
> creates
> AppDomains and the like... but it seems to be working now.
> 
> If this is a known issue, maybe it would make sense to post a warning
> somewhere about the .NET wrapper? I've seen a couple people (1 of them
> using
> quickfix) have this problem when using NUnit, as it creates AppDomains and
> apparently VSTO does so too.
> 
> I wasn't sure at first exactly *how* I was passing a GCHandle across
> appdomains. I mean, all of quickfix should be in the same appdomain,
> right?
> But the page I linked above seems to explain it pretty well. Apparently
> unmanaged code doesn't *have* an appdomain, and so when it calls into
> managed code, the compiler just *picks* a random one, namely the "first"
> one, which in this case might have been the default Excel appdomain.
> 
> The problem then is not caused by wanting to pass a handle between
> appdomains, but rather by the simple *existance* of more than one
> appdomain,
> which consequently causes the compiler to bork and say "meh, this code's
> not
> managed, we'll just choose any old appdomain we feel like to handle this
> callback!"
> 
> The solution, is to use delegates, so the compiler knows which appdomain
> to
> use when unmanaged code goes into managed code.
> 
> Losing the ability to use multiple appdomains has it's cost, most of which
> I'm clueless about, not really being an expert on all this stuff.
> 
> So that seems to be the long and short of it! Instead of posting a warning
> about your wrapper, maybe microsoft should post a warning whenever you try
> to use their compiler! (Or at least when unmanaged code calls back into
> managed code.)
> 
> Scott
> 
> On Mon, Jun 21, 2010 at 7:21 PM, Diego Frata <die...@gm...>
> wrote:
> 
>> Scott,
>>
>> Why do you need to pass a GCHandle across AppDomains?
>>
>> Diego Frata
>> die...@gm...
>>
>>
>> On Mon, Jun 21, 2010 at 1:59 PM, Scott Kathrein <
>> sc...@la...> wrote:
>>
>>> QuickFIX Documentation:
>>> http://www.quickfixengine.org/quickfix/doc/html/index.html
>>> QuickFIX Support: http://www.quickfixengine.org/services.html
>>>
>>>
>>>
>>> So here's the issue: I'm trying to create a COM object for use in Excel,
>>> and I'm using the quickfix .NET wrapper API from version 1.13.3. I'm
>>> compiling the quickfix library from source, but I have not made any
>>> changes
>>> to it.
>>>
>>> Most the time everything works fine, but when I do an
>>> "initiator.start()",
>>> at some point subsequently the Log class gets invoked to send out
>>> "Connecting to x on port x", and I receive a "Cannot pass a GCHandle
>>> across
>>> AppDomains" exception that occurs when the onEvent method of the Log
>>> class
>>> is (attempted to be) accessed.
>>>
>>> If this is what it looks like, then the solution is very complicated and
>>> uses delegates, and possibly a total rewrite of the .NET wrapper:
>>> http://lambert.geek.nz/2007/05/29/unmanaged-appdomain-callback/
>>>
>>> This appears to be a long standing problem with Quickfix. I've found a
>>> number of people receiving this exception.
>>> For example, here:
>>> http://article.gmane.org/gmane.comp.finance.quickfix.user/1362 (2009,
>>> has
>>> workaround)
>>> or here: http://osdir.com/ml/finance.quickfix.user/2006-10/msg00019.html
>>> (from
>>> 2006, says he contacted another user wit the same problem who had to
>>> develop
>>> his own fix implementation)
>>>
>>> Right now I can't directly search the mailing list (any search I do
>>> returns no results), so I guess my questions are this:
>>>
>>> Is this still a known problem with Quickfix and appdomains? Is the only
>>> real workaround to ensure that all of quickfix runs in one appdomain?
>>>
>>> If so, I'll have to look into doing that, or considering whether this
>>> project should be abandoned. It's not clear to me if it's possible to
>>> always
>>> ensure something is running in one appdomain, and I'd rather not invest
>>> a
>>> lot of time into this and have it run buggy.
>>>
>>> Scott
>>>
>>>
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>>
>>
> 
> ------------------------------------------------------------------------------
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> GeekDad Father's Day Giveaway. ONE MASSIVE PRIZE to the 
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