[Opensim-dev] Proposal for removing "ERROR: There was an error while scanning assembly:" messages

[Melanie]

Hi,

if you are looking into shell scripts, please consider that your 
normal Linux admin will run OpenSim as a separate user. The 
MONO_PATH can easily be set in that users .profile, making 
cumbersome shell scripts totally unnecessary.
So, if you do provide any shell scripting, please provide it as an 
_additional_ way to start the programs, don't go renaming programs.

Melanie


Justin Clark-Casey wrote:
> Hello,
> 
> This is a technical post but I'm copying it to users for information.  
> You may (or may not) want to stop reading quickly :-)
> 
> So, some of you may have noticed that the latest OpenSim revisions now 
> have many more of the subject error messages on the console.  The cause 
> is the Mono Addins manager we're using, which writes these errors to the 
> console if the dll doesn't contain the configuration data it's expecting.
> 
> So today I looked at removing these errors.  I had to follow several 
> lines of investigation.
> 
> 1.  My initial thought was to move all the external libraries which are 
> causing the problem to a separate $OPENSIM_ROOT/lib/ext directory.  
> However, this means changes to make sure that the dlls can be found in 
> the new directory.  For a cross platform application, it's hard.  On 
> Microsoft's CLR we can simply use <Probing> in config files.  However, 
> Mono does appear to support this, at least according to
> 
> http://www.mono-project.com/Assemblies_and_the_GAC
> 
> I tried it anyway, without success.  Instead, the only option on Mono is 
> to either set the MONO_PATH or put the assemblies in the Global Assembly 
> Cache.
> 
> 2.  This makes things awkward, so instead I looked at moving the plugin 
> dlls.  Same problem.
> 
> 3.  So instead I looked at simply suppressing the messages.  
> Unfortunately, the Mono addins code writes these messages out to the 
> console.  Although in theory you could give it an IProgressMonitor and 
> stop this, all the classes for this (and the interface) are internal and 
> hence not accessible.  Later versions of mono-addins than the one we are 
> using would appear to have the same problem.
> 
> So although we could hack the code in 3. to remove the message (or even 
> replace or code our own plugin solution), the fact is that we really 
> need to have dlls in different directories eventually anyway - bin/ is 
> already overloaded.  This means I'm forced to come back to suggestion 
> 1.  Putting things in the GAC is unrealistic at this stage I think, so 
> I'm proposing that we move all the external libraries to 
> $OPENSIM_ROOT/lib/ext and set the MONO_PATH environmental variable to 
> point to this directory.  Under Windows, we would instead put <Probing> 
> entries in the executable's config files.
> 
> I tried setting MONO_PATH programatically in OpenSimMain.cs, but the set 
> doesn't look like it is exported so the load fails.  The same path works 
> fine when exported from the command line.
> 
> If we go the MONO_PATH route, then I think we could provide shell 
> scripts for all the executables to set the path and then launch the 
> program, even though this is a little messy.  The executable itself 
> would complain loudly if it is not on Windows and MONO_PATH is unset 
> (which would be inconvenient for Windows mono users, though there may 
> not be that many of them).
> 
> I'm open to constructive suggestions on this, particularly from core 
> developers.
>