Could not locate Comsol 5.2 on Windows

[Darkforg]

Hello!

As seen in #150 I have the same problem, even though comsol is put on the default folder, mph cannot locate the installation. I understand (as I saw in documentaiton) that this is probably because of comsol's version (5.2). It is also classkit license but from what i saw, it is possible to work with that with the appropriate mph.options() command.

Right now, it is impossible for me to change comsol version. Is there a way I could recieve some guidance on how to make it work? I understand you will need more information on how the installation/folders are placed.

[john-hen]

The first step is to run the "discovery" part of the test suite. It should look something like this:

❯ python tools\test.py discovery --log
Running test group "discovery".
[00:00.659] Searching system for available Comsol back-ends.
[00:00.659] Searching Windows Registry for Comsol executables.
[00:00.659] Checking registry node "SOFTWARE\Comsol\COMSOL55".
[00:00.659] Checking installation folder "C:\Program Files\Comsol55\Multiphysics".
[00:00.659] Found Comsol executable "C:\Program Files\Comsol55\Multiphysics\bin\win64\comsol.exe".
[00:00.675] Looking for Comsol executable on system search path.
[00:00.675] Running shell command "where comsol".
[00:00.769] Command exited with an error.
[00:00.769] Checking executable "C:\Program Files\Comsol55\Multiphysics\bin\win64\comsol.exe".
[00:00.769] Found Java bridge configuration "C:\Program Files\Comsol55\Multiphysics\bin\win64\comsol.ini".
[00:00.769] System architecture is "win64".
[00:00.769] Java VM at relative path "..\..\java\win64\jre\bin\server\jvm.dll".
[00:00.785] Root folder is "C:\Program Files\Comsol55\Multiphysics".
[00:01.570] Reported version information is "COMSOL Multiphysics 5.5.0.359".
[00:01.570] Assigned name "5.5" to this installation.
Passed in 2 s.

You'll have to download or git clone the source code from here on GitHub. I'd also recommend you uninstall your existing MPh and install from source in editable mode: pip install -e .[dev]. This means you can change the source code as you wish and use that modified version in your Python scripts. The [dev] extra installs tools such as pyTest, which is needed to run the test suite. You are looking for differences between your Comsol 5.2 and Comsol 5.5, used in the test above. Differences in terms of where files/folders are located inside the Comsol folder.

[Darkforg]

The other options are:
Build the current JPype 1.4.1 from source using a Java 7 development kit, then pip-install that.

I am willing to give that a go if you could give me the general direction. I do understand I have already taken too much of your time and I would not want to impose.

[john-hen]

Instructions for building JPype from source can be found in its documentation: https://jpype.readthedocs.io/en/latest/install.html#build-and-install-manually

But first you'll need to install Java and C++ compilers. The latter means, get Visual Studio (the free Community Edition will do) and install the C++ tool chain. And you need a Java 7 development kit (JDK 7). I would try maybe winget install -i Azul.Zulu.7.JDK (but I haven't tried), otherwise google to find an installer. Obviously Java 7 is pretty old by now, so won't be that easily available anymore. Make sure you're setting the JAVA_HOME environment variable. Then compile JPype as per the docs.

[Darkforg]

Thank you for your invaluable help.

I will try to do it and contact you for the results a.s.a.p.

[john-hen]

I looked into this a little bit today. Unfortunately, I can't get any (reasonably recent) version of JPype to build with Java 7. So I guess when Thrameos (the JPype developer) said "It may still be possible to compile a library for the older Java versions", he was being optimistic. There is a Java 8 syntax feature (the double-colon operator, ::) that JPype has embraced quite a bit. And I, for one, do not know how to back-port all that to equivalent Java 7 syntax. So I think this is a dead end.

If you want to pursue the other option (running Comsol with an external Java 8 run-time environment), you'd have to patch the backend() function in discovery.py to return a dictionary with the correct values filled in. Something like:

def backend(version=None):
    build = 0   #  I don't know actual the build number, but it shouldn't matter.
    root = Path(r'C:\Program Files\COMSOL\COMSOL52\Multiphysics')
    jvm = Path('...')  # absolute path to the external Java 8 `jvm.dll`
    server = root/'bin'/'win64'/'comsolmphserver.exe'
    return  {
      'name':   '5.2',
      'major':  5,
      'minor':  2,
      'patch':  0,
      'build':  build,  
      'root':   root,
      'jvm':    jvm,
      'server': server,
    }

Everything else in discovery.py is then irrelevant and could even be removed. I'd install AdoptOpenJDK 8, as that's what Comsol uses in later versions, and it should be backward-compatible.

[Darkforg]

Thank you for the new information. Unfortunately I haven't managed to look at it yet due to other commitments. I will certainly look into it and notify you when there is something to share. It would be great if I managed to make a useful contribution.