[Ncep.list.nems.announce] Feedback requested on replacing the NEMS build system.

[Samuel Trahan - NOAA Affiliate]

Hi all,

The NEMS build system, NEMSAppBuilder, is causing a lot of problems,
especially for the atmospheric model developers.  We plan on replacing the
build system.  What do you want out of the new build system?  What do you
dislike about the old one?

Some questions to ponder:

- How should the build system work internally?  Shell script?  Make?  Cmake?

- How should you run the build system?  Shell script?  Run "make?"  Run a
GUI?

- When do we replace the build system?  Do we do it now, and risk breaking
coupled systems?  Do we wait until we can test it with the coupled
applications?

Feedback thus far:

1. It is difficult to navigate the 1900 line NEMSAppBuilder to figure out
how to change the build commands.

2. Some users want to be able to manually build the NEMS without running an
overarching script.

3. Some users want a simple graphical interface to select components and
build the NEMS.  (Yes, there are users that want this.)

4. Sometimes, components compile with options that are incompatible with
the linking options.  This is because each component has its own
configuration system.  This causes problems, as we saw with FV3.

5. The logic for building a component is in the NEMS framework level.  Any
time a component's build system changes, the NEMS framework has to be
updated, breaking applications that use older versions of the component.
This forces applications to use non-trunk versions of the NEMS.

6.  The NEMS/src/configure script contains application-specific logic.
This also forces applications to use non-trunk versions of the NEMS.

Sincerely,
Sam Trahan
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