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

[Gerhard Theurich]

Hi,

Just for the immediate, I am wondering what the problem is with 
NEMSAppBuilder on WCOSS? Has anybody looked into it? I thought Patrick 
was building the coupled system on WCOSS, so it does surprise me that 
Moorthi cannot get GSM standalone working.

Most important for the long term that I see is a _maintained_ system. 
Any system that is not maintained will break, especially if it has to 
cover a wide range of complex cases that keep changing (e.g. new 
components coming in). A maintained system will be able to change 
according to changing needs.

One fundamental concept of the NEMSAppBuilder was to provide a single 
place where the build recipes of all the various components are kept. 
That is why it is part of the NEMS infrastructure: any app that uses a 
specific model component (even if it is a different revision of that 
component) should be able to just tell the AppBuilder that it wants to 
build that certain component, not have to know how to do this. (In the 
current AppBuilder this is implemented via the build_xxx() routines in 
the script. E.g. build_cice() will tell the system how to build CICE. 
These routines are typically just a few lines long and use a few 
variables to get the job done.)

Another basic concept was that the configuration for an app should be 
provided by a very simple file, telling the app builder what components 
are to be built and linked together. Those are the *.appBuilder files.
Obviously the implementation details, including how maybe a GUI is 
implemented could change, but I do think the fundamental concepts and 
how they are divided between app layer and NEMS layer are still valid.

-Gerhard

On 02/07/2017 06:04 AM, Shrinivas Moorthi wrote:
> I can't compile standalone GSM on wcoss.  How do I do it without
> blackbox (appbuilder)?
> Thanks
> Moorthi
>
> On 02/07/2017 08:46 AM, Samuel Trahan - NOAA Affiliate wrote:
>> 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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>
>
> --
> Dr. Shrinivas Moorthi
> Research Meteorologist
> Global Climate and Weather Modeling Branch
> Environmental Modeling Center / National Centers for Environmental Prediction
> 5830 University Research Court - (W/NP23), College Park MD 20740 USA
> Tel:(301)683-3718
>
>
>
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