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[LDM #HII-218675]: Recommendations for calling decoders

Hi Justin,

This is the first time something like that has come up.

My preferred solution is identical to yours: have a symbolic-link reference the 
version-specific instance. This solution is even promoted for operations in the 
book "Continuous Delivery" by Humble and Farley.

I'm sure the operations people have good reasons for vetoing this solution. May 
I ask what they are?

An alternative would be to copy the version-specific decoders into an "active" 
directory every time an upgrade is performed.

In any case, because there's a period of time during which a pqact(1) process 
might not be able to invoke a decoder, the LDM system system should be stopped 
during the upgrade and restarted after it.

> Unidata,
> 
> Here at NCEP we are restructuring how our decoder software is organized on
> our supercomputers. Currently all of our decoders are stored in a generic
> directory structure that is simply overwritten when an upgraded decoder is
> put into production, we then restart LDM to pick up the new version. We are
> moving to a setup where each decoder will be stored in a directory that
> includes the decoder's version number. We are wondering if you have any
> suggestions on how to incorporate this into the pqact.conf. The most
> straightforward method would be to include the version number in the path
> to the decoder and just update the the path when a new version is made
> available, but that opens us up to typos or a situation where a new decoder
> is made available and we miss upgrading to it. We are considering using
> symbolic link that would always point to the latest decoder, the pqact.conf
> would use the symbolic link in its PIPE command. However, the production
> group is against symbolic links being set up in any of the production code
> areas.
> 
> Other organizations have had to have run into this issue, do you have any
> advice?
> 
> Thanks,
> 
> Justin Cooke
> NCEP Central Operations


Regards,
Steve Emmerson

Ticket Details
===================
Ticket ID: HII-218675
Department: Support LDM
Priority: Normal
Status: Closed