Message registries continuation

[James Feist]

On 6/16/2020 12:47 PM, Matt Spinler wrote:
> Hi James,
> 
> Picking up the discussion again from 
> https://lists.ozlabs.org/pipermail/openbmc/2020-February/020620.html
> about reading  in message registries...
> 
> When this was left off, I believe we were leaning toward being able to 
> copy message registry JSON files
> into some target directory on the BMC during the build where bmcweb 
> would load them on startup
> and leave them in their JSON objects, and they would be pulled from 
> there when LogService requests
> were made.
> 
> This was to be able to support multiple languages, and in general just 
> to support other registries besides
> the existing OpenBMC one that is hardcoded in a header file.  (We're 
> going to have an IBM registry we
> use together with our D-Bus logs based LogService.)

There's 3 registries, fwiw: 
https://github.com/openbmc/bmcweb/tree/master/redfish-core/include/registries

> 
> An open issue we still had was if these registries had to be validated, 
> or if that was left to whoever
> made them.  A stake in the ground could be that we leave the OpenBMC 
> registry as it is in a header
> file, which negates validation, or put it in JSON too and validate just 
> that one during the build.
> Or if there are any other ideas here...

Entity-manager uses valijson, in that way you could validate them 
against a schema: https://github.com/tristanpenman/valijson. It plays 
nicely with nlohmann-json. Although if these are compiled in json files, 
I'm not sure it's a large issue. We could just create a compile-time 
script to validate.

> 
> As far as the directory used, I think that /usr/share/bmcweb/ would be 
> appropriate, or maybe
> /usr/share/bmcweb/registries/ if either of those are OK with you.

I think the directory is a good idea so it can load any json file from 
that directory. Maybe /usr/share/bmcweb/registries/<language> even to 
make it easier to switch between languages?

> 
> Also, it may be overkill to need to  read in the same registry for every 
> language, as there could
> be dozens and realistically they will never all be used on a single 
> system, but if the desire is only
> to load them at startup before the current language is known I don't 
> really see a way around it.

I think this would require a default language and a bmcweb reload if the 
language changed? Its probably ok to change languages after startup, as 
long as the default language is loaded immediately to lower the chances 
of run-time issues. As changing languages is probably a very infrequent 
operation.

> 
> Thanks!
> Matt