[wildfly-dev] A few questions about the NoSQL MongoDB client subsystem configuration...

[Brian Stansberry]

On 6/8/16 9:39 AM, Scott Marlow wrote:
> [1] is an example of the MongoDB subsystem configuration (work in
> progress), that specifies three different connection profiles
> (mongodbtestprofile_ack, mongodbtestprofile_unack,
> mongodbtestprofile_custom).  It should be easy for users to specify one
> of the MongoDB constants for the write-concern setting, for each of the
> MongoDB profiles.  Specifying a custom write-concern is also possible
> (see mongodbtestprofile_custom and underlying MongoDB java driver api [2]).
>
> In [1], I prefer the first configuration example that names the custom
> write-concern element "custom-write-concern", as I thought it might be
> confusing if users used the same "write-concern" name in two different
> places, however, using "write-concern" for both, could be more consistent.
>
> Should we use "custom-write-concern" or "write-concern" for the custom
> configuration element?
>
> It comes down to a choice between:
>
> <mongo ...>
>    ...
>    <custom-write-concern name="default” w=“1” j=“true” wtimeout=“1”/>
> </mongo>
>
> OR
>
> <mongo ...>
>    ...
>    <write-concern name="default” w=“1” j=“true” wtimeout=“1”/>
> </mongo>
>
> For those not reading [1], we also can support one of the predefined
> write-concern constants via:
>
> <mongo ... write-concern="ACKNOWLEDGED">
>    ...
> </mongo>
>

I think it's confusing to have both an attribute and an element named 
"write-concern".

Also, in the management model you are going to need to have two 
attributes, one an enum for ACKNOWLEGED etc and then another for the 
custom write concern. (The attributes would be declared as alternatives 
to each other so the user can only configure one or the other. CUSTOM 
would not be a value for the enum.)

Since you'll have two attributes in the model, probably "write-concern" 
and "custom-write-concern", it will be even more confusing to call them 
both "write-concern" in the xml.

> Also, is the 'name="default"' setting required for addressing specific
> elements with the CLI tool?  I assume this is the case but don't
> remember for sure.
>

Can there be more than 1 custom-write-concern per profile?

If not I doubt that the config of the custom write concern should be 
done via a resource. It's a complex attribute of the profile resource, 
and any "name" is superfluous.

Even if you model it via a resource, if there is only one the value part 
of the final type=value element of its address can be statically 
defined; it doesn't need to be user configurable or stored in xml.

> Thanks for the input/discussion!  :-)
>
> Scott
>
> [1] https://gist.github.com/scottmarlow/6895f15219ca16a5bc95fc19ef5b397e
>
> [2]
> https://api.mongodb.com/java/3.1/com/mongodb/WriteConcern.html#WriteConcern-int-int-boolean-boolean-
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-- 
Brian Stansberry
Senior Principal Software Engineer
JBoss by Red Hat