On 06/09/2016 06:27 AM, Gunnar Morling wrote:

Hi,

My concern with the current proposal and its usage of dedicated
elements/attributes for specific options such as write concern is that
it easily leads into a catch-up game with datastore vendors as they keep
adding new options. That might create a constant effort for maintaining
this subsystem.

How about having a more generic approach which only has typed elements
for common properties/settings such as user, password, database name and
then allows to set custom things as part of the connection URL:

    <subsystem xmlns="urn:jboss:domain:nosql:1.0">
        <nosql-datasource jndi-name="java:jboss/nosql/mongodb_test">

<connection-url>nosql:mongdb:localhost:27017,otherhost:27017/somedatabase?writeConcern=ACKNOWLEDGED&readPreference=MAJORITY&...</connection-url>
            <security>
                <user-name>bob</user-name>
                <password>secret</password>
            </security>
        </datasource>
    </subsystem>

Here, the connection-url would be analyzed to load the right driver and
pass any configured settings to it.

While compact, that URL syntax might be confused with existing URI
schemes of specific stores, so an alternative might be this (a bit more
verbose, though):

    <subsystem xmlns="urn:jboss:domain:nosql:1.0">
        <nosql-datasource jndi-name="java:jboss/nosql/mongodb_test">
            <driver>mongodb</driver>
            <end-points>localhost:27017,otherhost:27017</end-points>

We cannot include hostname + port numbers directly, instead we reference host names/port pairs defined in the outbound-socket-binding section of standalone.xml.

            <database>somedatabase</database>
            <security>
                <user-name>bob</user-name>
                <password>secret</password>
            </security>
            <properties>
                <property name="writeConcern">ACKNOWLEDGED</property>
                <property name="readPreference">MAJORITY</property>
            </properties>
        </datasource>
    </subsystem>

+1 for the separate properties idea!

Both alternatives don't address custom write concerns, but I think you
foresee CDI producer methods for more advanced customizations, so that
might be fine. That'd also be needed for some other non-primitive
options (dbDecoderFactory, codecRegistry etc.), unless you provide a way
to configure classes here and have them instantiated.

I'm still learning more about how to use advance customizations in the CDI producer but yes, we definitely want to do this, to simplify application program use of NoSQL.

These more generic approaches will make it more robust towards new
options being added, but of course you also loose type-safety and I
suppose usability in the console which might provide dedicated editors
for real types such as boolean etc.

I think that about summarizes the difference.  Eventually, when the configuration options stabilize, it might be better to switch to dedicated editors, which would be a big one-off upgrade, I think.  If we used dedicated editors now, we will have several big (NoSQL subsystem configuration) upgrades, as the NoSQL database options may change over time.

Thanks,
Scott

--Gunnar




2016-06-08 22:18 GMT+02:00 Brian Stansberry <brian.stansberry@redhat.com
<mailto:brian.stansberry@redhat.com>>:

    On 6/8/16 9:44 AM, Jesper Pedersen wrote:
    > On 06/08/2016 10:39 AM, Scott Marlow wrote:
    >> For those not reading [1], we also can support one of the predefined
    >> write-concern constants via:
    >>
    >> <mongo ... write-concern="ACKNOWLEDGED">
    >>     ...
    >> </mongo>
    >>
    >
    > I would choose this approach, and support the predefined constants.
    >
    > Exposing MongoDB internal API details in the configuration seems to be
    > overkill, and put extra effort on your part when they change the API.
    >

    This is good input. If this ends up in WildFly or EAP, we have stringent
    compatibility guarantees, so be cautious about exposing things in
    your API.

    >
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    >


    --
    Brian Stansberry
    Senior Principal Software Engineer
    JBoss by Red Hat
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