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From David Lutterkort <lut...@redhat.com>
Subject Re: deltacloud as a lib and broker
Date Wed, 10 Apr 2013 17:39:06 GMT
Hi Martin,

On Wed, 2013-04-10 at 15:53 +0200, Martin Povolny wrote:
> I think that Jan's original idea was to expose sort-of-cleaned-up driver
> API as the universal library API.
> 
> That is mainly work through the controller methods that implement the
> API calls and
> 
>   * identify and fix the places where there is any other code then such
>     that parses and passes the inputs, outputs and error state between
>     the REST remote call and the drivers.
>   * unify the driver interface where differences exist
> 
> Then just provide some class that basically delegates everything to a driver.

If by 'delegate' you mean 'wrap', i.e. have a tiny little bit of logic
in between that allows us to adjust to changes in the driver API, then
yes. Just as an example: we recently went through and made driver
methods return empty arrays in a lot of places where they used to return
nils. We need to have a place where we insulate library users from these
sort of changes.

> As I read it, what you suggest is implementing a Ruby-style API on top
> of the cleaned-up driver API.
> 
> Having such layer on top of that is not what Jan suggested, but it would
> surely be convenient from consumer point of view.
> 
> Also it would allow more changes in the driver API if the Ruby-style API
> would be what is advertised as "the thing" to the community. The
> Ruby-style API could then be the "air bag" that keeps the backward
> compatibility even if the driver API changes.
> 
> I personally like the idea as it is surely more Ruby-dev (community)
> friendly. But it is then a thing of a wider scope.
> 
> We should probably take a look at other libraries out there (both
> provider-specific and sort-of-universal, such as the Fog) to see the
> programming idioms that people might be already used to.

The reason I suggested the more Ruby-ish API is that I agree that we
might be able to attract more people with the library API, but I don't
think the current driver API is very attractive for that.

Geemus used to be very proud of the fact that Fog exposes a AR-inspired
API - that's the kind of thing we should aim for here (not that I think
AR is the right metaphor, but it's a good inspiration)

David



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