launchpad-dev team mailing list archive

[Julian Edwards <julian.edwards@xxxxxxxxxxxxx>]

On Wednesday 19 May 2010 02:25:35 Robert Collins wrote:
> FWIW I think that refactoring to make the internal API match an ideal
> web services API is good in principle. However we may need to change
> our coding style substantially to end up with an ideal web services
> API - if you examine the EC2 API, which is nice to work with, to do
> fast operations on multiple objects is ingrained - its not ingrained
> for our local API.
> 
> And there is the issue I think: what makes a great web services API is
> fundamentally different to what makes a great in-app-server API. The
> latency and bandwidth constraints are radically different.
> 
> For instance, in a web services API consumer, you want the server to
> do as much filtering as possible, but then return *all* the relevant
> data at once. Round trips are terrible. (350ms from here).
> 
> In a in-app-server API you probably want an object model, with methods
> on self, rather than collections that mutate a set of objects.

To some extent I agree, but the performance implications still apply to the 
internal API.  We do quite a lot of utility code that will pull in many 
objects at once.  ORMs don't exactly encourage that :(