[sheepdog] [RFC] REST gateway design choice

[MORITA Kazutaka]

At Sun, 30 Jun 2013 17:57:38 +0800,
Liu Yuan wrote:
> 
> Hello list,
> 
>       I am writing REST gateway to support HTTP request via fastcgi. There is
> one fundamental choice regarding where we put the code and both has pros and
> cons:
> 
>  1. bulit-in the code inside the sheep binary
>     pros:
>      - share lots of infrastructure code, such as work queue, logger

We can reuse them like collie and shepherd because they are in the
lib directory.

>      - simpler interface, just start 'sheep' as usual we gain REST gateway
>        function, no extra parameter needed.

I think we need a parameter to enable (or disable) the REST gateway
for the users who don't use the interface.

>      - most efficient data transfer between sheep and REST code, no data
>        transfer at all since they both reside in the same address space.

I think this is the most important point.  Other softwares like Ceph
and GlusterFS implements the REST gateway in a standalone binary.  If
we implement this feature inside the sheep binary, it can be advantage
for us.

> 
>     cons:
>      - if REST code panic, sheep panic. (We might need many code that emulate
>        swift API that aren't necessarily included in the sheep binary)
> 
>  2. put REST gateway code in a standalone binary, switch the pros and cons of
>     choice 1.

Overall, I prefer the first one, but I'd like to hear more opinions.

Thanks,

Kazutaka