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Thanks your answer, I got it now.


On Fri, Apr 12, 2013 at 7:30 PM, Eoghan Glynn <eglynn at redhat.com> wrote:

>
> Hi Gareth,
>
> The swift backend optionally used by glance to store image content is
> just one of the stores supported by glance. Alternatively the image
> data can be stored in flat files (the default option), S3, RBD-based
> stores, or in external stores accessible via HTTP.
>
> In addition to being able to use alternative stores to swift, glance
> also manages image metadata independently of the backend, via a local
> RDBMS (generally mysql or posrtgresql).
>
> So to answer your question, glance is not just a thin layer over swift.
> You could of course re-implement a more limited glance-like image service
> in that way, but you would be losing some flexibility and also creating
> a maintenance headache for yourself in shadowing developments in the
> glance API to avoid breaking clients such as nova & cinder.
>
> Cheers,
> Eoghan
>
> ----- Original Message -----
> > Thanks for your answer, Iccha and Eoghan,
> >
> > I have another problem. After scanning the source codes, I found current
> > Glance is just managing image file （or disk file）, which I think its
> > functionality is subset of Swift. Both x-meta-image-* and
> > x-meta-image-property-* could store in Swift metadata, and ACLs could
> help
> > manage authorizing. And some new features like protected properties
> could be
> > implemented as middleware in Swift too. So, I'm not clear about the goal
> of
> > this project.
> >
> > Before reading the codes (I have to read codes because Glance documents
> is
> > not so helpful), I image this project could manage image file, and also
> data
> > in this image, such root password, default IP and so on. But it's not
> real.
> >
> > In short, if I want build a cloud with OpenStack and I have ability to
> write
> > my own codes, are there some reasons I setup Glance to manage images,
> not to
> > write a Swift middleware to avoid lots of middle-process?
> >
> >
> >
> >
> > On Fri, Apr 12, 2013 at 6:01 PM, Eoghan Glynn < eglynn at redhat.com >
> wrote:
> >
> >
> >
> >
> > > Gareth,
> > >
> > > There are a number of improvisations in v2 of Glance API. To name a
> few the
> > > registry layer is no longer been used in v2 of Glance API(so one less
> layer
> > > your request has to go through), image sharing has been designed to
> prevent
> > > spamming in v2, there are additional features like protected
> properties and
> > > multiple locations been worked on. I am sure there are several more.
> >
> >
> > One other bit of newness in v2 that's worth noting, because it's
> > actually used in anger by both cinder and nova currently, is the
> > direct_url metadata which if enabled in glance allows a client to
> > directly access image content from the backend store (if that can
> > be achieved more cheaply that way than by traversing the glance-api
> > service).
> >
> > Also there was a design document for the v2 API knocking around
> > that might be useful for background and detail. The latest draft
> > version I have to hand is:
> >
> >
> https://docs.google.com/document/d/1jPdgmQUzTuSt9iqcgPy74fbkzafCvqfQpvzRhwf2Kic
> >
> > though there may be a more recent version in existence.
> >
> > Cheers,
> > Eoghan
> >
> >
> > > Thanks,
> > > Iccha
> > >
> > > -----Original Message-----
> > > From: "Gareth" < academicgareth at gmail.com >
> > > Sent: Thursday, April 11, 2013 12:51am
> > > To: openstack-dev at lists.openstack.org
> > > Subject: [openstack-dev] [Openstack][Glance] difference api version
> between
> > > v1 and v2
> > >
> > > _______________________________________________
> > > OpenStack-dev mailing list
> > > OpenStack-dev at lists.openstack.org
> > > http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev
> > > Hi, Glance devs
> > >
> > > Any design purpose between v1 and v2 API?
> > >
> > > I know the url changed a little, but functionality seems same.
> > >
> > > So is there any further improvement in v2 API?
> > >
> > > Thanks
> > > --
> > > Gareth
> > >
> > > *Cloud Computing, Openstack, Fitness, Basketball
> > > *
> > > *OpenStack contributor*
> > > *My promise: if you find any spelling or grammar mistakes in my email
> from
> > > Mar 1 2013, notify me *
> > > *and I'll donate $1 or ￥1 to an open organization you specify.*
> > >
> > >
> > >
> > > _______________________________________________
> > > OpenStack-dev mailing list
> > > OpenStack-dev at lists.openstack.org
> > > http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev
> > >
> >
> > _______________________________________________
> > OpenStack-dev mailing list
> > OpenStack-dev at lists.openstack.org
> > http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev
> >
> >
> >
> > --
> > Gareth
> >
> > Cloud Computing, Openstack, Fitness, Basketball
> > OpenStack contributor
> > My promise: if you find any spelling or grammar mistakes in my email
> from Mar
> > 1 2013, notify me
> > and I'll donate $1 or ￥1 to an open organization you specify.
> >
> > _______________________________________________
> > OpenStack-dev mailing list
> > OpenStack-dev at lists.openstack.org
> > http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev
> >
>
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> OpenStack-dev at lists.openstack.org
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>



-- 
Gareth

*Cloud Computing, Openstack, Fitness, Basketball
*
*OpenStack contributor*
*My promise: if you find any spelling or grammar mistakes in my email from
Mar 1 2013, notify me *
*and I'll donate $1 or ￥1 to an open organization you specify.*
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