[rest-practices] Atom as a generic container? [was Re: Media types]

[Eoghan Glynn]

> If a content handler was written for this delta type you're talking about,

> then I could probably easily modify the lightweight Atom classes in
> RESTEasy to extract the object you're interested in.


Hi Bill,

I don't think any new type support is needed for the RFC3229+feed idea,
rather it would be more a case of just filtering out older entries from the
feed, and then marshalling the pruned feed in exactly the same format as
before (just with a different status code, 226 "IM Used", and also an extra
header IIRC).

I guess this filtering could be done manually, but we probably wouldn't want
to be creating separate new Feed objects for each different
If-Modified-Since timestamp that we see.

Cheers,
Eoghan


On 16 April 2010 21:38, Bill Burke <bburke at redhat.com> wrote:

>
>
> Eoghan Glynn wrote:
>
>>
>>  > On one hand maybe somebody wants to listen for updates to VMS.
>>  >
>>  > On the other hand, I don't see the point of using Atom for returning
>> collections.  It was written as a format for feeds not a collection format.
>>
>>
>> Hi Bill,
>>
>> So just to clarify, the original idea wasn't so much to wrap the VMs
>> collection in an Atom feed, but rather to use a feed to allow clients,
>> having previously executed a query over the VM collection, to receive
>> lightweight notifications of changes to the set of known VMs and their
>> status. For example a new VM appears, the status of another VM changes, a
>> third VM goes away, etc.
>>
>> This would allow clients to update their previous result set, without
>> necessarily re-issueing the original query. It would of course depend on the
>> feed being filtered on the client-side according the original query
>> constraints.
>>
>> To ensure that only genuinely fresh updates were received, idea was to use
>> delta encoding with the cleint setting the "A-IM: feed" header so that it
>> recieves only those entries that were updated later than the
>> If-Modified-Since header (set to the timestamp of the original query or the
>> last GET on the Atom feed, which-ever is the later). It was an open question
>> whether the RESTeasy Atom provider supported delta encoding in this way.
>> I'll need to check this out, unless you know off the top of your head?
>>
>>
> Resteasy's atom support is just a bunch of JAXB classes.  The Content class
> has a bit more logic in that it allows you to extract application-specific
> JAXB content.  That's it.
>
> If a content handler was written for this delta type you're talking about,
> then I could probably easily modify the lightweight Atom classes in RESTEasy
> to extract the object you're interested in.
>
>
> --
> Bill Burke
> JBoss, a division of Red Hat
> http://bill.burkecentral.com
>
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