Re: Hierarchical Collections

["Erling Wegger Linde" <erlingwl@xxxxxxxxx>]

Great initiative Dan!

On Thu, Jul 10, 2008 at 12:03 AM, John Panzer <jpanzer@xxxxxxx> wrote:
> Dan Diephouse wrote:
>
> One of the things that seems to come up repeatedly when designing APP apps
> is the concept of hierarchical collections. I'm wondering if people think
> there is a best practice here and if folks think we should agree on a
> standard way of doing this.
>
> Since I'm a practical guy, I thought I might lead with a few use cases.
> Other folks can debunk/expand on them if they wish.
>
> A way to browse around/create/delete collections of atom entries. For
> instance, I might want to list out a collection of collections. One of these
> collections might be a collection which represents a set of media entries
> which represent application resources (JARs, schemas, configurations). This
> is one of my primary uses cases at the moment as we (MuleSource, WSO2, and
> possibly some others) are trying to come up with a standard way to allow
> people to browse what is in our registry/repository products.
> A forum which contains topics which contain messages (I saw a thread on this
> earlier on the mailing list, but didn't see any suggestions about how the
> entries should look).
> A customer account which is associated with a collection of purchase orders
> and a collection of customer contacts.
>
> A couple ideas have been floating around that I've seen:
>
> 1. Embed a <collection> in an atom entry
>
> <entry>
>    <title>SomeCustomer</title>
>    ...
>    <collection href="http://example.com/customers/acme/contacts";
> rel="contacts">
>      <atom:title>Contacts</atom:title>
>    </collection>
>    <collection href="http://example.com/customers/acme/purchase-orders";
> rel="purchase-orders">
>      <atom:title>Purchase Orders</atom:title>
>    </collection>
> </entry>
>
> In this case I'm using a rel attribute to describe what relationship this
> collection has to the atom entry. Granted my example does not follow the
> <link> rel attribute rules here as those values are not registered, but you
> get the idea.
>
> 2. Use <link> relationships
>
> <entry>
>   ....
>   <link rel="some-defined-child-collection-relationship" href="..."/>
> </entry>
>
> For the customer/PO/Contact example I could define my own rel attributes.
> Downside here is that it'd be really nice to have a title inside the feed
> saying what this thing was.
>
> 3. Don't use AtomPub, use XXX (i.e. WebDAV)
>
> Maybe APP is the wrong thing for this, but I'm really looking to take
> advantage of the Atom's ubiquity.
>
> 4. Other?
>
> I'm sure I'm missing a thousand details here, so it'll be interesting to
> hear what the group has to say :-)
>
> 1. http://glendaniels.blogspot.com/2008/07/mule-galaxy-rolls-out.html
> 2. http://netzooid.com/blog/2008/07/01/open-repository-api/
>

John Panzer suggested:

Or, use <content src="..." type="application/atom+xml"/> for the
out-of-line case, and <content type="application/atom+xml"><feed ...>
... </feed></content> for the inline case.  (If you really mean to
create a totally generic way to represent collections of collections.)

This seems as a good idea to me, and one could use the Atom Format as
it is today. However, one cannot have multiple <content> elements in
an entry right? Maybe one should suggest to allow this?

- Erling


>
> --
> Dan Diephouse
> http://netzooid.com/blog
>



-- 
Med vennlig hilsen
Erling Wegger Linde