Slides from my "Extending OPDS" talk at the Making Books Apparent event in San Francisco.

1. Extending OPDS
Hadrien Gardeur
Feedbooks

2. OPDS is an extension

3. Basic OPDS catalog
Atom feeds
Same requirements than an Atom entry
 atom:title
 atom:author
 atom:id
 atom:updated
If it’s a publication, the requirement is at least one
acquisition link.

4. Scary but Cool stuff
element atom:entry {
atomCommonAttributes,
(atomAuthor*
& atomCategory*
& atomContent?
& atomContributor*
& atomId
& atomLink*
& atomPublished?
& atomRights?
& atomSource?
& atomSummary?
& atomTitle Cool !
& atomUpdated
& extensionElement*)
}

5. Metadata
 Atom
 DublinCore Terms (dcterms:issued)
 Prism (prism:issue)
 New attributes in the OPDS namespace
(opds:price, opds:gateway)

6. Link Relations
 For feed-level or entry-level links
 Give a meaning to what you’re linking to
 Different type, different meaning
In OPDS we use:
1. Link relations from the IANA link registry  Link header draft
2. Our own link relations (http://opds-spec.org/relation)

7. Why ?

8. More Metadata
 Support new type of publications
 Provide more and better information
… without affecting the user experience on mobile devices
 More meaningful links

9. New Features
 Comments (implemented on Feedbooks)
 Reviews
 Annotations
 Publishing (implemented on Feedbooks)
 OPDS shopping cart

10. How ?

11. Partial & Full Entries
Like in AtomPub, you shouldn’t assume that an entry in a
collection feed is a full entry
A partial entry can link to a full entry
<atom:link rel="alternate" type= "application/atom+xml;type=entry" href=" …" />
 Required & Recommended metadata MUST be in partial
You can add anything you want in full entries

12. New Link Relations
 Use link relations from the Link Header draft
 New features in OPDS: http://opds-spec.org/relation
 Create your own: http://mydomain.com/relation
Associate a link with a new type
… or media parameters in a type

13. Use AtomPub !
Don’t limit yourself to GET requests !
CRUD with POST, GET, UPDATE and DELETE
AtomPub = Service Documents, Workspaces and Collections
New link relations: edit, edit-media

14. Example: Comments

15. On Feedbooks
Based on the Atom Threading Extension
 Link Relations: replies, in-reply-to
 Attributes: thr:count, thr:updated
AtomPub to POST comment (no UPDATE or DELETE)

16. In our entries
Nothing in the partial entry, MUST GET full entry
<atom:link rel="replies" thr:count="2" thr:updated="…" />
 thr:count gives the total number of comments
 thr:updated is the timestamp for the last update (last comment)

17. Collection feed for
Comments
A comment is a normal Atom entry
 atom:author for the user
 atom:content for the comment
app:collection to POST content (no service document)
 href attribute for the URI
 app:accept to list the types (application/atom+xml;type=entry)

18. Best Practices
Don’t create stuff on your own
 search for RFCs
 read and participate on mailing lists: atom-syntax, atom & opds
 Use the IANA link registry and Link Header draft
Use link relations
Metadata not included in the specs MUST be in the full entry

19. That’s all folks !