Thank you for the update. Here are my comments:
* Transitional Links:
I do not see the need for two new annotations. It seems to be rather
complex. The provision of the links could be done simply by means of builder
API in terms of Java (like "Response.links(Collection<Link>)) which is easy
to read and to debug. I do not see what actual benefit the annotations will
bring, also I do not see why we should insist on people writing explicit
link builder methods (they just can create links inlined if they)?
* Structural Links:
If order contains items (<order><item/><item/><item/></order>, e. g. class
@XmlElement Order { private List<Item> items; }, then it is rather simple to
turn this into XML links by using one single annotation:
@XmlElement Order { @Ref private List<Item> items; }
where @Ref is nothing but providing some sugar around an Xml Java Type
Adapter replacing Item by URI and vice versa on the fly at marshalling /
unmarshalling. This is the most typical use case for structural links from
my experience (using this for months now and works pretty good) and in fact
this is what I expect to make most users happy in the first draft. BTW, I
personally would be more fluent and not name it @Ref but @Externalize (like
it is "@Inject" to have a verb what the processor does) -- "externalize"
since this is what the sugar will do: It replaces the Java "internal" link
by an "external" URL representation. The "only" question is what to do with
those not using JAXB? (Actually, how many are not using JAXB actually?)
Regards
Markus
From: Santiago Pericas-Geertsen [mailto:Santiago.PericasGeertsen_at_oracle.com]
Sent: Mittwoch, 20. Juli 2011 20:08
To: jsr339-experts_at_jax-rs-spec.java.net
Subject: [jsr339-experts] Hypermedia - Take 2
Hi Experts,
The wiki page on Hypermedia / HATEOAS has been updated after processing all
the feedback received on the declarative hyperlinking approach and related
topics.
After going through all the e-mail threads, I now believe it would be
useful to divide the hyperlinking problem into two parts: structural links
and transitional links (I came up with these terms, feel free to dislike
them :). See [1] for a discussion.
It appears that supporting transitional links is easier, and a simple,
non-declarative (annotation free) approach is described in [1]. Note that
transitional links are handled completely at the resource (controller) level
and are conveyed as Link Headers (my personal preference). Support in the
Client API is also straightforward (and similar to Restfulie).
Structural links are more complex to support given their interaction with
other parts of the system (readers, writers, JAXB, etc), and given their
impact on the model. A declarative, annotation-based approach may be the way
to go, but there are a number of issues that need to be sorted out.
In summary, [1] is an incomplete story, but wanted to direct your attention
to the new content to help us drive future discussions.
-- Santiago
[1]
http://java.net/projects/jax-rs-spec/pages/Hypermedia