On Jul 23, 2011, at 9:05 AM, Markus KARG wrote:
> 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)?
I agree that in the current proposal, there's not much added by using those annotations and methods.
>
> * 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?)
Yes, but the fact that this is JAXB specific is the issue. Also, the interaction with the new handlers and the MBR/MBW is unclear to me.
-- Santiago
>
> 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