Hi Dave
On 09/02/12 17:53, hdave wrote:
Sergey -- Just wanted to close the loop on this.
Because I will want to perform schema validation (in the future) on my
response payloads, it was necessary to add a collection of hyperlinks as a
Java/JAX-B type to every class in my domain model. I could see no way
around it. However, I judged this minor leakage of concerns to be far
better than creating 100+ JAX-B adapters.
Once I did this, all that was left was to insert the hyperlinks into the
domain objects response representation(s) from within my resource classes.
Knowing that I must, for performance reasons, send nested object graphs to
the client, I needed to traverse the response object graph to insert
hyperlinks. For this I used the visitor pattern. In this way, I
concentrated all the logic about hypermedia into a single HypermediaVisitor
class. All I have to do is invoke the visitor on the root object in the
response graph before return the value from my resource service method.
I thought about creating an annotation for this that would take the name of
the hypermedia visitor, but I don't know exactly how to do this and am
running short on time. I also thought about invoking the visitor using AOP,
but I am wary of having too much magic.
In any event, it works well and seems reasonably loosely coupled. I am
hoping the brain-trust behind REST 2.0 will do a good job and get something
out soon.
Thanks for this update. I guess when the links are part of the domain
schema it is probably not worth for the runtime to attempt to facilitate
the creation of these data.
However I'm interested to explore the idea of the runtime calling back
into custom visitors during the serialization process.
For example, please see option 2 & 3 for wrapping domain data such as
Book into Atom feed/entry transparently under the hood, and those custom
builders can be used to create the links:
https://cwiki.apache.org/confluence/display/CXF20DOC/JAX-RS+Data+Bindings#JAX-RSDataBindings-Atom,
for ex,
http://svn.apache.org/repos/asf/cxf/trunk/rt/rs/extensions/providers/src/main/java/org/apache/cxf/jaxrs/ext/provider/atom/AbstractAtomElementBuilder.java
So may be if say JAXBElementProvider gets a Visitor registered then it
can create a custom writer and call back to the visitor and request to
return a list of links for a given element...or something similar...
May be we can come up with some idea after all :-)
Thanks, Sergey
Best,
Dave
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Sergey Beryozkin
Talend Community Coders
http://coders.talend.com/
Blog: http://sberyozkin.blogspot.com
