How to merge JPA entity structure on a POST/PUT RESTful webapp - json

Question

I am starting to implement a REST layer to an existing JSF-webapp (using RESTEasy, with a Jettison provider). Since tutorials for Java REST layers are quite basic (simple objects) I am facing the question how existing JPA entity relations can be easily exposed to/consumed from the client. A simple "/user" REST-method already gives me successfully the output below, which is a good start. But my main question is - how to deal with this kind of structures. Is it common to use such structures through REST?
I don't want to expose all details or the whole entity-tree, wether it is because of irrelevance, saving traffic or security issues. Using #XmlTransient works fine for the #Procudes, but merging these entities on a #POST/#PUT all #XmlTransient properties are merged to NULL. What is right way of doing that?
Since #XMLTransient is a global and permanent setting - what is the right approach to dynamically decide which depth of entity-tree I want to expose?
thanks
Example JSON of User-entity:
{
"user": {
"id": ..,
"uuid": "1521ccad69ba4579bbe49e75181fefc1",
"image": "",
"contact": {
"id": ..,
"uuid": "8eb429dcca994834ae5c8cf07cba62a2",
"cellphone": "",
"city": "",
"country": "",
"email": "mail#foo.bar",
"fax": "",
"phone": 555,
...
},
"name": "...",
"account": {
"id": ...,
"uuid": "80b331f9e6644449bb3600b0e5145253",
"confirmed": true,
"profile": {
"id": ...,
"uuid": "e172bdcafe2645d7975852ca5685c98c",
"locale": "en",
"notifyMessage": false,
"notifyNews": true,
"notifyTask": true,
"timeZone": "Europe/Berlin"
},
"roleProfiles": {
"id": ..,
"uuid": "f1713758f3f2416faed3e68350f2d759",
"active": true,
"assemblies": [
{
"id": ..,
"uuid": "13d72449833a4eb0b5b4f62c729ee44f",
"image": "",
"commercialRegisters": [
123,
456
],
"contact": {
"id": ...,
"uuid": "bef3802297344e3c8c3619b6c91c345a",
"city": "",
"country": "",
...
},
"thumbnail": ""
},
{
...
}
],
},
"userName": "..."
},
"displayName": "...",
"firstName": "Foo",
"lastName": "Bar",
"salutation": "",
"title": ""
}
}

Answer 1

Hi references in your Java classes should be serialized to JSON as links and not as values.
This is how Spring REST does it.
The good thing is : That way you have a kind of lazy loading
The bad thing is that the client needs additional requests to get the values of the references.
I developed a complete solution for that, but that was a hard piece of work.
The client (in javascript) creates proxies for those references and resolves them on demand.
I have a demo of that at demo.appdriver.com
In the upper right corner you see a link 'REST API' click it and you can see the REST API of a rather complex domain model.
Now you can start to click on the user interface , create, change, delete etc.
and have a look at the traffic between client and server.
Hope it helps !