Hi,
you can create a service that simple get bookmarks for users and inject OSGI service in sling model using Inject or SlingObject
e.g.
@Inject
private HandleSession hs;
@SlingObject
private ResourceResolver resourceResolver;
Sling Models are Pure POJO which are automatically mapped from sling object.
For updating links you need to use other way , may be whenever user save links it triggers Java code which update the bookmarks.
Arun Patidar