Question

I have been learning java spring hibernate MVC for 3 months and got pretty idea of that . But i have not understood what JCR means.

I mean for e.g in my simple webiste in spring MVC what part can be done in JCR

Answer 1

JCR would be an alternative persistence mechanism used in place of JPA (Hibernate), which hides JDBC from your application. In theory, the Java classes you have in your model might remain the same as you have now. However, if any classes in your model came about only because you needed to model some lower-level data structures for JPA, then these classes might not be needed with JCR.

You’d need a good reason to replace an existing use of JPA with JCR. For example, you may have discovered that using JPA requires jumping through a lot of extra hoops and doing things you’d not really need to do.

Having said that, JCR certainly has some advantages and capabilities that are not otherwise found in JPA:

1. JCR supports structured data, unstructured data, and everything in between. JCR allows a flexible schema and can be very NoSQL-ish. JPA is very structured, with a fixed schema.
2. JCR is hierarchical – some use cases are extremely hierarchical, and doing that with a relational model can be very difficult/expensive
3. JCR has built-in events
4. Most JCR implementations can store content in a variety of systems. Some can even access and federate existing content in other systems.
5. No length limitation of string values
6. JCR has full-text search support
7. JCR has multiple query languages, including JCR-SQL2 (very SQL-like)
8. There are some libraries that map Java classes to your node structures, and thus are very similar to JPA/Hibernate

It all depends on whether these features are beneficial for your application.