java - JDO Java Data Objects example

Question

can someone help me to find a step-by-step example for developing JDO in a gwt project?

I really want to know and learn the jdo and differences between that and jpa

RGDS

Answer 1

I have used both jdo and jpa. I find it much easier using jpa for my work. If you are using datanucleus then you should look at the documentation on app engine located below.

JDO https://developers.google.com/appengine/docs/java/datastore/jdo/overview-dn2

JPA https://developers.google.com/appengine/docs/java/datastore/jpa/overview-dn2

These are the newer specs for app engine and if you are not using these then just about any database should be fairly straight forward.

I personally use jpa, request factory, service locators and a Dao pattern for accessing my objects. Here is something I posted earlier that has some code samples that may help. If you are not using app engine then a normal Long key should be easier.

GAE Datastore with GWT, making more friendly/smaller keys

You should also look at using a Servlet Filter for handling your EntityManager so that requestfactory can handle fetching your object graph using the .with("childGetterMethod") clause. This will save you quite a bit of coding to fetch child entities while the servlet filter handles opening and closing your entity manager.