Q: I am new to OJB. I wonder if OJB has something like Hibernate's component mapping, which makes code structure better and reuse easier.
A: Yes that's possible with OJB too! If your class has an attribute "address" of type Adress, the mapping for the "street" attribute of "address" would look like follows:
<field-descriptor
name="adress::street"
column="ADR_STREET"
jdbc-type="VARCHAR"
/>