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Chapter 8. Developing Entity Beans 117
8.12.4. min-pool-size
This optional integer value represents the minimum instances that will be created in the pool when the
bean is loaded. This will improve bean instance create time, at least for the first instances. The default
value is 0.
8.12.5. max-cache-size
This optional integer value represents the maximum of instances in memory. The purpose of this
value is to keep JOnAS scalable. The default value is “no limit.” If you know that instances will not
be reused, you should set a very low value to save memory.
8.12.6. is-modified-method-name
To improve performance of CMP 1.1 entity beans, JOnAS implements the isModified extension. Be-
fore performing an update, the container calls a method of the bean whose name is identified in the
is-modified-method-name
element of the JOnAS-specific deployment descriptor. This method is
responsible for determining if the state of the bean has been changed. By doing this, the container
determines if it must store data in the database or not.
Note
This is not required with CMP2 entity beans because the container does this automatically.
8.12.6.1. Example
The bean implementation manages a boolean
isDirty
and implements a method that returns the
value of the boolean
isModified
.
private transient boolean isDirty;
public boolean isModified() {
return isDirty;
}
The JOnAS-specific deployment descriptor directs the bean to implement an
isModified
method:
l
jonas-entity
m
l
ejb-name
m
Item
l
/ejb-name
m
l
is-modified-method-name
m
isModified
l
/is-modified-method-name
m
.....
l
/jonas-entity
m
Methods that modify the value of the bean must set the flag
isDirty
to
true
. Methods that restore
the value of the bean from the database must reset the flag
isDirty
to
false
. Therefore, the flag
must be set to
false
in the
ejbLoad()
and
ejbStore()
methods.