The main reason to support getter / setter access is for implementations that cannot intercept field accesses. So, the getters and setters are there so that the JPA implementation can create a subclass of your entity type (hence the no-final-classes rule) and track what happens as you invoke the setters and getters. In other words, your business methods become part of the JPA implementation's domain.
So, when using property access, your contract with the JPA provider is that you'll access persistent attributes only through the setters and getters, which allows the implementation to track what you do and when you do it. If you could directly access the underlying state, the implementation would have no way to know what happened during the course of a transaction. This, in turn, would mean that the implementation would have to keep a copy of every bit of data that you read during a transaction, and then at commit / flush time compare the current values with the original values to figure out what to write back to the database. As it turns out, when you use OpenJPA, all your direct field accesses are replaced with synthetic static methods anyways, so from a performance standpoint, you'll see equivalent behavior either way. In my experience, persistent domain model field access performance in tight loops is rarely actually a performance bottleneck; it's almost always going back and forth to the database that ends up being the bottleneck, and thus the most important place to optimize. -Patrick -- Patrick Linskey BEA Systems, Inc. _______________________________________________________________________ Notice: This email message, together with any attachments, may contain information of BEA Systems, Inc., its subsidiaries and affiliated entities, that may be confidential, proprietary, copyrighted and/or legally privileged, and is intended solely for the use of the individual or entity named in this message. If you are not the intended recipient, and have received this message in error, please immediately return this by email and then delete it. > -----Original Message----- > From: Phill Moran [mailto:[EMAIL PROTECTED] > Sent: Tuesday, April 03, 2007 10:02 PM > To: open-jpa-dev@incubator.apache.org > Subject: Forced getter/setter access > > Can anyone explain why this rule is in effect: > > When using property access, only the getter and setter method > for a property > should ever access the underlying persistent field directly. > Other methods, > including internal business methods in the persistent class, > should go through > the getter and setter methods when manipulating persistent > state. (section 2.1.4 > OpenJPA manual) > > This seems rather execution costly. If ,for instance, I have > a Size class with > hieght, width and length then to calculate and return volume > I suffer a three > method call overhead: > return getWidth() * getLength() * getHieght(); > > This is opposed to a more efficient > > Return height * width * length > > Phill > > Notice: This email message, together with any attachments, may contain information of BEA Systems, Inc., its subsidiaries and affiliated entities, that may be confidential, proprietary, copyrighted and/or legally privileged, and is intended solely for the use of the individual or entity named in this message. If you are not the intended recipient, and have received this message in error, please immediately return this by email and then delete it.
