Re: [JBoss-user] Different Commit Options

[David W. <dav...@do...>]

You can learn about options A, B and C in the ejb 2.0 servlet spec, 
section 10.5.9, page 186:

<quote>
10.5.9 Commit options

The Entity Bean protocol is designed to give the Container the 
flexibility to select the disposition of the instance state at 
transaction commit time. This flexibility allows the Container to 
optimally manage the association of an entity object identity with the 
enterprise bean instances.

The Container can select from the following commit-time options:

- Option A: The Container caches a  ready  instance between 
transactions. The Container ensures that the instance has exclusive 
access to the state of the object in the persistent storage. Therefore, 
the Container does not have to synchronize the instance s state from the 
persistent storage at the beginning of the next transaction.

- Option B: The Container caches a  ready  instance between 
transactions. In contrast to Option A, in this option the Container does 
not ensure that the instance has exclusive access to the state of the 
object in the persistent storage. Therefore, the Container must 
synchronize the instance s state from the persistent storage at the 
beginning of the next transaction.

- Option C: The Container does not cache a  ready  instance between 
transactions. The Container returns the instance to the pool of 
available instances after a transaction has completed.

The following table provides a summary of the commit-time options.

Note that the container synchronizes the instance s state with the 
persistent storage at transaction commit for all three options.

The selection of the commit option is transparent to the entity bean 
implementation the entity bean will work correctly regardless of the 
commit-time option chosen by the Container. The Bean Provider writes the 
entity bean in the same way. The object interaction diagrams in Section 
10.9 illustrate the three alternative commit options in detail.

Table 6
Summary of commit-time options
Write instance state to database | Instance stays ready | Instance state 
remains valid
Option A - Yes | Yes | Yes
Option B - Yes | Yes | No
Option C - Yes | No  | No

Note: The Bean Provider relies on the ejbLoad() method to be invoked 
when commit options B and C are used in order to resynchronize the bean 
s transient state with its persistent state. It is the responsibility of 
the container to call the ejbLoad()method at the beginning of a new 
transaction when commit option B or C is used.
</quote>

Option D is JBoss-specific, and deals with a refresh rate parameter. 
You can find more information about that in the JBossCMP docs, on the 
website docs, in the forums, in the lists......

David

--

Saroj Kumar wrote:
> Hi All,
> 
> There are 4 commit option A,B,C,D.
> 
> What is the diff. between them and when should one use them?
> 
> Forgive me for asking these basic questions.
> 
> TIA,
> Saroj