Some initial fetching strategy comments.

This commit is contained in:
Ben Alex 2005-05-12 06:29:31 +00:00
parent c5101a259a
commit c9fc2684ad
1 changed files with 33 additions and 1 deletions

View File

@ -23,7 +23,39 @@ package net.sf.acegisecurity.domain.dao;
* Structured as a separate interface (rather than a subclass of
* <code>Dao</code>), as it is not required for all persistence strategies.
* </p>
*
*
* <p>In general the recommended approach to lazy initialization is as follows:
*
* <ul>
*
* <li>Do not use OpenSessionInView. You can use it if you like, but you'll have
* less difficulty in the long-run if you plan your use cases and adopt the other
* recommendations below.</li>
*
* <li>Set your mapping documents to use lazy initialization where possible. Only
* mark an association as eager loaded if <b>every</b> single use case requires it
* and you are happy with this eager loading being reflected in a mapping document
* instead of Java code.</li>
*
* <li>Subclass the <code>Dao</code> implementation and add use case specific finder/read
* methods that will use the persistence engine's eager loading capabilities. <b>Generally
* this approach will deliver the best overall application performance</b>, as you will
* (i) only be eager loading if and when required and (ii) you are directly using the
* persistence engine capabilities to do so. It also places the eager loading management
* in the <code>Dao</code>, which is an ideal location to standardise it.</li>
*
* <li>If you would prefer to achieve persistence engine independence and/or reduce
* the number of <code>Dao</code> subclasses that exist in your application, you may
* prefer to modify your services layer so that it uses the <code>InitializationCapable</code>
* interface. However, this interface should be used judiciously given that it does
* not allow the persistence engine to optimise eager loading for given use cases
* and (probably) will lead to a mixture of places where fetching logic can be obtained.</li>
*
* <p>Generally your best strategy is subclassing the <code>Dao</code>. It means the
* most code, but it's also by far the most efficient and offers flexibility to further
* fine-tune specific use cases. Whichever way you go, try to be consistent throughout
* your application (this will ease your future migration and troubleshooting needs).
*
* @author Ben Alex
* @version $Id$
*/