I gave two 'pat' answers to these questions, but as I re-read them, I think abit more information is needed...
On Tue, 2002-01-29 at 13:58, Dan Finkelstein wrote: > 1. In JDO, if I perform a query like "get every customer", are all the > customers returned or is lazy loading used so that the UI can page through > the result set? If I have to write extra code to do this, can you describe > what is needed. See the webpage I mentioned for how to implement lazy-loading. (You place a line in the mapping.xml file, and retain the jdo reference/transaction while iterating through the list) However, what type of UI are you talking about? If its a swing UI, then you can easily store the reference locally. If its a webpage, then you don't want to keep the transaction open inbetween webpages. So you have lazy loading as an option, but make sure you understand the implications of the restrictions required by lazy-loading and how it impacts your application. > 2. In a scalable environment, with multiple servers running caster, how > does the built-in transaction support compare with that in EJB? I'm trying > to see under what circumstances castor or EJB might be a better choice. I mentioned in a previous email that castor doesn't handle caching completely in a 'virtual cluster'. (One server cannot update the other when a change occurs) And depending on your EJB server, you can have different needs. Example: JBoss 2.2.x supports the use of Castor in the entity bean container, but doesn't support clustering. (JBoss 3.x I believe will have clustering) WebLogic supports clustering but not Castor. (So you'd have to do BMP rather than CMP if you wanted to use Castor with WebLogic in an entity bean.) [disclaimer: I've not use castor personally with jboss, but from what I understand it can be done. Other people on this list are likely better able to help with that one than me.] Now, directly to your question, When you say 'castor vs EJB', that's not a 1-to-1 comparison. EJB has session beans and entity beans. Castor only helps with entity beans, which I assume is what you meant by that. I'll answer this one with the 'default' EJB answer. If you need deployment to determine transaction support of your encapsulated functions (beans), and the object-isolation and reference/lookup provided by the EJB framework, then you need EJB in general. Depending on your Entity beans, CMP or BMP is a decision left to your problem domain, and how you implement it. Castor helps generate applications that use the database quickly, staying in the OO world. (EJB doesn't help you create applications quickly, just 'cleanly' and maintainable.) I guess the short answer is, if you need a multiple cache-aware server implementation found in a virtual cluster, castor doesn't have it yet. -- Virtually, Ned Wolpert <[EMAIL PROTECTED]> D08C2F45: 28E7 56CB 58AC C622 5A51 3C42 8B2B 2739 D08C 2F45
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