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From Brian McCallister <>
Subject Re: Looking for data persistance method recommendation
Date Tue, 20 Jan 2004 18:33:55 GMT
I misread your statement - you are looking at collections coming back 
from the query, not object referenced collections. In this case the 
proxy-prefetch limit won't help you, however passing the lazy loading 
collection as the return value from whatever your query/repository/etc 
service is should do that for you =)

Hmm, you have me thinking. May have to implement this, though I doubt 
it would be useful enough to get included in commons-collections (and 
at their release rate of once every year or two, and 3.0 being due out 
any-day-now, it wouldn't be very helpful in the short term to ask them 
to include it anyway). Could hide it in with the convenience 
collections in OJB maybe, if it seems like it will be widely useful.


On Jan 20, 2004, at 1:28 PM, Brian McCallister wrote:

> If you are worried about the memory usage one thing you might want to 
> consider is the paging support for collections. Specify to use a proxy 
> for the collection, then set the proxy-prefetch-limit for the 
> collection to the value you need (iirc, the default is either 50 or 
> 200). It will only materialize object in hunks up to the 
> proxy-prefetch-limit value.
> Another possibility would be to use a lazy-loading collection 
> implementation that takes an iterator as a constructor and doesn't 
> traverse until it needs to. If the first and only call against it is 
> to Collection#iterator and it returns a wrapper around the initial 
> iterator you can get the same behavior.
> If this is all you need it for you could only implement this 
> collection wrapper and throw UnsupportedOperationExceptions for all 
> other operations (is it bad if I have "throw new 
> UnsupportedOperationException("");" as a live template in IDEA? ;-).
> -Brian
> On Jan 20, 2004, at 12:49 PM, mirko wrote:
>> Antonio Gallardo wrote:
>>> mirko dijo:
>>>> I forgot to ask: if I return a query results' iterator
>>>> (broker.getIteratorByQuery(query)), will I be able to pass it as a
>>>> parameter to flows's view and then iterate it in my JXTemplate? 
>>>> I've a
>>>> feeling that it won't work :(
>>> The iterator no, but a bean collection yes. We use OJB to develop DB
>>> application with flow+woody and jxtemplate and this is a paradise 
>>> compared
>>> with other approach.
>> Yes, I know I can pass collection of objects. But I'm afraid of 
>> memory usage if the collections are huge. :) But I think I'll do as 
>> you said, in the future maybe a iterator will be able to be passed :)
>> BTW Flow is the best new thing in Cocoon and the Woody becoming 
>> second one. If I only get OJB (or other) working with it I will be 
>> very happy.
>>> What else can you ask? ;-)
>> OK, but off topic :) A question about encoding in JXTransfomer: If I 
>> pass a string with national characters (ISO-8869-2) from flow to the 
>> view (JXTemplate) these characters do not show up correctly. Is there 
>> any issues?
>> Regards,
>> mirek
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