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https://issues.apache.org/jira/browse/WICKET-1784?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12651177#action_12651177
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R. Goodwin commented on WICKET-1784:
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For better load balancing our web apps run in a separate cluster to our core
services cluster. So lookups are often across boxes. There's also a legacy
rationale behind this, where grouping web apps to a select range of boxes
reduces the administration of those boxes in the load-balanced pool.
Admittedly, highly coupled services are grouped on the same boxes to reduce
expensive lookups and they're all running in the same data centre, but don't
think that should influence the debate.
Currently, Wicket-Lucene integration using standard Wicket components is just
plain wrong.
I'm not willing to re-write data provision classes AND re-write paging
mechanism.
And fortunately .. ha ha ... I don't have to ... because we're not using it in
production.
T'was just a wee experiment to test the cloudy waters.
Actually, I'm -(-1) for a Wicket improvement that doesn't force anyone to have
to abandon their preferred data access strategy.
> Enhance IDataProvider to support applications using the Transfer Object J2EE
> pattern
> ------------------------------------------------------------------------------------
>
> Key: WICKET-1784
> URL: https://issues.apache.org/jira/browse/WICKET-1784
> Project: Wicket
> Issue Type: Improvement
> Components: wicket
> Affects Versions: 1.3.3, 1.4-M3
> Environment: Wicket 1.3.3 and 1.4-M3
> Reporter: R. Goodwin
> Assignee: Igor Vaynberg
> Attachments: wicket-paging-experiment.zip
>
>
> In some environments searches are performed in 'single call' fashion, using a
> transfer object.
> E.g. two queries performed by the data services tier before returning
> combined results to the UI tier:
> i. Query for paged search results
> ii. Query for a 'count' value representing total possible results
> The contract between DataView and IDataProvider does not support a 'single
> call' environment as the give/take relationship between these classes is
> biased towards DataView.
> DataView expects IDataProvider to provide it's size before providing
> IDataProvider with its offset and count.
> * DataView may have good reasons for needing size before it can provide
> offset/count.
> * But IDataProvider has equally good reasons for needing offset/count before
> it can provide size.
> The circular dependency:
> 1. DataView calls IDataProvider.size()
> 2. IDataProvider cannot return size as it cannot start a query until it
> receives offset/count from DataView
> 3. These it does not receive until DataView calls IDataProvider.iterator()
> later on
> Others who experienced this problem (with CODE examples):
> * http://www.nabble.com/IDataProvider-and-Hibernate-Search-td15546101.html
> * http://www.mail-archive.com/[EMAIL PROTECTED]/msg14266.html
> ---
> The suggested solution of caching the combined search results and count value
> does not work if the search cannot begin until offset and count are
> available. And writing a custom DataView is not feasible either time wise as
> I understand that it cannot be done without needing to write a number of
> other classes too.
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