[jboss-user] [JBoss Seam] - Re: Seam Conversations - Best practices?

Delphi's Ghost do-not-reply at jboss.com
Fri Jun 22 15:57:26 EDT 2007


anonymous wrote : I would seam-gen up an application, add a couple of CRUD entities and take a look at the approach used there - it's what we would recommend. You "nest" as many CRUDs as you like using this pattern - it's simple to extend.

I did try to seam-gen up an application using my dummy dev database (Projects, and Issues per project), and it simply created pages to list, view and edit the projects or issues. I'm not sure whether it was supposed to pick up on the foreign key and list the issues per project or not, but it didn't work with either Seam 1.2.1 or 1.3 Alpha (I'm using mySQL for test dev work). 

So, with that in mind, I'm not quite sure what you mean by nesting CRUDs, but does it handle sharing the persistence contexts between multiple nested conversations and only flushing the item you are editing? Based on the docs and my experiences, nested conversations are about providing multiple continuation points within the same conversation as opposed to having the same amount of work in just one conversation.
Nesting is fine for browsing (i.e. breadcrumbs), but it seems that only one editing page can be involved in one conversation at a time when the flushMode is manual. While the logical flow may only provide one edit page within a conversation at a time, there is still the "open in new window" that could result in multiple editors within the conversation and an ensuing chaos.

I'm trying out a single conversation view page with the edit Widget page, and the Widget subDetail editing taking place in new separate top level conversations without any nesting involved. This way, the user can open editors in new windows, or tabs, without any dire consequences. I pass the Ids to the urls in an slink with a propagation of none, and the links are bookmarkeable.                              

Part of the reason for this was the lack of an immediately obvious way to click on a subDetail item to edit it which would then POST my changes to the currently edited widget , start a new conversation for the subDetail editor, and pass over some kind of value from the old conversation indicating which subDetail I am supposed to be editing. The s:link with propagation and a param does all that, except for the POST, hence it is being launched from a view only page.

It feels like the only option left, but at the same time, it feels like I'm only using a fraction of the power of Seam to do master/detail editing which is the bread and butter of software development. (Generate CRUD which is a close second is something Seam excels at). Alternatively, I could be using it exactly in the right way it was designed to be used for this particular scenario. It's hard to tell without any kind of standard best practices of how to use the different elements within seam.  The examples highlight particular parts of the framework as opposed to demonstrating how to use them all together. 


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