Re: [Springframework-developer] RFE: Multiple parents for ApplicationContext

[Andy D. <an...@ma...>]

I've run into the same thing when attempting to modularize our application and 
its Spring configuration.  As I didn't have time to really dig into an 
elegant solution, I came up with something quick and dirty - that is, using 
classpath*:/META-INF/module-context.xml as one of my config locations.  Each 
of our modules is contained in a single .jar on the classpath, with a 
"module-context.xml" located in its META-INF.  The above wildcard path will 
load all such Spring configs as one large context (basically by merging them 
all into one context).  This means all beans have access to all beans, but, 
as I said, this is a quick and dirty solution. :)  The other downside is that 
the list of "modules" are not dynamically loaded/unloaded at runtime, but 
rather fixed as defined by your classpath at start time.

  - Andy

On Wednesday 27 July 2005 12:36 am, Roland Huss wrote:
> Hi,
>
> we are using multiple application modules, which we are wiring together
> during a bootstrap process. Each module has it's own container which is
> connected to its dependent module via a parent-child relationship (as
> described in
> http://static.springframework.org/spring/docs/1.2.x/api/org/springframework
>/beans/factory/access/SingletonBeanFactoryLocator.html)
>
> However, the restriction to a strict treelike organization of
> ApplicationContext limits the usability of this pattern.
>
> E.g. imagine the following use case with four contexts:
>
>    * bootstrap-ctx.xml for defining base beans used by any other container
>    * dao-ctx.xml for defining DAOs. Depends on bootstrap-ctx.xml
>    * security-ctx.xml depends also on bootstrap-ctx.xml but not on
>      dao-ctx.xml
>    * service-ctx.xml which depends on beans defined in security-ctx.xml and
> dao-ctx.xml.
>
> Using an hierarchical container setup something like a 'diamond' (graph)
> would be appropriate:
>
>                             bootstrap
>                               /   \
>                              /     \
>                            dao    security
>                              \     /
>                               \   /
>                              service
>
> However, Spring doesn't allow multiple parent container, so we are left
> with the following linear setup:
>
>                              bootstrap
>
>                                 dao
>
>                               security
>
>                               service
>
> which has the undesired side-effect, that 'security' has access to 'dao'.
> Ok, this works for this simple setup, but one can easily imagine
> situations, where this 'linearity' restriction bites much harder.
>
> My question is, whether there are any plans for supporting
> ApplicationContext chaining in a more flexible way (i.e. with multiple
> parents) ?
>
> Or is there already another support for scoping beans coming from various
> application components ?
>
> For the moment, we switched to a single, big container which import various
> context snippets from the application modules and use bean-aliasing for
> scoping.
>
> ciao...