[hibernate-dev] EMF / EM properties

[Emmanuel Bernard]

Hardy,
How would it work for say a DirectoryProvider in Hibernate search (which is a plugin of HSearch which itself is a plugin of Core in a way - listener).

Remember we have the hibernate.search.default.[customproperty] category and the hibernate.search.[indexname].[customproperty] category. What would the the impl of PropertyConsumer#collectConsumedProperties like for Hibernate Search?


On 1 févr. 2010, at 16:28, Hardy Ferentschik wrote:

> The pull approach via an additional PropertyConsumer interface works for me.
> It seems to be a good trade-off. Least invasive while still getting some order
> into the properties.
> 
> --Hardy
> 
> 
> On Mon, 01 Feb 2010 12:14:02 -0300, Steve Ebersole <steve at hibernate.org> wrote:
> 
>> On Mon, 2010-02-01 at 09:49 +0100, Emmanuel Bernard wrote:
>>> Also "plugins" can make use of the general availability of properties.
>>> For example Hibernate Search reads everything under hibernate.search (and it's not a limited set of property names). Likewise, HSearch extensions can use whatever property name they want to configure say the custom backend or the directory providers (either custom or even one of the system properties).
>> 
>> The main use case I was keeping in mind along the way was caching.  I know in the JBC and Infinispan integrations they added the ability to read a lot of config information from our properties.
>> 
>> As long as it is something configured by the Configuration ->
>> Settings/SessionFactory process or the something is known to
>> SessionFactory at the end of its init it is workable.  For example, I
>> imagine Validator would be easy to tie in here because of the listeners;
>> they are known to the SessionFactory.  Not so sure about Search, it
>> registers listeners too so maybe its ok.
>> 
>> The first question is whether we want a push or pull (from perspective
>> of the things being configured) model here.  For example, would the
>> ConnectionProvider tell SessionFactory about the properties it consumed
>> (push)?  Or would the SessionFactory ask the ConnectionProvider for that
>> info (pull)?
>> 
>> The pull approach has the advantage of being the least trade-off .  We
>> could add an optional interface "PropertyConsumer" that things can
>> choose to implement.  If they do, the method would be something like
>> "collectConsumedProperties(Map copy)"; they would put all the property
>> keys/values into the given map.
>> 
>> Another potential "pull" approach is to not pass around j.u.Properties
>> into these things to configure themselves, but to instead wrap that in a
>> class that journals the key/values as they are requested.  That is a bit
>> more invasive though as it would mean changing quite a few contracts,
>> some of which are implemented by classes outside our control.
>> 
>> In the "push" strategy, the things configuring themselves somehow push
>> which properties (key/value) they are consuming.  Much like the second
>> pull-approach, this is pretty invasive because we would need to pass in
>> the mechanism for these "configurables" to report back which properties
>> they are consuming.  Not to mention its tedious.
>> 
>> Long term I like the second pull approach.  However, I personally think
>> it is too disruptive in the short term and that we should use the first
>> pull approach for now.
>> 
>> Thoughts?
>> 
>