[hibernate-dev] [HSearch] ServiceManager and services

[Hardy Ferentschik]

On 12 Jan 2012, at 3:00 PM, Steve Ebersole wrote:

> "Java services api" == ServiceLoader I assume?

correct 

> Going on that assumption:
> 
> No.  ServiceLoader is just a discovery mechanism.  There still needs to be something that, as you say, negotiates amongst the various discovered implementations of a particular service.  2 well known ServiceLoader uses are JDBC drivers and image processors, each illustrating a different approach that are really inherent to their respective problem domains.  In the case of JDBC drivers, the discovery is just used to register all the available drivers; users must still specify which driver they want via JDBC url protocol.  In the case of image processing (as I understand it anyway, not really my forte) the choice of processor is more intrinsic to the image you ask to have processed based on MIME type.
> 
> Here is sound like you more have the JDBC style, where discovery is just making the complete set of possibilities known.  The user would still need to make a distinction.  Or maybe you have some special rules like (a) using the standard service if it is the only one discovered; (b) using the "other" service if 2 are discovered; (c) requiring the user tell you if 3 or more are found. Many ways to skin that cat.

Right. I would expect the user to make this distinction via the configuration. 

I think really the problem is that what we have is actually not a ServiceManager (at least not what I understand under this term). It is a fancy way to instantiating a class and giving it a life cycle (aka #start(), #stop()).
We really have more of a BeanLifeCycleManager. 

--Hardy