[concurrency-interest] Hibernate domain objects

Ashley Williams ashpublic at mac.com
Thu Jun 25 07:02:19 EDT 2009

Many thanks for the help so far on resetting my way of thinking when  
it comes to concurrency.

I would like to apply those lessons on my hibernate codebase, which  
for the uninitiated, consists
of a bunch of java beans style pojos with getters and setters. These  
are automatically called from the
hibernate api in order to sync with the database rows. As I see it  
there are a number of options:

1. This is a case where the domain model is genuinely mutable.  
Following the path of least
resistance means that I shouldn't try to bend this domain layer into  
something it wasn't supposed
to be and therefore introduce a little concurrency api in order to  
make it threadsafe.

2. Manage the lifecycle of the domain objects to ensure they are only  
ever used locally to a
thread. This means that care would have to taken when for example  
using the long conversation
pattern, where the session and its domain objects need to outlive the  
current thread/transaction.
In other words don't make the domain objects threadsafe but work hard  
in the rest of the
application that there is never any contention over them.

3. Consider the domain objects as nothing more than parameter holders  
and wrap them
inside genuine rich, immutable domain objects.

I'm sure there are more options and that there is no simple answer,  
but I would welcome any

- Ashley Williams

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