Re: Hibernate
Re: Hibernate
- Subject: Re: Hibernate
- From: Mike Schrag <email@hidden>
- Date: Wed, 25 Feb 2009 13:21:51 -0500
- Delivered-to: email@hidden
- Delivered-to: email@hidden
1. the Session doesn't need to be tightly bound. unlike
EOEditingContext that's tightly bound to the EOObjectStoreCoordinator
I'm not exactly sure what you mean here, or what you the desired
features would be if you could "unbind" an EC from an OSC? You can
obviously just make an EC with a new instance of an OSC and have it
standalone, but I'd be curious to hear more about what kinds of
problems you're trying to solve.
For request-response loop 1, I could have Session bound to DB
connection 1, and for request-response loop 2 I could have the same
Session bound to DB Connection 2. As I understand EOEditingContexts
are bound to an OSC. So all the ECs for one OSC would contend for
the same DB connection and it would be harder to scale out?
Yes ... but :) So yes, an EC is bound to an OSC (its the EC's backing
cache), but you can distribute EC's across OSC's (wonder has OSC
pooling w/ OSC affinity). If you use a single OSC, then you will
contend for a single connection. The downside right now is that EOF
has a separate snapshot cache for each OSC, making the memory
footprint of multiple OSC's potentially kind of high. If snapshot
caching was separated out, though, this would be a much "thinner"
relationship and would make pooling significantly more desirable (in
exchange for a more complicated snapshot caching layer). This would be
a nice addition to EOF.
nd of similar to #1 above. It's easier to just take a free
connection from a DB connection pool. In essence a Hibernate
session directly binds to a DB connection and doesn't have an OSC
layer in between.
I think Hibernate must have the equiv of an OSC somewhere floating in
there, as you'd have to know which connections are available to your
session as well as which cache your session is backed by. The
difference, I think, is what I was above, in that the snapshot cache
for Hibernate can float between multiple sessions, whereas EOF's are
inline with that stack. This is definitely a + in the hibernate column
for flexibility.
Someone also mentioned annotations ... Hibernate also supports
declarative mapping with XML files (which you might as well call "an
eomodel"), so you don't necessarily have to annotate your code. There
is definitely some value in Hibernate doing class rewriting, so the
objects themselves can be used outside of a persistence context. EOF
tends to prefer a much "smarter" managed object, though, which makes
it kind of hard (or at least weird) to use in other contexts.
ms
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