Re: coarse-grained object and fine-grain object
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On Tue, 7 Sep 2010, Lew wrote:
Lew wrote:
Eric and Arved already answered that question.
gk wrote:
Did you read what I posted ? That is not the answer to what I posted .
Lew:
Yes, I did, O Snarky One. ?Did you read what they posted?
gk:
Yes. I read and posted the summary ?after reading from there also.
However,that was not exactly what I wanted to know. Please see my
latest post , I found my answer and just posted the answer. You will
get a feel what I was asking.
Your summary substantially restates what they told you.
That's what a summary is, isn't it?
I have to say, i've been following this thread, and i've realised i don't
have a very good grasp of what coarseness of grain means when applied to
objects. I can tell you what it means for locks - row vs table vs database
locks, for example, or device vs subsystem vs kernel - or access control,
but not really for objects.
I have a gut feeling for how it applies to distributed object systems,
which roughly boils down to whether you end up making lots of little
calls, or a few big ones. For example, a mortgage application processor
that looked like:
interface MortgageApplication {
void setProperty(Property house);
void addApplication(Applicant app);
void apply();
boolean hasBeenProcessed();
boolean accepted();
}
interface Property {
void setPostcode(Postcode pc);
void setValuation(int valuation);
}
// etc
Would be fine-grained. Whereas one which looked like:
interface MortgageApplicationProcessor {
boolean apply(Property house, List<Application> apps);
}
class Property implements Serializable [
}
// etc
Would be coarse-grained. But really, that's more about a sliding scale
between classical early-90s distributed-object style and a good old
fashioned RPC. I don't think the *objects* involved in either mode are
more fine-grained; after all, i have exactly the same set of types!
The problem with objects is that big ones are made of smaller ones. How
can you have anything other than fine-grained objects?
Perhaps coarseness of grain isn't about what the objects are, but what you
*do* with them - whether you lock one at a time, or hundreds; whether you
allow access to one at a time, or hundreds; whether you send one at a time
over the network, or hundreds. Maybe the objects are the ruler with which
you measure the grain.
tom
--
As far as I can tell it's a mixture of stream-of-consciousness writing,
random mathematical formulae, and half-crazed references to sex.
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