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From Emmanuel Lecharny <elecha...@gmail.com>
Subject Re: [ServerEntry API] AttributeType into Values
Date Sun, 16 Dec 2007 10:08:27 GMT
Alex Karasulu wrote:
> I thought about this a lot at one point and was compelled to add it.  
> The reason being the ability to request a normalized version of the 
> value without having to feed the attributeType into the normalize method.
Is there a place where we need to normalize a single value out of any 
context ?

> Or the need to ask the attribute to normalize the value on the value's 
> behalf since the attribute is what knows the attribute type and hence 
> has access to the normalizers.  
If the attribute is asked to normalize a value, then it already knows 
its attributeType. Then it's not really mandatory to store the AT into 
the value because we already have access to the AT (except if you need a 
normalizer with no parameter)

> So this allows an attribute value to be normalized without requiring 
> direct access to the attribute type by the caller. 
The main issue I have with this approach (feeding the value with the AT) 
is that it requires more work when creating the attribute and the value :
- you have to pass the AT to all the instances
- you have to store this AT many times (not very memory light)
- you have to check that a value has the same AT than the attribute for 
each new attribute

I'm not sure that it worth the price...

>
> Also we are thinking about making some default implementations of 
> various interfaces like Entry, and Attribute act as factories for the 
> objects they contain.  This way a value "belongs" to some 
> attributeType and attribute.  If you don't have a reference to the 
> attributeType the only other way to have an argument free normalize() 
> method on the value is to have a back reference to the attribute the 
> value belongs to in the value.  From there the attributeType can be 
> accessed and used to normalize without requiring the caller to provide 
> additional arguments like a norrmalizer or an attributeType.
It depends. We can have this normalize() method for entries and 
attributes, but do we need it for values, instead of a value.normalize( 
at ) ? The main pint is : do we manipulate value alone ? And if so, in 
which context ?
>
> At a high level in my mind an attribute value is closely associated 
> with an attributeType in terms of the way it is compared, returned and 
> set rather than with a specific attribute of a specific entry.  This 
> decoupling can be exploited in indices on specific attributeTypes 
> which will contain the values of various entries.
Indices should work on the normalized form of the value. In this case, 
there is no need to normalize the value again, without having access to 
its attribute. I think that the current version of the server does not 
work like this, as we are comparing not normalized values, doing the 
normalization inside the comparison. If we change the way we compare 
values by using normalized values instead, then this association ( value 
<-> attributeType) suddenly lose a lot of interest.

I still have to think more about it. I'm not arguing with you, just 
trying to see the light and push you a bit to see if I have missed 
something important. Whoever is right is not important, because we win 
in both case : if I'm right, we will have a better server, and if you 
are right, I will have a better understanding of the server (and there 
will be no way to improve the server in the direction I'm trying to take).

Thanks for the answers !

-- 
--
cordialement, regards,
Emmanuel L├ęcharny
www.iktek.com
directory.apache.org



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