Re: updatable views

Hi,

The reason why I would like a view concept, is not listed in your argument. I see this in a context of "fluid" software design, where the specification of a certain piece of behaviour on the data model might be easier if it could be specified on a view of the data model (which would need to be updatable in general of course). at runtime, new views would constantly be created and destroyed, forming a fluid "facade" on the real data model.

Cheers,

Hans

On Sun, 30 Jan 2005 00:15:17 +0100
Leo Mekenkamp <[email protected]> wrote:

> On Fri, 2005-01-28 at 19:38 +0100, SainTiss wrote:
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> > Certainly...
> > 
> > Try
> > http://citeseer.ist.psu.edu/rd/31714464,229922,1,0.25,Download/http://citeseer.ist.psu.edu/cache/papers/cs/1421/ftp:zSzzSzftp.fmi.uni-konstanz.dezSzpubzSzdbiszSzPublicationszSzSLT:DOOD91.pdf/scholl91updatable.pdf
> 
> Dry stuff. Where to start?
> 
> First of all, it is a bit late when I am typing this and English is not
> my first language. That alone can cause communication problems over
> e-mail, and when you add my genetic defect of having diplomatic skills
> that can be compared to an elephant in a porcelain shop, things can get
> really nasty ;-).
> 
> In short: this is my personal opinion; I do not want to stand on
> anyone's toes, and I'm sorry if I do.
> 
> Now to the article: "(...) any query (...)". Ah, that's where it goes
> wrong, right in the introduction. Why would we need a query? A query is
> _an_ implementation for getting data out of a database, not _the only_
> one. I for one do not like queries in a language that is different from
> the language I am writing in at that moment, if only for the fact that
> the compiler will not correct my ever so often occuring typing errors in
> queries. I absolutely despise two programming languages in one source
> file.
> 
> Now for the reasons for such views:
> 1) Size of the schema. I fail to see the reason why a schema need to be
> small to be manageable. Any OO application can have a zillion classes;
> as long as you keep inheritance logical (and with java: package
> structure logical) I see no reason to further split this up.
> 
> (Getting fed up with my arrogant tone yet? ;-)
> 
> 2) Authorization. Why not simply make some method calls unavailable? Why
> use views? Why not have the database throw an exception?
> 
> 3) Integration. Why not use value objects, delegates or whatever? There
> are perfect working patterns that every developer should know, why add
> another concept?
> 
> 4) Upward compatibility. Again, delegation/value pattern (Ozone uses yet
> another 'transparent' solution).
> 
> I fail to see any of these 4 points as a good reason. Therefor I fail to
> see the reason for views in an oodbms.
> 
> The article continues to use set-oriented algebra as if it were the only
> way. The talk about 'insert', 'delete' and 'update' further gives the
> impression that the writer thinks in a relational query structure. Ozone
> is not at all a relational database; the main thing it has in common
> with rdbms-es is that they both store data, and it pretty much ends
> there.
> 
> 
> Now what I think of Ozone: Ozone is a great way of making sure that
> objects and references to other objects are persisted from one instance
> of a JVM to another one starting up after the original JVM. The nicest
> thing about Ozone is that it can be almost invisible; it does not get in
> the way. You do not have to think that you use a database at all. No
> need to 'store objects', 'update objects' or whatever, you simply
> program in Java as you would normally do (with a few caveats of course),
> and your data is simply there. There is even a bloody garbage collector!
> 
> There are no queries in Ozone, simply because there are no queries in
> Java. Period. In Java, you get from one object to another by following a
> reference. In Ozone it is exactly the same. Ozone mimics the way Java
> works; it does not introduce alien concepts as queries, relations,
> views, etc.
> 
> 
> Now, back to your original question (if you could bare to read this
> far ;-): does Ozone support views. No, it does not. Question back to
> you: why should Ozone support views? More broadly: why should Java
> support views?
> 
> Cheers,
> Leo
> 
> 
> 
> 
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