Re: [Modeling-users] (LONG) Other OR-bridges?

[Sebastien B. <sbi...@us...>]

        Hi,

Mario Ruggier <ma...@ru...> writes:

> Ah, very good to have the script. Also the tutorial.
> If you like I can review the tutorial, as well the the other docs...

  If you have some time to review some of the documentations your
  comments and changes will for sure be greatly
  appreciated. Documentation is unfortunately not what I do best, and
  I'm afraid my english is not that good.

> Yes, it is there, but it reads more like a brief overview of main
> elements and attributes, leaving one wondering what the complete
> picture is.  Having the XML spec available will take off the pressure
> on the general explanation, allowing it to highlight only what is
> typically most pertinent and not get lost in detail.  The XML spec
> could be its XSD (although i'd prefer another more expressive (human)
> definition syntax... in any case, it should only be up to half a page
> long.

  Hopefully you will find the changes of some interest. I re-organized
  and rewrote part of chapter 2, the xml format is now fully
  documented. The description I made of the XML format is naive, but I'm
  not familiar with XML specification at all.

> Also, I do not think that validation of the XML (per se) would be
> particularly useful, as it would not imply much about how valid the
> represented model is anyway.

Agreed

> > I can't see precisely how to design a csv that maps nicely to the x=
ml,
> > but I'm open to suggestions! Same, anyone feeling like coding some=
=20
> > tools
> > will be welcome ;) and in that case, I'll start a dev-branch and sh=
are
> > the unreleased-coz'-unfinished code I already have.
>=20
> CSV may or may not be appropriate, given that you do have some nesting
> in your format. However, after I familiarize myself better with the
> schema, I could offer something more concrete. On this issue, another
> possibly interesting way to handle this "description language" is
> using a construct or mini language in python itself...

Here again, feel free to share your ideas ;) I've been working on this
for such a long time that it is difficult to get fresh new ideas.

[...]
> >> Again, cost of fetching is (much) less important here. In addition,
> >> normally data is modified in small units, typically 1 object at a
> >> time. But when browsing, it is common to request fetches of 1000s =
of
> >> objects...
> >
> > That's exactly why there should be the possibility to fetch and get=
 raw
> > rows, not objects.
>=20
> There isn't? But can always do a raw select...

Right. I meant a mean to fetch raw rows and then easily get (a subset o=
f)
corresponding objects within the framework. BTW, this is possible, but
undocumented... I'll check that tomorrow and a FAQ entry ; remind me of
that if I forget!

> Do not know if this is already there, but i guess it would be also
> useful to be able to simply request to force a fresh fetch -- if any
> of the objects are already in the store they are reloaded.

This is part of the current dev. effort and will be present in v0.9.

> [about pessimistic locking] In general I am wary of this kind of
> behaviour as (a) it probably increases the possibility of clashes and
> "deadlocks", as mentioned in the linked article and (b) it is heavier
> on the server and (c) more difficult to program for, and introduces an
> additional set of possible problems, e.g. what if, after the
> application, after acquiring a lock on some objects, runs into
> problems and never gives it up?  Bad programming? Maybe, but the
> program should not have to worry about this.

That's my point of view too, and for this reason pessimistic locking is
surely not on top of the list (optimistic locking is, btw).

> Also, on requiring an object to be modified by only one person at a
> time -- this can always be handled with the mechanism described above,
> namely that before committing a change, the "original" object is
> compared to the db object, and if different the error is raised (and
> may be ignored). Besides, when would such a case require this? Aside,
> even systems like CVS do not restrict that a co item be modified by
> only one person.

Know what? I have never worked on any applications that did require
pessimistic locking. But you can find it documented in many books or
articles --I would be very interested in hearing from projects where it
was/is required!

> Hey, my interest in Modeling is based on what it does, and how it does
> it...  But, as i mentioned above, it would help it if all that it
> actually does already is given more prominence...

Sure, and again, thanks for your comments which should /normally/ help
in achieving that goal! If you feel like making some changes on your
own, I'll be happy to grant you write-access to cvs, just email me
privately and we'll set this up.

        Regards,

-- S=E9bastien.