[fdo-dev] fdo 3.2

[Orest Halustchak]

Hi Haris,
 
Comments below ...
 
Thanks,
Orest.

  _____  

From: Haris Kurtagic [mailto:haris at sl-king.com] 
Sent: Wednesday, October 25, 2006 6:53 AM
To: dev at fdo.osgeo.org
Subject: [fdo-dev] fdo 3.2


I've read FDO 3.2 changes, and it looks like good changes.
One of things if I understood correctly is that we will be able to use
any characters in schema. 
[Orest] The provider can specify which characters are not allowed in a
name. But, if one provider decides to support a character that is not
supported by other providers, you may have problems applying schema used
in one provider against another provider unless you handle some sort of
name mangling.
 
I have couple of comments:
 
1. I saw changes in defining more exactly geometry type - good.
I miss very much rectangle or optimized rectangle especially in queries.
Now in filter provider gets polygon for some actions in MG, but
basically it is rectangle and
for some providers like for Oracle is important to know if it is
rectangle or really polygon.
Of course, provider can figure it out from points but it is no way it
should be. 
 
[Orest] The FGF polygon in this case is derived from the OGC simple
feature spec which I don't believe has an explicit optimized rectangle
representation such as in Oracle. While this is something Oracle
supports, other targets may not have such capabilities. It is something
that possibly could be added to the FGF spec, but we would then need to
add a capability for providers to indicate that they don't handle that
polygon representation. 
 
2. After coping fdo class from one provider to another, trough
AplySchema, it is difficult to get class definitions from newly created
classes.
   Geometry/Class/schema name can be changed from one provider to
another.
   It would be nice to have reader (like for insert geometries) which
would return map original class-new class, so the procedure is not
dependent on keeping same names. 
 
[Orest] Fdo does not expect that the class name would be changed by the
provider. That is, if you define a particular class name with apply
schema, a subsequent describe schema would return the same class name. A
provider may limit the allowable class names via length limits and valid
characters. Note that class names in FDO are logical schema concepts as
opposed to physical schema concepts such as table names. Providers that
can support a logical / physical mapping will map class names to table
names where a class name may not be identical to the physical table
name.
 
Haris
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