Slide 30 of 52
Notes:
RDBMS access will use SQL - but in what wire protocol ? It could be a proprietary (e.g. Oracle) wire protocol, which may use UDP or TCP or anything else; or it might use ODBC.
The spatial data could be access by SQL too (if it is in an RDBMS), but the non-RDBMS systems will use something else.
Different OO systems can have very, very different ways of working. Ardent systems us OQL (similar to SQL architecture, but no ODBC possibility). Some others use a proprietary object-service others just fix the file access authorities and let the client access the relevant files using NFS or SMB - in which case the client is 'heavy' and contains all the OO logic itself. Usually this is the case since otherwise it can't use caches effectively.
The attributes RDBMS may be directly accessed by the client, or some attributes may be under the control of the spatial server.
