[cap-talk] capability-enabled distributed spatial systems

David-Sarah Hopwood david-sarah at jacaranda.org
Wed Apr 22 11:11:33 EDT 2009


John Carlson wrote:
> I would rather focus on the network protocol rather than relational  
> versus object oriented (in other words, forget I said database).
> I think some typical things you might do in a SQL sense is:
> 
> SQL-like
> ------------
> INSERT an OBJECT2 into a OBJECT1 (say a scene)
> UPDATE position of OBJECT1, possibly relative to some other OBJECT2
> UPDATE the attribute ATTRIBUTE1 of and OBJECT1 with a value
> SELECT named OBJECTs contained in an OBJECT1
> SELECT_COPY of named OBJECTs contained in an Object1
> DELETE an OBJECT2 from an OBJECT1.
> 
> If you would prefer that I do something like:
> Object-Oriented                                               HTTP
> ------------------------------------------------------------  --------
> Object1.INSERT(Object2)                                       PUT
> Object1.UPDATE(Position1, Object2)                            POST
> Object1.UPDATE(Attribute1, value)                             POST
> List<Object> objects = Object1.SELECT(URI)                    GET
> Object1.DELETE(Object2)                                       DELETE	
> 
> I would think that these would be equivalent mechanisms

These are not simply equivalent syntaxes or mechanisms. In the
object-oriented or message-passing case, the operation is represented
by a message passed to the distinguished argument (Object1 above):

 - in all message passing systems, this affects which object/class
   definition is responsible for implementing the operation;
 - in a distributed system, this affects which node the message
   is sent to;
 - in a concurrent system, it may affect which object or vat is
   used for mutual exclusion;
 - in object-capability systems, it affects which authorities the
   implementation has access to (it may have greater access to
   "private" or otherwise encapsulated properties of Object1).

-- 
David-Sarah Hopwood ⚥





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