Re: Navigation question

On Feb 23, 10:10 am, "Walt" <wami..._at_verizon.net> wrote:
> "dawn" <dawnwolth..._at_gmail.com> wrote in message
<snip>
> > Add 8 "User Layer" to the OSI layers. My questions are regarding
> > layer 7, where "logical navigation" of a database might take place.
> > Does that work for you? --dawn
>
> what do you mean by "OSI layers?" Are you talking about layers of
> protocols? If so, it seems to me that application to
> database theory is limited to the areas where data is exchanged in some sort
> of formal protocol.

The database as well as all other aspects of application suites would be in layer 7, right? We are not crossing OSI layers with data model implementations nor other aspects of code interfacing with a DBMS.

> That sounds to me like the interface between the client
> (application software) and the server (DBMS software). If that layer uses
> SQL to express queries and updates,

SQL is not a bridge between any two of the 7 OSI layers. I'm not sure that is what you were suggesting, however.

> and some sort of data representation to
> pass result tables, then I would suggest that those who have said that
> "navigation is impossible at this layer" are correct.

Impossible in layer 7? Surely it is possible in our application layer, so to which OSI layer(s) are you referring?

> Whether applications should or should not navigate within their own data
> space is really not a question for database theory, is it?

My question was about navigating databases. Applications and non- -SQL-DBMS's have additional provisions for doing so as well (permitting link specifications, for example), but people seem to poohpooh  it. All such logical navigation takes place squarely within layer 7. Good enough? --dawn Received on Fri Feb 23 2007 - 19:47:47 CET