RE: Concurrency
I agree that each "page action" is by necessity a discrete transaction.
The issue is a standard multi-user problem - in the absence of a
stateful locking scheme is the data I am writing consistent with what I read
?
There are many approaches:
- re-read the record and compare each data item
- use timestamps on access
- track the keys of accessed items
-differentiate between operations that are obviously read-only versus r/w
etc.
Developers should be cognizant of all these issues and not take the
"hand-grenade" strategy or rely on low synchronicity.
As you commented - the key is to validate what you are doing at the back-end
in each operation.
RE: browser paradigm (back/forward)
Well, you are correct in stating that the developer must handle these
actions.
They won't go away by wishing it so...
I contend however that the reason we use the browser is not because of its
modeless paradigm but rather because of its ubiquity.
Deployment was the curse of application delivery - media costs,
installation,
config, support desks etc.
There's no denying that the look&feel defacto standards that users are now
familiar
with have dramatically reduced/eliminated the "learning curve" but I'd wager
that
no-one using their on-line banking/trading would miss the back/forward
buttons if
they simply weren't there.
The "browser" has become an application delivery platform and should mature
as such.
"Wizards" work back/forward because the "back/forward" operations are
submitted to the
server for processing. Browsers don't work because they take over and just
resort to the
cache which we know is implemented horribly and inconsistently.
Regards
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