Re: Memory space in a shared, private framework
Re: Memory space in a shared, private framework
- Subject: Re: Memory space in a shared, private framework
- From: Sherm Pendley <email@hidden>
- Date: Fri, 11 May 2007 08:19:26 -0400
On May 11, 2007, at 7:57 AM, Philip Dow wrote:
Let me see if I can clarify this the right way. Everything is being
done with Cocoa/Obj-C. I'd like to create a private framework that
is responsible for managing the data store of an application. Other
applications would be able to link against this framework and use
it to access the same data store.
My question concerns the "memory space" of the framework (is there
a better name for this?). Does the framework occupy the same memory
in both applications?
The framework's code is shared, that's all. Application data is
stored on the heap and the stack, neither of which is normally shared
with other applications.
For example, if one application added or modified an object, would
the other application be aware of this change? Or does the
framework exist independently in the two applications so that a
change from one would not be noticed in the other?
You could arrange for such sharing to take place, if you wanted it
to, through shared memory, distributed objects and/or notifications,
and the like. But it won't happen by default.
The best example I can think of is the AddressBook framework. Many
applications link against and use this framework. When one
application changes an AB record via the framework, other
applications immediately become aware of those changes, not only in
the data model but also in the interface thanks to the
AddressBookUI and bindings. Is this the de facto case with a shared
framework or is the AddressBook framework doing something special
here?
AddressBook is most likely just making changes to a common data store
on disk, and then firing off a distributed notification. Upon
receiving that notification, other AB instances can then simply
reload any effected records from disk.
There very well may be some shared-memory arrangement behind the
scenes, maybe using memory-mapped I/O for the data storage. If so, it
would be the result of the AB framework being specifically written
that way, not of any de facto default regarding frameworks.
sherm--
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