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C H A P T E R 1 1
Data Storage and Retrieval
About Data Storage on Newton Devices
applications might require notification include creating soups; deleting soups; and
adding, removing, or changing individual soup entries. The soup change
notification mechanism is discussed in more detail in "Using Soup Change
Notification" beginning on page 11-63.
In summary, most applications that work with dynamic data perform the following
operations, which are described in this chapter:
creating and using frames
storing frames as soup entries
querying soups to retrieve sets of entries
using cursor objects to work with sets of soup entries
extracting individual entries from cursor objects
manipulating individual soup entries as frame objects
returning modified entries to the soup from which they came
notifying other applications of changes to soups
Where to Go From Here
You should now have a general understanding of how stores, soups, queries,
cursors, and entries interact. It is strongly recommended that you read the remainder
of this section now--it provides important details you'll need to know in order to
work with the Newton data storage system. However, if you are anxious to begin
experimenting with Newton data storage objects, you can skip ahead to
"Programmer's Overview" on page 11-25 and read the remainder of this section at
another time.
Although soups and packages reside on stores, the occasions on which you'll need
to interact with stores directly are rare--the system manages hardware interaction
for you, creates union soups automatically as needed, and provides a programming
interface that allows you to perform most union soup operations without
manipulating the stores on which individual member soups reside. Occasionally,
you may need to message a store directly in order to create or retrieve a soup that is
not part of a union, or you may need to pass a store object as an argument to certain
methods; otherwise, most applications' direct interaction with stores is limited.
In general, only specialized applications that back up and restore soup data need to
manipulate stores directly. However, the system provides a complete developer
interface to stores, as documented in "Data Storage and Retrieval Reference"
(page 9-1) in Newton Programmer's Reference.
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