Slideshow:
How to store records whose
structure is
unknown !!
I.e.: we do not know the record format in advance
Prelude to storing records whose
structure is
unknown
Comment: if you know XML (Extensible Markup Language), this would be a set of standard tags)
How to store one data field
of a variable format record
|
Each field contains 3 required "header fields" (Meaning, Datatype and Length)
Note: using Length, we can find the start poistion of the next data field !!!
Example: storing variable format
records
Example: storing variable format
records
- Problem description:
- We want to store records
whose structure
is:
- Unknown or
- Variable
- We want to store records
whose structure
is:
- We must first
define an
onthology
- Onthology =
a naming scheme
for things that we want
to represent
(In other words: we must define a encoding scheme)
- Onthology =
a naming scheme
for things that we want
to represent
- Example:
N = Name R = Restaurant owned S = String I = Integer F = Float ...
- Principle:
- When you do not know the record format, you must include the record format as part of the record
- A field of
a variable format record
is as follows:
- Example:
- Suppose we want to store:
Name Restaurant owned +----------------+----------------------+ | Clint Eastwood | Hog's Breath Inn | +----------------+----------------------+Record stored as:
- Suppose we want to store: