لینک دانلود و خرید پایین توضیحات
دسته بندی : پاورپوینت
نوع فایل : .ppt ( قابل ویرایش و آماده پرینت )
تعداد اسلاید : 23 اسلاید
قسمتی از متن .ppt :
Beyond Record Structures
Dr. Robert J. Hammell
Assistant Professor
Towson University
Computer and Information Sciences Department
8000 York Road - Suite 406
Towson, MD 21252
http://triton.towson.edu/~rhammell/
Objectives
Examine file structures in terms of
Abstract data models
Metadata
Object-oriented file access
Extensibility
Examine portability and standardization
Beyond Record Structures
Abstract Data Models for file access
Computers can process sound, images, documents
“Information” not data stored as fields & records
Envision the data as objects
Sound objects; image objects; document objects
Abstract data model
Application-oriented view of data
Not a medium-oriented view
Describe organization & access from the application’s point of view
Headers & self-describing fields
Want to keep user from having to know about objects
One way is to put information in the file
Allows file-access software to understand objects
Put more information in the header
Makes the file self-describing
Information such as:
Name for each field
Width of each field
Number of fields per record
Can write program to read and print
Regardless of number of fields per record
With any combination of fixed-length fields