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Data Descriptive Language for Shared Data (RFC0242)

IP.com Disclosure Number: IPCOM000002996D
Original Publication Date: 1971-Jul-19
Included in the Prior Art Database: 2000-Sep-13
Document File: 9 page(s) / 17K

Publishing Venue

Internet Society Requests For Comment (RFCs)

Related People

L. Haibt: AUTHOR [+2]

Abstract

A primary consequence of the use of networks of computers is the demand for more efficient shared use of data.

This text was extracted from a ASCII Text document.
This is the abbreviated version, containing approximately 17% of the total text.

RFC 242

NIC 7672

Categories: D.4, D.7

DATA DESCRIPTIVE LANGUAGE FOR SHARED DATA

L. Haibt

A. Mullery

Thomas J. Watson Research Center

Yorktown Heights, N.Y.

July 19, 1971

Introduction

A primary consequence of the use of networks of computers is the

demand for more efficient shared use of data.

Many of the impedements to easy shared data follow from the many

diverse ways of representing and making reference to the same data.

Almost all of these problems have been known before data was shared

through computer networks, but the network facility has simply

emphasized the problems.

For convenience of discussion, representation differences will be

classified in three categories. The first category is one of very local

representation - the bit patterns for the character set, for fixed point

and floating point numbers. These differences are usually imposed by

differences in CPU's and storage devices. Translations from one

representation to another at another at this level can usually be made a

unit at a time (e.g. computer word by computer word) with the most

serious problems occurring when there are some values in one

representation scheme which have no corresponding meaning in the other

representation scheme, as, for expamble, when trying to translate

eight-bit bytes to six-bit bytes.

A second category of differences has to do with the representation

of collections of data, e.g., their size, ordering and location.

A third category of representation differences which is a little

difficult to characterize has to do with all the more complex structures

that data collections may have - for example, files with indexes, fields

with internal pointers and cross references, and collections of files

such as partitioned data sets and generation data sets in OS 360.

The approach to coping with these problems within our project of

Network/440 has been to work on the development of a descriptive

language which would permit the specification of those aspects of data

representation which would be subject to transformation in moving data

about in a network. Then, the network data managment system would be

able to refer to the descriptions as needed in the data management

function. For example, to a large extent, one could supply two

descriptions to the data manager, one wich indicates how data is now

represented, and one which indicates how a copy of it should look, and

the data managment systems could invoke the necessary transformations to

make the proper copy.

This approach to specifying data transformation contrasts somewhat

with systems, such as the RAND Form Machine, which provide a formalism

for specifying the particular translation alogrithms for changing form

one form to another. the descriptor-to descriptor approach seems to

simplyfy the programming burden when creating new field formats. Neither

method of specifying translations preclud...