Views on issues relevant to data sharing on computer networks
RFC 146

Document Type RFC - Unknown (May 1971; No errata)
Last updated 2013-03-02
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Network Working, Group                                P.M. Karp, MITRE
Request for Comments #146                             D.B. McKay, IBM
NIC 6742                                              D.C. Wood, MITRE
                                                      12 May 1971

Categories: D.4, D.7
Obsoletes: none
Updates: none

                Views on Issues Relevant to Data Sharing
                          on Computer Networks

Introduction

The formation of a committee to address the problems of achieving
data sharing on the ARPA Network, as suggested by Arie Shoshani
(RFC #140) is desirable at this point of network development.  We
concur with Shoshani's ideas (presented in an introductory paper
to the network data sharing meeting, scheduled for Tuesday, May 18)
and believe that purpose of the committee should be -

        a) to classify the issues involved and to propose various
           approaches;

        b) to integrate the hitherto independent network activities
           that address problems in the area of data sharing, and;

        c) to set up and coordinate appropriate experiments to test
           the services developed and to evaluate alternative
           approaches.

This position paper is intended to augment Shoshani's as a basis
for discussion at the data sharing meeting. No attempt is made
to discuss specific means of implementation since many approaches
to data handling problems are possible and have been proposed.
Rather, our viewpoint on what the committee's role should be in
giving some cohesion to various existing implementations is
presented.

                                                                [Page 1]
Our Views

    One approach to achieving data sharing on the ARPA Network can
be thought of as having three stages, which roughly correspond to
the modes of use or operation. Within each stage are various levels
of development required to get to the next stage. This development
is not necessarily sequential. A description of the three stages
follows.

Stage 1: Data handling services are provided at various Hosts.
         The user talks directly to the serving Host (via TELNET
         or by addressing a known socket) to explicitly access
         the service.  This mode of operation corresponds to
         Bhushan's category of "direct" usage (RFC #114).  The
         data services provided by the serving Host range from
         simple ones, such as White's file transfer system (RFC #122)
         to sophisticated systems such as the CCA's data machine
         (NIC 5791 and 6706).

Stage 2: The user has access to an intermediate process or data
         control facility* that routes his requests for a particular
         data service to the serving system. The user must explicitly
         identify the data services to the used.  This mode of
         operation corresponds to Bhushan's category of "indirect"
         access. The data control facility provides the necessary
         control commands, data transformations, and accessing
         methods. A single request would include the use of several
         interacting services. For example, Heafner's Data
         Reconfiguration Service (RFC #l38) could be used in
         conjunction with the use of CCA's data machine.

_______________
*The data control facility is not necessarily located at his local
Host. Such a facility may exist on from one to all Host (i.e.,
ranging from centralized to completely distributed).

                                                                [Page 2]
Stage 3: The user treats the network as a single resource and is
         unconcerned with the location of the services, data files,
         etc. All references are by name. In this mode of opera-
         tion, the data control facility can function as a referral
         center for data service requests by using the most ap-
         propriate data service available and by automatically
         combining the use of several services that may be needed
         to satisfy a request.  For example, data could be retrieved
         from several files, each managed by a different data
         management system. The data control facility must be
         cognizant of the location of data files, their structure,
         data management system capabilities, etc.

Some approaches to the design of the data control facility have
been suggested by Shoshani, notably the integrated data management
system (IDMS) and the unified data management system (UDMS). The
notion of the network machine (RFC #51) is closest to the capabilities
one would see in Stage 3.

Relevant Areas of Development

The data control facility can range anywhere from a simple inter-
face to an intelligent front-end processor to a network-wide re-
ferral system.  In any case, a common means is desirable for
handling applications such as file transfer, on-line update and
retrieval of data, information gathering and reporting, and program
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