RFC 144 (rfc144) - Page 2 of 6

Data sharing on computer networks

RFC 144            Data Sharing on Computer Networks       30 April 1971


      6. What are the implementation considerations?

      7.  What are speed considerations?

POSSIBLE APPROACHES

      1. Centralized data management system (CDMS).

         This approach is consistent with the idea that a Computer
         Network eventually will evolve into a collection of specialized
         service nodes, where each node would perform a specific
         function well.  Users will use services on nodes according to
         their needs.  For example, one node could be a PL/I machine
         (possibly a microprogrammed machine to perform PL/I compilation
         efficiently), another node could be a "number cruncher" for
         parallel-structured problems (ILLIAC IV), etc.  In the same way
         there will be a node responsible for all data management needs
         for the network.

         Depending on the assumptions made one of two ways can be
         chosen:

         a. As assumption that we must be able to share all data,
            implies that the same data management system can create and
            manipulate this data, and therefore must perform all the
            functions required of a data management system, regardless
            of the particular use.  It is generally agreed that such a
            task is monumental and impractical (if not impossible),
            since different data management systems are designed to
            perform specific functions well on the expense of degraded
            performance of other functions (e.g., fast retrieval of
            large files, limited updating capabilities).

         b. The assumption is made that users will share only data from
            the same file on a particular data management system.  In
            this case one can implement different data management
            services for different tasks, but put them all on the same
            node to provide a data management service to the Network
            users.  This approach can still use one common language to
            access these services.  This is apparently the approach
            taken by CCA as indicated in NIC memo 5791.

      2. Standardized data management system (SDMS).

         In this approach a particular data management system is adopted
         to be implemented on all nodes.  This provides for a
         standardized data management language as well as an identical
         logical data structures.  Alternatively, one can choose a set



Shoshani