RIL(ID:4564/)

Representation accessing language 

Representation Independent accessing Language
Related languages
RIL => FORAL   Evolution of
RIL => RDL   follow-up to
References:
  • Fehder, P. L. "The representation-independent language part 1: introduction and the subsetting~peration" RJ 1121, IBM Research San Jose, California 1972 view details
  • Fehder, P. L. "The representation-independent language part 2: derivation and insert, update, and delete operations" RJ 1251 IBM Research San Jose, California 1973 view details
  • Senko, Michael E. "DIAM II: The binary infological level and its database language - FORAL" view details Abstract: The notion of dividing complex problems into hierarchic levels of abstraction has a long history. Recently this approach under the name, structured programming, has been used in a pragmatic way to simplify the structure of procedural programs. The notion has also been used in the data base area - notable early papers include those of Madnick (1) and Meltzer (2). In these early papers, level structures (for example, involving logical and physical levels) were also relatively pragmatic creations. One new aspect of the DIAM I architecture (3) was that it defined a detailed, relatively formal basis for four levels of abstraction and the mappings between these levels. Each level had a small set of primitive generalized building blocks, each with its own small permanent set of parameters. By specifying values for these parameters, the user could define essentially any reasonable data structure and file organization he wished for his stored information.
    Extract: Introduction
    The notion of dividing complex problems into hierarchic levels of abstraction has a long history. Recently this approach under the name, structured programming, has been used in a pragmatic way to simplify the structure of procedural programs. The notion has also been used in the data base area - notable early papers include those of Madnick and Meltzer. In these early papers, level structures (for example, involving logical and physical levels) were also relatively pragmatic creations.
    One new aspect of the DIAM I architecture was that it defined a detailed, relatively formal basis for four levels of abstraction and the mappings between these levels. Each level had a small set of primitive generalized building blocks, each with its own small permanent set of parameters. By specifying values for these parameters, the user could define essentially any reasonable data structure and file organization he wished for his stored information.
    In DIAM I, the top level, the Entity Set Level was based on a data structure independent form of single level "logical record". Following Meltzer and Mealy, DIAM I emphasized a study of the semantic aspects of this level that was designed to be the End-user's data structure independent view of the real world.
    The lower levels were designed to provide progressively more detailed definitions of the stored data structure. The second level, the Access Path Level, provided a generalized set of possible access paths for connecting specified pieces of Entity Set Level "logical records". It allowed the user to select a specific set of efficient access paths from this generalized set. The third level, the Encoding Level, utilizing a Basic Encoding Unit (BEU), provided for the selection of a specific bit encoding for the access paths from a generalized set of encodings ranging from generalized list structures with variable length fields to contiguous fixed length fields in contiguous fixed length records. The fourth level, the Physical Device Level, provided a generalized access method model for record storage management.
    Given this generalized model for data structures there was still a need for a non-procedural, data structure independent language for accessing information at the Entity Set Level. A major consideration was that it be designed for use by non-programmers. A first approximation to this language was provided by the Representation Independent accessing Language (RIL). This language was supplemented by a procedural language, Representation Dependent Language (RDL), for following access paths at the Access Path Level. Finally, preliminary algorithms were published for selecting optimal search paths for processing of RIL statements and subsequent compilation of the statements into optimal searches in RDL.
    Recently, the ANSI SPARC Committee has published additional work in defining level structures. This group gave added stature to an External Schema (or End-User) Level above the four levels formally defined in the DIAM I structure. It also gave clear recognition to the requirements for a non-redundant, data independent Conceptual Level describing the real world enterprise.
    Using this new Work on level structure, along with the work of Levien and Maron, Langefors, Ash and Silbley, Sundgren, and Abrial on binary representations, the DIAM I model has been modified and improved. The new model, DIAM II contains an End-User Level which fulfills the requirements desired by the External Schema of ANSI SPARC and an lnfological Leve I (ANSI Conceptual Schema) based on a modified form of binary association. This central level with its language interface, FORAL, is a fundamental improvement in semantic integrity over the I Entity Set Model of DIAM I and the somewhat similar n-ary relational model.
    In this paper, we will focus on the characteristics of the Infological Level and FORAL, the user-oriented language for processing in binary association networks. In this discussion, we will cover the unique employment of "FORAL Context" for limiting the user to transaction statements that are semantically meaningful in terms of his information network. Finally, we will briefly note the new kind and level of challenge that the selection of optimum search paths for FORAL in a DIAM II environment poses for the optimizing compiler area
          in SIGPLAN Notices 11(02) February 1976 also Proceedings of the SIGPLAN '76 Conference on Data: Abstraction, Definition and Structure, Salt Lake City, Utah, USA, March 22-24, 1976 view details