Robert W. Taylor

Bio: Robert W. Taylor is an academic researcher from University of Massachusetts Amherst. The author has contributed to research in topics: Data independence & Data manipulation language. The author has an hindex of 4, co-authored 4 publications receiving 74 citations.

A data definition and mapping language

Abstract: : A data definition language is a declarative computer language for specifying data structures. Most data definition languages concentrate on the declaration of logical data structures with little concern for how these structures are physically realized on a computer system. However, the need for data definition languages which describe both the logical and physical aspects of data is increasingly apparent. Such languages will be a key element in the translation of data among computer systems, as well as in advanced data management systems and distributed data bases. The paper reviews past work in the data definition language for describing both logical and physical aspects of data. Applications of these generalized data definition languages are also discussed. (Author)

Data administration and the DBTG report

Abstract: The April, 1971, Data Base Task Group Report has already had a profound impact on the data base management community. At least five currently released systems claim to follow the report's guidelines. Yet the report was criticized at the time of its release for the lack of data independence in the Data Manipulation Language and excessive bookkeeping required of an application programmer. This paper demonstrates the use of a macro pre-processor which can increase data independence and greatly alleviate many of these shortcomings.

When are pointer arrays better than chains

Abstract: The DBTG [1] introduced two modes of set implementation--chain and pointer array. To review briefly, a set occurrence is an occurrence of the (unique) set owner along with zero or more occurrences of each of the set members. The mode of a set indicates the strategy to be used by the data management system in moving from one record occurrence to another within the same set occurrence.

Report on IFIP TC-2 conference: "a technical in-depth evaluation of the DDL"

Abstract: In response to increasing interest in data management, Technical Committee 2 of IFIP has been sponsoring a series of conferences over the past year. The most recent of these was held in Wepion, near Namur, Belgium, and dealt primarily with the Schema Language defined in the CODASYL Data Description Language Journal of Development. The CODASYL Schema Language has been widely discussed in the U.S. (witness the debate at the ACM SIGMOD Conference, held last May in Ann Arbor), and the interest in Europe on this same topic is at least as great. This conference was somewhat unique, however--the focus of the entire conference was on the single topic of the CODASYL DDL, hence the topic was discussed in more detail than probably it ever has been outside of DDLC (Data Description Language Committee) itself.

EXPRESS: a data EXtraction, Processing, and Restructuring System

Abstract: EXPRESS is an experimental prototype data translation system which can access a wide variety of data and restructure it for new uses The system is driven by two very high level nonprocedural languages: DEFINE for data description and CONVERT for data restructuring Program generation and cooperating process techniques are used to achieve efficient operationThis paper describes the design and implementation of EXPRESS DEFINE and CONVERT are summarized and the implementation architecture presentedThe DEFINE description is compiled into a customized PL/1 program for accessing source data The restructuring specified in CONVERT is compiled into a set of customized PL/1 procedures to derive multiple target files from multiple input files Job steps and job control statements are generated automatically During execution, the generated procedures run under control of a process supervisor, which coordinates buffer management and handles file allocation, deallocation, and all input/output requestsThe architecture of EXPRESS allows efficiency in execution by avoiding unnecessary secondary storage references while at the same time allowing the individual procedures to be independent of each other Its modular structure permits the system to be extended or transferred to another environment easily

Transferring data and storing metadata across a network

Abstract: Data is now able to be transferred back and forth between computer systems which have disparate file systems, e.g., between a computer having a hierarchical file system and a computer having a nonhierarchical file system. The differences, however, are not limited to the file storage system. Data may now be transferred across different platforms, different human and computer languages, different binary codes, etc. From one computer system the associated metadata is stored in a interpretable format on the second computer system so that when data and its associated metadata are transferred, the second computer system can interpret the transferred data. Data transfer can be accomplished in both directions. Thus, a tool writer or a software developer using a integrated development environment, such as Eclipse, on a Linux workstation with its hierarchical file system may download source files and other resources from an iSeries computer server with its OS/400 nonhierarchical file system, modify the resources, and then put them back onto the iSeries machine for use on the iSeries. The metadata of the source file and other resources are stored in a .properties file which, if in XML format, supports the transfer of resources across the Internet.

Evolution of Data-Base Management Systems

Abstract: This paper deals with the history and definitions common to data-base technology It delimits the objectives of data-base management systems, discusses important concepts, and defines terminology for use by other papers in this issue, traces the development of data-base systems methodology, gives a uniform example, and presents some trends and issues

CODASYL Data-Base Management Systems

Abstract: This paper presents in tutorial fashion the concepts, notation, aud data-base languages that were defined by the CODASYL Data Description Language and Programming Language Committees. Data structure diagram notation is explained, and sample data-base definition is developed along with several sample programs. \" Advanced features of the languages are discussed, together with examples of their use. An extensive bibliography is included.

Relational Data-Base Management Systems

Abstract: Before describing the relational model of data, we will briefly discuss some trends in data-base management which give motivation to the development of the relational model. The first large-scale, machine-readable collections of data were stored on external media such as cards or tape. Beginning in the late fifties and early sixties, data banks were being stored on-line using direct-access devices such as disks. Generalized software packages such as BDAM and ISAM [T2] were developed to aid programmers in accessing the data. During the late sixties and early seventies, the idea of an integrated data-base management system was developed. This concept allowed several applications to share a common bank of data, maintained and protected by a central system. In an integrated data-base environment, the data-base management system (DBMS) provides each application program with its own view of the common data, implements various operators for retrieval and update of data, and resolves interference between concurrent users. The overall trend which is visible in data-base management today is the following: users are becoming increasingly oriented toward the information content of their data, and decreasingly concerned with its repwaenta.tion details. Increasingly, the user interface of a modern DBMS deals with abstract information rather than with the various bits, pointers, arrays, lists, etc., which may be used to represent information. Responsibility for choosing an appropriate representation for the information is being assumed by the system and is not exposed to the end user; indeed, the representation of a given fact may change over time without the user being aware of the change. The general term for this trend away from representation details is data independence. If we attempt to extrapolate the trend toward data independence, we observe that most current DBMS present the user with a view of records connected in some sort of structure, such as a network or hierarchy. In such a view, information may be represented in at least three ways: 1) by the contenls of records (e.g., Smith’s employee record has DEPTNO = 50.); 2) by the connections between records e.g., Smith’s employee record occurs in the hierarchy below the department record for Dept. 50.); and