General specifications for the development of a PC-based simulator of the NASA RECON system

The general specifications for the design and implementation of an IBM PC/XT-based simulator of the NASA RECON system, including record designs, file structure designs, command language analysis, program design issues, error recovery considerations, and usage monitoring facilities are discussed. Once implemented, such a simulator will be utilized to evaluate the effectiveness of simulated information system access in addition to actual system usage as part of the total educational programs being developed within the NASA contract

Optimizing select-project-join queries

An optimal retrieval algorithm for relational database queries is a highly sought after ideal. A great amount of research has been applied in the quest for a better, faster, and cheaper universal retrieval scheme. Unfortunately there is no panacea, no single optimal method. With the many different database languages we find a variety of retrieval algorithms. This thesis explores heuristic methods for optimizing relational database query algorithms. It combines individual works on heuristics, cost modeling, decomposition, and join optimization. Lastly it assesses these optimization methods

A comparative study of structured and un-structured remote data access in distributed computing systems

Recently, the use of distributed computing systems has been growing rapidly due to the result of cheap and advanced microelectronic technology. In addition to the decrease in hardware costs, the tremendous development in machine to machine communication interfaces, especially in local area networking, also favours the use of distributed systems. Distributed systems often require remote access to data stored at different sites. Generally, two models of access to remote data storage exist: the un structured and structured models. In the former, data is simply stored as row of bytes, whereas in the latter, data is stored along with the associated access codes. The objective of this thesis is to compare these two models and hence determines the tradeoffs of each model. First of all, an extended review of the field of distributed data access is provided which addressing key issues such as the basic design principles of distributed computing systems, the notions of abstract data types, data inheritance, data type system and data persistence. Secondly, a distributed system is implemented using the persistent programming language PS-algol and the high level language C in conjunction with the remote procedure call facilities available in Unix(^1) 4.2 BSD operating system. This distributed system makes extensive use of Unix's software tools and hence it is called DCSUNIX for Distributed Computing System on UNIX. Thirdly, two specific applications which employ the implemented system will be given so that a comparison can be made between the two remote data access models mentioned above. Finally, the implemented system is compared with the criteria established earlier in the thesis. keywords: abstract data types, class, database management, data persistence, information hiding, inheritance, object oriented programming, programming languages, remote procedure calls, transparency, and type checking

The File Searching, Record Validating and Record Formatting Functions of the Supervisor for an Extended Data Management Facility

The purpose of the Supervisor in an Extended Data Management Facility (EDMF) is to direct the Facility\u27s handling of a user\u27s request for service. The Supervisor employs the five main functions of Access Controlling, Retrieval Optimizing, File Searching, Record Validating and Record Formatting in order to accomplish its task. This report is concerned mainly with the design and implementation of the File Searching and Record Validating Functions, although it also covers the Record Formatting Function. The File Searching and Record Validating Functions form that part of the Supervisor which actually controls the retrieval of records from the files of the EDMF. The major part of the report is concerned with discussing the File Searching Function because of the novel feature which has been implemented. This feature is the parallel processing of record lists in a generalized file structure, which eliminates redundant retrievals while at the same time reducing the access time of the device on which the records are stored. The Record Validating Function checks the record for compliance with the user\u27s request and verifies the user\u27s authority to access the record. A validated record is then subject to the Record Formatting Function which outputs it to the user

Meeting the Challenges of Met Data with Mysql

The objective of this project is to develop a relational database housing meteorological data used in direct support of emergency response activities for an atmospheric consulting firm, hereon referred to by the pseudonym WindInc. The intent is to demonstrate to WindInc how a relational database system would be superior to their present flat-file approach by providing the flexibility, performance, and reliability needed to meet their ever-increasing business demands, while simultaneously boosting the performance of their atmospheric dispersion modeling system

The Model Concept: Nonprocedural Programming for Nonprogrammers, II

This text contains description of the syntax and semantics of the language, MODEL, and techniques for its use. MODEL is a fifth-generation computer language. It is equational and non-procedural. (What these terms mean will be made clear to you as you begin to get involved in the MODEL system.) In this chapter, we shall discuss the value of the language. MODEL is a tool for systems and program design and development. Like most computer languages, the MODEL system comes with a compiler which is used to receive and analyze the language statements. But as we shall see later on, the whole process of analysis and coding is radically different in the MODEL system from programming methods in current practice. Using today\u27s conventional technology, it is necessary for the analyst to have knowledge of how a computer works internally. Otherwise, the analysis is often unusable by the programmers. To express data processing requirements that are translatable into a procedural language requires knowledge of how a computer executes the solution of the problem Non-procedural languages are problem-oriented and independent of knowledge of how the computer works. MODEL eliminates the need for transfer of information from analyst to programmer. The MODEL system uses the computer to perform program design and coding automatically. In traditional systems design, after the requirements and analysis phases are completed, the programming task begins. Specifications are given to programmers who fmt perform the program &sign and then write and debug the programs. In MODEL, once a specification is completed, the programming task is also done as a byproduct The specification itself is entered into the computer; submitted to the MODEL compiler. A PL/I program is generated, as well as a series of reports about the newly generated program. MODEL has facilities for automating all program development phases: design, coding and testing. It reduces the analyst\u27s involvement with computer execution through having the compiler interface with the computer and its environment. The analyst writes a specification which is entered into the computer. The specification is transformed into a PL/I program by the MODEL compiler. As soon as the specification is completed the system is ready for testing. In short, MODEL is an outgrowth of a widespread need to make programming more natural and more accessible to non-programmers. Welcome to the realm of non-procedurality. You are going to learn a new methodology for systems analysis. It will help you to complete complex projects and enable you to conceptualize problems in a clear, precise manner, without having to at the same time worry about its implementation in a computer

Access Control and Retrieval Optimization Functions of the Supervisor for an Extended Data Management Facility

The purpose of the Supervisor in an Extended Data Management Facility (EDMF) is to direct the Facility\u27s handling of a user\u27s request for service. The Supervisor fulfills its task through the use of five main functions: Access Control, Retrieval Initialization, File Searching, Record Validating and Record Formatting. The major and most important component of the Retrieval Initialization phase is the Retrieval Optimization subfunction. This report is concerned mainly with the design and implementation of the Access Control and Retrieval Optimization functions. Macro instructions are the mechanism through which a user\u27s program can call upon the ECMF. The Authority Item check is the EDMF\u27s security control over file access while the Prime Keyword Search is the method used to optimize the retrieval strategy. The Authority Item check and the Prime Keyword Search are two of the major concepts of the Extended Data Management Facility