O trabalho descreve uma extensão da linguagem COBOL e sua implementação, para permitir a manipulação de bancos de dados relacionais. Esta extensão é constituída por instruções que executam um subconjunto de operações de álgebra relacional. A implementação é feita através de um pré-processador, que reconhece e transforma as instruções pertencentes a extensão em rotinas COBOL inseridas no programa do usuário. / This work describes a COBOL extension that allows the manipulation of relational data bases. The extension is composed by instructions that execute a subset of relational algebra operations. The implementation is accomplished by a pre-processor that recognizes and translates the new instructions to COBOL routines that are included in to the user's program.

No description available.

No description available.

O trabalho descreve uma extensão da linguagem COBOL e sua implementação, para permitir a manipulação de bancos de dados relacionais. Esta extensão é constituída por instruções que executam um subconjunto de operações de álgebra relacional. A implementação é feita através de um pré-processador, que reconhece e transforma as instruções pertencentes a extensão em rotinas COBOL inseridas no programa do usuário. / This work describes a COBOL extension that allows the manipulation of relational data bases. The extension is composed by instructions that execute a subset of relational algebra operations. The implementation is accomplished by a pre-processor that recognizes and translates the new instructions to COBOL routines that are included in to the user's program.

O trabalho descreve uma extensão da linguagem COBOL e sua implementação, para permitir a manipulação de bancos de dados relacionais. Esta extensão é constituída por instruções que executam um subconjunto de operações de álgebra relacional. A implementação é feita através de um pré-processador, que reconhece e transforma as instruções pertencentes a extensão em rotinas COBOL inseridas no programa do usuário. / This work describes a COBOL extension that allows the manipulation of relational data bases. The extension is composed by instructions that execute a subset of relational algebra operations. The implementation is accomplished by a pre-processor that recognizes and translates the new instructions to COBOL routines that are included in to the user's program.

The purpose of this research was to predict a COBOL program's reliability from software characteristics that are found in the program's source code. The first step was to select factors based on the human information processing model that are associated with changes in computer program reliability. Then these factors (software metrics) were quantitatively studied to determine which factors affect COBOL program reliability. Then a statistical model was developed that predicts COBOL program reliability. Reliability was selected because the reliability of computer programs can be used by systems professionals and auditors to make decisions. Using the Human Information Processing Model to study the act of creating a computer program, several hypotheses were derived about program characteristics and reliability. These hypotheses were categorized as size, structure, and temporal hypotheses. These characteristics were then used to test several prediction models for the reliability of COBOL programs. Program characteristics were measured by a program called METRICS. METRICS was written by the author using the Pascal programming language. It accepts COBOL programs as input and produces as output seventeen measures of complexity. Actual programs and related data were then gathered from a large insurance company over the course of one year. The data were used to test the hypotheses and to find a model for predicting the reliability of COBOL programs. The operational definition for reliability was the probability of a program executing without abending. The size of a program, its cyclomatic complexity, and the number of times a program has been executed were used to predict reliability. A regression model was developed that predicted the reliability of a COBOL program from a program's characteristics. The model had a prediction error of 9.3%, a R2 of 15%, and an adjusted R2 of 13%. The most important thing learned from the research is that increasing the size of a program's modules, not the total size of a program, is associated with decreased reliability. / Ph. D.

No description available.

This study discusses how migrating a legacy system to an object-oriented language works, and what kind of effect it generates. There are various methods that an organization can use when they want to migrate their legacy systems. The three most common procedures we found are reengineering, wrapping and redevelopment. The study will focus on how migration can be done and what the impact might be. Our case study has involved studying a public authority which has mainly used redevelopment when implementing the migration, but they have also used both reengineering and wrapping on certain occasions. In summary, there are many problems that can occur when the system is to be moved away from COBOL to other languages and we will mainly focus on the decisions underlying its implementation, the different ways they can be carried through, and how the problems that can arise are handled during migration. The study showed that the aspects that had a major impact on the choice of method the time and funding. The authorities’ reason for the migration was to have better flexibility and availability which they have succeeded and is now, for example, available around the clock. The redevelopment that the authority has used in our case study does not show that migration makes maintenance costs decrease; rather increase because it added more features and the systems became more complex which resulted in higher expenses. The authorities’ migration project has had big delays and that is a trademark problem with redevelopment. One reason for this is because they are migrating the systems iteratively and migrates parts of systems when there is time and funding. This resulted in a big delay but they have also never failed a project in the aspect that they had to go back to COBOL or abort it. The study thereby shows that a project which uses iterative redevelopment will not work ideally if the work is time- or budget sensitive but the results will be beneficial and will increase mainly functionality and flexibility.

This thesis proposes a method for the re-modularisation of legacy COBOL. Legacy code often performs a number of functions that if split, would improve software maintainability. For instance, program comprehension would benefit from a reduction in the size of the code modules. The method aims to identify potential reuse candidates from the functions re-modularised, and to ensure clear interfaces are present between the new modules. Furthermore, functionality is often replicated across applications and so the re-modularisation process can also seek to reduce commonality and hence the overall amount of a company's code requiring maintenance. A 10 step method is devised which assembles a number of new and existing techniques into an approach suitable for use by staff not having significant reengineering experience. Three main approaches are used throughout the method; that is the analysis of the PERFORM structure, the analysis of the data, and the use of graphical representations. Both top-down and bottom-up strategies to program comprehension are incorporated within the method as are automatable, and user controlled processes to reuse candidate selection. Three industrial case studies are used to demonstrate and evaluate the method. The case studies range in size to gain an indication of the scalability of the method. The case studies are used to evaluate the method on a step by step basis; both strong points and deficiencies are identified, as well as potential solutions to the deficiencies. A review is also presented to assesses the three main approaches of the methods; the analysis of the PERFORM and data structures, and the use of graphical representations. The review uses the process of software evolution for its evaluation using successive versions of COBOL software. The method is retrospectively applied to the earliest version and the known changes identified from the following versions are used to evaluate the re-modularisations. Within the evaluation chapters a new link within the dominance tree is proposed as is an approach for dealing with multiple dominance trees. The results show that «ach approach provides an important contribution to the method as well as giving a useful insight (in the form of graphical representations) of the process of software evolution.

Le but de cette étude est de présenter rapidement (en français) le langage Cobol, de le comparer aux langages commerciaux qui l'ont précédé et d'en faire la critique en tant que langage commercial, de le comparer à Algol et de le critiquer en tant que langage peu formel, de présenter les grandes lignes d'un compilateur sur un machine binaire à mots avec toutes les difficultés que cela représente, et de conclure sur l'avenir de Cobol