Resolving feature convolution in middleware systems

Middleware provides simplicity and uniformity for the development of distributed applications. However, the modularity of the architecture of middleware is starting to disintegrate and to become complicated due to the interaction of too many orthogonal concerns imposed from a wide range of application requirements. This is not due to bad design but rather due to the limitations of the conventional architectural decomposition methodologies. We introduce the principles of horizontal decomposition (HD) which addresses this problem with a mixed-paradigm middleware architecture. HD provides guidance for the use of conventional decomposition methods to implement the core functionalities of middleware and the use of aspect orientation to address its orthogonal properties. Our evaluation of the horizontal decomposition principles focuses on refactoring major middleware functionalities into aspects in order to modularize and isolate them from the core architecture. New versions of the middleware platform can be created through combining the core and the flexible selection of middleware aspects such as IDL data types, the oneway invocation style, the dynamic messaging style, and additional character encoding schemes. As a result, the primary functionality of the middleware is supported with a much simpler architecture and enhanced performance. Moreover, customization and configuration of the middleware for a wide-range of requirements becomes possible

Assessment of Octave’s OO features based on GoF patterns

This thesis aims to evaluate the object-oriented (OO) features of the Octave programming language, through the implementation of the popular Gang-of-Four (GoF) design patterns. The study explores the fundamental principles of OO, including modularity, inheritance, encapsulation, polymorphism, and abstraction, and investigates how these concepts are supported by Octave. This research is conducted through the implementation of two complete collections of the GoF patterns originally coded in Java and the subsequent analysis of the quality of the implementations thus derived. This evaluation is based on comparisons with their Java counterparts as regards modularity and flexible module composition. To our knowledge, no study of this nature has been made on Octave. This thesis is intended to contribute to a better understanding of Octave’s current OO capabilities and limitations as well as its potential as a tool for developing complex software systems.Esta tese visa avaliar as características orientadas a objetos (OO) da linguagem de programação Octave, através da implementação dos populares design patterns dos Gang-of-Four (GoF). O estudo explora alguns princípios fundamentais de OO, incluindo modularidade, herança, encapsulamento, polimorfismo e abstração, e investiga o suporte de Octave a estes conceitos. Esta investigação é conduzida através da implementação de duas coleções completas dos padrões GoF originalmente desenvolvidos em Java e da análise subsequente à qualidade das implementações assim derivadas. Esta avaliação é baseada em comparações com os seus equivalentes Java no que diz respeito à modularidade e composição de módulos flexível. Segundo a nossa pesquisa, ainda não foi feito qualquer estudo desta natureza em Octave. Esta tese destina-se a contribuir para uma melhor compreensão das atuais capacidades e limitações do paradigma OO em Octave, bem como do seu potencial como ferramenta para o desenvolvimento de sistemas de software complexos

Programming language abstractions for extensible software components

With the growing demand for software systems that can cope with an increasing range of information processing tasks, the reuse of code from existing systems is essential to reduce the production costs of systems as well as the time to manufacture new software applications. For this reason, component-based software development techniques gain increasing attention in industry and research. Component technology is driven by the promise of building software by composing off-the-shelf components provided by a software component industry. Therefore, component technology emphasizes the independent development and deployment of components. Even though components look like perfect reusable assets, they embody general software solutions that need to be adapted to deploymentspecific needs and therefore cannot be deployed "as is" in general. Furthermore, as architectural building blocks, components are subject to continuous change. For these reasons, it is essential that components can easily be extended by both the component manufacturer to create new versions of components and by thirdparties that have to adapt components for use in specific software systems. Since in both cases concrete changes cannot be foreseen in general, mechanisms to integrate unanticipated extensions into components and component systems are required. While today many modern programming techniques, methodologies, and languages provide means that are well suited for creating static black-box components, the design and implementation of extensible components and extensible software systems often remains a challenge. In practice, extensibility is mostly achieved through ad-hoc techniques, like the disciplined use of design patterns and component frameworks, often in conjunction with meta-programming. The use of design patterns and component frameworks requires a rigorous coding discipline and often forces programmers to write tedious "boilerplate" code by hand, which makes this approach fragile and error-prone. Meta-programming techniques on the other hand are rather code-centric and mostly source code-based. Therefore, they are often not very suitable for today's component technology practice that stresses the binary reuse of black-box components. In this thesis I argue that technical difficulties in the development of extensible software components are due to the lack of appropriate programming language abstractions. To overcome the problems, concrete programming language mechanisms are proposed to facilitate the creation of extensible software. The proposed language features are strongly typed to help the programmer extend systems safely and consistently. The first part of the thesis illustrates the vision of truly extensible software components by proposing a simple theoretical model of first-class components built on top of a conventional class-based object-oriented language. This typed model includes a small set of primitives to dynamically build, compose, and extend software components safely, while supporting features like explicit context dependencies, late composition, unanticipated component extensibility, and strong encapsulation. The second part takes some ideas from the theoretical model and applies them in the design of the programming language Keris. Keris extends Java with an expressive module system featuring extensible modules. The main contributions are: A module system that combines the benefits of classical module systems for imperative languages with the advantages of modern component-oriented formalisms. In particular, modules are reusable, generic software components that can be linked with different cooperating modules without the need for resolving context dependencies by hand. A module composition scheme based on aggregation that makes the static architecture of a system explicit, and A type-safe mechanism for extending atomic modules aswell as fully linked systems statically by replacing selected subsystems with compatible versions without needing to re-link the full system. The extensibility mechanism is non-invasive; i.e. it preserves the original version and does not require access to source code. The overall design of the language was guided by the aim to develop a pragmatic, implementable, and conservative extension of Java which supports software development according to the open/closed principle: Systems written in Keris are closed in the sense that they can be executed, but they are open for unanticipated extensions that add, refine, or replace modules or whole subsystems. The last part of the thesis finally presents a case study which compares an extensible Java compiler implemented using mainstream object-oriented language features with one that was written in Keris. It shows how in practice, extensible modules can be used to develop extensible systems safely and efficiently

First-class features

Magdeburg, Univ., Fak. für Informatik, Diss., 2011von Sagar Sunkl

The Role of a Microservice Architecture on cybersecurity and operational resilience in critical systems

Critical systems are characterized by their high degree of intolerance to threats, in other words, their high level of resilience, because depending on the context in which the system is inserted, the slightest failure could imply significant damage, whether in economic terms, or loss of reputation, of information, of infrastructure, of the environment, or human life. The security of such systems is traditionally associated with legacy infrastructures and data centers that are monolithic, which translates into increasingly high evolution and protection challenges. In the current context of rapid transformation where the variety of threats to systems has been consistently increasing, this dissertation aims to carry out a compatibility study of the microservice architecture, which is denoted by its characteristics such as resilience, scalability, modifiability and technological heterogeneity, being flexible in structural adaptations, and in rapidly evolving and highly complex settings, making it suited for agile environments. It also explores what response artificial intelligence, more specifically machine learning, can provide in a context of security and monitorability when combined with a simple banking system that adopts the microservice architecture.Os sistemas críticos são caracterizados pelo seu elevado grau de intolerância às ameaças, por outras palavras, o seu alto nível de resiliência, pois dependendo do contexto onde se insere o sistema, a mínima falha poderá implicar danos significativos, seja em termos económicos, de perda de reputação, de informação, de infraestrutura, de ambiente, ou de vida humana. A segurança informática de tais sistemas está tradicionalmente associada a infraestruturas e data centers legacy, ou seja, de natureza monolítica, o que se traduz em desafios de evolução e proteção cada vez mais elevados. No contexto atual de rápida transformação, onde as variedades de ameaças aos sistemas têm vindo consistentemente a aumentar, esta dissertação visa realizar um estudo de compatibilidade da arquitetura de microserviços, que se denota pelas suas caraterísticas tais como a resiliência, escalabilidade, modificabilidade e heterogeneidade tecnológica, sendo flexível em adaptações estruturais, e em cenários de rápida evolução e elevada complexidade, tornando-a adequada a ambientes ágeis. Explora também a resposta que a inteligência artificial, mais concretamente, machine learning, pode dar num contexto de segurança e monitorabilidade quando combinado com um simples sistema bancário que adota uma arquitetura de microserviços