Towards evolvable software architectures based on systems theoretic stability

Abstract

SUMMARY In today's increasingly volatile environments, evolvability is quickly becoming the most desirable characteristic of information systems. Current information systems still struggle to provide these high levels of evolvability. Based on the concept of stability from systems theory, we require that information systems should be stable with respect to a set of anticipated changes in order to exhibit high evolvability. This requires that information systems should be free from so‐called combinatorial effects. Combinatorial effects occur when the impact of a change is dependent on the size of the information system. To eliminate these combinatorial effects, we propose four theorems that are constraints on the modular structure of software architectures. The theorems are prescriptive and ensure that stable information systems are built, thereby guaranteeing high evolvability. We further present five higher level modular structures called elements. These elements provide the core functionality of information systems and comply fully with the stringent constraints implied by the four theorems. The internal structure of these elements is described by design patterns which are eligible for automatic code generation. These design patterns offer a constructive proof that it is possible to build information systems in practice by applying this set of theorems. Copyright © 2011 John Wiley & Sons, Ltd.

Context Aware and Adaptive Systems

“…Rule-based regulation, on the other hand, can explicitly reference contextual variables in the form of rule conditions that regulate interactions over the program or composition structure. Challenges for rule-based regulation include ensuring consistency of the rule-base both in their definition and in application, and ensuring that valid, non-oscillatory desirable behavior results from the application of complex rules sets (Cheng et al 2008;Mannaert et al 2012). Adaptive reconfiguration on the other hand focuses on maintaining a model of the architectural structure of the system, i.e., how the system is composed from components or services.…”

Enabling Normalized Systems in Practice – Exploring a Modeling Approach

“…Therefore, 5 higher-level detailed design patterns (so-called elements) have been proposed to create NS software in practice (Mannaert et al 2012, each aggregating and encapsulating a set of software constructs and providing the basic functionality of an information system:…”

“…The theory exhibits several appealing and unique characteristics for tackling the agility challenge: it is grounded in concepts from systems theory, the derived theorems provide specific programming guidance while unifying multiple software design best practices, and it has proven its feasibility in practice by multiple implementations for different types of systems in industry (Mannaert et al 2012;van der Linden et al 2017;Eessaar 2016).…”

“…This endeavor is not trivial. To begin with, as the NS theorems imply a very dense and highly structured code base (which is hard and time-intensive to obtain by manual coding), it is advised to generate a large portion of the code by the recurrent use of a set of NS ''elements'' (Mannaert et al 2012. As a consequence, a good modeling method should allow the adequate representation of enterprise requirements in terms of these NS elements.…”

Normalization of Domain Modeling in Enterprise Software Development

“…New normalization theories -Normalization Process Theory (NPT), Normalized Systems Theory (NST) and Norm Analysis method (NA) have emerged in different, however, co-related areas of organizational management, organizational modeling, and requirements engineering (Van Nuffel et al, 2009), (Murray et al, 2010), (Mannaert et al, , 2011, (Eessaar, 2014), (Linden et al, 2012), , (Tan et al, 2004), (Chong and Liu, 2000).…”