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Designing Graceful Degradation in Software Systems

Dhall Rohit

Annals of Computer Science and Information Systems

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2017

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Vol. 10

171--179

EN

Graceful degradation is an aspect of a fault tolerant software system, where in case of some failures, system functionality is reduced to a smaller set of services/functionalities that can be performed by the system. During the period of graceful degradation, system runs and offers only the minimal set of critical services, thus avoiding total outages. This paper discusses some design approaches which can be used in a software system to handle graceful degradation. It also proposes and discusses the design of the ‘Capability Determination Model' (CDM), and how this model can be used to build and implement an IT software system with graceful degradation. This paper presents a high level design of the CDM and how different aspects of graceful degradation can be built into a software system using this model (CDM).Working of different components of CDM is also discussed. In the end, this paper talks about some of the alternatives of graceful degradation design and challenges associated with designing software systems with graceful degradation.

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From reliability to system dependability : theory and models

Zamojski W., Mazurkiewicz J.

Journal of Polish Safety and Reliability Association

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2011

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Vol. 2, No. 1

223--232

EN

The paper presents a novel approach to system dependability problem. The analysed systems and networks – characterised by different sets of features – are considered as a union of all their resources essential for the predicted tasks realisation. The system dependability is discussed with respect to the occurrence of incidents and treats that may cause to damage the system resources and – in consequence – to the collapse of the executed tasks. The maintenance policy system is based on two main concepts: detection of unfriendly events and system responses to them. The proposed analysis is realised from the user’s point of view, focusing on functional features described by business services available in the system.

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Dependability of discrete transport system : model, simulation, measures

Mazurkiewicz J.

Journal of Polish Safety and Reliability Association

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2011

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Vol. 2, No. 1

143--152

EN

The paper proposes a method of reliability and functional analysis related to discrete transport systems. The proposed analysis is based on modelling and simulating of the system behaviour. Monte Carlo simulation is used for proper reliability and functional parameters calculation. The simulator is built using Scalable Simulation Framework (SSF). No restriction on the system structure and on a kind of distribution is the main advantage of the method. The paper presents some exemplar system modelling. The authors stress the problem of influence of the reliability parameters for final functional measures (required time of delivery) – the key value to calculate the availability of the system. They also propose to measure the economic quality of discrete transport system by “profit function”. The presented problem is practically essential for defining an organization of vehicle maintenance and transportation system logistics.

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Critical situations and human resources in discrete transportation systems analysis

Walkowiak T., Mazurkiewicz J.

Journal of Polish Safety and Reliability Association

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2011

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Vol. 2, No. 1

205--216

EN

The paper presents an approach to critical situations analysis related to discrete transportation systems (DTS). The critical situation is understood as sudden shortage of some system recourses resulting in the transportation system performance degradation. The analysis is realized based on availability calculation of DTS. The system is described by the formal model, which includes reliability and functional parameters of DTS as well as human resources – drivers and management system. The availability and average availability of the system, defined in a functional way, is discussed as a function of different essential parameters of DTS. The proposed analysis is based on the modelling and simulating of the system behaviour using Monte-Carlo approach. The paper presents some exemplar systems – based on real Polish Post DTS – modelling and results.