Martin Naedele

Manufacturing execution systems

We describe manufacturing execution systems (MESs) as a vision for software development.We identify gaps between the MES vision and current software development practices.To narrow the gaps we prototype a Modularity Debt Management Decision Support System.We provide four case studies, realizing MES vision and illustrating its benefits. Software development suffers from a lack of predictability with respect to cost, time, and quality. Predictability is one of the major concerns addressed by modern manufacturing execution systems (MESs). A MES does not actually execute the manufacturing (e.g., controlling equipment and producing goods), but rather collects, analyzes, integrates, and presents the data generated in industrial production so that employees have better insights into processes and can react quickly, leading to predictable manufacturing processes. In this paper, we introduce the principles and functional areas of a MES. We then analyze the gaps between MES-vision-driven software development and current practices. These gaps include: (1) lack of a unified data collection infrastructure, (2) lack of integrated people data, (3) lack of common conceptual frameworks driving improvement loops from development data, and (4) lack of support for projection and simulation. Finally, we illustrate the feasibility of leveraging MES principles to manage software development, using a Modularity Debt Management Decision Support System prototype we developed. In this prototype we demonstrate that information integration in MES-vision-driven systems enables new types of analyses, not previously available, for software development decision support. We conclude with suggestions for moving current software development practices closer to the MES vision.

Fault-tolerant real-time scheduling under execution time constraints

The primary/backup with deallocation approach of S. Ghosh et al. (1997) is a strategy for the fault-tolerant online scheduling of hard realtime tasks. In this scheme, tasks are either rejected within a short time after the request or guaranteed to be executed even in case of a processor failure. In this paper several heuristics for the guarantee algorithm are investigated. For the first time different processor selection strategies for guarantee algorithms with execution time constraints are compared. In addition, the concept of a decision deadline is introduced which then leads to an extension of the primary and backup checking routines. The thus modified checking routines are shown to achieve a lower rejection ratio for right task deadlines and constrained scheduler execution times than the modification making use of task slack suggested S. Ghosh et al. (1997).

Making the case for a "manufacturing execution system" for software development

Seeking to improve information integration throughout the manufacturing process.

Characterizing variable task releases and processor capacities

Abstract For the schedulability analysis of hard real-time systems it is important to use task and resource models that appropriately capture the characteristics of the underlying system. In this paper a general task model, the Variable Task Model , most appropriate for tasks with bursty release characteristics, is formalized. Also, a new processor model, the Variable Processor Model , is suggested which allows to account for dead time and variable processing speed. It is shown how worst case bounds on task response time can be calculated. A general schedulability test is derived.

An approach to modeling and evaluation of functional and timing specifications of real-time systems

Abstract Real-time systems need to be correct with respect to both functional and timing behaviors. Specification and modeling methods for real-time systems must thus permit the evaluation of functional and timing properties. Conventional real-time schedulability analyzers and simulators are not based on a formal specification and a model can thus not be formally verified. Formal specifications, on the other hand, frequently ignore preemptive scheduling and resource access protocols and the results obtained are thus only of limited value for systems using state-of-the-art scheduling algorithms. This paper proposes a novel Petri net-based approach for constructing specifications that are both formally verifiable and operational. It presents a solution to the preemption problem and suggests a pragmatic generic real-time system model which can be easily transformed into models for formal verification of functionality and for scheduling simulation. The well-known mine drainage system case study is used to demonstrate the application of this approach.