Deriving complexity information from a formal communication protocol specification

Communication software systems have become very large and complex. Recognizing the complexity of such software systems is a key element in their development activities. Software metrics are useful quantitative indicators for assessing and predicting software quality attributes, like complexity. However, most of existing metrics are extracted from source programs at the implementation phase of the software life cycle. They cannot provide early feedback during the specification phase; and subsequently it is difficult and expensive to make changes to the system, if so indicated by the metrics. It is therefore important to be able to measure system complexity at the specification phase. However, most software specifications are written in natural languages from which metrics information is very hard to extract. In this paper, we describe how complexity information can be derived from a formal communication protocol specification written in Estelle so that it is possible to predict the complexity of its implementation and subsequently its development can be better managed. © 1998 John Wiley & Sons, Ltd.     

Integrated Estelle and ASN.1 specification approach to automatic implementation of application protocol

Estelle currently does not support ASN.1 and encoding and decoding rules. Tools developed for Estelle and ASN.1 have been developed independently of each other. As such, ASN.1 tools do not support Estelle and vice versa. At present, due to these two separate specifications, implementation is time consuming. It is imperative to find a way for ASN.1 and Estelle specifications to be efficiently integrated to facilitate fully automatic implementation. This paper describes how Estelle and ASN.1 can be integrated to give a unified specification which can then be fed into a software environment to produce a truly automatic implementation of an application protocol, including encoding and decoding of protocol data units, when application layer protocols are specified in Estelle and in ASN.1. The integration approach is based on the powerful programming concept, Data Abstraction. The software that implements this integrated specification approach to automatic implementation of application protocol is called EASE (Estelle and ASN.1 Software Environment). To demonstrate the viability of the approach, the unified specification of the ISO ACSE and Presentation protocols are also presented.     

EASE : A Software Environment for Automatic Implementation of Application Protocol

At present, ASN.1, and encoding and decoding rules, are not supported by Estelle. Estelle only specifies dynamic behaviours of protocols; and protocol data units of application layer protocol are specified in ASN.1. Hence, two standardized languages are required to specify an application protocol. In addition, Estelle and ASN.1 tools have been developed independently and do not support each other. As a result of these difficulties, the implementation of an application protocol is time consuming. To address this difficulty, we have proposed an approach which unified ASN.1 and Estelle specifications, and showed that the automatic implementation of an application protocol can be readily achieved by providing a software environment which supports this unified specification. This paper describes the detail of this software environment called EASE, and the results of using it to develop an implementation of the ISO FTAM protocol.     

A model for estimating the size of a formal communication protocol specification and its implementation

Good project management is key when developing a software system successfully. To manage a project well, it is important to have the optimal resource allocation which is affected by the size of an implementation. Early software size estimation is essential for good project management. Existing software size models estimate the size of an implementation usually in terms of the number of lines of code. The main drawback of these models is that there is a wide margin of uncertainty as the actual size depends on the type of application and the software development method adopted. To address this drawback, we focus our work on communication protocol, and propose that the size of a formal specification needs to be estimated from an informal specification. This paper presents a two-stage size model for estimating the sizes of a formal communication protocol specification and its implementation, with the model validated using a test data set. The main benefit of this work is that it can give an indication of the likely sizes of both a formal specification and its implementation early at the development stage, giving developers a technique for managing communication software project better.     

Measuring triggering-interaction complexity on active databases

Distinct software metrics have been proposed for programs. By contrast, metrics for databases have been neglected on the grounds that databases were mere plain files that do not affect considerably information systems maintainability. However, later enhancements on database systems have considerable increase the complexity of the elements kept within the database realm. Such complexity makes metrics a valuable tool to understand, monitor, control, predict and improve software development and maintenance database projects. Triggers are a case in point. Several reports warned about the difficulties to cope with large sets of triggers. Based on the difficulty to ascertain the causes that make a given rule to be triggered, this paper proposes three different metrics for measuring trigger complexity, namely, the triggering potential, the number of anchors and the distance of a trigger. These measures are characterised above the level of the ordinal scale using the measurement theory. Validation of the proposed metrics has been conducted through a set of empirical experiments.     

Improving the efficiency of automated protocol implementation using Estelle

Correctness and runtime efficiency are essential properties of software in general and of high-speed protocols in particular. Establishing correctness requires the use of FDTs during protocol design, and to prove the protocol code correct with respect to its formal specification. Another approach to boost confidence in the correctness of the implementation is to generate protocol code automatically from the specification. However, the runtime efficiency of this code is often insufficient. This has turned out to be a major obstacle to the use of FDTs in practice. One of the FDTs currently applied to communication protocols is Estelle. We show how runtime efficiency can be significantly improved by several measures carried out during the design, implementation and runtime of a protocol. Recent results of improvements in the efficiency of Estelle-based protocol implementations are extended and interpreted.     

Uncovering ISO ROSE protocol errors using Estelle

One of the main objectives of ISO in developing FDTs is that protocol specified in them can be verified. However, standardized FDTs have been designed largely for specification purpose; success of using them for protocol verification has been rarely reported. We have developed a technique of translating Estelle specifications into Numerical Petri nets, which can then be verified by a proven automated verification tool, PROTEAN. The merits of our approach are that specifications are fully based on standard Estelle, and dynamic behaviours of an Estelle specification can be handled. In this paper, we present a success story of using Estelle and the techniques we have developed to uncover ISO ROSE protocol errors. We find that Estelle is an FDT capable of analysing and verifying real protocols and it is therefore important to the development of ISO protocol standards.     

Semiautomatic implementation of protocols using an Estelle-Ccompiler

The basic ideas underlying an Estelle-C compiler, which accepts an Estelle protocol specification and produces a protocol implementation in C, are presented. The implementation of the ISO (International Organization for Standardization) class-2 transparent protocol, using the semiautomatic approach, is discussed. A manual implementation of the protocol is performed and compared to the semiautomatic implementation. The semiautomatic approach to protocol implementation offers several advantages over the conventional manual one, including correctness and modularity in protocol implementation code, conformance to the specification, and reduction in implementation time. Finally, ongoing development of a new Estelle-C compiler is presented     

OO metrics in practice

While it has long been recognized that software process improvement requires measuring both the process and its performance, experience has also shown that few universal metrics exist. The most effective measurement tools are specialized to some aspect of the task or domain being measured. The metrics as measures of code have often been related to external factors, such as software quality in the sense of defects. Software metrics studies often use single snapshots of a software project. Examining a project over a longer time frame allows consideration of other software quality facets, such as reuse and maintainability.     

产品线体系结构复杂性度量

产品线体系结构需要支持多种变化性以满足其内部成员特性，因而是重要又复杂的软件产品线子系统。本文通过分析产品线体系结构的vADL规约，充分考虑产品线体系结构变化性对其复杂性度量的影响，生成产品线体系结构信息流图PLA—IFG，基于PLA—IFG，实现自动化度量产品线体系结构复杂性，提出了支持变化性的产品线体系结构复杂性度量方法。     

基于多源特征空间的微服务可维护性评估

软件企业实践将遗留软件系统解耦成基于微服务架构的系统,以提高软件的可维护性,达到较快市场交付.评估微服务开发阶段的代码可维护性是一个关键问题,其面临数据多源化、可维护性关注点多样化的难点.通过分析源代码、代码运行轨迹、代码修订历史,提出一种多源特征空间模型以统一表示软件多源数据,并基于该模型,从功能性、模块性、可修改性...     

Complexity metrics for DMN decision models

Complexity impairs the maintainability and understandability of conceptual models. Complexity metrics have been used in software engineering and business process management (BPM) to capture the degree of complexity of conceptual models. The recent introduction of the Decision Model and Notation (DMN) standard provides opportunities to shift towards the Separation of Concerns paradigm when it comes to modelling processes and decisions. However, unlike for processes, no studies exist that address the representational complexity of DMN decision models. In this paper, we provide an initial set of complexity metrics for DMN models. We gather insights from the process modelling and software engineering fields to propose complexity metrics for DMN decision models. Additionally, we provide an empirical complexity assessment of DMN decision models. For the decision requirements level of the DMN standard 19 metrics were proposed, while 7 metrics were put forward for the decision logic level. For decision requirements, the model size-based metrics, the Durfee Square Metric (DSM) and the Perfect Square Metric (PSM) prove to be the most suitable. For the decision logic level of DMN the Hit Policy Usage (HPU) and the Total Number of Input Variables (TNIV) were evaluated as suitable for measuring DMN decision table complexity.     

Conceptual Association of Functional Size Measurement Methods

Functional size determines how much functionality software provides by measuring the aggregate amount of its cohesive execution sequences. Alan Albrecht first introduced the concept in 1979. Since he originally described the function point analysis (FPA) method, researchers and practitioners have developed variations of functional size metrics and methods. The authors discuss the conceptual similarities and differences between functional size measurement methods and introduce a model for unification.     

Complexity measures for assembly language programs

This paper presents the results of a study of the software complexity characteristics of a large real-time signal processing system for which there is a 6-yr maintenance history. The objective of the study was to compare values generated by software metrics to the maintenance history in order to determine which software complexity metrics would be most useful for estimating maintenance effort. The metrics that were analyzed were program size measures, software science measures, and control flow measures. During the course of the study two new software metrics were defined. The new metrics, maximum knot depth and knots per jump ratio, are both extensions of the knot count metric. When comparing the metrics to the maintenance data the control flow measures showed the strongest positive correlation.