An Initial Ontology for System Qualities

Abstract

Abstract. This paper presents an initial ontology for reasoning about a system's System Qualities (SQs), ilities, or non-functional requirements (reliability, usability, affordability, etc.). The need for such an ontology is based primarily on two factors. One is the importance of getting the SQs sufficiently well defined that the system's definition, development and evolution result in a satisfactory balance of SQ values for the system's success-critical stakeholders, given the frequent system shortfalls and overruns that occur when this balance is not achieved. The other is that current system acquisition and evolution guidance descriptions have numerous deficiencies and inconsistencies in their coverage of SQ considerations. This situation is becoming more serious as systems and their stakeholders become increasingly complex, dynamic, and diverse. This paper provides an elaboration of the needs, a set of initial SQ ontology elements and definitions, examples of their application to some key SQs and their relationships, and an identification of further research and development needed to make the ontology fully useful and evolvable.

Improving and balancing software qualities

“…It will then present recent US work in developing ontologies identifying the relations among and sources of variation in quantitative SQ values [3,4,11], and in coordinating these with counterpart efforts in Europe [10] and elsewhere.…”

“…The System Qualities Ontology, Tradespace, and Affordability (SQOTA) ontology presented in [3] and updated in [4] is based on the IDEF5 ontology framework, with the top-2 levels of a a classhierarchy SQ framework shown in the table below, and meansends relationships among the SQs. Unlike ISO/IEC 25010, which imposes a strict but unrealistic one-to-many SQ hierarchy, the SQOTA framework permits many-to many relations at level 2 (as with Maintainability) and at lower levels.…”

The Key Roles of Maintainability in an Ontology for System Qualities

“…. Tables 1 and 2 show the revisions (in italics) to the upper levels of the initial SQ stakeholder value-based means-ends class hierarchy in our INCOSE IS 2015 paper (Boehm & Kukreja, 2015) brought about by our recent Maintainability research and formalization of the SQ relationships Table 1. Upper Levels of Initial Stakeholder Value-Based SQ Means-Ends Hierarchy Stakeholder Value-Based SQ Ends Contributing SQ Means Mission Effectiveness Stakeholders-satisfactory balance of Physical…”

“…It also shows some enabling (and), but not alternative (or) subclasses of Modifiability, Repairability, and support of verification and validation, called "V&V-ity." These latter are Automated Analysis, Peer Reviews, and Execution Testing; their rating scales are provided in (Boehm & Kukreja, 2015), where they were taken from the Constructive Quality Model for estimating delivered software defect density (Boehm et al, 2000). Figure 2 also emphasizes the many-to-many relationships of Testability, as compared to the one-to-many relationship it has in ISO/IEC 25010 (ISO/IEC, 2011), where Testability only supports Maintainability.…”

“…In summary, Table 1 and Figures 1 and 2 summarize the class hierarchy of the primary stakeholder SQ end value classes of Mission Effectiveness, Life Cycle Efficiency, Dependability, and Changeability, along with their primary means-ends subclasses, and the primary composite SQs of Affordability and Resilience. The over-20 definitions of Resilience are discussed in (Boehm & Kukreja, 2015); their diversity can generally be traced to variations in their lower-level enablers. Each of the SQ classes and subclasses must also be characterized by the variation of their values with respect to their variation by Referents, States, Processes, and Relations, as will be described next in the context of Maintainability.…”