Mari Carmen Otero

A post-placement side-effect removal algorithm

Side-effects are widely believed to impede program comprehension and have a detrimental effect upon software maintenance. This paper introduces an algorithm for side-effect removal which splits the side-effects into their pure expression meaning and their state-changing meaning. Symbolic execution is used to determine the expression meaning, while transformation is used to place the state-changing part in a suitable location in a transformed version of the program. This creates a program which is semantically equivalent to the original but guaranteed to be free from side-effects. The paper also reports the results of an empirical study which demonstrates that the application of the algorithm causes a significant improvement in program comprehension.

Evaluation of the comprehension of the dynamic modeling in UML

Abstract There is a certain degree of difficulty in developing and understanding the diagrams used for representing the dynamic behavior of a software application, specified in the Unified Modeling Language (UML). In this paper we evaluate the comprehension of the dynamic modeling in UML designs by using two split-plot factorial experiments. The metrics used for assessing the results are the time spent and the scores obtained in answering a questionnaire. In the first study three factors were controlled: the diagram type (sequence, collaboration and state), the application domain of the UML designs and the order of presentation of the documents. We observe that state diagrams provide higher semantic comprehension of dynamic modeling in UML when the domain is real-time and sequence diagrams are better in the case of a management information application. In the second study two factors were controlled: the paired combination of dynamic diagrams and the application domain. The main conclusion of the second study is that regardless of the domain, a higher semantic comprehension of the UML designs is achieved when the dynamic behavior is modeled by using the pair Sequence–State. Combining the results of both experiments we obtain the conditions which must concur to get an effective comprehension of the UML dynamic models: (a) if it is a management information application, the diagrams are sequence or the composition Sequence–State or Collaboration–State; (b) for a real-time non-reactive system the diagrams are collaboration or the pair Collaboration–State or Sequence–State; and (c) finally, when it is the design of the real-time reactive system, the best diagram is the State.

An empirical investigation of the influence of a type of side effects on program comprehension

This paper reports the results of a study on the impact of a type of side effect (SE) upon program comprehension. We applied a crossover design on different tests involving fragments of C code that include increment and decrement operators. Each test had an SE version and a side-effect-free counterpart. The variables measured in the treatments were the number of correct answers and the time spent in answering. The results show that the side-effect operators considered significantly reduce performance in comprehension-related tasks, providing empirical justification for the belief that side effects are harmful.

An Initial Experimental Assessment of the Dynamic Modelling in UML

The goal of this empirical study is to compare the semantic comprehension of three different notations for representing the dynamic behaviour in unified modelling language (UML): (a) sequence diagrams, (b) collaboration diagrams, and (c) state diagrams. Eighteen students of Informatics analysed the three types of diagrams within three different application domains. We performed a 3 × 3 factorial experimental design with repeated measures. The metrics collected were total time and total score. The main conclusion of this study is that the comprehension of the dynamic modelling in object-oriented designs depends on the diagram type and on the complexity of the document. The software project design written in the UML notation is more comprehensible, when the dynamic behaviour is modelled in a sequence diagram. While if it is implemented using a collaboration diagram, the design turns out to be less comprehensible as the application domain, and consequently, the document is more complex.

An empirical comparison of the dynamic modeling in OML and UML

This paper presents an empirical research for evaluating the semantic comprehension of two standard languages, UML (Unified Modeling Language) versus OML (OPEN Modeling Language), from the perspective of the dynamic modeling. We carried out two controlled experiments using a 2x2 crossover design, where the metrics studied were the comprehension time and the total score. We examined the OML and UML interaction diagrams and the statecharts of each language corresponding to the design of a real-time embedded system. The results obtained reveal that the specification of the dynamic behavior using OML is faster to comprehend and easier to interpret than using the UML language, regardless of the dynamic diagram type.

Analyzing a ROS Based Architecture for Its Cross Reuse in ISO26262 Settings

The automotive industry is applying the latest technological advances in order to provide safety and security to drivers and pedestrians. In this sense, Robot Operating System (ROS) is used as a middleware to be adapted and deployed in cars. However, ROS has not been tested enough to be used in safety environments. Therefore, this paper reports an analysis of a ROS based architecture running in a prototype. We define a safety case based on the ISO 26262 Safety Element out of Context (SEooC) for its cross reuse, and we generate the required evidences related to the identified characteristics and thresholds. Goal Structuring Notation (GSN) is the notation used for the safety case definition and to argue conformance with respect to ISO 26262.