Required Behavior of Sequence Diagrams: Semantics and Refinement

Abstract

✦ Abstract-Sequence diagrams are a widely used design notation for describing software behaviors. Many reusable software artifacts such as design patterns and design aspects make use of sequence diagrams to describe interaction behaviors. When a pattern or an aspect is reused in an application, it is important to ensure that the sequence diagrams for the application conform to the corresponding sequence diagrams for the pattern or aspect. Reasoning about conformance relationship between sequence diagrams has not been addressed adequately in literature. In this paper, we focus on required behavior specified by a UML sequence diagram. A novel trace semantics is given that captures precisely required behavior specified by a sequence diagram and a conformance relation between sequence diagrams is formalized based on the semantics. Properties of the trace semantics and the conformance relation are studied.

Refinement of UML2.0 Sequence Diagrams for Distributed Systems

“…Refinement based on trace semantics requires a meticulous work that consists in generating of all possible traces of SD, then in their categorization into required and possible traces (Lu andKim., 2011) and(øys-tein Haugen et al, 2005); where possible traces correspond to all possible combinations of SD events, that are obtained by rules of derivation of traces of the considered semantics, and required traces are those that must be preserved when refining the SD. Moreover, these semantics are based on rules of standard semantics that are not suitable for SD that model distributed systems.…”

“…The majority of the existing approaches, (Harald, 2003), (Lu andKim., 2011), (øystein Haugen et al, 2005), of the second category, required the computation of positive and negative traces sets, but they are based on rules of standard semantics. Hence, they do not permit the computation of all possible traces for SD that models a distributed system.…”

“…They defined three types of refinement: i) supplementing that consists in categorizing inconclusive behaviours as either positive or negative; ii) narrowing that consists to reduce possible behaviours; iii) detailing that permits to increase the granularity of sequence diagram. In the work of (Lu and Kim., 2011), required behaviours are expressed by ALT CF; the authors defined a new semantics by extending the definition of trace by including the guard condition as an essential element. This extension is mainly made in order to preserve ALT branches when the SD is refined.…”

“…Although, in their works (Lu andKim., 2011), (øystein Haugen et al, 2005), the authors claimed that their approach supports, in addition to the semantic refinement, the structural one, in the formalized refinement relation, new labels are hidden without making any preliminary verification. This leads to many inconsistencies that can not be detected.…”

Required behavior of sequence diagrams

“…We shall use SDs in Figure 1 as a running example. These SDs have been used to illustrate refinement, a special case of conformance [Lu and Kim 2011]. In SD Login, the opt fragment is labeled a, and the sending and receiving events for a message are labeled with two consecutive numbers.…”