Huiqun Yu

Formally analyzing software architectural specifications using SAM

In the past decade, software architecture has emerged as a major research area in software engineering. Many architecture description languages have been proposed and some analysis techniques have also been explored. In this paper, we present a graphical formal software architecture description model called software architecture model (SAM). SAM is a general software architecture development framework based on two complementary formalisms--Petri nets and temporal logic. Petri nets are used to visualize the structure and model the behavior of software architectures while temporal logic is used to specify the required properties of software architectures. These two formal methods are nicely integrated through the SAM software architecture framework. Furthermore, SAM provides the flexibility to choose different compatible Petri net and temporal logic models according to the nature of system under study. Most importantly, SAM supports formal analysis of software architecture properties in a variety of well-established techniques--simulation, reachability analysis, model checking, and interactive proving, In this paper, we show how to formally analyze SAM software architecture specifications using two well-known techniques--symbolic model checking with tool Symbolic Model Verifier, and theorem proving with tool STeP.

Modeling and analyzing SMIL documents in SAM

A composite multimedia object has specific timing relationships among the different types of component media. Coordinating the real-time presentation of information and maintaining time-ordered relations among the component media is vital for satisfying quality of service (QoS) requirements. This paper proposes a formal approach to modeling and analyzing temporal aspects of SMIL documents using the Software Architecture Model (SAM), which is based on a dual formalism combining Petri nets and temporal logic. Synchronization elements of SMIL are systematically modeled by Petri nets. Useful QoS properties of SMIL documents are specified using temporal logic formulas and verified by automatic tools. Timelines of SMIL document presentation are analyzed using the reachability tree technique.

A formal method for analyzing software architecture models in SAM

The software architecture model (SAM) is a general software architecture model based on a dual formalism combining Petri nets and temporal logic. A SAM model contains a hierarchical set of compositions, each of which consists of a set of components, a set of connectors, and a set of constraints. This paper proposes a formal method for analyzing SAM models in both element (either component or connector) level and composition level. The basic idea is to simulate Petri net behaviors in terms of fair transition systems. The properties of individual components and connectors are verified either by deductive reasoning or model checking. The properties of the entire system is inferred from the properties of its constituents. A detailed case study of an electronic commerce system shows our approach to formally modeling, refining and analyzing software architecture models.

A formal approach to designing secure software architectures

Software architecture plays a central role in developing software systems that provide basic functionality and satisfy critical properties such as reliability and security. However, little has been done to formally model software architectures and to systematically enforce required properties. We aim to propose a formal approach to designing secure software architectures. We use the software architecture model (SAM), a general software architecture model combining Petri nets and temporal logic, as the underlying formalism. Architecture design consists of the functionality part and the security part. Guidelines are proposed to design functionality of software architectures at both element level and composition level. Software security is enforced by stepwise refinement.

Formal Methods for Specifying and Analyzing Complex Software Systems

Software has been a major enabling technology for advancing modern society, and is now an indispensable part of daily life. Because of the increased complexity of these software systems, and their critical societal role, more effective software development and analysis technologies are needed. How to develop and ensure the dependability of these complex software systems is a grand challenge.

Formal Analysis of Real-Time Systems with SAM

The Software Architecture Model (SAM) is a general software architecture model based on a dual formalism combining Petri nets and temporal logic. This paper proposes a formal method for modeling and analyzing real-time systems with SAM. A high level Petri net and a linear time temporal logic are used as the theoretical basis for SAM. Behaviors of real-time systems are modeled by Petri nets, while their properties are specified by temporal logic. By translating Petri nets into clocked transition systems, we can apply the Stanford Temporal Prover to automating the analysis of real-time systems. A case study of interactive multimedia documents demonstrates our approach to modeling and analyzing real-time systems with SAM.