Jinho On

An Abstraction Method for Mobility and Interaction in Process Algebra Using Behavior Ontology

A number of process algebras have been proposed to develop distributed mobile systems: Pi-Calculus[1,2], Mobile Ambients Calculus[3], Bigraph[4,5], etc. However the algebras are not well suitable for understanding the interactions and mobility of the processes in the large and complex systems due to the lack of abstraction to handle the size and complexity. This paper handles the size and complexity with a method of abstraction on the sequences of the interactions and movements, which can be further organized in the form of hierarchically structured lattices, namely, Prism. The theoretical principle of the abstraction is based on a new concept of Behavior Ontology, which is extended from Active ontology [9]. Prism makes the analysis of the systems systematic in the hierarchically organized semantic structure. Consequently the understanding of the systems becomes more meaningful. To demonstrate the feasibility of the approach, Prism is partially realized in SAVE Tool [6,7,8].

Behavior Ontology: A Framework to Detect Attack Patterns for Security

This paper presents a new method to detect attack patterns in security-critical systems, based on a new notion of Behavior Ontology. Generally security-critical systems are large and complex, and are subject to be attacked by attackers in every possible way. Therefore it is very complicated to detect various attacks systematically in some semantic structure. This paper handles the complication with Behavior Ontology, where patterns of attacks in the systems are defined as a sequence of actions on class ontology for the systems. By the nature of the actions, the attack patterns can be abstracted in hierarchical order, forming a lattice or a lattice of lattices, based on inclusion relations. Once the behavior ontology for the attach patterns are defined, the attacks in the target systems can be detected both semantically and hierarchically in the structure of the ontology. Compared with other attack models, the analysis on the behavior ontology shows that the approach in the paper is very effective and efficient in time and space. The approach can be considered as the first attempt to detect attack patterns with the notion of behavior ontology.

Visual Representation of Temporal Properties in Formal Specification and Analysis using a Spatial Process Algebra

There are a number of formal methods for distributed real-time systems in ubiquitous computing to analyze and verify the behavioral, temporal and the spatial properties of the systems. However most of the methods reveal structural and fundamental limitations of complexity due to mixture of spatial and behavioral representations. Further temporal specification makes the complexity more complicate. In order to overcome the limitations, this paper presents a new formal method, called Timed Calculus of Abstract Real-Time Distribution, Mobility and Interaction(t-CARDMI). t-CARDMI separates spatial representation from behavioral representation to simplify the complexity. Further temporal specification is permitted only in the behavioral representation to make the complexity less complicate. The distinctive features of the temporal properties in t-CARDMI include waiting time, execution time, deadline, timeout action, periodic action, etc. both in movement and interaction behaviors. For analysis and verification of spatial and temporal properties of the systems in specification, t-CARDMI presents Timed Action Graph (TAG), where the spatial and temporal properties are visually represented in a two-dimensional diagram with the pictorial distribution of movements and interactions. t-CARDMI can be considered to be one of the most innovative formal methods in distributed real-time systems in ubiquitous computing to specify, analyze and verify the spatial, behavioral and the temporal properties of the systems very efficiently and effectively. The paper presents the formal syntax and semantics of t-CARDMI with a tool, called SAVE, for a ubiquitous healthcare application.

An Abstraction Method of Behaviors for Process Algebra

In CCS, Milner defined the notion of Strong and Weak Bisimulations for behavioral equivalence between two processes or systems. However the notion has not been studied further in the perspective of abstraction for such behaviors in process algebra. In some sense, weak bisimulation could be interpreted as a kind of behavior equivalence between two processes at the certain degree of abstraction, based on observability. Here we noticed the possibility of representing such observable behaviors with a certain structure of abstraction and verify a number of behavioral equivalences in the structure. In the paper, such possibility has been realized with a new concept of Behavior Ontology. In the ontology, actions can be defined as an interaction between two processes or systems, and, further, behaviors can be defined as a sequence of such actions. Since some actions between the behaviors can be overlapped in some structural way, the behaviors can be organized in a lattice structure, namely, Behavior Lattice. Consequently, the lattice reveals certain levels of observability of the behaviors, based on degree of abstraction. From the lattice, a strong bisimulation and its weak bisimulations can be detected visually. The comparative study shows that the ontology is very effective and efficient for representing such abstract behaviors and verifying strong and weak bisimulations in a lattice structure. The ontology can be considered as one of the unique and innovative structure to represent such behaviors in a hierarchical structure of abstraction.

A Graphical Language to Integrate Process Algebra and State Machine Views for Specification and Verification of Distributed Real-Time Systems

Being very large and extremely complex, distributed real-time systems are specified by formal methods, such as state machines and process algebras, and are verified by temporal and spatial logics. However the methods have some limitations in the specification and verification, since process algebras mainly focus on the in-the-large view of the systems and, relatively, state machines mainly focus on the in-the-small view of the systems. Consequently there is a strong need for some intermediate methods to integrate these two views into one view to handle the size and complexity of the systems effectively. This paper presents such a visual formalism, namely, Onion, where processes and their transitive actions in the systems are graphically represented in one single entity, just like those of a real onion, over a geographical space. Further the temporal properties of mobility and interactions of the processes are specified in a geo-temporal space. Once these are done, the temporal and spatial requirements for the systems are graphically specified on the processes and actions using a visual logic. Finally, the specifications are visually analyzed and verified through simulation on the space for the requirements. The comparative study shows that Onion is very effective and efficient for the visualization of the systems and that it overcomes the stated limitations.

Meta-Modeling to Detect Attack Behavior for Security

This paper presents a new method to detect attack patterns in security-critical systems, based on a new notion of Behavior Ontology. Generally security-critical systems are large and complex, and they are subject to be attacked in every possible way. Therefore it is very complicated to detect various attacks through a semantic structure designed to detect such attacks. This paper handles the complication with Behavior Ontology, where patterns of attacks in the systems are defined as a sequences of actions on the class ontology of the systems. We define the patterns of attacks as sequences of actions, and the attack patterns can then be abstracted in a hierarchical order, forming a lattice, based on the inclusion relations. Once the behavior ontology for the attack patterns is defined, the attacks in the target systems can be detected both semantically and hierarchically in the ontology structure. When compared to other attack models, the behavior ontology analysis proposed in this paper is found to be very effective and efficient in terms of time and space.

Abstraction Method for Analysis of Mobility and Interaction in Process Algebra Using Behavioral Ontology

A number of process algebras have been proposed to develop distributed mobile real-time systems: pi-Calculus, Mobile Ambients Calculus, Bigraph, etc. However, as the systems get large and complex, the algebras become less suitable for understanding the interactions and mobility of the processes of the systems due to the size and complexity. Therefore it is necessary to handle the size and complexity for systematic understanding of the systems. This paper handles the size and complexity with a method of abstraction on sequences of interactions and movements of processes in the systems, which can be further organized in the form of hierarchically structured lattices, namely, Prism. The theoretical principle of the abstraction is based on a new concept of Behavior Ontology, which is extended from Active ontology. Prism allows the systems to be analyzed in the perspective of the lattices in Prism, which are characterized by the hierarchically organized behavioral properties of the developing systems, for systematic understanding the systems. In this way, the complexity of the interactions and the movements can be handled systematically in the semantically and hierarchically organized structure of the behavior.

A Calculus to Reduce Spatial and Temporal Complexity for Specification and Analysis of Complex Real-Time Systems

In order to make the methods suitable to complex real-time systems (CRS), it is necessary to reduce the complexity of CRS with a large number of heavily interacting mobile agents over spatial-temporal space. To demonstrate the necessity of the reduction, this paper presents a new formal method, namely, calculus of real-time distribution, mobility, and interaction (CARDMI). In CARDMI, the spatial requirements are described in the spatial map, called Reconfigurable hyper graph (RHG), for the geographical space where agents move and interact. The space is dynamically reconfigurable through mobility. The behaviors of the agents, that is, movements and interactions, can be hierarchically represented, analyzed and verified on RHG. Consequently, the separate representation reduces the complexity dramatically and makes the development of CRS more realistic and practical for industrial applications. This paper presents TAG (timed action graph) for the graphical representation of the results of the execution. It shows the movements and interactions of agents are visually understandable over the hierarchically organized spatial domain along with the temporal dimension. For the implementation of the method, we have developed a new tool, called specification, analysis and verification environment (SAVE) to demonstrate the efficiency and effectiveness of the approach in the paper.