International Journal of Software Engineering and Knowledge Engineering

Firstly, some novel understanding about agents and multi-agent systems, in particular, agentization and coordination, is presented to build a consensus. Afterwards, a brief overview is given of the papers that are included in this special issue.

This paper proposes an Agent Inference Model (AIM) for constructing intelligent software agents. AIM has the ability of representing various types of fuzzy concepts, temporal concepts, and dynamic causal relationships between concepts. It also has the ability of handling feedback and analyzing inference patterns over different causal impact models. Based on AIM, a new type of intelligent agent, Dynamic Inference Agent (DIA) is presented. A dynamic inference agent has the ability to model, infer and make decisions on behalf of human beings. It uses numeric representations and computation instead of symbolic representation and logic deduction to represent knowledge and to carry out the inferences respectively. Thus the construction of DIA is simplified and the implementation code is compact. The application of DIA to various areas, especially for electronic commerce over the Internet is exemplified.

Being autonomous, proactive and adaptive, an agent-based system may demonstrate emergent behaviours, which are neither designed by the developers nor expected by the users of the system. Whether or not such emergent behaviours are advantageous, methods for the specification of agent behaviours must be developed to enable software engineers to analyse agent-based systems before they are implemented. This paper presents a formal specification language SLABS for agent-based systems. It is a model-based specification language defined based on the notion of agents as encapsulations of data, operations and behaviours. The behaviour of an agent is defined by a set of rules that describe the action/reaction of the agent in certain environment scenarios. The style and expressiveness of the language is demonstrated by examples like ants, personal assistants and speech-act style of agent communications.

Evolution of automated systems, in particular evolution of automated agents based on agent deliberation, is the topic of this paper. Evolution is not a merely material process, it requires interaction within and between individuals, their environments and societies of agents. An architecture for an individual agent capable of (1) deliberation about the creation of new agents, and (2) (run-time) creation of a new agent on the basis of this, is presented. The agent architecture is based on an existing generic agent model, and includes explicit formal conceptual representations of both design structures of agents and (behavioural) properties of agents. The process of deliberation is based on an existing generic reasoning model of design. The architecture has been designed using the compositional development method DESIRE, and has been tested in a prototype implementation.

We review mobile agents in the context of distributed object computing and parallel processing. We compare these three paradigms qualitatively. For a quantitative comparison of RMI and Voyager as mobile agent platforms, we identify distributed information processing with flexible load balancing as a convincing application to evaluate the two platforms.

In the world of mobile agents, security aspects are being discussed extensively, with strong emphasis on how agents can be protected against malicious hosts and vice versa. While in recent years many research groups presented solutions offering protection schemes for hosts that receive and run un-trusted, possibly malicious agents, in the field of protecting the agent against malicious hosts, development seems to grow very slowly. This paper discusses a protocol for detecting modifications at the agent's binary code that, for a particular class of modifications, undoubtedly unmasks the attacking host. Furthermore, it is shown that in co-operation with a special kind of route protection in a lot of scenarios the protocol resists attacks from coaliting malicious hosts as well as from a single malicious host.

With increasing requirements of distributed software systems, software agents are becoming a mainstream technology for software engineering and data management. Scalability and adaptability are two key challenges that must be addressed. In this work a new model is introduced for building large-scale distributed software systems with high dynamics, using a hierarchy of homogeneous agents that has the capability of service discovery. The performance of the agent system can be improved using different combinations of optimisation strategies. A modelling and simulation environment has been developed to aid the performance evaluation process. Two case studies are given and simulation results are included that show the impact of the agent mobility and the choice of performance optimisation strategies on the overall system performance.