We present a programming framework based on the paradigm of generative application development for building context-aware collaborative applications. In this approach, context-aware applications are implemented using a domain-specific design model, and their execution environment is generated and maintained by the middleware. The key features of this design model include support for context-based service discovery and binding, context-based access control, context-based multiuser coordination, and context-triggered automated task executions. The middleware uses the technique of policy-based specialization for generating application-specific middleware components from the generic middleware components. Through a case-study example, we demonstrate this approach and present the evaluations of the design model and the middleware.

In this paper, multiuser collaboration systems are categorized into two groups-computer-supported cooperative work (CSCW) and workflow systems-based on a historic perspective of their introduction and on their emphasis on user- or process-centric interactions. The goal of the survey is to identify distinct security requirements-related to availability, integrity, confidentiality and privacy, and access leakage-of these systems. Existing role-based security models and their limitations to express security policies in distributed CSCW and workflow systems are presented. Last, we present an overview of a framework that we have developed to specify, verify, and enforce security policies in distributed CSCW systems.

Abstract In this paper we present a framework for building policy‐based autonomic distributed agent systems. The autonomic mechanisms of configuration and recovery are supported through a distributed event processing model and a set of policy enforcement mechanisms embedded in an agent framework. Policies are event‐driven rules derived from the system's functional and non‐functional requirements. Agents in the network monitor the system state for policy violation conditions, generate appropriate events, and communicate them to other agents for cooperative filtering, aggregation, and handling. A set of agents perform policy enforcement actions whenever events signifying any policy violation conditions occur. Policies are defined using a specification framework based on XML. The policy enforcement agents interpret the policies given in XML. We illustrate the utility of this framework in the context of an agent‐based distributed network monitoring application. We also present an experimental evaluation of our approach. Copyright © 2006 John Wiley & Sons, Ltd.

We present, in this paper, a role-based model for programming distributed CSCW systems. This model supports specification of dynamic security and coordination requirements in such systems. We also present here a model-checking methodology for verifying the security properties of a design expressed in this model. The verification methodology presented here is used to ensure correctness and consistency of a design specification. It is also used to ensure that sensitive security requirements cannot be violated when policy enforcement functions are distributed among the participants. Several aspect-specific verification models are developed to check security properties, such as task-flow constraints, information flow, confidentiality, and assignment of administrative privileges.

The focus of this paper is on a specification model for defining security and coordination policies for distributed collaboration and workflow systems. This work is motivated by the objective to build distributed collaboration systems from their high level specifications. We identify here unique requirements for secure collaboration, specifically role admission and activation constraints, separation of duties, dynamic access control, and a model for multiuser participation in a role. We present a role-based model for specifying coordination and dynamic security requirements in collaboration systems. It also supports hierarchical structuring of a large collaboration environment using the concept of activities, which define a naming scope and a protection domain to specify security and coordination policies. We have implemented this specification model in XML and used it to construct the runtime environments for distributed collaboration systems using a policy based middleware.

In this paper, we present static verification of security requirements for CSCW systems using finite-state techniques, i.e., model checking. The coordination and security constraints of CSCW systems are specified using a role based collaboration model. The verification ensures completeness and consistency of the specification given global requirements. We have developed several verification models to check security properties, such as task-flow constraints, information flow or confidentiality, and assignment of administrative privileges. The primary contribution of this paper is a methodology for verification of security requirements during designing collaboration systems.

We present the execution model of policy-driven middleware for building secure distributed collaboration systems from their high level specifications. Our specification model supports nested collaboration activities, and uses role-based security policies and event count based coordination specification. From the specifications of a collaboration environment, appropriate policy modules are derived for enforcing security and coordination requirements. Policy-driven distributed middleware provides services to users to join roles in an activity, perform role specific operations, or create new activities. We describe the design challenges for middleware and present the run-time structures and protocols supported by it for creating activities, roles, and objects.

We present here a framework together with a set of paradigms for mobile agent based active monitoring of network systems. In our framework mobile agents are used to perform remote information filtering and control functions. Such agents can detect basic events or correlate existing events that are stored in a database to enforce system policies. A system administrator can securely modify the monitoring policies and information filtering functions of its agents, or install new agents at a node. The framework presented here includes monitor, subscriber, auditor and inspector agents. The policies and itineraries of these agents can be modified dynamically. In response to certain trigger events agents may change their itineraries to correlate event data. We present here a set of experiments that we have conducted using the Ajanta mobile agent system to evaluate and demonstrate the capabilities of our mobile agent framework.

The paper gives an overview of Ajanta, a Java based system for mobile agent programming. We outline the Ajanta architecture, and discuss the basic elements that comprise an agent based application. Ajanta's programming environment is defined in terms of a set of primitive operations for agent creation, dispatch, migration and remote control. Agents can access server resources using a proxy based access control mechanism. We describe a scheme for agent migration based on the composition of some basic migration patterns which incorporate exception handling mechanisms. Finally, we present two agent based distributed applications implemented using the Ajanta system. One is a middleware which supports file sharing over the Internet and the other is a distributed calendar manager.