Katrine Stemland Skjelsvik

A Data Sharing Facility for Mobile Ad-Hoc Emergency and Rescue Applications

Efficient information sharing is very important for emergency and rescue operations. Mobile ad-hoc Networks (MANETs) are often the only network environment for such operations. We have developed the MIDAS data space (MDS) to transparently share information among rescue applications in such environments. To achieve the required level of availability for important information, MDS performs optimistic replication. The problems caused by optimistic replication, like consistency management, are not solved by standard solutions; instead we employ tailor-made solutions for emergency and rescue applications.

Supporting multiple subscription languages by a single event notification overlay in sparse MANETs

The subscription language is an important design decision for distributed event notification services (DENS). In order to minimize resource consumption and enable applications to use rich and complex subscription languages only when they are really needed, we have developed a DENS that separates the concerns of delivering subscriptions and notifications from the subscription specification and event filtering, i.e., the subscription language. To resolve the conflict between subscription language independence in DENS and a strict decoupling of publishers and subscribers through the DENS, we request that for each new subscription language three language specific plug-ins are provided. In this paper, we present the technical details of this solution and describe our proof-of-concept implementation that supports a simple attribute-value based subscription language and a fuzzy concept-based language.

Middleware Services for Information Sharing in Mobile Ad-Hoc Networks

Information sharing is a mission critical key element in rescue and emergency operations. Mobile ad-hoc networks (MANETs) could provide a useful infrastructure to support information sharing, but appropriate applications are needed. To facilitate efficient application development for this type of infrastructure, middleware support is needed. In the Ad-Hoc InfoWare project, we are currently developing corresponding middleware services. In this paper, we discuss the application requirements that are imposed onto the middleware services, and we outline our technical approach to address the corresponding challenges. The architecture we propose comprises five main building blocks, namely knowledge management, a local and a distributed event notification service, resource management, and security and privacy management. We indicate design alternatives for these building blocks, identify open problems and relate our approach to the state-of-the-art.

Distributed Event Notification for Mobile Ad Hoc Networks

Emergency-and-rescue applications must be continually available, placingstrong demands on middleware solutions running over mobile ad hoc networks.This highly available distributed event notification service can help byreaching the different network partitions and providing a useful deliverysemantic.

Information Sharing in Mobile Ad-Hoc Networks: Evaluation of the MIDAS Data Space Prototype

Information sharing in dynamic mobile ad-hoc networks is a challenging task. High data availability in the presence of short and long term disconnections can be obtained by replicating shared data. The number of replicas must however be balanced against the cost of consistency management. In the MIDAS Data Space (MDS) we use optimistic replication together with internal versioning of data; this allows application-specific conflict resolution when reconciling replicas at network mergings. We have made a proof-of-concept implementation to perform experiments and to demonstrate through real-life field tests the usefulness of our design. In this paper we report our results. We have conducted a number of experiments on a small network formed by real devices to obtain a detailed performance evaluation. Using an emulation environment we have analysed and quantified the cost of consistency management, the impact of MDS operations, and the relationship between data availability and replication.

Using Continuous Queries for Event Filtering and Routing in Sparse MANETs

In our project, we design middleware services for emergency and rescue scenarios in sparse mobile ad-hoc networks (SMANETs). One of these services is a distributed event notification service (DENS) for asynchronous communication. The DENS architecture allows several subscription languages for different kinds of subscriptions. To support complex subscriptions, we use a data stream management system (DSMS) for filtering of the data streams and matching of filtered events and subscriptions. We have designed a simple rescue scenario to investigate the possibilities of using a DSMS together with the DENS middleware layer. In this paper we discuss the design of our implementation and first experimental results of our ongoing work

Admission Control and Resource Reservation Framework for the OMODIS QoS Framework

In this paper, we describe our Admission Control and Resource Reservation (ACRA) framework and explain how it is integrated in the OMODIS QoS management framework. Normally, admission control and resource management is tightly integrated into the system components, which makes it difficult to manage it as part of the QoS management framework. HavingACRA as part of the QoS management framework – and not hidden in the system components – provides us with a general means to control end-to-end QoS in distributed systems. To achieve this goal, we have separated the general ACRA mechanisms from the component-specific resource model, which are specially configured for every system component. We explain how ACRA can be configured for a specific component, i.e., a tactical QoS manager for a multimedia database management system (MMDBMS) used for a distance learning scenario. Admission control and resource reservation for a MMDBMS is especially difficult, because distributed interactive multimedia applications managed by MMDBMS have to handle all types of resources in an integrated manner.