Trude Hafsøe Bloebaum

Mist: A Reliable and Delay-Tolerant Publish/Subscribe Solution for Dynamic Networks

In this paper, we present Mist: a reliable and delay-tolerant middleware for information dissemination between highly mobile devices. Mist provides publish/subscribe with guaranteed message delivery in fully connected networks. Through emulation we show how the middleware is effective in static networks, as well as in dynamic topologies with high mobility. We describe how Mist is able to scale using a topic routing mechanism, allowing groups of mobile units to cooperate with infrastructure-based P2P-networks. Finally, we describe recent experiments where Mist has been employed successfully in real-life deployments. The implementation of the middleware, written in Java, is released as open source.

Information-centric networking in the tactical domain

Information-centric networking is a communication paradigm where there is no focus on endpoint addressing; rather, it is an attempt to achieve efficient information dissemination by focusing on the content that is distributed. In this article we describe how information-centric networking can be leveraged in order to extend NATO core enterprise services (CES) into the tactical domain. The paradigm can be implemented using decentralized publish/subscribe along with content caching. We present our information-centric middleware, Mist, and perform a comparative evaluation with an existing framework called Haggle. Mist is tailored to mitigate challenges encountered in mobile ad hoc networks. As a proof of concept, we implement a gateway between Mist and WS-Notification, which is the standard used in the Publish/Subscribe CES. This shows that with little effort it is possible to create gateways from networks using Mist to Web services-enabled infrastructure networks, ensuring compatibility and interoperability with higher levels in the chain of command, and also with other nations.

SOA and Wireless Mobile Networks in the tactical domain: Results from experiments

The NATO research task group IST-118 titled “SOA recommendations for disadvantaged grids in the tactical domain” is addressing the challenge of implementing the Service Oriented Architecture (SOA) paradigm at the tactical level by providing guidance and best practices in the form of a Tactical SOA Profile. The group will conduct identification and feasibility assessments of possible improvements of the Tactical SOA Profile, over a series of live and emulated experiments. In this paper, we describe our first experiments in applying SOA Web services to mobile nodes that are connected using Wireless Broadband Mobile Networks (WBMN) in the tactical domain. The experiments involved components provided by various nations, including radio hardware equipment, the Publish/Subscribe messaging service and NATO Friendly Force Information (NFFI) (as our functional service). We measured the system performance at service and physical (radio) levels in the presence of network disruption. We conclude by presenting the results of the experiments and a view of future work.

Toward federated mission networking in the tactical domain

NATO is currently working on the Federated Mission Networking (FMN) concept, which will become the foundation for establishing mission networks in the future. The realization of the FMN concept is described in the NATO FMN Implementation Plan (NFIP). The information infrastructure outlined in NFIP today builds on the concept of service-oriented architecture in order to achieve interoperability, and bases itself on many of the same standards and specifications as the ones identified through NATO Network Enabled Capabilities (NNEC). The NNEC SOA Baseline [1] identifies a number of core enterprise services that represent the common functionality needed to build an interoperable service-oriented infrastructure in a federation. It further identifies which standards should be used to realize these core services while ensuring interoperability between the federation members. A subset of these capabilities includes messaging services, collaboration services, service discovery, and security services. This article looks into each of these foundational core services, presents the challenges related to extending support for these services into the tactical domain, and identifies potential solutions.

Evaluating publish/subscribe approaches for use in tactical broadband networks

The publish/subscribe messaging pattern is particularly useful in limited resource networks due to it offering asynchronous messaging. It also requires fewer messages to be sent over the network than what is the case for the request/response messaging pattern. NATO has identified the WS-Notification standard as the publish/subscribe pattern to use for Web services, but other standards, such as the Advanced Message Queuing Protocol (AMQP) and MQTT are gaining momentum as alternatives to WS-Notification. In this paper we investigate the performance of these three protocols in resource constrained networks in order to determine if using one or more of these is a viable alternative to resorting to proprietary or special purpose protocols that are designed for one specific networking scenario.

Bandwidth optimizations for standards-based publish/subscribe in disadvantaged grids

NATO has identified Web services as a key enabler for its network enabled capability. Web services facilitate interoperability, easy integration and use of commercial off-the-shelf components, and while request/response-based schemes have hitherto been predominant, publish/subscribe-based services are gaining ground. SOAP-based Web services, however, introduce considerable communication overhead, and optimization must be done to enable use on the tactical level. Data compression is one such optimization, and it works well for large messages. We claim that the inherent characteristics of publish/subscribe-based Web services are such that using difference-based compression will allow effective compression also for small messages. In this paper we present the design and implementation of a proof-of-concept mechanism called ZDiff, which we have tested on several types of military data formats. Together with our SOAP-based proxy system it can be used together with commercial off-the-shelf Web services software. The results show that difference-based compression outperforms traditional compression for small messages, at the same time as it never performs worse than traditional compression for larger messages.

Trusted Service Discovery through Identity Management

Service oriented environments face threats from unauthorized clients and fake or compromised services. The threats exist both during service discovery and service invocation, and should be mitigated through the same security framework. Through the use of a modern identity management system which offers a combination of key attestation and attributes for access control, more threats can be appropriately addressed. The combination of discovery and identity management results in a more comprehensive threat mitigation, scalable maintenance of security related information and easier federations of security domains. The architecture and protocols of this system combination are presented and discussed.

Recommendations for realizing SOAP publish/subscribe in tactical networks

In this paper, we investigate the publish/subscribe standard WS-Notiflcation with respect to deployment and use in the tactical domain. We leverage a network emulator, CORE, to generate a testbed for controlled and repeatable experiments exhibiting typical tactical network traits: Limited data rates, delays, and packet loss, as well as node mobility and subsequent sporadic loss of connectivity. The work was performed in context of the NATO CSO/IST-118 “SOA recommendations for disadvantaged grids in the tactical domain” group. Our goal was not only to see how the WS-Notification standard behaves in the tactical domain, but also to investigate optimizations (here: compression) as part of our work for giving recommendations towards tactical SOA deployment. Our findings include that compression in general is beneficial and should be leveraged. However, the broker-based nature of WS-Notification proved, as expected, to be problematic in disruptive environments (single point of failure), and so measures that can mitigate this should be investigated further.

Recommendations for increased efficiency of Web services in the tactical domain

The C3 Board has chosen Service Oriented Architecture (SOA) realized using Web services to achieve interoperable software in NATO. The NATO research group IST-118 “SOA recommendations for disadvantaged grids in the tactical domain” aims to provide guidance on how to make SOA applicable at the tactical level. The focus of the group is to investigate how Core Enterprise Services can be applied in the tactical domain, as these form a basis one can use to build other services on. In this paper, we investigate how tuning application server parameters affects the performance of Web services in different emulated tactical networks.

Topic discovery for publish/subscribe web services

Using the publish/subscribe paradigm for information exchange allows for loose coupling between information sources and consumers. It also reduces network usage because it ensures that information is only transmitted when there is new information available. This is particularly useful in mobile networks, where network capacity can be low. Subscription based information exchange is often built around the concept of topics, where a consumer subscribes to the topics it is interested in. Consumers then need to be able to find out which topics are available to subscribe to, and where to subscribe to them. When using Web services, the consumer uses a discovery mechanism to find information sources, but the current standards for service discovery do not support discovery based on topics. In this paper we extend the WS-Discovery standard with a topic matching rule, which enables consumers to search for Web services providing information about a given topic.