F.T. Johnsen

University of Oslo, Kristiania (historical), Oslo County, Norway

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Publications (20)14.64 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Web services can be used as a middleware for standardized, interoperable machine-to-machine communication. However, the technology has communication overhead, leading to a need to investigate ways to optimize its resource use when applying the technology in limited capacity networks. There exist several approaches to optimization, and in this paper we investigate potential gains from replacing the commonly used HTTP/TCP transport for Web services with alternative transport protocols. We study four different protocols (TCP, UDP, SCTP, and AMQP) for conveying Web services traffic, evaluating them in an emulator under typical civil and military networking conditions.
    Military Communications and Information Systems Conference (MCC), 2013; 01/2013
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    ABSTRACT: 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.
    IEEE Communications Magazine 01/2013; 51(10):34-41. · 3.66 Impact Factor
  • F.T. Johnsen, T.H. Bloebaum
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    ABSTRACT: 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.
    Wireless Communications and Mobile Computing Conference (IWCMC), 2012 8th International; 01/2012
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    ABSTRACT: 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.
    New Technologies, Mobility and Security (NTMS), 2012 5th International Conference on; 01/2012
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    ABSTRACT: The objective of the IST-090 group is to investigate challenges of SOA applications in disadvantaged networks. The group studies possible solutions that can improve the overall efficiency of information dissemination when facing different disruptions. This paper presents lessons learned from the real-life experiment and demonstration that was carried out by IST-090 group members during the MCC 2011 conference. We evaluated several solutions, namely the WS-DDS interface, the DSProxy, the Mist protocol, and ESBs that were used as SOA solutions enabling efficient information exchange in a disadvantaged environment. The experiment was preceded by separate tests of each solution. However, in the combined scenario, the aim was to evaluate the interoperability of these solutions and define a long-term plan for either their application in operations or for further functionality development. The paper gives an overview of the solutions we investigated, presents a rough model of the network environment used, and discusses the results observed and the lessons learned.
    Communications and Information Systems Conference (MCC), 2012 Military; 01/2012
  • M. Skjegstad, F.T. Johnsen, J. Nordmoen
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    ABSTRACT: In this paper we present our framework for emulated evaluation of service discovery protocols in mobile ad-hoc networks (MANETs). Emulation is preferable to simulation when evaluating real world software implementations, as it provides a controlled network environment without requiring modifications to the software. We base our work on the open-source simulator ns-3, which also has support for network emulation. Our own test framework consists of a set of scripts running in Linux Containers, providing a means to bootstrap and populate service discovery protocols with services and queries. Our setup allows us to perform controlled and repeatable service discovery protocol experiments in MANETs with a high degree of automation. Experiment series are set up, controlled, and statistics calculated by scripts, thus enabling complex, large, and real-time evaluations to be performed without human interaction.
    New Technologies, Mobility and Security (NTMS), 2012 5th International Conference on; 01/2012
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    ABSTRACT: We have designed and implemented a prototype system providing role based Quality of Service (QoS) for Web services in heterogeneous networks. We leverage industry standards to the fullest extent, in an attempt to bring role based QoS support to standard Web services. We have extended an existing enterprise service bus to accommodate the changes necessary for prioritization on the server side, and created a custom client library to ensure prioritization in both the request and the response of the Web services message exchange. Finally, roles are defined using Security Markup Assertion Language (SAML) tokens. Our framework has been released as open source. Our evaluation shows that the concept is viable, and that prioritization on the application level of the OSI model, combined with network level prioritization as provided by DiffServ, is beneficial in networks with low bandwidth.
    Globecom Workshops (GC Wkshps), 2012 IEEE; 01/2012
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    ABSTRACT: 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.
    MILITARY COMMUNICATIONS CONFERENCE, 2012 - MILCOM 2012; 01/2012
  • F.T. Johnsen, T. Hafsøe
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    ABSTRACT: Web services technology is in widespread use, but employing the technology in highly dynamic environments is a challenge. The current Web services discovery standards are tailored for use in fixed infrastructure networks and single hop ad hoc networks. They are not suitable for use in highly dynamic multi-hop mobile ad hoc networks (MANETs), such as the networks employed in search and rescue operations. In a search and rescue operation we also need to know about not only the available services, but also where the nodes participating in the operation are. In this paper we address these needs by designing an experimental Web services discovery protocol that can be used in such multi-hop MANETs. We combine service and location discovery in our novel Web services discovery protocol called SAM, which we have implemented, tested in a field trial, and released as an open source project.
    GLOBECOM Workshops (GC Wkshps), 2010 IEEE; 01/2011
  • J. Flathagen, F.T. Johnsen
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    ABSTRACT: Wireless Sensor Networks (WSNs) are expected to provide greatly enhanced situational awareness for warfighters in the battlefield. Sensors widespread in the battlefield are however, of very limited value unless the sensors are reliable during the entire operation and the information produced is accessed in a timely manner. In this paper we focus on these issues by enabling WSNs as a capability in the NATO Network Enabled Capability (NNEC) using Web services. We demonstrate that Web services is an enabling technology for information-sharing, facilitating presentation of sensed data and alarms to a battlefield management system. In addition, we show the feasibility of using a Web services approach as a query processing tool enabling multi-sensor fusion and data aggregation in the WSN domain. The networking protocols can in this way inherently adjust data-aggregation and -processing criteria according to the requirements posed by external subscriber systems. In this way, energy efficiency, which is paramount in WSNs, is optimized without sacrificing the flexibility of Web services. Our proposed methods are tested using practical experiments with TelosB sensing nodes.
    MILITARY COMMUNICATIONS CONFERENCE, 2011 - MILCOM 2011; 01/2011
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    M. Skjegstad, F.T. Johnsen, T. Hafsoe, K. Lund
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    ABSTRACT: Existing service discovery mechanisms for ad hoc networks are often designed with one specific network type in mind. Solutions capable of handling highly mobile nodes usually have high bandwidth requirements, particularly as the number of nodes increases. The bandwidth requirement can be reduced by locally caching state information, but this increases the risk of nodes having outdated state information when mobility is high. Some solutions avoid these two issues by tightly coupling service discovery with the routing mechanism itself. However, this requires that nodes are homogeneous on the network layer. We propose a solution that leverages the special properties inherent in broadcast-based radio networks. In such networks, every node within transmission range will hear a transmission, be it unicast or broadcast. Each node therefore aggregates relevant service information and broadcasts it at regular intervals. Unnecessary transmissions are suppressed by efficiently synchronizing local state information. In this paper, we describe the Mist-protocol, a robust and efficient adaptive service discovery protocol, that supports large, highly mobile networks consisting of heterogeneous nodes. We test the protocol in large scale simulations in both static and mobile environments. Finally, we show that it is feasible to actually implement the design by providing a proof-of-concept prototype, which has been evaluated in a small scale experiment.
    MILITARY COMMUNICATIONS CONFERENCE, 2010 - MILCOM 2010; 12/2010
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    ABSTRACT: NATO has identified Web services standards as a key enabler for interoperability between the different military systems used by various NATO nations. Compared to many civilian systems, military networks vary greatly in terms of computing resources, network bandwidth, mobility and stability, and distributed applications use several different networks concurrently or interact across them. In such dynamic and heterogeneous environments, runtime service discovery is a necessity. According to the W3C, discovery is the act of locating a machine-processable description of a Web service-related resource that may have been previously unknown and that meets certain functional criteria. In this article we present our approach to service discovery, where we combine Web services standards and proprietary solutions using our prototype interoperability gateway. This approach has been experimentally evaluated in a military experiment featuring both mobile ad hoc networks and fixed infrastructure networks, and the results show that transparent discovery between proprietary solutions and Web services discovery standards can be achieved.
    IEEE Communications Magazine 11/2010; · 3.66 Impact Factor
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    ABSTRACT: NATO Network Enabled Capability is first and foremost about achieving better interaction between the different actors involved in military operations. This implies more efficient exchange of information. Consequently, the NATO information infrastructure will consist of a federation of systems, including a plethora of different information and communication systems, as well as a mix of new and legacy systems. NATO recommends a service-oriented architecture approach based on Web services to enable such a federation. In this article we explain how the communication protocols normally used in Web services are unsuited for disadvantaged and heterogeneous networks. We then present our prototype proxy, which enables the use of standard unmodified Web services across all network types, including tactical networks with low data rates and frequent disruptions. It is designed to work with existing security mechanisms, and also offers further optimizations in the form of optional plug-ins.
    IEEE Communications Magazine 11/2010; · 3.66 Impact Factor
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    M. Skjegstad, U. Roedig, F.T. Johnsen
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    ABSTRACT: A recent feasibility study suggests that a Service Oriented Architecture (SOA) will be central within the NATO Network Enabled Capabilities information infrastructure. An important element of a SOA is the service discovery process, but existing solutions are not sufficient in military networks. We suggest to use a robust Peer-to-Peer (P2P) network as a complement. Unfortunately, available P2P search algorithms have high bandwidth requirements which cannot be supported by low-bandwidth links in tactical networks. This paper describes a new search algorithm named Search+ which is designed for tactical networks with limited bandwidth resources. The evaluation of Search+ presented in this paper shows that it outperforms existing search algorithms in terms of bandwidth consumption while achieving comparable search success rates.
    Military Communications Conference, 2009. MILCOM 2009. IEEE; 11/2009
  • E. Skjervold, T. Hafsoe, F.T. Johnsen, K. Lund
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    ABSTRACT: Web services technology is considered a key enabler for NEC. However, existing Web service protocols are designed for use over the Internet, and cannot necessarily be directly applied in military tactical networks where bandwidths are low and communication disruptions are frequent. In this paper we present a novel prototype proxy solution which adds both delay and disruption tolerance to SOAP. The ¿Delay and disruption tolerant SOAP Proxy¿ solution can bridge heterogeneous networks and offers store-and-forward capabilities, delay tolerant network capabilities and swappable transport protocols while retaining backward compatibility with COTS Web service clients and servers. The proxy solution does not rely upon parsing or inspecting the SOAP messages, which allows for end-to-end security through encryption.
    Military Communications Conference, 2009. MILCOM 2009. IEEE; 11/2009
  • F.T. Johnsen, J. Flathagen, T. Hafse
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    ABSTRACT: The Service Oriented Architecture concept is vital in order to interconnect different systems and to achieve a functional Network Centric Warfare (NCW). In order to realize an architecture based on loosely coupled services, a well-designed and efficient means of discovering the available services in the network is crucial. The service discovery mechanism used in any network must take the capabilities and limitations of the network into account. Due to the large variation in network capabilities on different operational levels, one single service discovery mechanism can not be chosen. Thus, there is a need for a toolkit consisting of different service discovery mechanisms so that each network can use the mechanism that is most suited for that particular network. In NCW, information exchange, and thus service discovery, must be available across network boundaries. This means that the different service discovery mechanisms must be able to interact with each other without the need for manual configuration. In this paper we present our novel prototype solution integrating WS-Discovery, a Web Services discovery mechanism, with Mercury, our proposed cross-layer service discovery solution tailored for use in MANETs. By using an interoperability gateway, service discovery is feasible across network boundaries, connecting mobile soldier systems and deployed tactical systems.
    Military Communications Conference, 2009. MILCOM 2009. IEEE; 11/2009
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    A. Fongen, F.T. Johnsen, E. Winjum
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    ABSTRACT: Certificate validation in tactical wireless networks and MANETs is a hard problem, due to low bandwidth and frequent disconnections. We suggest a cooperative caching approach with an overlay network of XKMS proxies. The overlay network is discovered and maintained with only marginal increase in the network traffic. This is due to a cross layer design where the XKMS proxies tap into the OLSR routing protocol and utilize the topology information provided by the OLSR path discovery mechanisms.
    Military Communications Conference, 2008. MILCOM 2008. IEEE; 12/2008
  • K. Lund, A. Eggen, D. Hadzic, T. Hafsoe, F.T. Johnsen
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    ABSTRACT: The principles of network enabled capability highlight the need for seamless information exchange. The service oriented architectural paradigm has been recognized as one of the key enablers to achieve this. At the same time, Web services have become the de facto standard for implementing service oriented architecture. However, these technologies have been developed for environments with abundant data rates, environments which are very different from military tactical networks. In this article, we present possible solutions and remaining challenges on the way toward also realizing service oriented architecture on the tactical level. Our goal is to make it possible to take advantage of the benefits promised by this architectural paradigm at all military levels, ranging from strategic to tactical networks.
    IEEE Communications Magazine 11/2007; · 3.66 Impact Factor
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    ABSTRACT: This paper focuses on design issues for multimedia distribution architectures and the impact workload characteristics have on architecture design. Our contribution is an analysis of server load and user behavior in a news-on-demand environment, with focus on access patterns, popularity modeling, and the formation of traffic peaks. Finally, we evaluate an existing synthetic workload generator, MediSyn, and suggest some enhancements which will improve its suitability for news-on-demand workload modeling.
    Performance, Computing, and Communications Conference, 2007. IPCCC 2007. IEEE Internationa; 05/2007
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    ABSTRACT: On-demand access to remote multimedia content via the Internet is becoming increasingly popular. Applications like video on demand and news on demand are increasingly based on structured multimedia presentations, which give users more options and freedom to interact with the content than just VCR-like operations. For example, authors provide multiple choices for parts of the presentation and the user can select the most interesting one. Distributing such presentations in hierarchical distribution systems comprised of origin server and proxies can lead to new challenges for proxies since entire presentations are large but only small parts of them are actually consumed by each user. We have analyzed this problem for interactive presentations encoded in MPEG-4 and found that we can use the internal structure of MPEG-4 objects to improve performance in a distribution system based on proxy caching.
    Performance, Computing, and Communications Conference, 2006. IPCCC 2006. 25th IEEE International; 05/2006