Due to complex interdependencies and feedback loops between network layers and nodes, the development of adaptive applications is difficult. As networking applications respond nonlinearly to changes in the environment and adaptations, defining concrete adaptation rules is nontrivial. In this paper, we present the offline learner Fossa, which uses genetic programming to automatically learn suitable Event Condition Action (ECA) rules. Based on utility functions defined by the developer, the genetic programming learner generates a multitude of rule sets and evaluates them using simulations to obtain their utility. We show, for a concrete example scenario, how the genetic programming learner benefits from the clear model of the ECA rules, and that the methodology efficiently generates ECA rules which outperform nonadaptive and manually tuned solutions.

Today's smartphones feature sophisticated computational capabilities as well as a plethora of sensors, enabling new kinds of applications. One popular example are pervasive mobile multiplayer games, where interactions with other users or physical objects in the real world are part of the gameplay. This induces a notion of locality, as a user's actions affect other nearby users. However, this locality in the interaction is not reflected in the underlying communication system. Events triggered by users are sent via the cellular connection to a remote data center, where they are processed and then distributed to other players, again via the cellular link. In this work, we demonstrate an event dissemination system that utilizes the available local communication interfaces of today's smartphones to distribute events in groups of nearby players. The system executes transitions between different communication interfaces (e.g., Bluetooth or Wi-Fi Direct) and the utilized dissemination protocol depending on the size and density of the group of players, thereby exploiting the characteristics of the chosen interface. Attendees can experience the resulting benefits in terms of latency and update frequency by playing our mobile pervasive multiplayer game TowerWorld at the venue.

In distributed real-time applications, such as online games or interactive conferencing systems, timeliness of update event dissemination is a prevailing requirement. Direct connections are often the best solution. However, participants' connection bandwidths, especially uplink capacities of asymmetric end user Internet connections, impose a limit to this. We present and evaluate a lightweight local algorithm that optimizes many-to-many event dissemination in highly dynamic scenarios. The algorithm exploits the high clustering of interest networks, as observed in virtual environments based on local vision, but also in social networks of many kinds. Our approach allows reducing traffic by aggregating messages as well as balancing traffic among participants based on their capabilities.

In Networked Virtual Environments (NVE), Interest Management (IM) is a key part of the system that determines which of a participant's actions have to be communicated to which subset of the other participants. Since traditional client/server approaches have several drawbacks, a variety of alternative peer-to-peer (P2P) approaches have been presented by the community [1]. In many of these approaches, interest management is also responsible for maintaining connectivity of the P2P network. Aiming for latency-sensitive applications, systems like VON [2] and pSense [3] use mutual notification mechanisms, building the topology based on the participants' virtual world proximities. A common limitation of these, however, is their fixed dimensionality: most are only designed for two spatial dimensions, a few are capable of handling three. In this work, we discuss options for dealing with an arbitrary number of dimensions. We propose a dynamic localized peer-to-peer IM that supports and exploits any number of dimensions. In our IM, peers communicate directly within their vision range. The space outside of the vision range is divided in sectors, each guarded by a sensor node that notifies them of approaching peers. We determine criteria for an efficient sector partitioning, discuss several approaches and present a suitable algorithm.

Peer-to-peer overlays for Networked Virtual Environments have recently gained much research interest, resulting in a variety of different approaches for spatial information dissemination. Although designed for the same purpose, the evaluation methodologies used by particular authors differ widely. This makes any comparison of existing systems difficult, if not impossible. To overcome this problem we present a benchmarking methodology which allows for a fair comparison of those systems. We, therefore, define a common set of workloads and metrics. We demonstrate the feasibility of our approach by testing four typical systems for spatial information dissemination and discovering their specific performance profiles.

In this demo we present a testbed environment for Peer-to-Peer (P2P) game architectures. It is based on Planet PI4, an online multiplayer game whose gameplay provides a standard workload for a set of gaming-specific network interfaces. Its pluggable architecture allows for the evaluation and comparison of existing and new P2P networking approaches. Planet PI4 can run on a real network for prototypical evaluation as well as in a discrete-event simulator providing a reproducible environment.

Different evaluation methods for distributed systems like prototyping, simulation and emulation have different tradeoffs. We present a testbed for Internet applications that supports real-network prototypes and multiple simulators with unchanged application code. To ensure maximum portability between runtimes, a compact but flexible system interface is defined.

Simulation has become an important evaluation method in the area of Peer-to-Peer (P2P) research due to the scalability limitations of evaluation test beds such as Planet Lab or G-Lab. Current simulators provide various abstraction levels for different underlay models, such that applications can be evaluated at different granularity. However, existing simulators suffer from a lack of interoperability and portability making the comparison of research results extremely difficult. To overcome this problem, we present an approach for a generic application interface for discrete-event P2P overlay network simulators. It enables porting of the same implementation of a targeted application once and then running it on various simulators as well as in a real network environment, thereby enabling a diverse and extensive evaluation. We established the feasibility of our approach and showed negligible memory and runtime overhead.

This paper presents a novel transport protocol, CUSP, specifically designed with complex and dynamic network applications in mind. Peer-to-peer applications benefit in particular, as their requirements are met by neither UDP nor TCP. While other modern transports like SCTP or SST have also tried to combine the advantages of TCP and UDP, CUSP overcomes their technical and conceptual shortcomings. CUSP makes it possible to directly express application logic in the message flow. Modern applications need a mixture of request-response, request-multiple-response, publish-subscribe, and message-passing. All of these operations can be conveniently implemented using CUSP's unidirectional streams. We separate low-level packet management from streams into reusable channels. A channel connects two applications providing negotiation, congestion control, and cryptography. Developers operate on the stream level, sending messages as reliable and ordered byte-streams. Although they may share a common channel, a stall or loss in one stream does not block the others.

In this demo we present a performance evaluation testbed for peer-to-peer gaming overlays. It consists of a 3D first person shooter game that is designed to run in a simulated network environment as well as on a real network. Simulation with autonomous players (bots) guarantees scalability, a controlled workload, and reproducible results; a prototype deployment on a real network can then validate the simulation results. The information dissemination overlay pSense is implemented as a first subject for evaluation.