Pal Varga

The arrowhead approach for SOA application development and documentation

The Arrowhead project aims to address the technical and applicative issues associated with cooperative automation based on Service Oriented Architectures. The problems of developing such kind of systems are mainly due to the lack of adequate development and service documentation methodologies, which would ease the burden of reusing services on different applications. The Arrowhead project proposes a technical framework to efficiently support the development of such systems, which includes several tools for documentation of services and to support the development of SOA-based installations. The work presented in this paper describes the approach which has been developed for the first generation pilots to support the documentation of their structural services. Each service, system and system-of-systems within the Arrowhead Framework must be documented and described in such way that it can be implemented, tested and deployed in an interoperable way. This paper presents the first steps of realizing the Arrowhead vision for interoperable services, systems and systems-of-systems.

Making system of systems interoperable The core components of the arrowhead framework

The objective of the Arrowhead Framework is to efficiently support the development, deployment and operation of interconnected, cooperative systems. It is based on the Service Oriented Architecture philosophy. The building elements of the framework are systems that provide and consume services, and cooperate as systems of systems. Some commonly used systems, such as orchestration, authorization or service registry are considered as core. These can be used by any system of systems that follow the guidelines of the Arrowhead Framework.Within the framework, systems using different information exchange technologies during collaboration are helped through various approaches. These include the so-called Interoperability Layer, as well as systems and services for translation. Furthermore, one of the main problems of developing such highly interoperable systems is the lack of understanding between various development groups. Adequate development and service documentation methodologies can help to overcome this issue.The design, development and verification methodology for each service, system and system of systems within the Arrowhead Framework supports that these can be implemented, verified, deployed, and run in an interoperable way. This paper presents an overview of the framework together with its core elements and provides guidelines for the design and deployment of interoperable, Arrowhead-compliant cooperative systems.

Translation error handling for multi-protocol SOA systems

The IoT research area has evolved to incorporate a plethora of messaging protocol standards, both existing and new, emerging as preferred communications means. The variety of protocols and technologies enable IoT to be used in many application scenarios. However, the use of incompatible communication protocols also creates vertical silos and reduces interoperability between vendors and technology platform providers. In many applications, it is important that maximum interoperability is enabled. This can be for reasons such as efficiency, security, end-to-end communication requirements etc. In terms of error handling each protocol has its own methods, but there is a gap for bridging the errors across protocols. Centralized software bus and integrated protocol agents are used for integrating different communications protocols. However, the aforementioned approaches do not fit well in all Industrial IoT application scenarios. This paper therefore investigates error handling challenges for a multi-protocol SOA-based translator. A proof of concept implementation is presented based on MQTT and CoAP. Experimental results show that multi-protocol error handling is possible and furthermore a number of areas that need more investigation have been identified.

A case study on correlating video QoS and QoE

Finding the correlation among Quality of Experience (QoE) for video, measured Quality of Service (QoS) parameters in the network, and objective video performance metrics is a challenging task. This paper provides some analysis results on this issue. Our motivation is that streaming media content gets dominant position in the global traffic mix within the next few years. With the evolution of personal devices, demand for High Definition (HD) resolution contents is dynamically increasing. Traversing real-time media across public packet-switched networks is a complex task, especially if quality of service should be sustained. The issue gets more complicated when the traffic is forwarded through heterogeneous infrastructures. Media content with various resolutions and bit rates show different sensitivity to transmission anomalies. Our paper investigates the correlation between subjective quality assessment (i.e., Mean Opinion Score, MOS evaluation), measured QoS parameters (packet loss, jitter) and objective video performance metrics (Video Quality Metric - VQM, Structural Similarity - SSIM, Peak Signal Noise Ratio - PSNR) in the context of real-time HD video streaming (i.e., IPTV and MobileTV). In twelve scenarios, packet-level perturbations were emulated in our laboratory testbed during the transmission of short video sequences with three different resolutions (480p, 720p and 1080p). Later the videos were evaluated using subjective and objective assessment methods.

Analyzing Packet Interarrival Times Distribution to Detect Network Bottlenecks

This paper analyzes the properties of packet interarrival time (PIT) distribution functions of network segments including bottlenecks. In order to show the correlation between bottleneck behavior and packet interarrival time distribution, the alteration of probability distribution function (PDF) is observed through simulations including tighter and tighter bottleneck connections. The process of network bottleneck detection by passive monitoring requires effective metrics for distinguishing seriously congested links from normal or underutilized connections. The paper evaluates the third and fourth central moments (skewness and kurtosis, respectively) of PIT distribution as possible metrics for bottleneck detection. Simulation results as well as real measurement data analysis showed that PIT kurtosis can be a powerful measure of bottleneck behavior.

Utilizing higher order statistics of packet interarrival times for bottleneck detection

This paper introduces a new approach for determining bottleneck link locations in a network. The considered measurement model is passive monitoring of a backbone link. We analyze the properties of packet interarrival time (PIT) distribution functions of network segments and make decisions whether the extracted properties of a link suggest bottleneck behavior or not. The correlation between bottleneck behavior and packet interarrival time distribution is demonstrated through simulations featuring tighter and tighter bottleneck connections. Locating shared bottlenecks with passive monitoring requires effective metrics for distinguishing seriously congested links from normal or underutilized connections. The current paper presents the third and fourth central moments (skewness and kurtosis, respectively) of PIT distribution as possible and promising metrics for bottleneck detection. According to the simulation results, kurtosis of PITs is found to be a powerful measure of bottleneck behavior. This is further validated by investigation of real measurement data.

Enabling IoT automation using local clouds

Various forms of cloud computing principles and technologies are becoming important recently. This paper addresses cloud computing for automation and control applications. Its argued that the open Internet cloud idea has such limitations that its not appropriate for automation. Since automation is physically and geographically local, it is inevitable to introduce the concept of local automation clouds. Its here proposed that local automation clouds should be self contained an be able to execute the intended automation functionalities without any external resources. Thus providing a fence at the rim of the local cloud preventing any inbound or outbound communication. Such a local cloud provides possibilities to address key requirements of both todays and future automation solutions. Adding mechanisms for secure inter-cloud administration and data tranfere enables local automation cloud to meet IoT automation system requirements as: 1) Interoperability of a wide range of IoT and legacy devices 2) Automation requirement on latency guarantee/prediction for communication and control computations. 3) Scalability of automation systems enabling very large integrated automation systems 4) Security and related safety of automation systems 5) Ease of application engineering 6) Multi stakeholder integration and operations agility. How these requirements can be met in such a local automation cloud is discussed with references to proposed solutions. The local automation cloud concept is further verified for a compartment climate control application. The control application included an IoT controller, four IoT sensors and actuators, and a physical layer communication gateway. The gateway acted as host for local cloud core functionalities. The climate control application has successfully been implemented using the open source Arrowhead Framework and its supports for design and implementation of self contained local automation clouds.

Towards estimating video QoE based on frame loss statistics of the video streams

This paper describes a unique path of estimating the Quality of Experience (QoE) for streaming video. Instead of following the widely researched idea of correlating video degradation with Quality of Service (QoS) metrics of the network, we propose to merely analyze the nature of packet losses. The majority of todays streaming video traffic is using compressed formats, where the videos are composed from a series of key, predicted, and bi-predictive frames (I frame, P frame, B frame, respectively). The content of these frames gets packetized, and sent over the network as video traffic. Losing packets that belong to I, P and B frames lead to QoE degradations of different severity. The degrading effect of these packet losses depend on the type of the video (two extremes can be slowly moving balloons versus fireworks in the sky), the type of frame, the volume of the lost packets, and further factors. The aim of this paper is to introduce a measurement and analysis method for correlating packet loss patterns of key, predicted and bi-predictive frames with objective quality metrics, such as the SSIM (Structural SIMilarity index). Furthermore, measurement results on the effect of such packet losses for various video types are also presented in this paper.

Advanced Security Considerations in the Arrowhead Framework

The Arrowhead Framework aims to create collaborative automation using networked embedded devices by establishing a service oriented approach to govern them. Various cyber-physical Systems can provide and consume Services from one another in closed automation clouds. These System-of-Systems has been introduced by the Arrowhead framework as Local Clouds. These clouds – being high value targets – can then be subject to an extensive amount of threats. This paper is dedicated towards revising the Arrowhead framework to further enhance its security solutions. A certificate-based architecture is presented to solve authentication and authorization tasks not just within, but in-between Local Clouds by using a token concept applied for services. This schema also allows the integration of resource constrained devices in coexistence with different levels of security.

Organizing IoT Systems-of-Systems from standardized engineering data

Tackling current challenges in production automation requires the involvement of new concepts like Internet of Things, System-of-Systems and local automation clouds. The objective of this paper is to address the actual process of defining a cloud based automation system. More specifically the design, engineering, operation and maintenance of an automation system must be captured and managed between all stakeholders involved. This is critical to create the expected benefits from the local automation cloud approach. This paper addresses the capability of capturing plant designs and coordinating information exchange based on the captured architecture. For this purpose an architectural component - Plant Description - is proposed to be used in the Arrowhead Framework, based on already existing plant automation standards. An overview of methodologies on how it can interact with the Arrowhead Frameworks Orchestration process describes the usefulness in managing large-scale automation systems. A qualitative evaluation for one of the proposed approaches is also described in a water control use case that can be found both in process and building automation.