Towards a Definition of Role-related Concepts for Business Modeling

Abstract—While several role-related concepts play an\ud important role in business modeling, their definitions,\ud relations, and use differ greatly between languages, papers,\ud and reports. Due to this, the knowledge captured by models is\ud not transferred correctly, and models are incomparable. In this\ud paper, we provide a meta-model and definitions for several\ud role-related concepts based on the practice of existing modeling\ud languages and ontological analysis. This forms a basis for\ud creating comparable, formal business models, which enable\ud further enterprise engineering, in a repeatable wa

Burstiness predictions based on rough network traffic measurements

To dimension network links, such that they will not become QoS bottle- necks, the peak rate on these links should be known. To measure these peaks on sufficiently small time scales, special measurement tools are needed. Such tools can be quite expensive and complex. Therefore network operators often rely on more cheap, standard tools, like MRTG, which were designed to measure average traffic rates (m) on time scales such as 5 minutes. For estimating the peak traffic rate (p), operators often use simple rules, such as p = α · m. In this paper we describe measurements that we have performed to investigate how well this rule describes the relation between peak and average traffic rate. In addition, we pro- pose some more advanced rules, and compare these to the simple rule mentioned above. The analyses of our measurements, which have been performed on differ- ent kinds of networks, show that our advanced rules more adequately describe the relation between peak and average traffic rate

Math saves the forest

Wireless sensor networks are decentralised networks consisting of sensors that can detect events and transmit data to neighbouring sensors. Ideally, this data is eventually gathered in a central base station. Wireless sensor networks have many possible applications. For example, they can be used to detect gas leaks in houses or fires in a forest.\ud In this report, we study data gathering in wireless sensor networks with the objective of minimising the time to send event data to the base station. We focus on sensors with a limited cache and take into account both node and transmission failures. We present two cache strategies and analyse the performance of these strategies for specific networks. For the case without node failures we give the expected arrival time of event data at the base station for both a line and a 2D grid network. For the case with node failures we study the expected arrival time on two-dimensional networks through simulation, as well as the influence of the broadcast range

Analysing the Impact of a DDoS Attack Announcement on Victim Stock Prices

DDoS attacks are increasingly used by 'hackers' and 'hacktivists' for various purposes. A number of on-line tools are available to launch an attack of significant intensity. These attacks lead to a variety of losses at the victim's end. We analyse the impact of Distributed Denial-of-Service (DDoS) attack announcements over a period of 5 years on the stock prices of the victim firms. We propose a method for event studies that does not assume the cumulative abnormal returns to be normally distributed, instead we use the empirical distribution for testing purposes. In most cases we find no significant impact on the stock returns but in cases where a DDoS attack creates an interruption in the services provided to the customer, we find a significant negative impac

Measuring the Impact of a Successful DDoS Attack on the Customer Behaviour of Managed DNS Service Providers

Distributed Denial-of-Service (DDoS) attacks continue to pose a serious threat to the availability of Internet services. The Domain Name System (DNS) is part of the core of the Internet and a crucial factor in the successful delivery of Internet services. Because of the importance of DNS, specialist service providers have sprung up in the market, that provide managed DNS services. One of their key selling points is that they protect DNS for a domain against DDoS attacks. But what if such a service becomes the target of a DDoS attack, and that attack succeeds? In this paper we analyse two such events, an attack on NS1 in May 2016, and an attack on Dyn in October 2016. We do this by analysing the change in the behaviour of the service's customers. For our analysis we leverage data from the OpenINTEL active DNS measurement system, which covers large parts of the global DNS over time. Our results show an almost immediate and statistically significant change in the behaviour of domains that use NS1 or Dyn as a DNS service provider. We observe a decline in the number of domains that exclusively use NS1 or Dyn as a managed DNS service provider, and see a shift toward risk spreading by using multiple providers. While a large managed DNS provider may be better equipped to protect against attacks, these two case studies show they are not impervious to them. This calls into question the wisdom of using a single provider for managed DNS. Our results show that spreading risk by using multiple providers is an effective countermeasure, albeit probably at a higher cost

An interconnection architecture for micropayment systems

In the next years the market for low value online content, like music and videos, is expected to grow substantially. To allow �pay-per-use� of such content, micropayment systems are expected to play an important role. Since there are already many competing micropayment systems on the market, customers and merchants are forced to use multiple systems. To overcome the problems associated with using multiple systems, the research presented in this paper builds upon the idea of payment gateways that interconnect these systems. We introduce a generally applicable interconnection method such that the interconnection of these systems can be easily realized in a systematic way. This approach consists of (de)enhancing the existing micropayment services towards a uniform service level before the interconnection takes place. This paper presents the main functional characteristics\ud of existing payment systems, and proposes modification strategies for existing micropayment systems to provide the uniform payment service. The modifications are required before the interconnection can take place

Extending CORBA with specialised protocols for QoS provisioning

The CORBA layer in a distributed system hides the heterogeneity of the underlying computer network. The interactions of objects located at different computing systems are described in terms of IDL specifications and the ORB takes care of the actual transfer of messages along the wire. In fact, an object interaction is translated into the transfer of GIOP messages over TCP/IP networks (IIOP). The advantages in terms of interoperability and portability are obvious. Currently, OMG is in the process of standardising the Open Communication Interface (OCI). Through OCI, a protocol module can be plugged into any ORB and hence, the distributed application including the ORB can be put on top of any network without changing the application’s code, thus implementing network transparency. Obviously, the QoS of distributed applications depends on the QoS of the underlying network protocols, e.g., best effort versus guaranteed bandwidth. Through OCI we are able to use the network protocol that is needed to satisfy the QoS requirements of a specific distributed application. In this paper, we propose to extend CORBA with specialised protocols for QoS provisioning using OCI. We have prototyped protocol plug-in’s, including a plug-in that exploits IP Multicast. The IP Multicast plug-in can be used in situations where one client communicates with a group of replicated servers. In fact, we have used this mechanism to implement replication transparency in CORBA. We have shown that the OCI interface can be used for QoS provisioning in CORBA. Based on our hands-on experience, we also have identified some shortcomings in the proposed OCI specification

Middleware support for media streaming establishment driven by user-oriented QoS requirements

. The requirements for the QoS of distributed applications are traditionally expressed in terms of network oriented or systems oriented parameters. In general, the users of these services are not interested or capable of specifying the QoS of their services in such technical terms. In this paper, we propose modeling and engineering concepts for the mapping of end user QoS onto system and network QoS. We introduce QoS agents in structured object middleware that relate end-user QoS specifications to multimedia stream bindings. In fact, the middleware layer supports QoS classes, i.e., a set of QoS characteristics. The end user QoS requirements, generally a set of nonorthogonal specifications, must be supported using the available middleware QoS classes. We also describe the experimental environment that will be used to refine the QoS mapping mechanisms. 1. Introduction Object middleware, such as CORBA, DCOM and Java RMI, is gaining rapid acceptance as a means to quickly and c..