Marcin Bienkowski

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In a (randomized) oblivious routing scheme the path chosen for a request between a source <i>s</i> and a target <i>t</i> is independent from the current traffic in the network. Hence, such a scheme consists of probability distributions over <i>s-t</i> paths for every source-target pair <i>s,t</i> in the network.In a recent result [11] it was shown that for(More)
Network virtualization promises a high flexibility by decoupling services from the underlying substrate network and allowing the virtual network to adapt to the needs of the service, e.g., by migrating servers or/and parts of the network. We study a system (e.g., a gaming application) where network virtualization is used to support thin client applications(More)
Today's trend toward network virtualization and software-defined networking enables flexible new distributed systems where resources can be dynamically allocated and migrated to locations where they are most useful. This paper proposes a competitive analysis approach to design and reason about online algorithms that find a good tradeoff between the benefits(More)
Network virtualization allows one to build dynamic distributed systems in which resources can be dynamically allocated at locations where they are most useful. In order to fully exploit the benefits of this new technology, protocols need to be devised which react efficiently to changes in the demand. This paper argues that the field of online algorithms and(More)
The Joint Replenishment Problem (JRP) deals with optimizing shipments of goods from a supplier to retailers through a shared warehouse. Each shipment involves transporting goods from the supplier to the warehouse, at a fixed cost C, followed by a redistribution of these goods from the warehouse to the retailers that ordered them, where transporting goods to(More)
In Peer-to-Peer networks based on consistent hashing and ring topology, each server is responsible for an interval chosen (pseudo-) randomly on a unit circle. The topology of the network, the communication load, and the amount of data a server stores depend heavily on the length of its interval. Additionally, the nodes are allowed to join the network or to(More)
We study packet buffering, a basic problem occurring in network switches. We construct an optimal 16/13-competitive randomized online algorithm PB for the case of two input buffers of arbitrary sizes. Our proof is based on geometrical transformations which allow to identify the set of sequences incurring extremal competitive ratios. Later we may analyze the(More)
The dynamic page migration problem [4] is defined in a distributed network of n mobile nodes sharing one indivisible memory page of size D. During runtime, the nodes can both access a unit of data from the page and move with a constant speed, thus changing the costs of communication. The problem is to compute online a schedule of page movements to minimize(More)
We survey data management problems in the light of competitive analysis. We review classic results on the file allocation, the page migration, and the page replication problems in a model in which the total cost of communication is subject to optimization. We also briefly present classic and recent extensions of these problems, such as versions that(More)
In the last couple of decades, network connected systems have gradually replaced centralized parallel computing machines. To provide smooth operation of network applications, the underlying system has to provide so-called basic services. One of the most crucial services is to provide a transparent access to data like variables, databases, memory pages, or(More)