Henning Pagnia

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Recently, research has focused on enabling fair exchange between payment and electronically shipped items. The reason for this is the growing importance of Electronic Commerce and the increasing number of applications in this area. Although a considerable number of fair exchange protocols exist, they usually have been defined for special scenarios and thus(More)
The notion of fairness is a very general concept and can be used to coin terms in many different application areas. Recently, the term fairness has appeared in the context of electronic commerce. Here, the term fair exchange refers to the problem that two parties want to swap some distinct items in a way which ensures that no participant can gain advantage(More)
Mobile agents have been advocated to support electronic commerce over the Internet. While being a promising paradigm, many intricate problems need to be solved to make this vision reality. The problem of fair exchange between two agents is one such fundamental problem. Informally speaking, this means to exchange two electronic items in such a way that(More)
Grid-based data replication protocols have been proven to be extremely eecient due to the high availability and the low cost of read and write operations they ooer. However, although each grid protocol uses logical grids, the semantics and interpreting algorithms vary from scheme to scheme. This has the disadvantage that switching from one protocol to(More)
Replicating data in a distributed system is a suitable means for increasing the availability as well as the performance of data access operations. Unfortunately, there exists a trade-oo between these two properties: a replica control protocol which exhibits, e.g., a high read availability and low read operation costs usually suuers from low write(More)
We present a method of combining a self-stabilizing algorithm with a hierarchical structure to construct a self-stabilizing algorithm with improved stabilization time complexity and fault-containment features. As a case study, a self-stabilizing spanning-tree algorithm is presented which in favorable settings has logarithmic stabilization time complexity.