@inproceedings {INPROC-2013-01,
   author = {Bj{\"o}rn Schilling and Boris Koldehofe and Kurt Rothermel and Umakishore Ramachandran},
   title = {{Access Policy Consolidation for Complex Event Processing}},
   booktitle = {IEEE Conference on Networked Systems (NetSys)},
   publisher = {IEEE},
   institution = {Universit{\"a}t Stuttgart, Fakult{\"a}t Informatik, Elektrotechnik und Informationstechnik, Germany},
   pages = {92--101},
   type = {Konferenz-Beitrag},
   month = {M{\"a}rz},
   year = {2013},
   doi = {10.1109/NetSys.2013.18},
   keywords = {Event processing; Complex event processing; CEP; Security; Access Control; Bayesian network},
   language = {Englisch},
   cr-category = {C.2.4 Distributed Systems},
   ee = {ftp://ftp.informatik.uni-stuttgart.de/pub/library/ncstrl.ustuttgart_fi/INPROC-2013-01/INPROC-2013-01.pdf},
   department = {Universit{\"a}t Stuttgart, Institut f{\"u}r Parallele und Verteilte Systeme, Verteilte Systeme},
   abstract = {In distributed complex event processing, event streams are processed over a chain of subsequent operators. For large-scale applications like a logistic chain these operators may be hosted by different entities and thus are spread over different security domains. Current approaches for complex event processing cannot preserve the privacy of an operator’s incoming event streams. An adversary may infer the original input stream from its legally received event streams. In this paper we present a fine-grained access management for complex event processing. We show how to enforce privacy of events throughout the chain of dependent operators by specifying appropriate access policies and proposing an algorithm for policy consolidation. Furthermore, we introduce the calculation of obfuscation achieved in a correlation step. This allows us to ignore access requirements once a sufficient obfuscation level has been achieved, the proposed algorithms is capable to reduce the required overhead in the enforcement of access policies. We prove correctness and evaluate the cost in establishing policy consolidation.},
   url = {http://www2.informatik.uni-stuttgart.de/cgi-bin/NCSTRL/NCSTRL_view.pl?id=INPROC-2013-01&engl=0}
}
@inproceedings {INPROC-2011-43,
   author = {Bj{\"o}rn Schilling and Boris Koldehofe and Kurt Rothermel},
   title = {{Efficient and Distributed Rule Placement in Heavy Constraint-Driven Event Systems}},
   booktitle = {Proceedings of the 13th IEEE International Conference on High Performance Computing and Communications (HPCC-2011)},
   publisher = {IEEE},
   institution = {Universit{\"a}t Stuttgart, Fakult{\"a}t Informatik, Elektrotechnik und Informationstechnik, Germany},
   pages = {355--364},
   type = {Konferenz-Beitrag},
   month = {September},
   year = {2011},
   doi = {10.1109/HPCC.2011.53},
   language = {Englisch},
   cr-category = {C.2.4 Distributed Systems},
   ee = {ftp://ftp.informatik.uni-stuttgart.de/pub/library/ncstrl.ustuttgart_fi/INPROC-2011-43/INPROC-2011-43.pdf,     http://dx.doi.org/10.1109/HPCC.2011.53},
   department = {Universit{\"a}t Stuttgart, Institut f{\"u}r Parallele und Verteilte Systeme, Verteilte Systeme},
   abstract = {Complex Event Processing (CEP) is of increasing importance in many industrial applications to integrate a huge number of events in a scalable manner. A core challenge towards scalable CEP is to efficiently distribute the rules which define how correlations between events can be detected within an event processing network. Furthermore, migration of rules is essential to adapt to changing conditions. While recently significant effort has been spent on optimizing CEP with respect to dedicated optimization goals, such as minimizing latency and bandwidth usage, there remains a fundamental gap in supporting requirements that emerge from deploying CEP over heterogeneous and independent processing environments. Heterogeneity typically imposes many constraints on the placement of rules, which increases the complexity of the underlying optimization problem and cannot be handled efficiently by existing solutions. In this paper we examine the distributed placement, migration and optimization of rules in the context of the constraint optimization problem to minimize network usage. We propose and evaluate a placement algorithm that efficiently finds valid solutions in scenarios where the solution space is heavily restricted by constraints. The algorithm operates in a decentralized way and is adaptive to dynamic changes of processing nodes, rules, and load characteristics of the event processing network. The optimization algorithm adopts techniques from simulated annealing to avoid local minima. Furthermore, the proposed rule migration policies resolve invalid placements quickly and therefore ensure high availability. The evaluations show that the proposed algorithm is able to efficiently find near optimum solutions within heavy constraint-driven network conditions.},
   url = {http://www2.informatik.uni-stuttgart.de/cgi-bin/NCSTRL/NCSTRL_view.pl?id=INPROC-2011-43&engl=0}
}
@inproceedings {INPROC-2010-22,
   author = {Bj{\"o}rn Schilling and Boris Koldehofe and Udo Pletat and Kurt Rothermel},
   title = {{Distributed Heterogeneous Event Processing: Enhancing Scalability and Interoperability of CEP in an Industrial Context}},
   booktitle = {Proceedings of the 4th ACM International Conference on Distributed Event-Based Systems (DEBS); Cambridge, United Kingdom, July 12-15, 2010},
   publisher = {ACM},
   institution = {Universit{\"a}t Stuttgart, Fakult{\"a}t Informatik, Elektrotechnik und Informationstechnik, Germany},
   pages = {150--159},
   type = {Konferenz-Beitrag},
   month = {Juli},
   year = {2010},
   isbn = {1827418.1827453},
   language = {Deutsch},
   cr-category = {C.2.1 Network Architecture and Design,     C.2.4 Distributed Systems},
   ee = {ftp://ftp.informatik.uni-stuttgart.de/pub/library/ncstrl.ustuttgart_fi/INPROC-2010-22/INPROC-2010-22.pdf,     http://portal.acm.org/citation.cfm?doid=1827418.1827453},
   department = {Universit{\"a}t Stuttgart, Institut f{\"u}r Parallele und Verteilte Systeme, Verteilte Systeme},
   abstract = {Although a significant amount of research has investigated the benefits of distributed CEP in terms of scalability and extensibility, there is an ongoing reluctance in deploying distributed CEP in an industrial context. In this paper we present the DHEP system developed together with the IBM laboratory in B{\"o}blingen. It addresses some of the key problems in increasing the acceptance of distributed CEP, for example supporting interoperability between heterogeneous event processing systems. We present the concepts behind the DHEP system and show how those concepts help to achieve scalable and extensible event processing in an industrial context. Moreover, we verify in an evaluation study that the additional cost imposed by the DHEP system is moderate and 'affordable' for the benefits provided.},
   url = {http://www2.informatik.uni-stuttgart.de/cgi-bin/NCSTRL/NCSTRL_view.pl?id=INPROC-2010-22&engl=0}
}
@article {ART-2009-14,
   author = {Bj{\"o}rn Schilling and Udo Pletat and Kurt Rothermel},
   title = {{Event Correlation in Heterogeneous Environments}},
   journal = {it --- Information Technology -- Complex Event Processing},
   publisher = {Oldenbourg Wissenschaftsverlag GmbH},
   pages = {270--275},
   type = {Artikel in Zeitschrift},
   month = {Oktober},
   year = {2009},
   language = {Deutsch},
   cr-category = {C.2.1 Network Architecture and Design,     C.2.4 Distributed Systems},
   ee = {ftp://ftp.informatik.uni-stuttgart.de/pub/library/ncstrl.ustuttgart_fi/ART-2009-14/ART-2009-14.pdf,     http://www.oldenbourg-wissenschaftsverlag.de/olb/de/1.c.1495462.de},
   department = {Universit{\"a}t Stuttgart, Institut f{\"u}r Parallele und Verteilte Systeme, Verteilte Systeme},
   abstract = {The condition and location of a business item are of central interest in many business applications such as supply chain management, manufacturing, or ensuring safety and security for people and goods. Recent advances in sensor technology allow to transmit condition and location information about goods, materials and people to enterprise software systems in real-time. In this context, complex event processing is an emerging software technology for detecting business-relevant situations in streams of events and for providing these detected situations to various business processes. While currently complex event processing systems are mostly deployed within a single business domain at a limited scale, the cooperative nature of business applications gives reason that complex event processing will soon address multiple business domains and involve an increasingly large number of business events. In order to ensure interoperability as well as efficient utilization of processing and network capability, we motivate the need for heterogeneous correlation technology in the context of business applications. In this article we give an overview of the project $\backslash$emph{Distributed heterogeneous event processing} (DHEP) involving the IBM B{\"o}blingen lab and the Universit{\"a}t Stuttgart. In particular, we highlight how business applications can benefit from using event correlation technology in heterogeneous environments. The key aspects of the project address the deployment of collections of event correlation rules to a network of heterogeneous event correlation engines. We give an overview of challenges and possible solutions for the dynamic configuration of such environments and present our architecture which supports network-wide cooperation between different correlation engines.},
   url = {http://www2.informatik.uni-stuttgart.de/cgi-bin/NCSTRL/NCSTRL_view.pl?id=ART-2009-14&engl=0}
}