Funding: SFB 901, TP A1 und C1, 2011-2019

Here we investigate methods to design and develop distributed algorithms and data structures that are highly scalable. One major requirement towards these methods is an applicability in completely decentralized and highly dynamic systems, i.e., an ability to react to system changes with little effort.  Additionally, we want to emphasize the robustness of our methods, i.e., they are able to recover from an illegal state to a legal state of that algorithm/ data structure even when parts of the system behave erroneous or adversarial during the recovery phase.
 

This sub-project started in 2011 with the aim of researching the possibilities and limitations of local methods for controlling and optimising large dynamic networks. Our focus is on overlay networks that enable interaction between OTF market players (the customers) and service providers to support services and infrastructure provision. “Local” in this context means that control and optimisation is not performed by a central entity, but is distributed by the actors based on their local information. In the first funding period, we focused on the development and analysis of algorithms that enable, for example, the efficient search for services, the distributed organisation of actors into groups or the adaptation of the positioning of resources in an overlay to the needs of customers.

In the second phase, we will expand the focus of our research in two directions: First, we will look at the dynamics of applications. This dynamism manifests itself, for example, in the fact that the co-operation partner of an actor changes or the resources provided change. Supporting such dynamic interaction requirements requires continuous adaptation of the overlay. Our focus is on how we can react to changing requirements with small modifications of the overlay. Secondly, we will look at the external dynamics. These dynamics are outside the control of our algorithms. These can be faulty states or network load from external applications.

The project is concerned with the robustness and security of the on-the-fly scenario. This includes methods for synchronisation, behaviour control and data management in dynamic networks. Dynamically changing co-operations also require suitable cryptographic methods - especially for authentication and ensuring confidentiality, but also for access control - which we will develop on the basis of identity-based cryptography. In addition to these security goals, we also want to achieve data protection and legal security for the participants - which leads to technical and legal challenges.