Universität Duisburg-Essen
Verteilte Systeme
Replication Mechanisms in Geostry
Prüfer Prof. Dr.-Ing. Torben Weis
Betreuer Dipl.-Inf. Mirko Knoll
Bearbeiter Haitham Abbadi
Beginn April 2007
Dauer 6 Monate

Context-based systems have become more and more popular recently. There are new applications that help people to easily access information, which is available digitally on the net. However, the amount of information available in the digital world steadily increases and with it the costs for managing the data. That's why the client-server architecture with its huge data centers will not be able to handle massive requests in the near future. To cope with these requirements, several projects started using peer-to-peer (p2p) technology. In doing so, data and management tasks will be distributed to the participants of the p2p network, thus eliminating the need for data centers. Whereas many popular p2p systems replicate data over the internet to guarantee access to it, Geostry optimizes for locality of data. This means, that data (primarily frequent sensor data) is stored close to the geographical location the data is about. Geostry then implements a routing alogrithm that allows requests for information about a certain location to be routed directly towards the target destination.

Geostry offers the possibility to request data for a specific GPS location and retrieve information from the node which is the geographically closest. As in every p2p system, nodes come and go, not necessarily announcing their intentions before. To cope with this behaviour, intelligent replication mechanisms have to be used. Otherwise information might get lost in case of a network partition or node failure. Popular p2p systems e.g. like OceanStore replicate their data all over the world to guarantee access even in the case of large network failures. Geostry builds on locality of data. Therefore, replication mechanisms in Geostry need to take locality into account.

The major challenges of this work are:

  • Acquisition of available replication mechanisms (even beyond p2p systems)
  • Analysis of existing approaches in reference to the scenario given in Geostry
    • Replication frequency decreases with replication distance
    • Dynamica replication to cope with massive queries at a single location
  • Discussion of enhancements for one or multiple existing approaches or development of a new replication method
  • Simulation / Evaluation of replication concepts

The practicability of the developed concepts should be presented using a prototype implementation. We expect the implementation to be developed with Microsoft's .NET platform technology using a supported such as C# or VB.NET. Knowledge about networks and network protocols is expected.

 

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