P2P, ad hoc and sensor networks – All the different or all the same?

Currently, data management technologies are in the process of finding their way into evolving networks, i.e. P2P, ad hoc and wireless sensor networks. We examine the properties, differences and commonalities of the different types of evolving networks, in order to enable the development of adequate technologies suiting their characteristics. We start with presenting definitions for the different network types, before arranging them in a network hierarchy, to gain a clear view of the area. Then, we analyze and compare the example applications for each of the types using different design dimensions. Based on this work, we finally present a comparison of P2P, ad hoc and wireless sensor networks

On the complexity of intersecting finite state automata and NL versus NP

AbstractWe consider uniform and non-uniform assumptions for the hardness of an explicit problem from finite state automata theory. First we show that a small improvement in the known straightforward algorithm for this problem can be used to design faster algorithms for subset sum and factoring, and improved deterministic simulations for non-deterministic time.On the other hand, we can use the same improved algorithm for our FSA problem to prove complexity class separation results (NL is not equal to P, or NP for the non-uniform case). This result can be viewed either as a hardness result for the FSA intersection problem, or as a method for separating NL from P or NP. It is interesting to note that this approach is based on a more general method for separating two complexity classes, using algorithms rather than lower bounds

Hardware-assisted transaction processing : NVM

A transaction is a demarcated sequence of application operations, for which the following properties are guaranteed by the underlying transaction processing system (TPS): atomicity, consistency, isolation, and durability (ACID). Transactions are therefore a general abstraction, provided by TPS that simplifies application development by relieving transactional applications from the burden of concurrency and failure handling. Apart from the ACID properties, a TPS must guarantee high and robust performance (high transactional throughput and low response times), high reliability (no data loss, ability to recover last consistent state, fault tolerance), and high availability (infrequent outages, short recovery times). The architectures and workhorse algorithms of a high-performance TPS are built around the properties of the underlying hardware. The introduction of nonvolatile memories (NVM) as novel storage technology opens an entire new problem space, with the need to revise aspects such as the virtual memory hierarchy, storage management and data placement, access paths, and indexing. NVM are also referred to as storage-class memory (SCM)