In this paper we describe UML-Ψ, a software performance evaluation tool based on process-oriented simulation. The tool can be used to evaluate performances of software systems described as annotated UML diagrams. UML-Ψ transforms the software model into a performance model based on process-oriented simulation, executes the performance model and collects results. Performance results are inserted into the software model as tagged values associated to the relevant UML elements.

Similarity search for content-based retrieval (where content can be any combination of text, image, audio/video, etc.) has gained importance in recent years, also because of the advantage of ranking the retrieved results according to their proximity to a query. However, to use similarity search in real world applications, we need to tackle the problem of huge volumes of such mixed multimedia data (e.g., coming from Web sites) and the problem of their distribution on multiple cooperating nodes. This is the situation of the NeP4B project (Networked Peers for Business), where the distributed nodes (i.e., peers) represent aggregations of SME’s with similar activities and the multimedia objects are descriptions/presentations of their products/services extracted from the companies ’ Web sites. In this paper we approach this problem by considering a scenario of a network of autonomous peers maintaining a local collection of metric objects (i.e., mixed mode multimedia content). This network forms a distributed Peer–to–Peer (P2P) search engine for similarity search based on the paradigm of Routing Index. Each peer in the network thus maintains both an index of its local resources and a table for every neighbor, summarizing the objects that are reachable from it. The paper presents techniques that aim to make our P2P similarity-based search system viable, trading approximate results for scalable solutions. Results of simulations that use real collections of images are discussed.

The convergence of the Grid and Peer-to-Peer (P2P) worlds has led to many solutions that try to efficiently solve the problem of resource discovery on Grids. Some of these solutions are extensions of P2P DHT-based networks. We believe that these systems are not flexible enough in case the indexed data are very dynamic, i.e., the values of the resource attributes change very frequently over time. This is a common case for some data managed by typical Grid systems, like CPU loads, queue occupation, etc. Moreover, since common requests for Grid resources may be expressed as multi-attribute range queries, we think that the DHTbased P2P solutions that have been proposed so far with the aim of supporting such type of queries can suffer from poor flexibility and efficiency. In this paper we thus present a couple of P2P systems. Both the systems are based on Routing Indexes, used to efficiently route queries and update messages in the presence of highly variable data. The first system needs the adoption of a tree-shaped overlay network. The second one, which is an evolution of the first, is based on a two-level hierarchical network topology, where tree topologies must only be maintained at the lower level of the

The convergence of the Grid and Peer-to-Peer (P2P) worlds has led to many solutions that try to efficiently solve the problem of resource discovery on Grids. Some of these solutions are extensions of P2P DHT-based networks. We believe that these systems are not flexible enough in the case the data present in the network is very dynamic, i.e. the data values change very frequently over time. This a very common case for some kind of data in typical Grid systems, like CPU loads, queue occupation, etc. In this paper we present a variation of a previous work based on a tree-shaped P2P overlay network. The system uses Routing Indexes to efficiently route queries and update messages in the presence of highly variable data. The new system is based on a twolevel hierarchical network topology, where tree topologies must be only maintained at the lower level of the hierarchy. The main aim of this new organization is to achieve a simpler maintenance of the overall P2P graph topology. This is reached at the cost of some imprecision in the routing indexes built at the upper level of the graph hierarchy.