Carles Pairot

PlanetSim: a new overlay network simulation framework

Current research in peer to peer systems is lacking appropriate environments for simulation and experimentation of large scale overlay services. This has led to a plethora of custom made simulators that waste development resources and hinder fair comparisons between different approaches. In this paper we present a new simulation / experimentation framework for large scale overlay services with three main contributions: i) provide a unifying approach to simulation/ experimentation that eases the transition from simulation to network testbeds, ii) it clearly distinguish between the design of overlay algorithms (key based routing), and the applications and services built on top of them, iii) offer a layered and modular architecture with clear hotspots, and pervasive use of design patterns. We have used PlanetSim to implement and evaluate overlay networks such as Chord and Symphony, and overlay services such as Scribe application level multicast, and keyword query systems over distributed hash tables.

MOVE:: component groupware foundations for collaborative virtual environments

The design of a Virtual Environment (VE) is a distributed problem of multi-user access to shared resources. Such problem requires careful design decisions in order to provide a seamless system infrastructure capable of supporting flexible interactions in the shared scenarios.The complexity of this domain has led to intricate software systems that provide ad-hoc solutions to specific problems. Furthermore, many of them have gone to a dead end, due to their non-extensible design and their lack of code and module reuse.This paper presents a VE that is constructed on top of a component groupware framework. Our major aim is to provide an extensible infrastructure offering a set of collaborative services in a seamless way. At the conceptual level, it provides essential collaborative services: shared sessions, support for synchronous and asynchronous components, security, coordination, and a server-side awareness infrastructure. At the architectural level, the framework is constructed on top of a middleware integration platform and uses high performance publish/subscribe notification services. Finally, we present the advantages and limitations of this approach.

Enabling Wide-Area Service Oriented Architecture through the p2pWeb Model

In this paper we present the p2pWeb service oriented architecture (SOA). The p2pWeb model offers decentralized solutions for service description, publication, discovery and availability, following the Web services standards. The three innovative contributions in p2pWeb SOA are: easy integration of Web services into a p2pWeb network, secure and decentralized Web services deployment, and transparent location, load balancing and fault-tolerance peer-to-peer mechanisms. We believe that all the features our p2pWeb model offers can be of special interest for the creation of communities, and for the development of future collaborative decentralized applications

CloudSNAP: A transparent infrastructure for decentralized web deployment using distributed interception

Abstract Over the last years we have seen the proliferation of many new popular web applications, which are commonly used on a daily basis by most of us. The challenges that have to be overcome by web application designers include how to make these applications support as much concurrent users as possible, without degrading application’s performance, and without single points of failure. Such complex task would be much easier to achieve if designers could concentrate on the application functionalities without worrying about its wide-area scope and derived problems. In this article, we introduce CloudSNAP, a decentralized web deployment platform. CloudSNAP allows transforming any actual web application into a globally-enabled and scalable one. By using a distributed Peer-to-Peer (P2P) Cloud interception middleware, all necessary functionalities are injected into existent web infrastructures in a transparent way. Therefore, CloudSNAP provides many benefits from P2P Cloud computing, like a decentralized deployment environment as well as a set of distributed mechanisms, like load balancing, fault tolerance, dynamic activation, persistence and replication. Moreover, our solution offers important advantages: (i) a high degree of transparency and decoupling in all provided services by means of distributed interception techniques, and (ii) the direct deployment of existent Java Enterprise Edition (Java EE) applications and services with practically no changes on them. In summary, CloudSNAP makes it easy to deploy any Java EE web application into a P2P Cloud infrastructure, and immediately benefit from all of its inherent services at a minimal development and infrastructure cost.

Building a distributed AOP middleware for large scale systems

Building large scale applications is nowadays a complex challenge. Such complexity is determined by several factors like distributed application development, deployment or management, to name a few. Adaptive middleware plays an important role in achieving such task, and abstracts developers from the underlying layer issues like persistence, fault tolerance, and load balancing, among others. Distributed Aspect Oriented Programming (AOP) is a promising paradigm that offers new ideas in the middleware arena. Several models like remote pointcut or component-aspects for designing wide-area distributed systems exist in such setting, but none of them completely fulfill the scalability requirement. In this paper we present a distributed aspect middleware for large-scale systems mainly offering three contributions. Firstly we introduce a complete aspect remoting service with one-to-one and one-to-many abstractions. Secondly, we outline the construction of a distributed aspect meta-model that provides a novel distributed meta-pointcut mechanism to intercept remote services. Finally, the distributed aspect composition model that allows connection mechanisms in design, activation, and runtime phases. The last part of the paper includes a proof-of-concept, consisting of an adaptive Distributed Hash Table (DHT), which is a clear example of how a wide variety of distributed aspects on large-scale scenarios can be implemented by using our model.

DERMI: a decentralized peer-to-peer event-based object middleware

We present DERMI, a decentralized wide-area event-based object middleware built on top of a peer-to-peer substrate. Its main building block is the underlying publish/subscribe event notification system provided by the peer-to-peer layer. By using this methodology, innovative benefits like distributed interception, high performance synchronous/asynchronous one-to-one/one-to-many notifications and decentralized object location services are provided. Moreover, new programming abstractions (anycall and manycall) are introduced, which allow the programmer to make calls to groups of objects without taking care of which of them responds until a determinate condition is met. We believe that such middleware is a solid building block for future wide-area distributed component infrastructures.

Designing a distributed AOP runtime composition model

In this paper we present Damon, a new distributed aspect-oriented composition model. Our model mimics the CCM and is based on computational reflection, component-based design, and separation of concerns. Moreover, we benefit from the peer-to-peer substrate to implement these services in a decentralized and efficient way. Damon aims to provide new distributed concerns (i.e. replication) to existent or new applications transparently. It reduces the complexity of application development and allows runtime reconfiguring. The innovative contributions of our approach are composition capabilities in design, load-time and runtime phases, including the definition of distributed aspects and meta-aspects.

A Decoupled Architecture for Action-Oriented Coordination and Awareness Management in CSCL/W Frameworks

This paper introduces AORTA, a software architecture that provides object- level coordination and shared workspace awareness support to synchronous and distributed collaborative applications. AORTA is motivated by the need to enhance current coordination and awareness capabilities of existing software component frameworks for the domains of CSCL (Computer-Supported Collaborative Learning) and CSCW (Computer-Supported Cooperative Work). AORTA is characterized by the use of actions as its key abstraction instead of low-level events, the support for mutual influence between coordination and awareness, the use of coordination and awareness policies for supporting complex and dynamic collaboration scenarios, and the use of software design patterns in order to decouple coordination and awareness from the development of other aspects of CSCL/W applications. The paper motivates, justifies, and describes the main functional features of AORTA as well as its proposed software architecture. The paper also introduces a prototype of AORTA that adds coordination and awareness support to an existing groupware framework called ANTS. Finally it describes a CSCL application developed on top of both AORTA and ANTS that has been used to validate some of the presented contributions: application development is decoupled from coordination/awareness aspects, application development is facilitated by the use of action-orientation, and application coordination/awareness behavior can be configured and changed without modifying the application itself.

Damon: a decentralized aspect middleware built on top of a peer-to-peer overlay network

In this paper we present Damon, a decentralized wide-area runtime aspect middleware built on top of a structured peer-to-peer (p2p) substrate and a dynamic Aspect Oriented Programming (AOP) framework. By using this methodology, we provide innovative benefits like aspect persistence and discovery, a high performance one-to-one/one-to-many messaging system, reflective skills, and a decentralized aspect container. Furthermore, new pointcut abstractions (anypointcut, manypointcut and multipointcut) are introduced, which allow development of shared aspect functionalities in a transparent way. We believe that such middleware is a novel solution for allowing decentralized crosscutting concerns like fault-tolerance or load-balancing for distributed systems. This paper describes these ideas and it presents a use case of our middleware implementation.

Building wide-area collaborative applications on top of structured peer-to-peer overlays

In this paper we present p2pCM, a new distributed component-oriented model aimed to wide-area environments. Our model offers traditional component services like naming, activation, event notifications, and persistence on top of a structured peer-to-peer overlay. We benefit from the peer-to-peer substrate to implement these services in a decentralized and efficient way. The innovative contributions of our approach are a lightweight distributed container model, an adaptive component activation mechanism, which takes into account network locality, and a decentralized component location and deployment service. We focus on how the services provided by p2pCM can be used to implement essential computer-supported cooperative work (CSCW) services, like shared session management, awareness and coordination policies, and show a sample application which uses them. We believe that all of the features our component-oriented model provides can be very promising for the development of future wide-area distributed CSCW applications.