4,445 research outputs found
A Peer-to-Peer Middleware Framework for Resilient Persistent Programming
The persistent programming systems of the 1980s offered a programming model
that integrated computation and long-term storage. In these systems, reliable
applications could be engineered without requiring the programmer to write
translation code to manage the transfer of data to and from non-volatile
storage. More importantly, it simplified the programmer's conceptual model of
an application, and avoided the many coherency problems that result from
multiple cached copies of the same information. Although technically
innovative, persistent languages were not widely adopted, perhaps due in part
to their closed-world model. Each persistent store was located on a single
host, and there were no flexible mechanisms for communication or transfer of
data between separate stores. Here we re-open the work on persistence and
combine it with modern peer-to-peer techniques in order to provide support for
orthogonal persistence in resilient and potentially long-running distributed
applications. Our vision is of an infrastructure within which an application
can be developed and distributed with minimal modification, whereupon the
application becomes resilient to certain failure modes. If a node, or the
connection to it, fails during execution of the application, the objects are
re-instantiated from distributed replicas, without their reference holders
being aware of the failure. Furthermore, we believe that this can be achieved
within a spectrum of application programmer intervention, ranging from minimal
to totally prescriptive, as desired. The same mechanisms encompass an
orthogonally persistent programming model. We outline our approach to
implementing this vision, and describe current progress.Comment: Submitted to EuroSys 200
Transparent Persistence with Java Data Objects
Flexible and performant Persistency Service is a necessary component of any
HEP Software Framework. The building of a modular, non-intrusive and performant
persistency component have been shown to be very difficult task. In the past,
it was very often necessary to sacrifice modularity to achieve acceptable
performance. This resulted in the strong dependency of the overall Frameworks
on their Persistency subsystems.
Recent development in software technology has made possible to build a
Persistency Service which can be transparently used from other Frameworks. Such
Service doesn't force a strong architectural constraints on the overall
Framework Architecture, while satisfying high performance requirements. Java
Data Object standard (JDO) has been already implemented for almost all major
databases. It provides truly transparent persistency for any Java object (both
internal and external). Objects in other languages can be handled via
transparent proxies. Being only a thin layer on top of a used database, JDO
doesn't introduce any significant performance degradation. Also Aspect-Oriented
Programming (AOP) makes possible to treat persistency as an orthogonal Aspect
of the Application Framework, without polluting it with persistence-specific
concepts.
All these techniques have been developed primarily (or only) for the Java
environment. It is, however, possible to interface them transparently to
Frameworks built in other languages, like for example C++.
Fully functional prototypes of flexible and non-intrusive persistency modules
have been build for several other packages, as for example FreeHEP AIDA and LCG
Pool AttributeSet (package Indicium).Comment: Talk from the 2003 Computing in High Energy and Nuclear Physics
(CHEP03), La Jolla, Ca, USA, March 2003. PSN TUKT00
Early aspects: aspect-oriented requirements engineering and architecture design
This paper reports on the third Early Aspects: Aspect-Oriented Requirements Engineering and Architecture Design Workshop, which has been held in Lancaster, UK, on March 21, 2004. The workshop included a presentation session and working sessions in which the particular topics on early aspects were discussed. The primary goal of the workshop was to focus on challenges to defining methodical software development processes for aspects from early on in the software life cycle and explore the potential of proposed methods and techniques to scale up to industrial applications
Aspect-oriented interaction in multi-organisational web-based systems
Separation of concerns has been presented as a promising tool to tackle the design of complex systems in which
cross-cutting properties that do not fit into the scope of a class must be satisfied. Unfortunately, current proposals
assume that objects interact by means of object-oriented method calls, which implies that they embed interactions with
others into their functional code. This makes them dependent on this interaction model, and makes it difficult to reuse
them in a context in which another interaction model is more suited, e.g., tuple spaces, multiparty meetings, ports, and
so forth. In this paper, we show that functionality can be described separately from the interaction model used, which
helps enhance reusability of functional code and coordination patterns. Our proposal is innovative in that it is the first
that achieves a clear separation between functionality and interaction in an aspect-oriented manner. In order to show
that it is feasible, we adapted the multiparty interaction model to the context of multiorganisational web-based systems
and developed a class framework to build business objects whose performance rates comparably to handmade implementations;
the development time, however, decreases significantly.Comisión Interministerial de Ciencia y Tecnología TIC2000-1106-C02-0
A Generic Storage API
We present a generic API suitable for provision of highly generic storage
facilities that can be tailored to produce various individually customised
storage infrastructures. The paper identifies a candidate set of minimal
storage system building blocks, which are sufficiently simple to avoid
encapsulating policy where it cannot be customised by applications, and
composable to build highly flexible storage architectures. Four main generic
components are defined: the store, the namer, the caster and the interpreter.
It is hypothesised that these are sufficiently general that they could act as
building blocks for any information storage and retrieval system. The essential
characteristics of each are defined by an interface, which may be implemented
by multiple implementing classes.Comment: Submitted to ACSC 200
Scalability of broadcast performance in wireless network-on-chip
Networks-on-Chip (NoCs) are currently the paradigm of choice to interconnect the cores of a chip multiprocessor. However, conventional NoCs may not suffice to fulfill the on-chip communication requirements of processors with hundreds or thousands of cores. The main reason is that the performance of such networks drops as the number of cores grows, especially in the presence of multicast and broadcast traffic. This not only limits the scalability of current multiprocessor architectures, but also sets a performance wall that prevents the development of architectures that generate moderate-to-high levels of multicast. In this paper, a Wireless Network-on-Chip (WNoC) where all cores share a single broadband channel is presented. Such design is conceived to provide low latency and ordered delivery for multicast/broadcast traffic, in an attempt to complement a wireline NoC that will transport the rest of communication flows. To assess the feasibility of this approach, the network performance of WNoC is analyzed as a function of the system size and the channel capacity, and then compared to that of wireline NoCs with embedded multicast support. Based on this evaluation, preliminary results on the potential performance of the proposed hybrid scheme are provided, together with guidelines for the design of MAC protocols for WNoC.Peer ReviewedPostprint (published version
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