4,009 research outputs found
Session Types with Runtime Adaptation: Overview and Examples
In recent work, we have developed a session types discipline for a calculus
that features the usual constructs for session establishment and communication,
but also two novel constructs that enable communicating processes to be
stopped, duplicated, or discarded at runtime. The aim is to understand whether
known techniques for the static analysis of structured communications scale up
to the challenging context of context-aware, adaptable distributed systems, in
which disciplined interaction and runtime adaptation are intertwined concerns.
In this short note, we summarize the main features of our session-typed
framework with runtime adaptation, and recall its basic correctness properties.
We illustrate our framework by means of examples. In particular, we present a
session representation of supervision trees, a mechanism for enforcing
fault-tolerant applications in the Erlang language.Comment: In Proceedings PLACES 2013, arXiv:1312.221
Proving Properties of Rich Internet Applications
We introduce application layer specifications, which allow us to reason about
the state and transactions of rich Internet applications. We define variants of
the state/event based logic UCTL* along with two example applications to
demonstrate this approach, and then look at a distributed, rich Internet
application, proving properties about the information it stores and
disseminates. Our approach enables us to justify proofs about abstract
properties that are preserved in the face of concurrent, networked inputs by
proofs about concrete properties in an Internet setting. We conclude that our
approach makes it possible to reason about the programs and protocols that
comprise the Internet's application layer with reliability and generality.Comment: In Proceedings WWV 2013, arXiv:1308.026
The Clarens web services architecture
Clarens is a uniquely flexible web services infrastructure providing a
unified access protocol to a diverse set of functions useful to the HEP
community. It uses the standard HTTP protocol combined with application layer,
certificate based authentication to provide single sign-on to individuals,
organizations and hosts, with fine-grained access control to services, files
and virtual organization (VO) management. This contribution describes the
server functionality, while client applications are described in a subsequent
talk.Comment: Talk from the 2003 Computing in High Energy and Nuclear Physics
(CHEP03), La Jolla, Ca, USA, March 2003, 6 pages, LaTeX, 4 figures, PSN
MONT00
Encapsulation and Aggregation
A notion of object ownership is introduced as a solution to difficult problems of specifying and reasoning about complex linked structures and of modeling aggregates (composit objects). Syntax and semantics are provided for extending Eiffel with language support for object ownership annotation and checking. The ideas also apply to other OOPLs such as C++
Theory and Practice of Transactional Method Caching
Nowadays, tiered architectures are widely accepted for constructing large
scale information systems. In this context application servers often form the
bottleneck for a system's efficiency. An application server exposes an object
oriented interface consisting of set of methods which are accessed by
potentially remote clients. The idea of method caching is to store results of
read-only method invocations with respect to the application server's interface
on the client side. If the client invokes the same method with the same
arguments again, the corresponding result can be taken from the cache without
contacting the server. It has been shown that this approach can considerably
improve a real world system's efficiency.
This paper extends the concept of method caching by addressing the case where
clients wrap related method invocations in ACID transactions. Demarcating
sequences of method calls in this way is supported by many important
application server standards. In this context the paper presents an
architecture, a theory and an efficient protocol for maintaining full
transactional consistency and in particular serializability when using a method
cache on the client side. In order to create a protocol for scheduling cached
method results, the paper extends a classical transaction formalism. Based on
this extension, a recovery protocol and an optimistic serializability protocol
are derived. The latter one differs from traditional transactional cache
protocols in many essential ways. An efficiency experiment validates the
approach: Using the cache a system's performance and scalability are
considerably improved
World-wide web: The information universe
The World-Wide Web (W 3) initiative is a practical project to bring a global information universe into existence using available technology. This article describes the aims, data model, and protocols needed to implement the âwebâ, and compares them with various contemporary systems. The Dream Pick up your pen, mouse or favorite pointing device and press it on a reference in this document- perhaps to the authorâs name, or organization, or some related work. Suppose you are directly presented with the background material- other papers, the authorâs coordinates, the organizationâs address and its entire telephone directory. Suppose each of these documents has the same property of being linked to other original documents all over the world. You would have at your fingertips all you need to know about electronic publishing, high-energy physics or for that matter Asian culture. If you are reading this article on paper, you can only dream, but read on
Resource design in constrained networks for network lifetime increase
As constrained "things" become increasingly integrated with the Internet and accessible for interactive communication, energy efficient ways to collect, aggregate, and share data over such constrained networks are needed. In this paper, we propose the use of constrained RESTful environments interfaces to build resource collections having a network lifetime increase in mind. More specifically, based on existing atomic resources, collections are created/designed to become available as new resources, which can be observed. Such resource design should not only match client's interests, but also increase network lifetime as much as possible. For this to happen, energy consumption should be balanced/fair among nodes so that node depletion is delayed. When compared with previous approaches, results show that energy efficiency and network lifetime can be increased while reducing control/registration messages, which are used to set up or change observations
Perfect periodic scheduling for binary tree routing in wireless networks
In this paper we tackle the problem of coordinating transmission of data across a Wireless Mesh Network. The single task nature of mesh nodes imposes simultaneous activation of adjacent nodes during transmission. This makes the coordinated scheduling of local mesh node traffic with forwarded traffic across the access network to the Internet via the Gateway notoriously difficult. Moreover, with packet data the nature of the coordinated transmission schedule has a big impact upon both the data throughput and energy consumption. Perfect Periodic Scheduling, in which each demand is itself serviced periodically, provides a robust solution. In this paper we explore the properties of Perfect Periodic Schedules with modulo arithmetic using the Chinese Remainder Theorem. We provide a polynomial time, optimisation algorithm, when the access network routing tree has a chain or binary tree structure. Results demonstrate that energy savings and high throughput can be achieved simultaneously. The methodology is generalisable
- âŠ