4,158 research outputs found
Timed Automata Semantics for Analyzing Creol
We give a real-time semantics for the concurrent, object-oriented modeling
language Creol, by mapping Creol processes to a network of timed automata. We
can use our semantics to verify real time properties of Creol objects, in
particular to see whether processes can be scheduled correctly and meet their
end-to-end deadlines. Real-time Creol can be useful for analyzing, for
instance, abstract models of multi-core embedded systems. We show how analysis
can be done in Uppaal.Comment: In Proceedings FOCLASA 2010, arXiv:1007.499
Scheduling of Early Quantum Tasks
An Early Quantum Task (EQT) is a Quantum EDF task that has shrunk its first period into one quantum time slot. Its purpose is to be executed as soon as possible, without causing deadline overflow of other tasks. We will derive the conditions under which an EQT can be admitted and can have an immediate start. The advantage of scheduling EQTs is shown by its use in a buffered multi-media server. The EQT is associated with a multimedia stream and it will use its first invocation to fill the buffer, such that a client can start receiving data immediately
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
Multi-Threaded Actors
In this paper we introduce a new programming model of multi-threaded actors
which feature the parallel processing of their messages. In this model an actor
consists of a group of active objects which share a message queue. We provide a
formal operational semantics, and a description of a Java-based implementation
for the basic programming abstractions describing multi-threaded actors.
Finally, we evaluate our proposal by means of an example application.Comment: In Proceedings ICE 2016, arXiv:1608.0313
Autonomous Agents for Business Process Management
Traditional approaches to managing business processes are often inadequate for large-scale organisation-wide, dynamic settings. However, since Internet and Intranet technologies have become widespread, an increasing number of business processes exhibit these properties. Therefore, a new approach is needed. To this end, we describe the motivation, conceptualization, design, and implementation of a novel agent-based business process management system. The key advance of our system is that responsibility for enacting various components of the business process is delegated to a number of autonomous problem solving agents. To enact their role, these agents typically interact and negotiate with other agents in order to coordinate their actions and to buy in the services they require. This approach leads to a system that is significantly more agile and robust than its traditional counterparts. To help demonstrate these benefits, a companion paper describes the application of our system to a real-world problem faced by British Telecom
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