Context-aware process networks

Abstract

In industry, embedded systems for stream-based 1: IntroductionEmbedded systems for stream-based processing (video, audio) are often found in consumer electronics applications. They need to operate flawlessly and hence much effort is spent in the design and verification of these applications. A popular model of computation for these applications is the Kahn process network model (KPN). The Kahn model is compositional and allows asynchronous coupling of the processing nodes in a network. An important advantage of Kahn networks is that verification of the concurrency properties of a network can be done without knowing the internal processing details of the nodes, provided that the port scans of a node are done in prescribed way.Apart from handling streams, embedded systems need to be able to handle events. A simple example of an event is a user pushing a button. Incorporating events in Kahn networks is awkward, often events are turned into a stream, e.g., a coherent stream of "on" and "off" events.However, modern embedded systems require more complex forms of handling events. Events, typically, represent changes in the context of the embedded system. The button example represents a discrete change in the mode of the operation of the embedded system, but changes of context can also be more gradual. An example of a gradual change is an increase or decrease in transmission rate of a system due to external causes (e.g. a wireless link).Proper system integration in embedded systems relies on the availability of determinate -and thus compositional -components in order to optimise functionality, performance, and resource utilisation. Unless one effectively can capture (isolate) their context dependent parts, any composition of indeterminate components yields a non-deterministic system. Although examples of working non-deterministic systems are ubiquitous, the current practice is not satisfactory.Having a proper Model of Computation (MoC) greatly improves the effectiveness of the system integration phase in developing context-aware embedded systems. Basically there exist two approaches. One either develops a MoC based on discrete-event processing or a MoC based on

A Novel Process Network Model for Interacting Context-Aware Web Services

“…In order to facilitate asynchronous coordination, H. van Dijk et al [21] extended the Kahn model of computations to Context-aware Process Network (CAPN) with a simple indeterminate construct, i.e. a unidirectional non-blocking register link (REG), which has destructive and replicative behavior.…”

“…Its design idea comes from a dataflow and channel based model of cooperative computation, i.e. Context-aware Process Network [20], [21]. Next, we briefly introduce the model of context-aware process network.…”

“…But the behavior semantic of a register link and a FIFO buffered channel is very different. In [21], the behavior of a register link is defined as follows.…”

“…A novel approach is proposed to model dynamic behaviors of interacting context-aware web services, aiming to effectively process and take advantage of contexts and realize behavior adaptation of web services and further to facilitate the development of context-aware application of web services. We present an interaction model of context-aware web services based on a formal model, Context-aware Process Network (CAPN) [20], [21], which is a dataflow and channel based model of cooperative computation. CAPN is extended to context-aware web service network by adding a kind of additional sensor processes which is used to catch contextual data from external environment.…”

Towards Multi-application Workload Modeling in Sesame for System-Level Design Space Exploration

“…Several researchers have proposed extensions to the KPN model of computation to resolve this [7][8][9]. Our two multiapplication workload modeling techniques support the modeling of reactive behavior between applications, which could each be specified as a regular KPN.…”