Alexander Paar

An ontology-based framework for dynamic resource management in ubiquitous computing environments

Ubiquitous computing applications are supported by sophisticated middleware components enabling dynamic discovery, invocation and management of resources, as well as reasoning in cases of uncertainty. This paper advocates semantic Web technologies as primary vehicles to achieve dynamic management of resources in ubiquitous computing infrastructures and services. We introduce a framework for implementing ubiquitous computing services comprising a large number of sensors and perceptive interfaces, emphasizing the role of knowledge bases for dynamic registration and invocation of resources. We present the use of ontology-based mechanisms for controlling sensors and actuators. Moreover, we describe the implementation of a knowledge base server that can leverage different ontology management systems, while also exposing a host to different client access interfaces. The introduced framework has been exploited in implementing real prototype ubiquitous computing services, which we also outline in the paper.

Improving the operation autonomy of SIMD processing elements by using guarded instructions and pseudo branches

This paper presents a novel method for improving the operation autonomy of the processing elements (PE) of SIMD-like machines. By combining guarded instructions and pseudo branches it is possible to achieve higher operation autonomy and higher instruction level parallelism than in previous SIMD/ASIMD architectures. The paper shows that it is feasible to avoid most branches and it is also possible to emulate conditional execution on the processing elements, either by using guarded instructions or by using pseudo branches, thus avoiding unnecessary intervention by the array control unit in data-dependant computations. Pseudo branches are used when it is not possible to use guarded instructions. Additionally, they also support the implementation of complex nested if-then-else constructs, improving the execution of irregular dataparallel applications. The paper also shows that the simplicity of the method allows it to be implemented both in fine-grain and coarse-grain SIMD/ASIMD architectures because it does not require significant additional silicon area. Finally, it is shown that pseudo branches can be used to control the power saving of those processing elements that have instructions nullified.

The BTRC Bluetooth remote control system

AbstractEmerging radio technologies like WLAN and Bluetooth enable electronic devices of any kind to communicate with one another. A simple and easy to implement application layer protocol called BTRC protocol was developed allowing devices to exchange data of any kind and format over different protocols like TCP/IP or Bluetooth. Based upon this protocol a universal remote control system was implemented. Software applications simulating cellular phones and personal digital assistants (PDA) were developed as remote control devices. BTRC server devices send their graphical XML based user interface to the remote control. In this way, the use of household devices is simplified significantly.

Semantic software engineering approaches for automatic service lookup and integration

Using Web services today has two major drawbacks: firstly, a programmer has to guess the appropriate service operations by interpreting syntactic operation names provided by WSDL descriptions, and secondly, the decision which services to use is fixed at design time. Using ontological descriptions, we automate the lookup of services. The lookup occurs at runtime, supporting location aware selection and the choice of more relevant or alternate services. We use Semantic Web techniques such as DAML-OIL to avoid the exact match between services invocations and make both service lookup and invocation independent of the strict syntactic Web services description.

A Formally Specified Ontology Management API as a Registry for Ubiquitous Computing Systems

Recently, several standards have emerged for ontology markup languages that can be used to formalize all kinds of knowledge. However, there are no widely accepted standards yet that define APIs to manage ontological data. Processing ontological information still suffers from the heterogeneity imposed by the plethora of available ontology management systems. Moreover, ubiquitous computing environments usually comprise software components written in a variety of different programming languages, which makes it even more difficult to establish a common ontology management API with programming language agnostic semantics. We implemented an ontological Knowledge Base Server, which can expose the functionality of arbitrary off-the-shelf ontology management systems via a formally specified and well defined API. A case study was carried out in order to demonstrate the feasibility of our approach to use an ontological Knowledge Base Server as a registry for ubiquitous computing systems.

A Novel Predication Scheme for a SIMD System-on-Chip

This paper presents a novel predication scheme that was applied to a SIMD system-on-chip. This approach was devised by improving and combining the unrestricted predication model and the guarded execution model. It is shown that significant execution autonomy is added to the SIMD processing elements and that the code size is reduced considerably. Finally, the implemented predication scheme is compared with predication schemes of general purpose processors, and it is shown that it enables more efficient if-conversion compilations than previous architectures.

Semantic software engineering tools

Recently, the paradigm of software engineering has shifted significantly to service orientation based on Web services. Web Services Description Language interface specifications provide sufficient information to physically access a service. However, these interface descriptions are semantically bleak. This work introduces a number of tools, which were developed to augment strict syntactic service descriptions with semantic information in order to elucidate the meaning of processed data and provided functionality. Semantic Web technologies such as DAML+OIL were supplemented with natural language support for usability improvements both at design- and at runtime.

A Bluetooth Remote Control System

Emerging radio technologies like WLAN and Bluetooth enable electronic devices of any kind to communicate with one another. A simple and easy to implement application layer protocol called BTRC protocol was developed allowing devices to exchange data of any kind and format over different protocols like TCP/IP or Bluetooth. Based upon this protocol a universal remote control system was implemented. Software applications simulating cellular phones and personal digital assistants (PDA) were developed as remote control devices. BTRC server devices send their graphical XML based user interface to the remote control. This way the use of devices is simplified significantly.

Programming Language Inherent Support for Constrained XML Schema Definition Data Types and OWL DL

Recently, the Web Ontology Language (OWL) and XML schema definition (XSD) have become ever more important when it comes to conceptualize knowledge and to define programming language independent type systems. However, writing software that operates on ontological data and on XML instance documents still suffers from a lack of compile time support for OWL and XSD. Especially, obeying lexical- and value space constraints that may be imposed on XSD simple data types and preserving the consistency of assertional ontological knowledge is still error prone and laborious. Validating XML instance documents and checking the consistency of ontological knowledge bases according to given XML schema definitions and ontological terminologies, respectively, requires significant amounts of code. This paper presents novel compile time- and code generation features, which were implemented as an extension of the C# programming language. Zhi# provides compile time-and runtime support for constrained XML schema definition simple data types and it guarantees terminological validity for modifications of assertional ontological data

A novel method for improving the operation autonomy of SIMD processing elements

A novel method for improving the operation autonomy of the processing elements (PE) of SIMD-like machines is presented and discussed in this paper. The paper shows that it is feasible to avoid most branches and it is also possible to emulate nested if-then-else sentences on the processing elements by combining guarded instructions and pseudo branches. This prevents unnecessary intervention by the array control unit in many data-dependant computations, particularly those with short branch sections. The paper also shows that the simplicity of the method allows it to be implemented both in fine-grain and coarse-grain SIMD/ASIMD architectures because it does not require significant additional silicon area. Finally, it is shown that pseudo branches can be used to control the power saving of those processing elements that have instructions nullified.