Stefan G. Hild

Generation of Java Beans to access XML data

Describes a technique to automatically generate a set of Java Beans accessing data encoded according to some XML document type definition (DTD). This technique does not support any XML-based markup but can be applied to a sufficiently large class of XML-compliant markup language to make the approach of practical interest. The generated Java Beans can be used as data accessors to deliver dynamic or static content for markup pages used in an Internet-style application. We briefly describe the technology environment into which our solution is embedded and provide an in-depth treatment of the mapping from XML data on to a flattened relational data model, including an example to illustrate our approach.

Controlled availability of pervasive Web services

The increasing use of computers to manage everyday business poses problems for workers when they are away from their home environment. There are two key problems: . How can a mobile worker share a limited part of their home environment with colleagues in a foreign environment while maintaining its security? . How can a mobile worker identify and interact with local services available in a foreign environment? This paper describes a scheme for controlling access to pervasive Web services together with a tangible user interface for their presentation.

Neighbor Turn Taking MAC - A Loosely Scheduled Access Protocol for Wireless Networks

In this paper a new approach to medium access in a wireless ad hoc network based on neighbor knowledge and their activity is presented. Nodes take turns to transmit based on their neighbors and their transmissions, which reduces the collision probability and avoids the latency due to backoff (and exponential backoff) experienced in random access protocols. The scheme uses features from 802.11 DCF MAC and adopts a loose scheduling approach which is distributed. The performance of this scheme is compared with 802.11 DCF MAC as this is the more popular random access MAC for wireless ad hoc networks.

A Turn Taking Medium Access Protocol for Wireless Ad Hoc Networks

MAC protocols for wireless networks can be broadly categorized as scheduled or random access protocols. Random access protocols continue to be popular for wireless ad hoc networks, because of their robustness and ease of implementation over multihop scenarios. However under heavy traffic load conditions the performance of random access protocol deteriorates and fairness becomes a serious issue. In this paper, we propose a MAC scheme, where nodes take turns to access the media based on local neighbor knowledge and their transmission activity that reduces the impact of random access and ensuing contention resolution leading to exponential backoff and high delays. In the proposed turn taking mechanism the nodes self-schedule in a distributed manner. Through simulations the performance of the neighbor knowledge based turn taking MAC was compared with IEEE 802.11 CSMA/CA (carrier sense multiple access with collision avoidance).

Quests in a tetherless world

Wireless research activities span a wide range of disciplines: communications engineering, software engineering and computer sciences covering all aspects of communication and services including client platforms and server deployment, network protocols and infrastructure, service development and deployment and so on. Our research group at the IBM T. J. Watson Research Center has initiated a number of research activities covering several aspects of the wireless research. In this paper, we highlight our work on the Bluetooth™ wireless technology and the BlueDrekar™ software stack, the WebSplitter middleware for content distribution, and we will share our vision for interconnecting trillion devices. Copyright