Gert Brettlecker

DelosDLMS - the integrated DELOS digital library management system

DelosDLMS is a prototype of a next-generation Digital Library (DL) management system. It is realized by combining various specialized DL functionalities provided by partners of the DELOS network of excellence. Currently, DelosDLMS combines text and audio-visual searching, offers new information visualization and relevance feedback tools, provides novel interfaces, allows retrieved information to be annotated and processed, integrates and processes sensor data streams, and finally, from a systems engineering point of view, is easily configured and adapted while being reliable and scalable. The prototype is based on the OSIRIS/ISIS platform, a middleware environment developed by ETH Zurich and now being extended at the University of Basel.

Hyperdatabases for peer-to-peer data stream processing

New sensor technologies, powerful mobile devices, and wireless communication standards strongly proliferate ubiquitous and pervasive computing. This is particularly true for healthcare applications. Modern non-invasive unobtrusive sensors enable sophisticated monitoring of the human body. As a result of this monitoring a growing amount of elderly people suffering from chronic diseases will benefit from an enhanced quality of life and improved treatment. Healthcare applications process a vast amount of continuously generated data, this has become a serious challenge. Data stream management addresses this problem in general. However, healthcare applications have additional requirements, e.g., flexibility and reliability. As a consequence, we propose the combination of a sophisticated information infrastructure, called hyperdatabase, and data stream management. Hyperdatabases already allow for reliable process management in a peer-to-peer fashion. In this paper, we elaborate the close relation between distributed process management and data stream management. Further, we show that data stream processing can significantly benefit from an infrastructure for reliable process management. We present the architecture of our prototype infrastructure that supports processing of continuous data streams with a high degree of flexibility and reliability.

ISIS and OSIRIS: a process-based digital library application on top of a distributed process support middleware

Future information spaces such as Digital Libraries require new infrastructures that allow to use and to combine various kinds of functions in a unified and reliable way. The paradigm of service-oriented architectures (SoA) allows providing application functionality in a modular, self-contained way and to individually combine this functionality. The paper presents the ISIS/OSIRIS system which consists of a generic infrastructure for the reliable execution of distributed service-based applications (OSIRIS) and a set of dedicated Digital Library application services (ISIS) that provide, among others, content-based search in multimedia collections.

Efficient and coordinated checkpointing for reliable distributed data stream management

Data Stream Management (DSM) addresses the continuous processing of sensor data. DSM requires the combination of stream operators, which may run on different distributed devices, into stream processes. Due to the recent advantages in sensor technologies and wireless communication, DSM is increasingly gaining importance in various application domains. Especially in healthcare, the continuous monitoring of patients at home (telemonitoring) can significantly benefit from DSM. A vital requirement in telemonitoring is however that DSM provides a high degree of reliability. In this paper, we present a novel approach to efficient and coordinated stream operator checkpointing supporting reliable DSM while maintaining the high result quality needed for healthcare applications. Furthermore, we present evaluation results of our checkpointing approach implemented within our process and data stream management infrastructure OSIRIS-SE. OSIRIS-SE supports flexible failure handling and efficient and coordinated checkpointing by means of consistent operator migration. This ensures complete and consistent continuous data stream processing even in the case of failures.

Reliable distributed data stream management in mobile environments

The proliferation of sensor technology, especially in the context of embedded systems, has brought forward novel types of applications that make use of streams of continuously generated sensor data. Many applications like telemonitoring in healthcare or roadside traffic monitoring and control particularly require data stream management (DSM) to be provided in a distributed, yet reliable way. This is even more important when DSM applications are deployed in a failure-prone distributed setting including resource-limited mobile devices, for instance in applications which aim at remotely monitoring mobile patients. In this paper, we introduce a model for distributed and reliable DSM. The contribution of this paper is threefold. First, in analogy to the SQL isolation levels, we define levels of reliability and describe necessary consistency constraints for distributed DSM that specify the tolerated loss, delay, or re-ordering of data stream elements, respectively. Second, we use this model to design and analyze an algorithm for reliable distributed DSM, namely efficient coordinated operator checkpointing (ECOC). We show that ECOC provides lossless and delay-limited reliable data stream management and thus can be used in critical application domains such as healthcare, where the loss of data stream elements cannot be tolerated. Third, we present detailed performance evaluations of the ECOC algorithm running on mobile, resource-limited devices. In particular, we can show that ECOC provides a high level of reliability while, at the same time, featuring good performance characteristics with moderate resource consumption.

Technology in Healthcare

The term “e-health” was born in 1999 to represent the provision of healthcare services through Internet [11], and was heavily promoted by the industry and commercial sectors in order to take advantage of the power and excitement that other “e-” terms like e-commerce and e-business had recently created in society [8, 6]. Nevertheless, the academic world would soon adopt it, leading to what some authors call “the death of telemedicine” [14].

The OSIRIS-SE (stream-enabled) infrastructure for reliable data stream management on mobile devices

The proliferation of software and hardware sensors which continuously create large amounts of data has significantly facilitated novel types of applications such as healthcare telemonitoring or roadside traffic management. All these applications demand new mechanisms for online processing and analysis of relevant data coming from multiple data streams. Especially telemonitoring applications in healthcare require a high degree of reliability and must be able to be deployed in a distributed environment. We present OSIRIS-SE, an infrastructure for reliable data stream management in a failure-prone distributed setting including resource-limited mobile devices. OSIRIS-SE supports the combination of different data stream operators into stream processes and offers efficient coordinated operator check pointing for the execution of these stream processes. In order to support mobile devices, OSIRIS-SE is able to deal with multiple failures, offers fine-grained reliability at operator level, and supports decentralized stream process orchestration in a peer-to-peer fashion. Moreover, OSIRIS-SE is fully implemented in Java and thus can be run on different platforms. The demo shows the reliable execution of stream processes in a health monitoring application including a wearable ECG sensor, a Bluetooth enabled blood pressure sensor, and a web cam as data sources. Operators are hosted at mobile devices (PDAs, smart phones) of a patient and at a laptop computer which also acts as base station. An important feature of the demo is to show that sensor data can losslessly be processed by seamlessly migrating stream processing to other devices in the network even in case of multiple failures.

Integration of reliable sensor data stream management into digital libraries

Data Stream Management (DSM) addresses the continuous processing of sensor data. DSM requires the combination of stream operators, which may run on different distributed devices, into stream processes. Due to the recent advantages in sensor technologies and wireless communication, the amount of information generated by DSM will increase significantly. In order to efficiently deal with this streaming information, Digital Library (DL) systems have to merge with DSM systems. Especially in healthcare, the continuous monitoring of patients at home (telemonitoring) will generate a significant amount of information stored in an e-health digital library (electronic patient record). In order to stream-enable DL systems, we present an integrated data stream management and Digital Library infrastructure in this work. A vital requirement for healthcare applications is however that this infrastructure provides a high degree of reliability. In this paper, we present novel approaches to reliable DSM within a DL infrastructure. In particular, we propose information filtering operators, a declarative query engine called MXQuery, and efficient operator checkpointing to maintain high result quality of DSM. Furthermore, we present a demonstrator implementation of the integrated DSM and DL infrastructure, called OSIRIS-SE. OSIRIS-SE supports flexible and efficient failure handling to ensures complete and consistent continuous data stream processing and execution of DL processes even in the case of multiple failures.

DelosDLMS A Next-generation Digital Library Management System

DelosDLMS is a prototype of a next-generation digital library (DL) management system. Its core is a highly scalable and reliable middleware environment (OSIRIS) that allows combining and invoking distributed DL services. In addition to the ISIS Digital Library services that support content-based retrieval in multimedia collections, DelosDLMS has integrated a rich set of DL functionality from various partners within the DELOS network of excellence. These services include text and audio-visual searching, new information visualization and relevance feedback tools and novel interfaces. Moreover, DelosDLM allows retrieved information to be annotated and processed and also integrates reliable processing of sensor data streams.