Annika Hinze

Event-based applications and enabling technologies

Event processing has become the paradigm of choice in many monitoring and reactive applications. However, the understanding of events, their composition and level of abstraction, the style of processing and the quality of service requirements vary drastically across application domains. We introduce the basic notions of event processing to create a common understanding, present the enabling technologies that are used for the implementation of event-based systems, survey a wide range of applications identifying their main features, and discuss open research issues.

Location- and Time-Based Information Delivery in Tourism

Today’s mobile devices allow end users to get information related to a particular domain based on their current location, such as the fastest route to the nearest drugstore. However, in such Location-Based Services (LBS), richer and more targeted information is desirable. In many applications, end users would like to be notified about relevant events or places to visit in the near future according to their profile. They also do not wish to get the same information many times unless they explicitly ask for it. In this paper, we describe our system, TIP (Tourism Information Provider), which delivers various types of information to mobile devices based on location, time, profile of end users, and their “history”, i.e., their accumulated knowledge. The system hinges on a hierarchical semantic geospatial model as well as on an Event Notification System (ENS).

Storing RDF as a graph

RDF is the first W3C standard for enriching information resources of the Web with detailed meta data. The semantics of RDF data is defined using a RDF schema. The most expressive language for querying RDF is RQL, which enables querying of semantics. In order to support RQL, a RDF storage system has to map the RDF graph model onto its storage structure. Several storage systems for RDF data have been developed, which store the RDF data as triples in a relational database. To evaluate an RQL query on those triple structures, the graph model has to be rebuilt from the triples. We present a new approach to store RDF data as a graph in a object-oriented database. Our approach avoids the costly rebuilding of the graph and efficiently queries the storage structure directly. The advantages of our approach have been shown by performance test on our prototype implementation OO-Store.

Hermes: a notification service for digital libraries

The high publication rate of scholarly material makes searching and br owsing an inconvenient way to keep oneself up-to-date. Instead of being the active part in information access, researchers want to be notified whenever a new paper in ones research area is published. While more and more publishing houses or portal sites offer notification services this approach has several disadvantages. We introduce the Hermes alerting service, a service that integrates a variety of different information providers making their heterogeneity transparent for the users. Hermes offers sophisticated filtering capabilities preventing the user from drowning in a flood of irrelevant information. From the users point of view it integrates the providers into a single source. Its simple provider interface makes it easy for publishers to join the service and thus reaching the potential readers directly. This paper presents the architecture of the Hermes service and discusses the issues of heterogeneity of information sources. Furthermore, we discuss the benefits and disadvantages of message-oriented middleware for implementing such a service for digital libraries.

Efficient filtering of composite events

Event Notification Services (ENS) are used in various applications such as remote monitoring and control, stock tickers, traffic control, or facility management. The performance issues of the filtering of primitive events has been widely studied. However, for a growing number of applications, the rapid notification about the occurrence of composite events is an important issue. Currently, the detection of composite events requires a second filtering step after the identification of the primitive components. In this paper, we propose a single-step method for the filtering of composite events. The method has been implemented and tested within our ENS prototype CompAS. Using our method, the filter response time for composite events is significantly reduced. Additionally, the overall performance of the event filtering has been improved.

Book selection behavior in the physical library: implications for ebook collections

Little is known about how readers select books, whether they be print books or ebooks. In this paper we present a study of how people select physical books from academic library shelves. We use the insights gained into book selection behavior to make suggestions for the design of ebook-based digital libraries in order to better facilitate book selection behavior.

TIP: personalizing information delivery in a tourist information system.

Advanced tourist information systems should offer more than relatively static information about sights and places. Instead, semantically rich information about sights should be delivered to the mobile users. Furthermore, tourists should not be overwhelmed by a stream of superfluous data that are unrelated to their interest, location, and knowledge of a place. Personalization of the information delivery to each traveler, together with their travel history, is therefore crucial. This article presents the major design issues of the personalized Tourist Information Provider (TIP). TIP is a combination of an event-based system (EBS) and a location-based service (LBS) applied to a mobile environment. We discuss the lessons learned from developing its kernel using a semantic network of sight-related information and considering the travelers’ interest and travel route, with emphasis on modeling decisions and their impact on the final system.

A parameterized algebra for event notification services

Event notification services are used in various applications such as digital libraries, stock tickers, traffic control, or facility management. However to our knowledge, a common semantics of events in event notification services has not been defined so far. We propose a parameterized event algebra which describes the semantics of composite events for event notification systems. The parameters serve as a basis for flexible handling of duplicates in both primitive and composite events.

Principles and Applications of Distributed Event-Based Systems

Literary Education and Digital Learning: Methods and Technologies for Humanities Studies provides insight into the most relevant issues in literary education and digital learning. This unique reference fills a gap in literature teaching, covering literary aspects both from educational and research perspectives.

A generic alerting service for digital libraries

Users of modern digital libraries (DLs) can keep themselves up-to-date by searching and browsing their favorite collections, or more conveniently by resorting to an alerting service. The alerting service notifies its clients about new or changed documents. Proprietary and mediating alerting services fail to fluidly integrate information from differing collections. So far, no sophisticated service has been proposed that is integrated with the digital library software and covers heterogeneous and distributed collections. This paper analyses the conceptual requirements of this much-sought after service for digital libraries. We demonstrate that the differing concepts of digital libraries and its underlying technical design has extensive influence (a) the expectations, needs and interests of users regarding an alerting service, and (b) on the technical possibilities of the implementation of the service. Our findings show that the range of issues surrounding alerting services for digital libraries, their design and use is greater than one may anticipate. We also show that, conversely, the requirements for an alerting service have considerable impact on the concepts of DL design. Our findings should be of interest for librarians as well as system designers. We highlight and discuss the far-reaching implications for the design of, and interaction with, libraries. This paper discusses the lessons learned from building such a distributed alerting service. We present our prototype implementation as a proof-of-concept for an alerting service for open DL software