Users often quit an information retrieval system (IR system) very frustrated, because they cannot find the information matching their information needs. We have identified the following two main reasons: too high expectations and wrong use of the system. Our approach which addresses both issues is based on the transfer of the concept of Quality of Service to IR systems: The user first negotiates the retrieval success rates with the IR system, so he knows what to expect from the system in advance. Second, by dynamic adaptation to the retrieval context, the IR system tries to improve the user's queries and thereby tries to exploit the underlying information source as best as possible.

Summary form only given. Today's distributed information systems often are collections of existing information sources and as such heterogeneous. Technical integration of heterogeneous sources is supported by CORBA. However, CORBA provides very general support and does not take source specific semantics into account. This also applies to CORBA's Event Service. Our objective is to enhance CORBA by mechanisms that allow to add application semantics. Our key idea is to provide a flexible configurable event monitoring service, which accepts heterogeneity, for a CORBA environment. Configurable means that we are able to generate code templates at compile time and to provide dynamic parametrization of parts of the service. Event passing semantics follow those developed for active database Event-Condition-Action (ECA) rules.

article Free Access Share on Databases on the Web: technologies for federation architectures and case studies Author: Ralf Kramer Forschungszentrum Informatik (FZI), Haid-und-Neu-Str. 10-14, D-76131 Karlsruhe, Germany Forschungszentrum Informatik (FZI), Haid-und-Neu-Str. 10-14, D-76131 Karlsruhe, GermanyView Profile Authors Info & Claims ACM SIGMOD RecordVolume 26Issue 2June 1997 pp 503–506https://doi.org/10.1145/253262.253372Online:01 June 1997Publication History 5citation804DownloadsMetricsTotal Citations5Total Downloads804Last 12 Months8Last 6 weeks2 Get Citation AlertsNew Citation Alert added!This alert has been successfully added and will be sent to:You will be notified whenever a record that you have chosen has been cited.To manage your alert preferences, click on the button below.Manage my AlertsNew Citation Alert!Please log in to your account Save to BinderSave to BinderCreate a New BinderNameCancelCreateExport CitationPublisher SiteeReaderPDF

Many application areas require the integration of heterogeneous information sources into a coherent distributed information system. With such systems, users frequently need not only be able to access information, but they also have to be notified automatically when new information that is relevant to their work becomes available. For example, an our environmental systems project, a civil servant needs to be informed when a measured air quality parameter exceeds a certain threshhold. Detection of such a critical situation requires subsequent monitoring of several data sources (e.g., a database recording measurement values and a database with limit values). The paper presents an approach for such situation monitoring which is based on CORBA, for the technical integration of heterogeneous systems and on active DBMS-style ECA-rules. In particular, it discusses how ECA-rules can be adopted in a CORBA environment, and describes a CORBA-based system for situation monitoring. The major implementation issues addressed are event detection within autonomous component systems and detection of complex distributed situations.