Achim Kraiss

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Multimedia applications demand specific support from database management systems due to the characteristics of multimedia data and their interactive usage. This includes integrated support for high–volume and time–dependent (continuous) data types like audio and video. One critical issue is to provide handling of continuous data streams including buffer(More)
Large multimedia document archives may hold a major fraction of their data in tertiary storage libraries for cost reasons. This paper develops an integrated approach to the vertical data migration between the tertiary, secondary, and primary storage in that it reconciles speculative prefetching, to mask the high latency of the tertiary storage, with the(More)
Although today’s computers provide huge amounts of main memory, the ever-increasing load of large data servers, imposed by resource-intensive decision-support queries and accesses to multimedia and other complex data, often leads to memory contention and may result in severe performance degradation. Therefore, careful tuning of memory mangement is crucial(More)
Since mobile commerce (m-commerce) started to be intensively discussed in the press, financial service companies are said to be the winners of m-commerce. But looking at existing m-commerce applications, you will find <i>really</i> interesting information only on few sites. In addition, there are many of these applications, which are just in a prototype(More)
In this paper, we consider the problem of exploiting I/O parallelism for efficient access to transaction-time temporal databases. As temporal databases maintain historical versions of records in addition to current ones, we consider range queries in both time dimension and key dimension. Multiple disks can be used to read sets of disk blocks in parallel,(More)
The developmental and reproduction pattern as well as the nondiapause behaviour of Argas (Argas) africolumbae, reared on domestic chickens and held at 27 degrees C and 90% RH, indicate that there may be 2-3 generations annually. The minimum incubation period of eggs requires 16.2 days (mean), irrespective of the day of oviposition. Larvae feed for 5-6 days(More)
Multimedia applications require continuous delivery of time-dependent data. In best-effort systems where no resource reservation is possible, adaptation strategies are necessary in case of high system load. We propose an adaptation framework for a client-pull architecture where continuous data are requested and buffered by the presenting client. The current(More)
Workflow management systems (WFMSs) that are geared for the orchestration of enterprise-wide or even “virtual-enterprise”-style business processes across multiple organizations are complex distributed systems. They consist of multiple workflow engines, application servers, and ORB-style communication servers. Thus, deriving a suitable configuration of an(More)
Large multimedia document archives hold most of their data in near-line tertiary storage libraries for cost reasons. This paper develops an integrated approach to the vertical data migration between the tertiary and secondary storage in that it reconciles speculative preloading, to mask the high latency of the tertiary storage, with the replacement policy(More)