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<pre>
        Proceedings of the 1st Workshop on
      High-Level Declarative Stream Processing


              HiDeSt ’15

      22nd September, 2015 in Dresden, Germany
co-located with the 38th German AI conference KI 2015
                                          Preface


Stream processing as an information processing paradigm appears in various applications and has
been investigated by various research communities within computer science. Next to algorithmic
oriented research on low-level stream processing (e.g., for sensor networks), stream-related re-
search of recent years resulted also in declarative stream processing frameworks, which are in the
focus HiDeSt ’15. Declarative stream processing frameworks such as data stream management
systems or systems for complex event processing (CEP) provide amongst other things stream
query languages with a clear-cut semantics.
    The progress of technologies and computer science as a whole has brought up new challenges
for stream processing that call for the modeling of knowledge and the construction of query
engines which account for the knowledge. In ontology-based streams access (OBSA) as needed,
e.g., in Semantic Web, queries are answered over data streams that contain declarative asser-
tions with symbols from an ontology. Query answering now has to incorporate reasoning over
the ontology in order to guarantee completeness of the set of answers. Also context-aware rea-
soning for streams or CEP have to incorporate some form of reasoning in order to deal with the
consequences that the context/entity models have for the set of query answers.
    All of the papers of the HiDeSt ’15 proceedings (5 long papers, 1 short paper) contribute to
results in high-level declarative stream processing.
    The paper “Towards Enriching CQELS with Complex Event Processing and Path Navigation”
by Minh Dao-Tran and Danh Le-Phuoc describes extensions of the stream query language CQELS
in two directions: adding RDFS stream reasoning support and adding query constructors known
from CEP (in particular a constructor for path queries which support a limited kind of recursion).
    The paper entitled “Towards Comparing RDF Stream Processing Semantics” by Minh Dao-
Tran, Harald Beck and Thomas Eiter compares the semantics of two query languages for RDF
streams, the above mentioned CQELS and C-SPARQL. The comparison is done by a translation
into a logical framework (LARS) developed by the authors.
    Whereas both papers above deal with light-weight ontology languages as provided by RDFS,
the paper “Dealing Efficiently with Ontology-Enhanced Linked Data for Multimedia” by Oliver
Gries, Ralf Möller, Anahita Nafissi, Maurice Rosenfeld, Kamil Sokolski, and Sebastian Wandelt
incorporates (efficient) reasoning over streams w.r.t. expressive ontologies. The authors describe
an approach—developed in the CASAM project—for abductive interpretation of semantically
annotated video streams.
    Both papers by Ralf Möller, Christian Neuenstadt, and Özgür L. Özçep (“Stream-temporal
Querying with Ontologies” and “OBDA for Temporal Querying and Streams”) contribute to
OBSA, describing the architecture and evaluations os stream engines based based on the query
language framework STARQL. The former describes an engine using a transformation via Dat-
alog, whereas the latter describes in detail a transformation algorithm adapted from database
theory.
    The paper “Towards Temporal Fuzzy Query Answering on Stream-based Data” by Anni-
Yasmin Turhan and Erik Zenker can be considered as a contribution to OBSA too. They authors
provide a pragmatical approach for answering conjunctive queries extended with temporal oper-
ators where the background ontology is formulated in a fuzzy DL-Lite ontology and where the
stream of data is a (potentially growing) finite sequenced of data sets (ABoxes).
    In addition to the main program, we invited a keynote from the data stream management
community. Marco Grawunder will introduce “Odysseus – An Extensible Research Platform
for Streaming”, an open source platform that can serve as basis for future works on high-level
declarative stream reasoning research.
    We thank all authors for their contributions, our reviewers for their detailed and timely
reviews and look forward to interesting and fruitful discussions at the workshop.

September 2015                                               Daniela Nicklas, Özgür L. Özçep
                                                                           (Program Chairs)
                        Workshop Organization


Chairs
Daniela Nicklas           University of Bamberg, Germany
Özgür L. Özçep        University of Lübeck, Germany


Program Committee
Martin Bauer              NEC Heidelberg, Germany
Jean-Paul Calbimonte      Ecole Polytechnique Federale de Lausanne,
                          Switzerland
Sven Groppe               University of Lübeck, Germany
Evgeny Kharlamov          University of Oxford, UK
Yannis Kotidis            Athens University of Economics and Business,
                          Greece
Sven Meister              Fraunhofer ISST, Dortmund, Germany
Daniele Riboni            Universit degli Studi di Milano, Italy
Stephan Scheele           University of Bamberg, Germany
Manfred Wojciechowski     University of Applied Sciences, Düsseldorf
Matthias Wieland          University of Stuttgart, IPVS/AS

</pre>