Semantic Web http://www.roland-stuehmer.de/tags/semantic-web en Workshop on Situation Recognition (SIREMTI2015) http://www.roland-stuehmer.de/content/workshop-situation-recognition-siremti2015 <span property="schema:name" class="field field-node--title field-name-title field-type-string field-label-hidden">Workshop on Situation Recognition (SIREMTI2015)</span> <span rel="schema:author" class="field field-node--uid field-name-uid field-type-entity-reference field-label-hidden"><a title="View user profile." href="/users/rolandstuehmer" lang="" about="/users/rolandstuehmer" typeof="schema:Person" property="schema:name" datatype="" class="username">roland.stuehmer</a></span> <span property="schema:dateCreated" content="2015-04-10T12:04:50+00:00" class="field field-node--created field-name-created field-type-created field-label-hidden">Fri, 04/10/2015 - 14:04</span> <div property="schema:text" class="clearfix field field-node--body field-name-body field-type-text-with-summary field-label-hidden"> <div class="field-items"> <div property="schema:text" class="field-item"><p><strong>UPDATE 2</strong>: The deadline for submissions was extended to 30th September, 2015.</p> <p><strong>UPDATE</strong>: The workshop was relocated to <a href="http://mobicase.org/2015/show/home">MobiCASE2015 conference</a> in November 2015, Berlin, Germany. <strike>The deadline for submissions is currently 11th September 2015.</strike></p> <p>(I am on the Programme Committee.)</p> <p><a href="https://sites.google.com/site/siremitei2015/">Important dates and submission information: Workshop Homepage</a></p> <p>From the CfP:</p> <blockquote> <p>This workshop aims at merging research works relevant to mining temporal information from any kind of data with a special focus on (but not limited to) the following methods:</p> <ul> <li>Trend Mining</li> <li>Temporal Data Mining</li> <li>Topic Mining and Mining of Users Posts</li> <li>Data-based Situation Recognition</li> <li>Intelligent Situation Recognition</li> <li>Wireless Data Mining</li> <li>Signal Detection and Analysis</li> <li>Complex Event Processing and Messaging Analytics</li> <li>Semantic Complex Event Processing</li> <li>Data Stream Processing</li> <li>Data Mining on Streaming Data</li> <li>Semantic Technologies for Situation Recognition</li> </ul> </blockquote> </div> </div> </div> <section class="field field-node--comment-node-article field-name-comment-node-article field-type-comment field-label-hidden comment-wrapper"> </section> <div class="field field-node--field-tags field-name-field-tags field-type-entity-reference field-label-inline clearfix"> <div class="field-label">Tags</div> <div class="field-items"> <div class="field-item"><a href="/tags/siremti2015" property="schema:about" hreflang="en">SIREMTI2015</a></div> <div class="field-item"><a href="/tags/workshop" property="schema:about" hreflang="en">workshop</a></div> <div class="field-item"><a href="/tags/mobicase" property="schema:about" hreflang="en">MobiCASE</a></div> <div class="field-item"><a href="/tags/2015" property="schema:about" hreflang="en">2015</a></div> <div class="field-item"><a href="/tags/cfp" property="schema:about" hreflang="en">CfP</a></div> <div class="field-item"><a href="/tags/semantic-web" property="schema:about" hreflang="en">Semantic Web</a></div> <div class="field-item"><a href="/tags/event-processing" property="schema:about" hreflang="en">Event Processing</a></div> </div> </div> Fri, 10 Apr 2015 12:04:50 +0000 roland.stuehmer 50 at http://www.roland-stuehmer.de/drupal-8 RDF Stream Processing Workshop at ESWC2015, Call for Papers http://www.roland-stuehmer.de/rsp-workshop-2015 <span property="schema:name" class="field field-node--title field-name-title field-type-string field-label-hidden">RDF Stream Processing Workshop at ESWC2015, Call for Papers</span> <span rel="schema:author" class="field field-node--uid field-name-uid field-type-entity-reference field-label-hidden"><a title="View user profile." href="/users/rolandstuehmer" lang="" about="/users/rolandstuehmer" typeof="schema:Person" property="schema:name" datatype="" class="username">roland.stuehmer</a></span> <span property="schema:dateCreated" content="2015-01-23T14:18:04+00:00" class="field field-node--created field-name-created field-type-created field-label-hidden">Fri, 01/23/2015 - 15:18</span> <div property="schema:text" class="clearfix field field-node--body field-name-body field-type-text-with-summary field-label-hidden"> <div class="field-items"> <div property="schema:text" class="field-item"><p>In conjunction with the 12th Extended Semantic Web Conference (<a href="http://2015.eswc-conferences.org/">ESWC 2015</a>). May 31th, 2015 in Portoroz, Slovenia.</p> <p>From the <a href="http://www.w3.org/community/rsp/rsp-workshop-2015/">Call for Papers</a>:</p> <blockquote> <p>The goal of this workshop is to bring together interested members of the community to:</p> <ul> <li>Demonstrate their latest advances in stream processing systems for <abbr title="Resource Description Format">RDF</abbr>.</li> <li>Foster discussion for agreeing on a core model and query language for <abbr title="Resource Description Format">RDF</abbr> streams.</li> <li>Involve and attract people from related research areas to actively participate in the <abbr title="RDF Stream Processing">RSP</abbr> Community Group.</li> </ul> </blockquote> <p>(I am on the Programme Committee.)</p> <p>Another workshop was accepted, called <a href="https://derive2015.wordpress.com/call-for-papers/">DeRiVE</a> which seems to focus more on <em>applications</em> of <abbr title="Resource Description Format">RDF</abbr> events whereas <abbr title="RDF Stream Processing">RSP</abbr> ist more technical focusing on streaming and processing real-time streams.</p> </div> </div> </div> <section class="field field-node--comment-node-article field-name-comment-node-article field-type-comment field-label-hidden comment-wrapper"> </section> <div class="field field-node--field-tags field-name-field-tags field-type-entity-reference field-label-inline clearfix"> <div class="field-label">Tags</div> <div class="field-items"> <div class="field-item"><a href="/tags/rsp" property="schema:about" hreflang="en">RSP</a></div> <div class="field-item"><a href="/tags/eswc" property="schema:about" hreflang="en">ESWC</a></div> <div class="field-item"><a href="/tags/cfp" property="schema:about" hreflang="en">CfP</a></div> <div class="field-item"><a href="/tags/workshop" property="schema:about" hreflang="en">workshop</a></div> <div class="field-item"><a href="/tags/semantic-web" property="schema:about" hreflang="en">Semantic Web</a></div> </div> </div> Fri, 23 Jan 2015 14:18:04 +0000 roland.stuehmer 48 at http://www.roland-stuehmer.de/drupal-8 An RDF Model for Events http://www.roland-stuehmer.de/content/rdf-model-events <span property="schema:name" class="field field-node--title field-name-title field-type-string field-label-hidden">An RDF Model for Events</span> <span rel="schema:author" class="field field-node--uid field-name-uid field-type-entity-reference field-label-hidden"><a title="View user profile." href="/users/rolandstuehmer" lang="" about="/users/rolandstuehmer" typeof="schema:Person" property="schema:name" datatype="" class="username">roland.stuehmer</a></span> <span property="schema:dateCreated" content="2014-12-12T12:22:34+00:00" class="field field-node--created field-name-created field-type-created field-label-hidden">Fri, 12/12/2014 - 13:22</span> <div property="schema:text" class="clearfix field field-node--body field-name-body field-type-text-with-summary field-label-hidden"> <div class="field-items"> <div property="schema:text" class="field-item"><p>Why do we need an event model? Many <abbr title="Resource Description Format">RDF</abbr> streaming systems discussed have little or no model for the real-time data they ingest. These systems make the lowest common assumptions about the structure of the data, i.e. that the data consist of a stream of <abbr title="Resource Description Format">RDF</abbr> triples. Thus, each piece of real-time data (event) is one triple. One triple, however, cannot hold a lot of information. For example: flexibility in timstamping (one vs. two timestamps or application time vs. system time) is only possible if timstamps can be attached to event structure. Flat triples cannot do that. Another example is when typing data, the triple <code>&lt;myInstance&gt; rdf:type &lt;MyClass&gt;</code> can introduce a type, but the event (one triple) is "full". This means that any structure in the data must be inferred from more than one event. However, consumers cannot make assumptions about events which are not yet received: Events occur spontaneously and event consumers are often decoupled from the senders (cf. publish/subscribe systems). Therefore, structure is needed in individual events.</p> <p>Events should be self-describing. A common understanding of data is crucial for consumers and producers <sup id="fnref:Rozsnyai et al. 2007b"><a href="#fn:Rozsnyai et al. 2007b" class="footnote-ref">1</a></sup>, especially in a distributed and heterogeneous system such as the Web. Therefore, a consumer must find a way to understand received events which entails the need for a universal event model <sup id="fnref2:Rozsnyai et al. 2007b"><a href="#fn:Rozsnyai et al. 2007b" class="footnote-ref">1</a></sup>.</p> <h2>Model</h2> <p>The figure shows the event model in a class diagram <sup id="fnref:Stühmer 2014"><a href="#fn:Stühmer 2014" class="footnote-ref">2</a></sup>. The class "Event" at bottom left of the figure is the superclass for any event to conform to our model. This class makes use of related work by inheriting from the class "<abbr title="DOLCE+DnS Ultralite">DUL</abbr>:Event" from Dolce Ultralight based on DOLCE <sup id="fnref:Gangemi et al. 2002"><a href="#fn:Gangemi et al. 2002" class="footnote-ref">3</a></sup>. That class provides a notion of time and helps distinguish events (things that happen) from facts (which are always valid).</p> <p><img src="http://www.roland-stuehmer.de/sites/default/files/eventclassdiagram.png" alt="Event Model" title="Event Model (Class Diagram)" /></p> <p>In accordance with our requirements <sup id="fnref2:Stühmer 2014"><a href="#fn:Stühmer 2014" class="footnote-ref">2</a></sup> some properties are mandatory while the rest are optional. An instance of class Event MUST have (i) a type, (ii) at least one timestamp and (iii) a relevant stream. We describe the event properties in detail as follows.</p> <p>The type of an event must be specified using <strong><code>rdf:type</code></strong>. The type must be the class Event or any subclass.</p> <p>The event model supports interval-based events as well as point-based events by either using just the property <strong><code>:endTime</code></strong> for a point or both <strong><code>:startTime</code></strong> and <code>:endTime</code> for an interval. The property <code>:endTime</code> thus has a cardinality of <code>[1..1]</code> whereas <code>:startTime</code> has a cardinality of <code>[0..1]</code>. Both temporal properties are subproperties of <abbr title="DOLCE+DnS Ultralite">DUL</abbr>:hasEventDate from the super class. We improve the semantics by distinguishing start from end whereas the superclass has an alternative, more difficult way of formulating intervals using subobjects reifying the interval.</p> <p>The property <strong><code>:stream</code></strong> associates an event with a stream. Streams are used in our system as a unit of organisation for events governing publish/subscribe and access control. Streams themselves are modelled using title, description and a topic needed for topic-based publish/subscribe.</p> <p>The first optional property is <strong><code>:location</code></strong>. For for geo-referencing of events (where necessary) we re-use the basic geo vocabulary from the <abbr title="World Wide Web Consortium">W3C</abbr> <sup id="fnref:Brickley 2003"><a href="#fn:Brickley 2003" class="footnote-ref">4</a></sup>. The property may be used to locate events in physical locations on the globe. The property is subproperty of <code>DUL:hasLocation</code> and <code>geo:location</code> to inherit the semantics from those schemas.</p> <p>Inter-event relationships may be supported by linking a complex event to the simple events which caused it. Thus, <abbr title="Resource Description Format">RDF</abbr> Lists may be used in <strong><code>:members</code></strong> to maintain an ordered and complete account of member events. The linked events are identified by their URI. These linked events could have further member events themselves. This facilitates modelling of <em>composite</em> events <sup id="fnref:Luckham and Schulte 2011"><a href="#fn:Luckham and Schulte 2011" class="footnote-ref">5</a></sup>. The <code>:members</code> property is a subproperty of <code>DUL:hasConstituent</code> from the superclass.</p> <p>The property <strong><code>:eventPattern</code></strong> may be used to link a complex event to the pattern which caused the event to be detected. Direct links to event patterns may be provided by RESTful services. Using such links can help in recording provenance of derived events.</p> <p>The source of an event may be specified using the <strong><code>:source</code></strong> property. This is an optional property to record the creator of an event where needed. The property is a subproperty of <code>DUL:involvesAgent</code>. Agents may be human or non-human.</p> <p>A human readable synopsis of an event may be added using the <strong><code>:message</code></strong> property. This proves useful in scenarios where events are received by human end users. The <code>:message</code> property is a subproperty of <code>dc:title</code>, a popular way of describing things using natural language. Multilingualism is provided by the feature of language tags for string literals in <abbr title="Resource Description Format">RDF</abbr> <sup id="fnref:Klyne and Carroll 2004"><a href="#fn:Klyne and Carroll 2004" class="footnote-ref">6</a></sup>.</p> <p>N-ary predicates <sup id="fnref:Noy and Rector 2006"><a href="#fn:Noy and Rector 2006" class="footnote-ref">7</a></sup> may be used to maintain event properties which are valid only for a specific event, e.g. a volatile sensor reading such as the temperature measurement belonging to a specific event. For example, instead of plainly stating the disputable fact that "the city of Nice has a temperature in Celsius of 23 degrees" which looks like this:</p> <p>[geshifilter-code langauge="ttl"]&#10;dbpedia:Nice :curTemp &quot;23&quot; .&#10;[/geshifilter-code]</p> <p>We can instead state that the city of Nice has said temperature but qualified by the conjunction with a given event "e2" in the following n-ary predicate:</p> <p>[geshifilter-code langauge="ttl"]&#10;dbpedia:Nice :curTemp [&#10; rdf:value &quot;23&quot; ;&#10; :event &lt;http://events...org/ids/e2#event&gt;&#10;] .&#10;[/geshifilter-code]</p> <p>Endowment of further structure for events is left to domain-specific schemas. For example the <abbr title="World Wide Web Consortium">W3C</abbr> Semantic Sensor Network (<abbr title="Semantic Sensor Network">SSN</abbr>) Ontology may be added if fine-grained modelling of sensors and pertaining sensor readings is needed.</p> <h2>Example</h2> <p>The listing below shows several facts about our event model along an example. The listing uses the example of a Facebook event generated by our event adapter described in <sup id="fnref3:Stühmer 2014"><a href="#fn:Stühmer 2014" class="footnote-ref">2</a></sup>.</p> <p>[geshifilter-code langauge="ttl"]&#10;@prefix : &lt;http://events.event-processing.org/types/&gt; .&#10;@prefix e: &lt;http://events.event-processing.org/ids/&gt; .&#10;@prefix user: &lt;http://graph.facebook.com/schema/user#&gt; .&#10;@prefix xsd: &lt;http://www.w3.org/2001/XMLSchema#&gt; .&#10;&#10;e:5534987067802526 {&#10; &lt;http://events.event-processing.org/ids/5534987067802526#event&gt;&#10; a :FacebookStatusFeedEvent ;&#10; :endTime &quot;2012-03-28T06:04:26.522Z&quot;^^xsd:dateTime ;&#10; :status &quot;I bought some JEANS this morning&quot; ;&#10; :stream &lt;http://streams...org/ids/FacebookStatusFeed#stream&gt; ;&#10; user:id &quot;100000058455726&quot; ;&#10; user:link &lt;http://graph.facebook.com/roland.stuehmer#&gt; ;&#10; user:location &quot;Karlsruhe, Germany&quot; ;&#10; user:name &quot;Roland Stühmer&quot; .&#10;}&#10;[/geshifilter-code]</p> <ol> <li>The example shows an event <strong>using quadruples</strong> in TriG syntax <sup id="fnref:Bizer and Cyganiak 2014"><a href="#fn:Bizer and Cyganiak 2014" class="footnote-ref">8</a></sup>. The graph name (a.k.a context) before the curly braces is used as a unique identifier, e.g. to enable efficient indexing of contiguous triples in the storage backend for historic events.</li> <li>The event in this example has the ID <code>5534987067802526</code> as part of its URI. There is a distinction made between <strong>URIs for things</strong> and URIs for their information resources, i.e. the event object <code>5534987067802526#event</code> and the Web document <code>5534987067802526</code> describing the event. The two URIs might carry, e.g. a different creation date, which is why it can be important to separate them. The fragment identifier <code>#event</code> is used to differentiate them. See <sup id="fnref:Berners-Lee 2005"><a href="#fn:Berners-Lee 2005" class="footnote-ref">9</a></sup> for an in-depth discussion of the matter of disambiguation (also known as the <em>httpRange-14</em> issue).</li> <li>There is an <strong>event type hierarchy</strong> from which the type Facebook-StatusFeedEvent is inherited. This hierarchy can be extended by any user by referencing the <abbr title="Resource Description Format">RDF</abbr> type <code>:Event</code> as a super class.</li> <li>The event may link to entities from static <strong>Linked Data</strong> where further context for the event can be retrieved. In this example the event uses <code>user:link</code> where further context for the event can be retrieved, in this case from the Facebook Graph <abbr title="application programming interface">API</abbr>. Facebook started publishing Linked Data as <abbr title="Resource Description Format">RDF</abbr> <sup id="fnref:Weaver and Tarjan 2012"><a href="#fn:Weaver and Tarjan 2012" class="footnote-ref">10</a></sup>.</li> <li>The event links to a <strong>stream</strong> which is a URI where current events can be obtained in real-time by dereferencing the link.</li> <li>The namespace <code>event-processing.org</code> is chosen as a generic home for this schema.</li> </ol> <h2>Conclusion</h2> <p>We are re-using and creating domain vocabularies to subclass the class Event. For example in the Facebook case we use the schema from the <abbr title="Resource Description Format">RDF</abbr>/Turtle <abbr title="application programming interface">API</abbr> provided by Facebook <sup id="fnref2:Weaver and Tarjan 2012"><a href="#fn:Weaver and Tarjan 2012" class="footnote-ref">10</a></sup>.</p> <p>We developed this event model to satisfy requirements of an open platform where data from the Web can be re-used and which is extensible for open participation. Future updates to the event schema can be tracked on-line at <sup id="fnref:Harth and Stühmer 2011"><a href="#fn:Harth and Stühmer 2011" class="footnote-ref">11</a></sup>.</p> <div class="footnotes"> <hr /> <ol> <li id="fn:Rozsnyai et al. 2007b"> <p>Rozsnyai, S.; Schiefer, J. &amp; Schatten, A. Concepts and models for typing events for event-based systems Proceedings of the 1st ACM International Conference on Distributed Event-Based Systems, ACM, 2007, 62-70&#160;<a href="#fnref:Rozsnyai et al. 2007b" class="footnote-backref">&#8617;&#xFE0E;</a> <a href="#fnref2:Rozsnyai et al. 2007b" class="footnote-backref">&#8617;&#xFE0E;</a></p> </li> <li id="fn:Stühmer 2014"> <p>Stühmer, R. <a href="http://dx.doi.org/10.5445/KSP/1000043122">Web-oriented Event Processing Karlsruhe Institute of Technology, KIT Scientific Publishing, Karlsruhe, 2014</a>&#160;<a href="#fnref:Stühmer 2014" class="footnote-backref">&#8617;&#xFE0E;</a> <a href="#fnref2:Stühmer 2014" class="footnote-backref">&#8617;&#xFE0E;</a> <a href="#fnref3:Stühmer 2014" class="footnote-backref">&#8617;&#xFE0E;</a></p> </li> <li id="fn:Gangemi et al. 2002"> <p>Gangemi, A.; Guarino, N.; Masolo, C.; Oltramari, A. &amp; Schneider, L. Sweetening Ontologies with DOLCE Proceedings of the 13th International Conference on Knowledge Engineering and Knowledge Management. Ontologies and the Semantic Web, Springer-Verlag, 2002, 166-181&#160;<a href="#fnref:Gangemi et al. 2002" class="footnote-backref">&#8617;&#xFE0E;</a></p> </li> <li id="fn:Brickley 2003"> <p>Brickley, D. <a href="http://www.w3.org/2003/01/geo/">Basic Geo (WGS84 lat/long) Vocabulary, 2003</a>&#160;<a href="#fnref:Brickley 2003" class="footnote-backref">&#8617;&#xFE0E;</a></p> </li> <li id="fn:Luckham and Schulte 2011"> <p>Luckham, D. C. &amp; Schulte, R. <a href="http://www.complexevents.com/2011/08/23/event-processing-glossary-version-2-0/">Event Processing Glossary - Version 2.0, 2011</a>&#160;<a href="#fnref:Luckham and Schulte 2011" class="footnote-backref">&#8617;&#xFE0E;</a></p> </li> <li id="fn:Klyne and Carroll 2004"> <p>Klyne, G. &amp; Carroll, J. J. <a href="http://www.w3.org/TR/rdf-concepts/">Resource Description Framework (<abbr title="Resource Description Format">RDF</abbr>): Concepts and Abstract Syntax 2004</a>&#160;<a href="#fnref:Klyne and Carroll 2004" class="footnote-backref">&#8617;&#xFE0E;</a></p> </li> <li id="fn:Noy and Rector 2006"> <p>Noy, N. &amp; Rector, A. <a href="http://www.w3.org/TR/swbp-n-aryRelations/">Defining N-ary Relations on the Semantic Web World Wide Web Consortium, 2006</a>&#160;<a href="#fnref:Noy and Rector 2006" class="footnote-backref">&#8617;&#xFE0E;</a></p> </li> <li id="fn:Bizer and Cyganiak 2014"> <p>Bizer, C. &amp; Cyganiak, R. <a href="http://www.w3.org/TR/trig/"><abbr title="Resource Description Format">RDF</abbr> 1.1 TriG, 2014</a>&#160;<a href="#fnref:Bizer and Cyganiak 2014" class="footnote-backref">&#8617;&#xFE0E;</a></p> </li> <li id="fn:Berners-Lee 2005"> <p>Berners-Lee, T. <a href="http://www.w3.org/DesignIssues/HTTP-URI2.html">What HTTP URIs Identify? -- Design Issues, 2005</a>&#160;<a href="#fnref:Berners-Lee 2005" class="footnote-backref">&#8617;&#xFE0E;</a></p> </li> <li id="fn:Weaver and Tarjan 2012"> <p>Weaver, J. &amp; Tarjan, P. <a href="http://dx.doi.org/10.3233/SW-2012-0078">Facebook Linked Data via the Graph <abbr title="application programming interface">API</abbr> Semantic Web Journal, IOS Press, 2012</a>&#160;<a href="#fnref:Weaver and Tarjan 2012" class="footnote-backref">&#8617;&#xFE0E;</a> <a href="#fnref2:Weaver and Tarjan 2012" class="footnote-backref">&#8617;&#xFE0E;</a></p> </li> <li id="fn:Harth and Stühmer 2011"> <p>Harth, A. &amp; Stühmer, R. <a href="http://km.aifb.kit.edu/sites/lodstream/">Publishing Event Streams as Linked Data Karlsruhe Institute of Technology, FZI Forschungszentrum Informatik, 2011</a>&#160;<a href="#fnref:Harth and Stühmer 2011" class="footnote-backref">&#8617;&#xFE0E;</a></p> </li> </ol> </div> </div> </div> </div> <section class="field field-node--comment-node-article field-name-comment-node-article field-type-comment field-label-hidden comment-wrapper"> </section> <div class="field field-node--field-tags field-name-field-tags field-type-entity-reference field-label-inline clearfix"> <div class="field-label">Tags</div> <div class="field-items"> <div class="field-item"><a href="/tags/rdf" property="schema:about" hreflang="en">RDF</a></div> <div class="field-item"><a href="/tags/rsp" property="schema:about" hreflang="en">RSP</a></div> <div class="field-item"><a href="/tags/schema" property="schema:about" hreflang="en">schema</a></div> <div class="field-item"><a href="/tags/ontology" property="schema:about" hreflang="en">ontology</a></div> <div class="field-item"><a href="/tags/semantic-web" property="schema:about" hreflang="en">Semantic Web</a></div> <div class="field-item"><a href="/tags/event-processing" property="schema:about" hreflang="en">Event Processing</a></div> </div> </div> Fri, 12 Dec 2014 12:22:34 +0000 roland.stuehmer 45 at http://www.roland-stuehmer.de/drupal-8 RDF Access Control http://www.roland-stuehmer.de/content/rdf-access-control <span property="schema:name" class="field field-node--title field-name-title field-type-string field-label-hidden">RDF Access Control</span> <span rel="schema:author" class="field field-node--uid field-name-uid field-type-entity-reference field-label-hidden"><a title="View user profile." href="/users/rolandstuehmer" lang="" about="/users/rolandstuehmer" typeof="schema:Person" property="schema:name" datatype="" class="username">roland.stuehmer</a></span> <span property="schema:dateCreated" content="2014-10-02T13:39:50+00:00" class="field field-node--created field-name-created field-type-created field-label-hidden">Thu, 10/02/2014 - 15:39</span> <div property="schema:text" class="clearfix field field-node--body field-name-body field-type-text-with-summary field-label-hidden"> <div class="field-items"> <div property="schema:text" class="field-item"><p>There are several approaches to modelling access control using <abbr title="Resource Description Format">RDF</abbr>. The approaches use <abbr title="Resource Description Format">RDF</abbr> as a modelling language for permissions linking users with user's rights on the one hand and on the other hand are used on <abbr title="Resource Description Format">RDF</abbr> data granting access to users (linking permissions with data). All approaches <em>grant</em> access to <abbr title="Resource Description Format">RDF</abbr> resources while assuming what is not granted is forbidden.</p> <h2>Related Work</h2> <p>The <strong>S4AC Vocabulary</strong> Specification 0.2<sup id="fnref:Villata et al. 2011"><a href="#fn:Villata et al. 2011" class="footnote-ref">1</a></sup> defines access rights tailored towards <abbr title="Resource Description Format">RDF</abbr> query answering, i.e. <abbr title="SPARQL Protocol and RDF Query Language">SPARQL</abbr> processing. The vocabulary defines access rights Create, Read, Update and Delete. The model is very expressive by allowing fine-grained access condition modelled as contextual queries against arbitrary context data to check. However, the integration with <abbr title="SPARQL Protocol and RDF Query Language">SPARQL</abbr> is not applicable for our system as not all operations require a query such as a plain subscription to a stream.</p> <p><strong><abbr title="Semantically-Interlinked Online Communities">SIOC</abbr> Access</strong> is a part of the <abbr title="Semantically-Interlinked Online Communities">SIOC</abbr> specification<sup id="fnref:Berrueta 2010"><a href="#fn:Berrueta 2010" class="footnote-ref">2</a></sup>. It is a very simple but extensible vocabulary to define permissions in the scope of the social Web. The vocabulary does not have any predefined rights. The lack of rights, the focus on social communities and its lack of traction on the Web are the drawbacks of this candidate when choosing a model for access control in our system.</p> <p>The <abbr title="World Wide Web Consortium">W3C</abbr> <strong>WebAccessControl (<abbr title="WebAccessControl">WAC</abbr>)</strong><sup id="fnref:Berners-Lee 2009"><a href="#fn:Berners-Lee 2009" class="footnote-ref">3</a></sup> is a generic vocabulary declaring some predefined rights (Read, Write, Append, Control) on Web information resources. Streams in our system are information resources so the vocabulary can be used without change. Access rights must be extended for our system to govern the real-time access <code>Notify</code> and <code>Subscribe</code> in addition to the predefined rights <code>Read</code> and <code>Write</code> for static data.</p> <h2>Our System, Using Access Control for Streaming Data</h2> <p>Data in our system<sup id="fnref:Stühmer et al. 2013"><a href="#fn:Stühmer et al. 2013" class="footnote-ref">4</a></sup> is organized in streams (cf. topic-based publish/subscribe). Attributing access control on a per-stream granularity was chosen. Finer granularity such as per-event attribution was discarded. The expected performance impact at runtime was thought to be unnecessarily high when having to check each event for each of its recipients before delivery. Coarser granularity such as granting access to all streams at once, however, was contradicting our requirement for multitenancy without having the ability to separate users.</p> <p>After analysing the existing <abbr title="Resource Description Format">RDF</abbr> models for access control mentioned above we concluded that <em><abbr title="World Wide Web Consortium">W3C</abbr> WebAccessControl</em> was the most viable candidate of the three available candidates S4AC, <abbr title="Semantically-Interlinked Online Communities">SIOC</abbr> Access and the <abbr title="World Wide Web Consortium">W3C</abbr> WebAccessControl. Reasons were its traction on the Web, its generality, and its ease of use compared to the other candidates (e.g. linking permissions with plain <abbr title="Resource Description Format">RDF</abbr> resources instead of complex <abbr title="SPARQL Protocol and RDF Query Language">SPARQL</abbr> queries to define rights).</p> <p>The figure below shows the concepts of WebAccessControl (<abbr title="WebAccessControl">WAC</abbr>). The bottom of the figure shows that a single permission (<code>Authorization</code> in <abbr title="WebAccessControl">WAC</abbr> terms) is a ternary relation. It consists of an agent (who can access), an information resource (what) and a mode (how), cf. middle line of the figure. An example ternary relation is: <code>Roland</code> can access the <code>TwitterFeed</code> with permissions <code>Subscribe</code> and <code>Read</code>. The top left of the figure shows an agent can be either a group or an individual user's account. User accounts can be members in groups. If accounts are defined in several locations, they can be declared to be the same.</p> <p><img src="http://www.roland-stuehmer.de/sites/default/files/accesscontrol.png" alt="Access Control Lists" title="Access Control Lists using the W3C WebAccessControl Vocabulary (Class Diagram)" /></p> <p>In the figure the concepts from the <abbr title="WebAccessControl">WAC</abbr> vocabulary are highlighted in blue colour. <abbr title="WebAccessControl">WAC</abbr> has predefined access rights <code>Read</code> and <code>Write</code> for static data, cf. top right of the figure. For the use with real-time data we extended <abbr title="WebAccessControl">WAC</abbr> with the rights <code>Notify</code> and <code>Subscribe</code>. The classes on white background in the figure are defined as part of this work. Finally, the classes in yellow are from the <abbr title="Semantically-Interlinked Online Communities">SIOC</abbr> vocabulary.</p> <p>The following listing in Turtle syntax shows two example authorizations <code>p0001</code> and <code>p0002</code> in the namespace <code>permission</code> starting on line 10 and 15. A user <code>person:rs</code> who is member of the group <code>group:administrators</code> is shown starting on line 20. Both permissions exhibit the ternary relation between who, what and how access is granted. The first permission states that Roland (<code>rs</code>) can access the <code>TwitterFeed</code> with permissions <code>Subscribe</code> and <code>Read</code>. The second permission states that <code>group:administrators</code> can access the <code>FacebookStatusFeed</code> with permission <code>Write</code>.</p> <p>[geshifilter-code langauge="ttl"]&#10;@prefix acl: &lt;http://www.w3.org/ns/auth/acl#&gt; .&#10;@prefix foaf: &lt;http://xmlns.com/foaf/0.1/&gt; .&#10;@prefix group: &lt;http://groups.event-processing.org/id/&gt; .&#10;@prefix permission: &lt;http://permissions.event-processing.org/id/&gt; .&#10;@prefix person: &lt;http://www.roland-stuehmer.de/profile#&gt; .&#10;@prefix s: &lt;http://streams.event-processing.org/ids/&gt; .&#10;@prefix sioc: &lt;http://rdfs.org/sioc/ns#&gt; .&#10;@prefix wsnt: &lt;http://docs.oasis-open.org/wsn/b-2/&gt; .&#10;&#10;permission:p0001&#10; acl:accessTo s:TwitterFeed ;&#10; acl:agent person:rs ;&#10; acl:mode wsnt:Subscribe , acl:Read .&#10;&#10;permission:p0002&#10; acl:accessTo s:FacebookStatusFeed ;&#10; acl:agent group:administrators ;&#10; acl:mode acl:Write .&#10;&#10;person:rs&#10; sioc:member_of group:administrators ;&#10; owl:sameAs &lt;http://data.semanticweb.org/person/roland-stuehmer&gt; .&#10;[/geshifilter-code]</p> <p>When defining permissions, the streams are modelled as information resources (e.g. <code>http://.../TwitterFeed</code> on line 11 without the trailing <code>#stream</code>). Elsewhere, streams are modelled with their non-information resource (e.g. <code>http://.../TwitterFeed#stream</code>). Making this distinction (cf. the so-called <a href="http://en.wikipedia.org/wiki/HttpRange-14">httpRange-14 issue</a>) we can attribute different metadata to the information for the stream (e.g. annotate permissions) and to the real-world stream (e.g. annotate its real-world event source or author).</p> <div class="footnotes"> <hr /> <ol> <li id="fn:Villata et al. 2011"> <p>Villata, S.; Delaforge, N. &amp; Gandon, F. <a href="http://ns.inria.fr/s4ac">S4AC Vocabulary Specification 2011</a>&#160;<a href="#fnref:Villata et al. 2011" class="footnote-backref">&#8617;&#xFE0E;</a></p> </li> <li id="fn:Berrueta 2010"> <p>Berrueta, D. <a href="http://rdfs.org/sioc/spec/"><abbr title="Semantically-Interlinked Online Communities">SIOC</abbr> Core Ontology Specification 2010</a>&#160;<a href="#fnref:Berrueta 2010" class="footnote-backref">&#8617;&#xFE0E;</a></p> </li> <li id="fn:Berners-Lee 2009"> <p>Berners-Lee, T. <a href="http://www.w3.org/wiki/WebAccessControl">WebAccessControl, 2009</a>&#160;<a href="#fnref:Berners-Lee 2009" class="footnote-backref">&#8617;&#xFE0E;</a></p> </li> <li id="fn:Stühmer et al. 2013"> <p>Stühmer, R.; Verginadis, Y.; Alshabani, I.; Morsellino, T. &amp; Aversa, A. <a href="http://hal.inria.fr/docs/00/91/63/86/PDF/paper_CR_v1.1.pdf">PLAY: Semantics-based Event Marketplace 14th IFIP Working Conference on Virtual Enterprise -- Special Session on Event-Driven Collaborative Networks (2013)</a>&#160;<a href="#fnref:Stühmer et al. 2013" class="footnote-backref">&#8617;&#xFE0E;</a></p> </li> </ol> </div> </div> </div> </div> <section class="field field-node--comment-node-article field-name-comment-node-article field-type-comment field-label-hidden comment-wrapper"> </section> <div class="field field-node--field-tags field-name-field-tags field-type-entity-reference field-label-inline clearfix"> <div class="field-label">Tags</div> <div class="field-items"> <div class="field-item"><a href="/tags/rdf" property="schema:about" hreflang="en">RDF</a></div> <div class="field-item"><a href="/tags/access-control" property="schema:about" hreflang="en">Access Control</a></div> <div class="field-item"><a href="/tags/web" property="schema:about" hreflang="en">Web</a></div> <div class="field-item"><a href="/tags/semantic-web" property="schema:about" hreflang="en">Semantic Web</a></div> </div> </div> Thu, 02 Oct 2014 13:39:50 +0000 roland.stuehmer 42 at http://www.roland-stuehmer.de/drupal-8 Highlights from Research Project PLAY http://www.roland-stuehmer.de/content/highlights-research-project-play <span property="schema:name" class="field field-node--title field-name-title field-type-string field-label-hidden">Highlights from Research Project PLAY</span> <span rel="schema:author" class="field field-node--uid field-name-uid field-type-entity-reference field-label-hidden"><a title="View user profile." href="/users/rolandstuehmer" lang="" about="/users/rolandstuehmer" typeof="schema:Person" property="schema:name" datatype="" class="username">roland.stuehmer</a></span> <span property="schema:dateCreated" content="2013-12-08T19:05:53+00:00" class="field field-node--created field-name-created field-type-created field-label-hidden">Sun, 12/08/2013 - 20:05</span> <div property="schema:text" class="clearfix field field-node--body field-name-body field-type-text-with-summary field-label-hidden"> <div class="field-items"> <div property="schema:text" class="field-item"><p>My research project <a href="http://www.play-project.eu/">PLAY</a> has had its final review meeting on Tuesday, November 26th, 2013.</p> <p>Notable<strong> highlights </strong>from the project are:</p> <ul> <li>Use of open Web Standards for event modelling, pattern modelling, access control for real-time/streaming data</li> <li>Integrated Prototype (delivering a runnable architecture with all Open Source components)</li> <li>Contribution to Open Source community, e.g. continued maintenance of RDF2Go, MultiActive objects for ProActive</li> </ul> <p><strong>Benefits</strong> PLAY can provide as a semantics-based event-driven platform for a use case of nuclear <strong>crisis management</strong>:</p> <ul> <li>Eliminating superfluous, inaccurate or irrelevant information</li> <li>Automating some analysis or actions based on predefined business rules</li> <li>Reducing the time of information transmission between devices, stakeholders and decision makers</li> <li>Increasing the reliability of knowledge (exhaustiveness)</li> <li>Improving the agility capability of the crisis stakeholders</li> </ul> <p><strong>Benefits</strong> and opportunity PLAY can provide as an Event-driven Architecture and elastic platform to <strong>ORANGE Telecom</strong>:</p> <ul> <li>QoS problems experienced by customers of LiveBox Pro can be detected in real-time</li> <li>Improvement of knowledge about customer experience, reduction of after-sales costs with residential customers of 2G/3G data mobile services</li> <li>Ability to to compare/challenge other Open Source platforms with PLAY such as Storm/kafka  + Hadoop/Hbase and commercial middleware products</li> </ul> <p><em>Links:</em></p> <ol> <li>Opher Etzion (who is reviewer of PLAY together with Silvia Vecchi) blogged about PLAY: <a href="http://epthinking.blogspot.de/2013/11/on-play-project.html">http://epthinking.blogspot.de/2013/11/on-play-project.html</a></li> <li>Project reports and published papers are here: <a href="http://www.play-project.eu/publications">PLAY publications</a></li> </ol> <p> </p> </div> </div> </div> <section class="field field-node--comment-node-article field-name-comment-node-article field-type-comment field-label-hidden comment-wrapper"> </section> <div class="field field-node--field-tags field-name-field-tags field-type-entity-reference field-label-inline clearfix"> <div class="field-label">Tags</div> <div class="field-items"> <div class="field-item"><a href="/tags/play" property="schema:about" hreflang="en">PLAY</a></div> <div class="field-item"><a href="/tags/research" property="schema:about" hreflang="en">research</a></div> <div class="field-item"><a href="/tags/project" property="schema:about" hreflang="en">project</a></div> <div class="field-item"><a href="/tags/play-project" property="schema:about" hreflang="en">PLAY-Project</a></div> <div class="field-item"><a href="/tags/rdf" property="schema:about" hreflang="en">RDF</a></div> <div class="field-item"><a href="/tags/semantic-web" property="schema:about" hreflang="en">Semantic Web</a></div> <div class="field-item"><a href="/tags/event-processing" property="schema:about" hreflang="en">Event Processing</a></div> </div> </div> Sun, 08 Dec 2013 19:05:53 +0000 roland.stuehmer 37 at http://www.roland-stuehmer.de/drupal-8 Tutorial on Complex Event Processing http://www.roland-stuehmer.de/content/tutorial-complex-event-processing <span property="schema:name" class="field field-node--title field-name-title field-type-string field-label-hidden">Tutorial on Complex Event Processing</span> <span rel="schema:author" class="field field-node--uid field-name-uid field-type-entity-reference field-label-hidden"><a title="View user profile." href="/users/rolandstuehmer" lang="" about="/users/rolandstuehmer" typeof="schema:Person" property="schema:name" datatype="" class="username">roland.stuehmer</a></span> <span property="schema:dateCreated" content="2012-01-12T10:54:18+00:00" class="field field-node--created field-name-created field-type-created field-label-hidden">Thu, 01/12/2012 - 11:54</span> <div property="schema:text" class="clearfix field field-node--body field-name-body field-type-text-with-summary field-label-hidden"> <div class="field-items"> <div property="schema:text" class="field-item"><p>I gave a tutorial about Complex Event Processing and more specifically the <a href="http://www.play-project.eu/">PLAY</a> semantic event format and query language at the <a href="http://ct3.ijs.si/coin-planetdata-school-2011/">Winter School on Knowledge Technologies for Complex Business Environments</a> in Ljubljana on December 2, 2011 at the <a href="http://www.fs.uni-lj.si/eng/">Faculty of Mechanical Engineering (FME)</a>.<br /> <a href="http://videolectures.net/coinplanetdataschool2011_stuehmer_cep/"><img src="http://videolectures.net/coinplanetdataschool2011_stuehmer_cep/thumb.jpg" /><br /> CEP - Complex Event Processing</a><br /> Roland Stühmer</p> <h2> Abstract:</h2> <p><em>Real-time has become one of the crucial characteristics of modern applications and is completely changing the game in the data processing. Due to its capability to support continual monitoring, real-time data processing has become a very important mechanism in many application areas: traffic management, logistics, eHealth, smart grids, to name but a few. In this talk we present technologies to deal with real-time data on-the-fly, challenges and possible solutions to deal with these challenges such as using Web-friendly standards to create open and extensible systems for real-time data.</em></p> <h2> See also:</h2> <ul> <li> <a href="http://news.play-project.eu/talk-at-winter-school-on-knowledge-technologi">Announcement in PLAY Project News </a></li> <li> <a href="http://epthinking.blogspot.com/2011/12/new-tutorial-on-event-processing.html">Opher Etzion's blog entry</a></li> <li> <a href="http://videolectures.net/coinplanetdataschool2011_ljubljana/">Other talks from the Winter School</a></li> </ul> </div> </div> </div> <section class="field field-node--comment-node-article field-name-comment-node-article field-type-comment field-label-hidden comment-wrapper"> </section> <div class="field field-node--field-tags field-name-field-tags field-type-entity-reference field-label-inline clearfix"> <div class="field-label">Tags</div> <div class="field-items"> <div class="field-item"><a href="/tags/cep" property="schema:about" hreflang="en">CEP</a></div> <div class="field-item"><a href="/tags/bdpl" property="schema:about" hreflang="en">BDPL</a></div> <div class="field-item"><a href="/tags/event-processing" property="schema:about" hreflang="en">Event Processing</a></div> <div class="field-item"><a href="/tags/semantic-web" property="schema:about" hreflang="en">Semantic Web</a></div> </div> </div> Thu, 12 Jan 2012 10:54:18 +0000 roland.stuehmer 18 at http://www.roland-stuehmer.de/drupal-8