EXPRESS: Resource-oriented and RESTful Semantic Web services

This thesis investigates an approach that simplifies the development of Semantic Web services (SWS) by removing the need for additional semantic descriptions.The most actively researched approaches to Semantic Web services introduce explicit semantic descriptions of services that are in addition to the existing semantic descriptions of the service domains. This increases their complexity and design overhead. The need for semantically describing the services in such approaches stems from their foundations in service-oriented computing, i.e. the extension of already existing service descriptions. This thesis demonstrates that adopting a resource-oriented approach based on REST will, in contrast to service-oriented approaches, eliminate the need for explicit semantic service descriptions and service vocabularies. This reduces the development efforts while retaining the significant functional capabilities.The approach proposed in this thesis, called EXPRESS (Expressing RESTful Semantic Services), utilises the similarities between REST and the Semantic Web, such as resource realisation, self-describing representations, and uniform interfaces. The semantics of a service is elicited from a resource’s semantic description in the domain ontology and the semantics of the uniform interface, hence eliminating the need for additional semantic descriptions. Moreover, stub-generation is a by-product of the mapping between entities in the domain ontology and resources.EXPRESS was developed to test the feasibility of eliminating explicit service descriptions and service vocabularies or ontologies, to explore the restrictions placed on domain ontologies as a result, to investigate the impact on the semantic quality of the description, and explore the benefits and costs to developers. To achieve this, an online demonstrator that allows users to generate stubs has been developed. In addition, a matchmaking experiment was conducted to show that the descriptions of the services are comparable to OWL-S in terms of their ability to be discovered, while improving the efficiency of discovery. Finally, an expert review was undertaken which provided evidence of EXPRESS’s simplicity and practicality when developing SWS from scratch

Design of a Linked Data-enabled Microservice Platform for the Industrial Internet of Things

Während der aktuelle Trend in Richtung hochgradig digitalisierter Smart Factories für die Fertigungsindustrie beträchtliches Potential zur Steigerung von Leistungsfähigkeit, Flexibilität und Produktivität birgt, tun sich Unternehmen im Allgemeinen noch immer schwer, entsprechende Technologie einzuführen. Ein Kernproblem ist der Mangel an einheitlichen, standardisierten Lösungen, die auf dem Hallenboden ohne spezifisches Expertenwissen und einen hohen Zeit- und Kostenaufwand integriert werden können. Im Hinblick darauf präsentiert diese Arbeit sowohl Architektur, als auch konkrete Implementierung einer Internet of Things Softwareplattform mit Fokus auf technologische Einheitlichkeit und unkomplizierte Integration und Benutzung. Als Richtlinie hierfür wird in Kooperation mit Industriepartnern ein praxisnaher Anwendungsfall erarbeitet. DesWeiteren wird präsentiert, wie universelleWebtechnologie gewinnbringend mit neusten Software-Design Trends, mächtigen Techniken der Maschine-zu-Maschine Interaktion und allgemein verständlichen Konzepten im Bereich User Experience kombiniert werden kann. Dabei wird ausführlich auf Struktur der Software, Möglichkeiten zur Echtzeitkommunikation und Machine-zu-Maschine Interaktion, sowie auf einheitliche Datenintegration und Benutzerfreundlichkeit eingegangen. Am Ende des Prozesses steht eine fertige Softwarelösung als Proof-of-Concept, sowie eine Sammlung von Vorschlägen und Best Practices zur Integration von smarter Technologie auf dem Hallenboden. In einer abschließenden Evaluierung wird die Leistungsfähigkeit und Tauglichkeit der Softwareplattform für bestimmte praktische Anwendungsfälle untersucht. Zudem werden abschließend noch offene Fragen und weiterhin benötigte Entwicklungsschritte bis hin zu einem fertigen Produkt aufgezeigt

Linked Research on the Decentralised Web

This thesis is about research communication in the context of the Web. I analyse literature which reveals how researchers are making use of Web technologies for knowledge dissemination, as well as how individuals are disempowered by the centralisation of certain systems, such as academic publishing platforms and social media. I share my findings on the feasibility of a decentralised and interoperable information space where researchers can control their identifiers whilst fulfilling the core functions of scientific communication: registration, awareness, certification, and archiving. The contemporary research communication paradigm operates under a diverse set of sociotechnical constraints, which influence how units of research information and personal data are created and exchanged. Economic forces and non-interoperable system designs mean that researcher identifiers and research contributions are largely shaped and controlled by third-party entities; participation requires the use of proprietary systems. From a technical standpoint, this thesis takes a deep look at semantic structure of research artifacts, and how they can be stored, linked and shared in a way that is controlled by individual researchers, or delegated to trusted parties. Further, I find that the ecosystem was lacking a technical Web standard able to fulfill the awareness function of research communication. Thus, I contribute a new communication protocol, Linked Data Notifications (published as a W3C Recommendation) which enables decentralised notifications on the Web, and provide implementations pertinent to the academic publishing use case. So far we have seen decentralised notifications applied in research dissemination or collaboration scenarios, as well as for archival activities and scientific experiments. Another core contribution of this work is a Web standards-based implementation of a clientside tool, dokieli, for decentralised article publishing, annotations and social interactions. dokieli can be used to fulfill the scholarly functions of registration, awareness, certification, and archiving, all in a decentralised manner, returning control of research contributions and discourse to individual researchers. The overarching conclusion of the thesis is that Web technologies can be used to create a fully functioning ecosystem for research communication. Using the framework of Web architecture, and loosely coupling the four functions, an accessible and inclusive ecosystem can be realised whereby users are able to use and switch between interoperable applications without interfering with existing data. Technical solutions alone do not suffice of course, so this thesis also takes into account the need for a change in the traditional mode of thinking amongst scholars, and presents the Linked Research initiative as an ongoing effort toward researcher autonomy in a social system, and universal access to human- and machine-readable information. Outcomes of this outreach work so far include an increase in the number of individuals self-hosting their research artifacts, workshops publishing accessible proceedings on the Web, in-the-wild experiments with open and public peer-review, and semantic graphs of contributions to conference proceedings and journals (the Linked Open Research Cloud). Some of the future challenges include: addressing the social implications of decentralised Web publishing, as well as the design of ethically grounded interoperable mechanisms; cultivating privacy aware information spaces; personal or community-controlled on-demand archiving services; and further design of decentralised applications that are aware of the core functions of scientific communication

Atomic Distributed Transactions: a RESTful Design

ABSTRACT The REST architectural style supports the reliable interaction of clients with a single server. However, no guarantees can be made for more complex interactions which require to atomically transfer state among resources distributed across multiple servers. In this paper we describe a lightweight design for transactional composition of RESTful services. The approach -based on the TryCancel/Confirm (TCC) pattern -does not require any extension to the HTTP protocol. The design assumes that resources are designed to comply with the TCC pattern and ensures that the resources involved in the transaction are not aware of it. It delegates the responsability of achieving the atomicity of the transaction to a coordinator which exposes a RESTful API

Linked data as medium for distributed Multi-Agent Systems

The conceptual design and discussion of multi-agents systems (MAS) typically focuses on agents and their models, and the elements and effects in the environment which they perceive. This view, however, leaves out potential pitfalls in the later implementation of the system that may stem from limitations in data models, interfaces, or protocols by which agents and environments exchange information. By today, the research community agrees that for this, that the environment should be understood as well as abstraction layer by which agents access, interpret, and modify elements within the environment. This, however, blurs the the line of the environment being the sum of interactive elements and phenomena perceivable by agents, and the underlying technology by which this information and interactions are offered to agents. This thesis proposes as remedy to consider as third component of multi agent systems, besides agents and environments, the digital medium by which the environment is provided to agents. "Medium" then refers to exactly this technological component via which environment data is published interactively towards the agents, and via which agents perceive, interpret, and finally, modify the underlying environment data. Furthermore, this thesis will detail how MAS may use capabilities of a properly chosen medium to achieve coordinating system behaviors. A suitable candidate technology for digital agent media comes from the Semantic Web in form of Linked Data. In addition to conceptual discussions about the notions of digital agent media, this thesis will provide in detail a specification of a Linked Data agent medium, and detail on means to implement MAS around Linked Data media technologies.Sowohl der konzeptuelle Entwurf von, als auch die wissenschaftliche Diskussion über Multi-Agenten-Systeme (MAS) konzentrieren sich für gewöhnlich auf die Agenten selbst, die Agentenmodelle, sowie die Elemente und Effekte, die sie in ihrer Umgebung wahrnehmen. Diese Betrachtung lässt jedoch mögliche Probleme in einer späteren Implementierung aus, die von Einschränkungen in Datenmodellen, Schnittstellen, oder Protokollen herrühren können, über die Agenten und ihre Umgebung Informationen miteinander austauschen. Heutzutage ist sich die Forschungsgemeinschaft einig, dass die Umgebung als solche als Abstraktionsschicht verstanden werden sollte, über die Agenten Umgebungseffekte und -elemente wahrnehmen, interpretieren, und mit ihnen interagieren. Diese Betrachtungsweise verschleiert jedoch die Trennung zwischen der Umgebung als die Sammlung interaktiver Elemente und wahrnehmbarer Phänomene auf der einen Seite, und der zugrundeliegenden Technologie, über die diese Information den Agenten bereitgestellt wird, auf der anderen. Diese Dissertation schlägt als Lösung vor, zusätzlich zu Agenten undUmgebung ein digitales Medium, über das Agenten die Umgebung bereitgestellt wird, als drittes Element von Multi-Agenten-Systemen zu betrachten. Der Begriff "Medium" bezieht sich dann genau auf diese technologische Komponente, über die Umgebungsinformationen Agenten interaktiv bereitgestellt werden, und über die Agenten die zugrundeliegenden Daten wahrnehmen, interpretieren, und letztendlich modifizieren. Desweiteren wird diese Dissertation aufzeigen, wie die Eigenschaften eines sorgfältig gewählten Mediums ausgenutzt werden können, um ein koordiniertes Systemverhalten zu erreichen. Ein geeigneter Kandidat für ein digitales Agentenmedium findet sich im Ökosystem des „Semantic Web”, in Form von „Linked Data”, wörtlich („verknüpfte Daten”). Zusätzlich zu einer konzeptionellen Diskussion über die Natur digitaler Agenten- Media, spezifiziert diese Dissertation „Linked Data” als Agentenmedium detailliert aus, und beschreibt im Detail die Mittel, wie sich MAS um Linked Data Technologien herum implementieren lassen

Tiedon synkronointi sosiaalisen verkostopalvelun ja RFD -varaston välillä käyttäen julkaisu / tilaus -viestintää

Tämä diplomityö esittelee julkaisu/tilaus -välittäjäsovelluksen tiedon synkronointiin Nokia Smart-M3:n, RDF-pohjaisen henkilökohtaisen Smart Space:n ja Aalto Social Interfacen (ASI), Googlen OpenSocial -tyylisen REST-pohjaisen web servicen välillä. Hyödyllinen tieto on usein hajallaan monen eri internet-resurssin takana, jolloin tiedon yhteen kokoaminen ja tarjoaminen yhteisen rajapinnan kautta on oleellista. Semanttisen webin teknologiat tarjoavat dynaamisesti laajennettavan alustan yhdisteltyjen palvelujen tarjoamiseen. Tällä hetkellä kuitenkin tarvittavien työkalujen puute hankaloittaa tiedon jakamista semanttisten tietokantojen ja perinteisten web-palvelujen välillä. Tätä ongelmaa lähestyttiin ensin kirjallisuustutkimuksella nykyisistä teknologioista. Tuloksia hyödynnettiin synkronointiagentin toteuttamisessa Smart-M3:n ja ASI:n välille, joista jälkimmäinen sisältää olemassa olevaa käyttäjädataa. Python valittiin ohjelmointikieleksi sen monipuolisuuden ja Smart-M3:n tarjoaman kirjastotuen takia. Funktio kirjoitettiin ASI:n hierarkkisen ontologian muuntamiseen RDF-verkoksi, ja molemmat osapuolet yhdistettiin välittäjäagenttisovelluksella. Lopuksi sovelluksen toiminnallisuutta ja suorituskykyä arvioitiin. Tämän työn päätuloksena syntyi Smart-M3:n ja ASI:n välillä synkronointia varten virheensietokykyinen agenttisovellus, sekä sen arviointi. Sovellusta voi käyttää sellaisenaan, ja se tarjoaa myös pohjan uusien Aalto-palveluita hyödyntävien agenttien yhdistämiseen Smart-M3:een tai muuhun semanttiseen tietokantaan. Tämä helpottaa henkilökohtaisen Smart Space -käsitteen hyödyntämistä älykkääseen ja tiedon jakamiseen olemassa olevien internet-resurssien välillä, vaatimatta muutoksia niiden toteutukseen.This Thesis presents a publish/subscribe mediator application for synchronizing data between an RDF-based personal Smart Space, provided by Nokia Smart-M3, and Aalto Social Interface (ASI), a Google OpenSocial inspired RESTful Web Service. As useful information is scattered over a multitude of different internet resources, aggregating data to enable accessing them through a single interface becomes essential. The Semantic Web technologies provide a dynamically extensible platform for building composite services. However, currently there is a lack of necessary tools to enable sharing data between semantic databases and traditional Web Services in practice. This problem was approached by first conducting a literature study about the current technologies. The results were used in implementing a synchronization agent between Smart-M3 and ASI, which provides existing user data. Python was chosen as the programming language for its flexibility and the provided Smart-M3 Python knowledge processor library. Functions for mapping ASI's hierarchical ontology and data to an RDF graph were written, and both sides were connected with the mediator agent application. Finally, the application's functionality and performance were evaluated. The main result of this Thesis is a fault-tolerant agent software for synchronizing between Smart-M3 and ASI, and an evaluation of the software and its future possibilities. The agent can be used as such, and it also provides a basis for implementing further agents that connect other Aalto services to Smart-M3 or some other semantic database. This will facilitate wider adoption of the personal Smart Space concept as a framework for intelligently and non-intrusively sharing data between existing internet resources