Dagstuhl News January - December 1999

"Dagstuhl News" is a publication edited especially for the members of the Foundation "Informatikzentrum Schloss Dagstuhl" to thank them for their support. The News give a summary of the scientific work being done in Dagstuhl. Each Dagstuhl Seminar is presented by a small abstract describing the contents and scientific highlights of the seminar as well as the perspectives or challenges of the research topic

Applications integration for manufacturing control systems with particular reference to software interoperability issues

The introduction and adoption of contemporary computer aided manufacturing control systems (MCS) can help rationalise and improve the productivity of manufacturing related activities. Such activities include product design, process planning and production management with CAD, CAPP and CAPM. However, they tend to be domain specific and would generally have been designed as stand-alone systems where there is a serious lack of consideration for integration requirements with other manufacturing activities outside the area of immediate concern. As a result, "islands of computerisation" exist which exhibit deficiencies and constraints that inhibit or complicate subsequent interoperation among typical MCS components. As a result of these interoperability constraints, contemporary forms of MCS typically yield sub-optimal benefits and do not promote synergy on an enterprise-wide basis. The move towards more integrated manufacturing systems, which requires advances in software interoperability, is becoming a strategic issue. Here the primary aim is to realise greater functional synergy between software components which span engineering, production and management activities and systems. Hence information of global interest needs to be shared across conventional functional boundaries between enterprise functions. The main thrust of this research study is to derive a new generation of MCS in which software components can "functionally interact" and share common information through accessing distributed data repositories in an efficient, highly flexible and standardised manner. It addresses problems of information fragmentation and the lack of formalism, as well as issues relating to flexibly structuring interactions between threads of functionality embedded within the various components. The emphasis is on the: • definition of generic information models which underpin the sharing of common data among production planning, product design, finite capacity scheduling and cell control systems. • development of an effective framework to manage functional interaction between MCS components, thereby coordinating their combined activities. • "soft" or flexible integration of the MCS activities over an integrating infrastructure in order to (i) help simplify typical integration problems found when using contemporary interconnection methods for applications integration; and (ii) enable their reconfiguration and incremental development. In order to facilitate adaptability in response to changing needs, these systems must also be engineered to enable reconfigurability over their life cycle. Thus within the scope of this research study a new methodology and software toolset have been developed to formally structure and support implementation, run-time and change processes. The tool set combines the use of IDEFO (for activity based or functional modelling), IDEFIX (for entity-attribute relationship modelling), and EXPRESS (for information modelling). This research includes a pragmatic but effective means of dealing with legacyl software, which often may be a vital source of readily available information which supports the operation of the manufacturing enterprise. The pragmatism and medium term relevance of the research study has promoted particular interest and collaboration from software manufacturers and industrial practitioners. Proof of concept studies have been carried out to implement and evaluate the developed mechanisms and software toolset

Mobilité et bases de données : Etat de l'art et perspectives: 1ère partie. Action spécifique CNRS « Mobilité/Accès aux données »

National audienceThis paper is the result of the collective work done within the CNRS specific action Mobility/Data access with seven french laboratories IMAG-LSR, INT-Evry, LIP6, LORIA, PRiSM, EPFL, LIRMM . All pursuiving research in mobile computing and mobile databases. The action started in October 2001 for an initial period of one year. The activities and results of this action are available online at [AS_BDMobile]. The objective of this paper is to review the state of progress in mobile databases and identify major research directions. However, the research domain is so broad that we cannot pretend to be exhaustive. First, we propose a classification of mobile applications and a characterization of their execution environments. Then, we analyze the following issues: management of localization data, data access models, copy consistency and synchronization, management of embedded data, data confidentiality, and adaptability of software infrastructures to mobility and disconnection. For editorial reasons, this paper is published as a chronicle with two parts of equal importance.Ce document est le résultat d'un travail collectif réalisé par les membres de l'action spécifique CNRS « Mobilité/Accès aux données ». Il fait le point sur l'état d'avancement des travaux réalisés dans le domaine des bases de données mobiles et identifie quelques orientations de recherche jugées particulièrement pertinentes. Compte tenu de la largeur du domaine, ce document ne prétend cependant pas à l'exhaustivité. Après une classification des applications mobiles et une caractérisation de leur environnement d'exécution, les problématiques suivantes sont analysées : gestion des données de localisation, modèles d'accès aux données, cohérence des traitements et synchronisation de copies, gestion de données embarquées, confidentialité des données et enfin adaptabilité des infrastructures logicielles à la mobilité et à la déconnexion

Preventing Domestic Abuse for Children and Young People (PEACH): A Mixed Knowledge Scoping Review

Background: A range of interventions that aim to prevent domestic abuse has been developed for children and young people in the general population. While these have been widely implemented, few have been rigorously evaluated. This study aimed to discover what was known about these interventions for children and what worked for whom in which settings. Review methods: This mixed knowledge review was informed by realist principles and comprised four overlapping phases: an online mapping survey to identify current provision; a systematic review of the existing literature; a review of the UK ‘grey’ literature; and consultation with young people and experts. Information from these four sources of evidence informed analysis of costs and benefits. Results: The evidence for interventions achieving changes in knowledge and attitudes was stronger than that for behavioural change. Shifting social norms in the peer group emerged as a key mechanism of change. Media campaigns act to influence the wider social climate within which more targeted interventions are received, and they are also a source for programme materials. While most interventions are delivered in secondary schools, they are increasingly targeted at younger children. The review emphasised the importance of a school’s ‘readiness’ to introduce preventative interventions which need to be supported across all aspects of school life. Involving young people in the design and delivery of programmes increases authenticity and this emerged as a key ingredient in achieving impact. Longer interventions delivered by appropriately trained staff appeared likely to be more effective. Teachers emerged as well placed to embed interventions in schools but they require training and support from those with specialist knowledge in domestic abuse. There was evidence that small groups of students who were at higher risk might have accounted for some results regarding effectiveness and that programme effectiveness may vary for certain subgroups. Increasingly, boys are being identified as a target for change. The study identified a need for interventions for disabled children and children and young people from black, Asian, minority ethnic and refugee groups and a particular lack of materials designed for lesbian, gay, bisexual and transgender young people. Limitations: Very little evidence was identified on costs and cost-effectiveness. Few studies showed an effect at the level of significance set for the review. Where it did exist, the effect size was small, except in respect of improved knowledge. The inability to calculate a response rate for the mapping survey, which used a snowballing approach, limits the ability to generalise from it. Conclusions: While it is appropriate to continue to deliver interventions to whole populations of children and young people, effectiveness appeared to be influenced by high-risk children and young people, who should be directed to additional support. Programmes also need to make provision to manage any resulting disclosures. Interventions appear to be context specific, and so those already being widely delivered in the UK and which are likely to be acceptable should be robustly tested. Funding: The National Institute for Health Research Public Health Research programme

Towards the development of a strategy for a national spatial data infrastructure

In today's world of ever advancing technology the time is precisely right for investment in the development and implementation of a national spatial data infrastructure. This implies that all spatial data presently scattered in different departments and organisations are coordinated and shared. In the Kingdom of Saudi Arabia there are a number of different mapping and Geographic Information System (GIS) activities being implemented within various government organisations, each with its own merits. Certain research and pilot projects have also been carried out aiming to provide help and recommendations with regard to spatial data sharing and to promote awareness of the importance of spatial data to the Kingdom's development. However, there is an urgent need for a consolidation of effort to avoid the costly mistake of duplication of work; hence the need for a unified national spatial data infrastructure. This research aims to develop a conceptual framework for a strategy for a national spatial data infrastructure (SNSDI) including its main components. A proposal is presented for a Saudi national spatial data infrastructure (which happens to have the same abbreviation - SNSDI) to consolidate isolated mapping and spatial data efforts in the Kingdom of Saudi Arabia in place of the current practice of each agency acting independently. This research project will hopefully provide a leadership role in developing a Kingdom-wide spatial data infrastructure

Automatic Geospatial Data Conflation Using Semantic Web Technologies

Duplicate geospatial data collections and maintenance are an extensive problem across Australia government organisations. This research examines how Semantic Web technologies can be used to automate the geospatial data conflation process. The research presents a new approach where generation of OWL ontologies based on output data models and presenting geospatial data as RDF triples serve as the basis for the solution and SWRL rules serve as the core to automate the geospatial data conflation processes

Coordination between multiple microservices: a systematic mapping study

Mikropalveluarkkitehtuurin suosio on kasvanut huomattavisti viimeisen kymmenen vuoden aikana sen tarjoamien hyötyjen takia, jotka ovat osittain seurausta palveluiden vähentyneestä riippuvuudesta toisiinsa. Riippumattomuutta lisää esimerkiksi hajautettu tiedonhallinta, jonka mukaan jokaisen palvelun tulisi olla vastuussa omistamansa tiedon hallinasta käyttäen sopivinta tietokantateknologiaa. Vaikka tällä voidaan saavuttaa useita etuja, aiheuttaa se myös uusia ongelmia etenkin tiedon yhtenäisyyden hallinnassa kun usean palvelun hallitsemaa tietoa täytyy muokata yhteistyössä. Tämä ongelma voitaisiin välttää käyttämällä yhteistä tietokantaa palveluiden välillä, mutta se osittain poistaisi mikropalvelun hyödyt tuomalla lisää riippuvuusuhteita mikropalveluiden välille. Tästä syystä on tärkeää tarkastella muita vaihtoehtoja hajautetun tiedon hallintaan siten, että mikropalvelun hyötyjä on mahdollista ylläpitää. Tässä työssä toteutetaan systemaattinen kirjallisuuskartoitus, jonka tavoitteena on löytää sopivia malleja usean mikropalvelun väliseen koordinointiin. Aluksi työssä tunnistetaan koordinointimallit, joista käydään paljon keskustelua kirjallisuudessa. Tämän jälkeen jokaisesta valitusta mallista keskustellaan käyttäen yhteistä keskustelukaavaa, joka sisältää mallin määrittelyn sekä hyötyjen ja haittojen listaamisen. Kirjallisuuskartoituksessa saatujen tulosten perusteella huomattiin, että mikropalveluarkkitehtuurissa suositaan malleja jotka tarjoavat lopulta yhtenäistä tulosta (eng. eventual consistent). Tämä eroaa huomattavasti perinteisistä ohjelmistoista, joissa yhtenäisyyden täytyy olla ehdoton ja toteuttaa kaikki ACID periaatteet. Ero johtuu osittain siitä, että mallit joilla voidaan tarjota ehdoton johdonmukaisuus usean palvelun välillä vähentää mahdollisuutta rinnakkaisuudelle ja lisäksi vaikuttaa palveluiden saavutettavuuteen heikentävästi. Tästä syystä mikropalveluarkkitehtuurissa usein luovutaan ehdottomasta yhtenäisyydestä, koska sen seuraksena voidaan saavuttaa korkeampi suorituskyky ja lisääntynyt saavutettavuus. Etenkin saga-mallin havaittiin olevan suosittu yhtenäisyyden hallintaan mikropalveluiden välillä, koska siitä keskusteltiin ja siihen liittyviä parannusehdotuksia ja toteutustapoja ehdotettiin useissa töissä. Vaikkakin saga-malli on tällä hetkellä yleisesti käytetty tapa mikropalveluiden välisessä koordinoinnissa, valitusta kirjallisuudesta huomattiin myös tarve ehdottoman johdonmukaisuuden toteuttaville malleille. Useita uusia malleja ehdotettiin ratkaisemaan tämänhetkisissä ratkaisuissa olevia ongelmia, mutta myös ratkaisuja joilla voitaisiin poistaa tarve usean palvelun väliseen koordinointiin ehdotettiin. Vaikka ehdotetut mallit ovatkin lupaavia, ne ovat vasta suunnitteluvaiheessa eikä niitä voida käyttää luotettavasti tai helposti teollisuusympäristössä. Tästä syystä lisätutkimuksia tarvitaan näiden uusien mallien jalostamiseen tai kokonaan uusien mallien visiontiin.The popularity of microservice architecture has risen recently due to its multiple advantages partly related to the increased independence of services. One of the features that improve independence is decentralized data management, which outlines that each service should manage its own data with preferred data management technologies. However, the usage of decentralized data management brings problems, especially with data consistency when data owned by separate microservices must be modified in coordination. To alleviate this, a shared database between services could be used as it removes the need for coordination altogether, but then again, the usage of a single database could defeat some of the benefits of microservice architecture by increasing tight coupling between services. Therefore, it is important to consider other possibilities to manage the coordination while maintaining the independence of the services. We conducted a systematic mapping study to find out suitable design patterns to manage the coordination between multiple microservices. Firstly, design patterns that seemed widely discussed and adopted were identified. After this, these patterns were presented using a template that included advantages and disadvantages for each pattern. The results gathered in the systematic mapping study show that even though traditional systems pursue strict consistency with ACID guarantees, eventual consistency patterns, such as the saga pattern, seem to be more popular in the microservice environment. This is due to drawbacks within distributed transaction protocols including limited concurrency and reduced availability which makes developers choose loosened consistency as a trade-off for higher availability and increased performance. The prevalence of the saga pattern can be seen in the selected works as there are multiple articles proposing methods to manage different parts of the pattern. Also, implementation details were mainly related to the saga pattern in the selected works. Even though the saga pattern is currently the most prevalent option, there is still interest in highly consistent coordination methods in the research community. Multiple solutions have been proposed, which either propose new consistency protocols with strict consistency guarantees or entirely new solutions to remove the need for coordination completely. However, there are no novel solutions that could manage the requirements of microservice architecture reliably in the industry setting yet. Therefore, further research is still required to refine already proposed solutions or to vision new solutions for this problem

Digital ecosystems : a distributed service oriented approach for business transactions

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