Design and validation of stateful composite RESTful web services

A web service is a software system that provides a machine-processable interface to the other machines over the network using different Internet protocols. They are being increasingly used in the industry in order to automate different tasks and offer services to a wider audience. The REST architectural style aims at producing scalable and extensible web services using technologies that play well with the existing tools and infrastructure of the web. It provides a uniform set of operation that can be used to invoke a CRUD interface (create, retrieve, update and delete) of a web service. The stateless behavior of the service interface requires that every request to a resource is independent of the previous ones facilitating scalability. Automated systems, e.g., hotel reservation systems, provide advanced scenarios for stateful services that require a certain sequence of requests that must be followed in order to fulfill the service goals. Designing and developing such services for advanced scenarios with REST constraints require rigorous approaches that are capable of creating web services that can be trusted for their behavior. Systems that can be trusted for their behavior can be termed as dependable systems. This thesis presents an integrated design, analysis and validation approach that facilitates the service developer to create dependable and stateful REST web services. The main contribution of this thesis is that we provide a novel model-driven methodology to design behavioral REST web service interfaces and their compositions. The behavioral interfaces provide information on what methods can be invoked on a service and the pre- and post-conditions of these methods. The methodology uses Unified Modeling Language (UML), as the modeling language, which has a wide user base and has mature tools that are continuously evolving. We have used UML class diagram and UML state machine diagram with additional design constraints to provide resource and behavioral models, respectively, for designing REST web service interfaces. These service design models serve as a specification document and the information presented in them have manifold applications. The service design models also contain information about the time and domain requirements of the service that can help in requirement traceability which is an important part of our approach. Requirement traceability helps in capturing faults in the design models and other elements of software development environment by tracing back and forth the unfulfilled requirements of the service. The information about service actors is also included in the design models which is required for authenticating the service requests by authorized actors since not all types of users have access to all the resources. In addition, following our design approach, the service developer can ensure that the designed web service interfaces will be REST compliant. The second contribution of this thesis is consistency analysis of the behavioral REST interfaces. To overcome the inconsistency problem and design errors in our service models, we have used semantic technologies. The REST interfaces are represented in web ontology language, OWL2, that can be part of the semantic web. These interfaces are used with OWL 2 reasoners to check unsatisfiable concepts which result in implementations that fail. This work is fully automated thanks to the implemented translation tool and the existing OWL 2 reasoners. The third contribution of this thesis is the verification and validation of REST web services. We have used model checking techniques with UPPAAL model checker for this purpose. The timed automata of UML based service design models are generated with our transformation tool that are verified for their basic characteristics like deadlock freedom, liveness, reachability and safety. The implementation of a web service is tested using a black-box testing approach. Test cases are generated from the UPPAAL timed automata and using the online testing tool, UPPAAL TRON, the service implementation is validated at runtime against its specifications. Requirement traceability is also addressed in our validation approach with which we can see what service goals are met and trace back the unfulfilled service goals to detect the faults in the design models. A final contribution of the thesis is an implementation of behavioral REST interfaces and service monitors from the service design models. The partial code generation tool creates code skeletons of REST web services with method pre and post-conditions. The preconditions of methods constrain the user to invoke the stateful REST service under the right conditions and the post condition constraint the service developer to implement the right functionality. The details of the methods can be manually inserted by the developer as required. We do not target complete automation because we focus only on the interface aspects of the web service. The applicability of the approach is demonstrated with a pedagogical example of a hotel room booking service and a relatively complex worked example of holiday booking service taken from the industrial context. The former example presents a simple explanation of the approach and the later worked example shows how stateful and timed web services offering complex scenarios and involving other web services can be constructed using our approach.

SimpleREST -RESTful DSpace API

Poster at Open Repositories 2014, Helsinki, Finland, June 9-13, 2014

Vårdande och icke-vårdande tröst

The aim of the thesis is, from a caring science perspective including a caring theology perspective, to illustrate the meaning of the phenomenon consolation and howconsolation relates to suffering and care. Two studies were completed where staff and elderly care receivers were interviewed and a third study focused on an analysis of consolation as it is presented in the Book of Job in the Old Testament. These studies deal with carers' experiences of consolation and consoling, elderly care receivers' experiences of consolation, and Job's experience of consolation. Phenomenology and hermeneutics form the basis for the methodological approach. A phenomenological- hermeneutic method, inspired by Paul Ricoeur, has been used for the text analyses. The thesis also covers significant aspects of poetical and religious texts. The metaphors that occur in the interview studies with the carers and the elderly are analysed in order to take care of the excess of meaning that, according to Ricoeur, can be expressed in metaphors. The result showfive overall meanings: The contradictory consolation, The bonding consolation, The mute and rigid consolation, The uncontrolled consolation and The restful consolation. A caring consolation is contradictory in the sense that it entails that the sufferer on the one hand passes on his or her suffering to someone else and on the other hand that the suffering can be returned to be suffered. Consolation can thus entail suffering. The bonding consolation is present, i.e. is with the sufferer and is based on that person's suffering. This consolation is characterised by a close fellowship, a feeling of being understood at a deeper level. The results also reveal a consolation that is mute and rigid. This consolation does not respond to the sufferer's experience of his or her suffering, is shapeless and therefore unable to follow the suffering. An example of a mute, rigid and non-caring consolation is the consolation of the friends in the Book of Job. This consolation is not capable of consoling because it does not correspond to where Job is, i.e. in his experience of his suffering. A caring consolation is also uncontrolled because it is on the one hand spontaneous and on the other hand helps the sufferer to lose control over the suffering. To lose control entails, amongst other things, the sufferer giving up trying to understand suffering and instead lets that which is incomprehensible be incomprehensible. A consoling and health-bringing rest in or from the struggle with suffering presents itself by giving up what in various ways is tied to the suffering. The result as a whole is interpreted from a caring science perspective with the following important concepts: caring relationship, faith, health and sacrifice. Consolation as health is considered on the basis of a theoretical model inspired by Katie Eriksson's ontological health model. The research is also illustrated from a philosophical-ethical perspective, mainly based on the work of Emmanuel Levinas. The findings are discussed in relation to previous research and also to caring science, society and care.

Elasticsearch as a new search engine for Invenio and more

Presentation at Open Repositories 2014, Helsinki, Finland, June 9-13, 2014

ZENODO - an open dependable home for the long-tail of science

Poster at Open Repositories 2014, Helsinki, Finland, June 9-13, 2014

Development of an Ecology-Oriented Software-Defined Networking Framework

ICT contributed to about 0.83 GtCO2 emissions where the 37% comes from the telecoms infrastructures. At the same time, the increasing cost of energy has been hindering the industry in providing more affordable services for the users. One of the sources of these problems is said to be the rigidity of the current network infrastructures which limits innovations in the network. SDN (Software Defined Network) has emerged as one of the prominent solutions with its idea of abstraction, visibility, and programmability in the network. Nevertheless, there are still significant efforts needed to actually utilize it to create a more energy and environmentally friendly network. In this paper, we suggested and developed a platform for developing ecology-related SDN applications. The main approach we take in realizing this goal is by maximizing the abstractions provided by OpenFlow and to expose RESTful interfaces to modules which enable energy saving in the network. While OpenFlow is made to be the standard for SDN protocol, there are still some mechanisms not defined in its specification such as settings related to Quality of Service (QoS). To solve this, we created REST interfaces for setting of QoS in the switches which can maximize network utilization. We also created a module for minimizing the required network resources in delivering packets across the network. This is achieved by utilizing redundant links when it is needed, but disabling them when the load in the network decreases. The usage of multi paths in a network is also evaluated for its benefit in terms of transfer rate improvement and energy savings. Hopefully, the developed framework can be beneficial for developers in creating applications for supporting environmentally friendly network infrastructures.