57 research outputs found
Real-World Choreographies
Choreographies are a relatively new tool for designing distributed systems from a global viewpoint. Moreover, choreographies are also free from deadlocks and race conditions by design. Recent theoretical results defined proper Endpoint Projection (EPP) functions to compile choreographic specifications into their single components. Since EPPs are behavioural preserving, projected systems also enjoy freedom from deadlocks and races by construction.
Aim of this PhD is to formalise non-trivial features of distributed systems with choreographies and to translate our theoretical results into the practice of implemented systems. To this purpose, we provide two main contributions.
The first contribution tackles one of the most challenging features of distributed development: programming correct and consistent runtime updates of distributed systems. Our solution is a theoretical model of dynamic choreographies that provides a clear definition of which components and behaviours can be updated. We prove that compiled choreographic specifications are correct and consistent after any update. We also refine our theoretical model to provide a finer control over updates. On this refinement, we develop a framework for programming adaptable distributed systems.
The second contribution covers one of the main issues of implementing theoretical results on choreographies: formalising the compilation from choreographies to executable programs. There is a sensible departure between the present choreographic frameworks and their theoretical models because their theories abstract communications with synchronisation on names (a la CCS/Ï-calculus) yet they compile to Jolie programs, an executable language that uses correlation â a renown technology of Service-Oriented Computing â for message routing. Our solution is a theory of Applied Choreographies (AC) that models correlation-based message passing. We pinpoint the key theoretical problems and formalise the principles that developers should follow to obtain correct implementations. Finally, we prove our approach by defining a correct compiler from AC to the calculus behind the Jolie language
Dynamic Choreographies - Safe Runtime Updates of Distributed Applications
Programming distributed applications free from communication deadlocks and
races is complex. Preserving these properties when applications are updated at
runtime is even harder. We present DIOC, a language for programming distributed
applications that are free from deadlocks and races by construction. A DIOC
program describes a whole distributed application as a unique entity
(choreography). DIOC allows the programmer to specify which parts of the
application can be updated. At runtime, these parts may be replaced by new DIOC
fragments from outside the application. DIOC programs are compiled, generating
code for each site, in a lower-level language called DPOC. We formalise both
DIOC and DPOC semantics as labelled transition systems and prove the
correctness of the compilation as a trace equivalence result. As corollaries,
DPOC applications are free from communication deadlocks and races, even in
presence of runtime updates.Comment: Technical Repor
Dynamic Choreographies: Theory And Implementation
Programming distributed applications free from communication deadlocks and
race conditions is complex. Preserving these properties when applications are
updated at runtime is even harder. We present a choreographic approach for
programming updatable, distributed applications. We define a choreography
language, called Dynamic Interaction-Oriented Choreography (AIOC), that allows
the programmer to specify, from a global viewpoint, which parts of the
application can be updated. At runtime, these parts may be replaced by new AIOC
fragments from outside the application. AIOC programs are compiled, generating
code for each participant in a process-level language called Dynamic
Process-Oriented Choreographies (APOC). We prove that APOC distributed
applications generated from AIOC specifications are deadlock free and race free
and that these properties hold also after any runtime update. We instantiate
the theoretical model above into a programming framework called Adaptable
Interaction-Oriented Choreographies in Jolie (AIOCJ) that comprises an
integrated development environment, a compiler from an extension of AIOCs to
distributed Jolie programs, and a runtime environment to support their
execution.Comment: arXiv admin note: text overlap with arXiv:1407.097
Choral: Object-Oriented Choreographic Programming
We present Choral, the first choreographic programming language based on
mainstream abstractions. The key idea in Choral is a new notion of data type,
which allows for expressing that data is distributed over different roles. We
use this idea to reconstruct the paradigm of choreographic programming through
object-oriented abstractions. Choreographies are classes, and instances of
choreographies are objects with states and behaviours implemented
collaboratively by roles.
Choral comes with a compiler that, given a choreography, generates an
implementation for each of its roles. These implementations are libraries in
pure Java, whose types are under the control of the Choral programmer.
Developers can then modularly compose these libraries in their own programs, in
order to participate correctly in choreographies. Choral is the first
incarnation of choreographic programming offering such modularity, which
finally connects more than a decade of research on the paradigm to practical
software development.
The integration of choreographic and object-oriented programming yields other
powerful advantages, where the features of one paradigm benefit the other in
ways that go beyond the sum of the parts. The high-level abstractions and
static checks from the world of choreographies can be used to write concurrent
and distributed object-oriented software more concisely and correctly. We
obtain a much more expressive choreographic language from object-oriented
abstractions than in previous work. For example, object passing makes Choral
the first higher-order choreographic programming language, whereby
choreographies can be parameterised over other choreographies without any need
for central coordination. Together with subtyping and generics, this allows
Choral to elegantly support user-defined communication mechanisms and
middleware
Insider Threats in Emerging Mobility-as-a-Service Scenarios
Mobility as a Service (MaaS) applies the everything-as- \ a-service paradigm of Cloud Computing to transportation: a MaaS \ provider offers to its users the dynamic composition of solutions of \ different travel agencies into a single, consistent interface. \ Traditionally, transits and data on mobility belong to a scattered \ plethora of operators. Thus, we argue that the economic model of \ MaaS is that of federations of providers, each trading its resources to \ coordinate multi-modal solutions for mobility. Such flexibility comes \ with many security and privacy concerns, of which insider threat is \ one of the most prominent. In this paper, we follow a tiered structure \ â from individual operators to markets of federated MaaS providers \ â to classify the potential threats of each tier and propose the \ appropriate countermeasures, in an effort to mitigate the problems
A Language-based Approach for Interoperability of IoT Platforms
The Internet of Things (IoT) promotes the communication among heterogeneous entities, from small sensors to Cloud systems. However, this is realized using a wide range of communication media and data protocols, usually incompatible with each other. Thus, IoT systems tend to grow as homogeneous isolated platforms, which hardly interact. To achieve a higher degree of interoperability among disparate IoT platforms, we propose a language-based approach for communication technology integration. We build on the Jolie programming language, which allows programmers to easily make the same logic work over disparate communication stacks in a declarative, dynamic way. Jolie currently supports the main technologies from Service-Oriented Computing, such as TCP/IP, Bluetooth, and RMI at transport level, and HTTP and SOAP at application level. As technical result, we integrate in Jolie the two most adopted protocols for IoT communication, i.e., CoAP and MQTT. In this paper, we report our experience and we present high-level concepts valuable both for the general implementation of interoperable systems and for the development of other language-based solutions
Towards a Composition-based APIaaS Layer
International audienceApplication Programming Interfaces (APIs) are a standard feature of any application that exposes its functionalities to external invokers. APIs can becomposed thus obtaining new programs with new functionalities. However API composition easily becomes a frustrating and time-costly task that hinders API reuse. The issue derives from technology-dependent features of API composition such as the need of extensive documentation, protocol integration, security issues, etc.. In this paper we introduce the perspective of the API-as-a-Service (APIaaS) layer as tool to ease the development and deployment of applications based on API composition, abstracting communication protocols and message formats. We elicit the desirable features of such a layer and provide a proof-of-concept prototype implemented using a service-oriented language
Federated Platooning: Insider Threats and Mitigations
Platoon formation is a freight organization system where a group of vehicles follows a predefined trajectory maintaining a desired spatial pattern. Benefits of platooning include fuel savings, reduction of carbon dioxide emissions, and efficient allocation of road capacity. While traditionally platooning has been an exclusive option limited to specific geographical areas managed by a single operator, recent technological developments and EU initiatives are directed at the creation of an international, federated market for platooning, i.e., a consortium of platoon operators that collaborate and coordinate their users to constitute freights covering international routes. In this paper, we look at federated platooning from an insiders\u27 perspective. In our development, first we outline the basic elements of platooning and federation of platooning operators. Then, we provide a comprehensive analysis to identify the possible insiders (employees, users, operators, and federated members) and the threats they pose. Finally, we propose two layered, composable technical solutions to mitigate those threats: \emph{a}) a decentralized overlay network that regulates the interactions among the stakeholders, useful to mitigate issues linked to data safety and trustworthiness and \emph{b}) a dynamic federation platform, needed to monitor and interrupt deviant behaviors of federated members
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