Saverio Giallorenzo

Microservices: Yesterday, Today, and Tomorrow

Microservices is an architectural style inspired by service-oriented computing that has recently started gaining popularity. Before presenting the current state-of-the-art in the field, this chapter reviews the history of software architecture, the reasons that led to the diffusion of objects and services first, and microservices later. Finally, open problems and future challenges are introduced. This survey primarily addresses newcomers to the discipline, while offering an academic viewpoint on the topic. In addition, we investigate some practical issues and point out some potential solutions.

AIOCJ: A Choreographic Framework for Safe Adaptive Distributed Applications

We present AIOCJ, a framework for programming distributed adaptive applications. Applications are programmed using AIOC, a choreographic language suited for expressing patterns of interaction from a global point of view. AIOC allows the programmer to specify which parts of the application can be adapted. Adaptation takes place at runtime by means of rules, which can change during the execution to tackle possibly unforeseen adaptation needs. AIOCJ relies on a solid theory that ensures applications to be deadlock-free by construction also after adaptation. We describe the architecture of AIOCJ, the design of the AIOC language, and an empirical validation of the framework.

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.

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 (DIOC), 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 DIOC fragments from outside the application. DIOC programs are compiled, generating code for each participant in a process-level language called Dynamic Process-Oriented Choreographies (DPOC). We prove that DPOC distributed applications generated from DIOC 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 DIOCs to distributed Jolie programs, and a runtime environment to support their execution.

Data security issues in MaaS-enabling platforms

Mobility as a Service takes the concept of XaaS to transportation: a MaaS provider shall merge transport options from different mobility providers, seamlessly handling the whole experience of traveling, from providing information, to travel planning, and payments handling. To effectively support the creation of a market of MaaS providers, we envision the creation of ICT infrastructures based on microservices, a modern and renowned development model that fosters the creation of an ecosystem of reusable components. The flexibility of such platforms is their key advantage, yet it poses many security issues. In this paper, we look at these problems through the lens of our experience on one of such platforms, called SMAll. We classify the most relevant vulnerabilities related to data reliability, integrity, and authenticity, and we investigate directions for their mitigation.

Self-Reconfiguring Microservices

Microservices is an emerging paradigm for the development of distributed systems that, originating from Service-Oriented Architecture, focuses on the small dimension, the loose coupling, and the dynamic topology of services. Microservices are particularly appropriate for the development of distributed systems in the Cloud. However, their dynamic nature calls for suitable techniques for their automatic deployment. In this paper we address this problem and we propose JRO Jolie Redeployment Optimiser, a tool for the automatic and optimised deployment of microservices written in the Jolie language. The tool uses Zephyrus, a state of the art tool that automatically generates a fully detailed Service-Oriented Architecture configuration starting from a partial and abstract description of the target application.

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 — from individual operators to markets of federated MaaS providers — to classify the potential threats of each tier and propose the appropriate countermeasures, in an effort to mitigate the problems.

Developing correct, distributed, adaptive software

We illustrate our approach to develop and verify distributed, adaptive software systems. The cornerstone of our framework is the use of choreography languages, which allow us to obtain correctness by construction. Workflow Patterns are also used as abstract tools to design real systems, while techniques based on abstract interpretation and on dynamic verification are integrated in our framework to reduce the complexity of verification. We develop a methodology for verifying distributed, adaptive software systems.The cornerstone of our framework is the use of choreography languages.We integrate also different techniques based on abstract interpretation and on dynamic verification.

Service-Oriented Architectures: from Design to Production exploiting Workflow Patterns

In Service-Oriented Architectures (SOA) services are composed by coordinating their communications into a flow of interactions. Coloured Petri nets (CPN) offer a formal yet easy tool for modelling abstract SOAs. Still, mapping abstract SOAs into executable ones requires a non-trivial and time-costly analysis. Here, we propose a methodology that maps CPN-modelled SOAs into executable Jolie SOAs (our target language). To this end, we employ a collection of recurring control-flow patterns, called Workflow Patterns, as composable blocks of the translation. Following our methodology, we discuss how the Workflow Patterns we consider are translated in Jolie. Finally, we validate our methodology with a realistic use case. As additional result of our research, we could pragmatically assess the expressiveness of Jolie with relation to the considered Workflow Patterns.

Cloud-of-Things meets Mobility-as-a-Service: An insider threat perspective

Abstract 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 revise and extend previous work where we classified the potential threats of individual operators and markets of federated MaaS providers, proposing appropriate countermeasures to mitigate the problems. In addition, we consider the emerging case of Cloud-of-Things (CoT) for mobility, i.e., networks of ubiquitous, pervasive devices that provide real-time data on objects and people. Automation and pervasiveness of CoT make an additional attack surface for insiders. In an effort to limit such phenomenon, we present an overlay networking architecture, based on gossip protocols, that lets users share information on mobility with each other. A peculiarity of the architecture is that it both constrains the quality and quantity of data obtainable by insiders, optimizing the routing of requests to involve only users that are able to answer them.