Programming adaptive microservice applications: An AIOCJ tutorial

This tutorial describes AIOCJ, which stands for Adaptive Interaction Oriented Choreographies in Jolie, a choreographic language for programming microservice-based applications which can be updated at runtime. The compilation of a single AIOCJ program generates the whole set of distributed microservices that compose the application. Adaptation is performed using adaptation rules. Abstractly, each rule replaces a pre-delimited part of the program with the new code contained in the rule itself. Concretely, at runtime, the application of a rule updates part of the microservices that compose the application so to match the behavior specified by the updated program. Thanks to the properties of choreographies, the adaptive application is free from communication deadlocks and message races even after adaptation

Guess Who\u2019s Coming: Runtime Inclusion of Participants in Choreographies

In Choreographic Programming, a choreography specifies in a single artefact the expected behaviour of all the participants in a distributed system. The choreography is used to synthesise correct-by-construction programs for each participant. In previous work, we defined Dynamic Choreographies to support the update of distributed systems at runtime. In this work, we extend Dynamic Choreographies to include new participants at runtime, capturing those use cases where the system might be updated to interact with new, unforeseen stakeholders. We formalise our extension, prove its correctness, and present an implementation in the AIOCJ choreographic framework

Microservice Transition and its Granularity Problem: A Systematic Mapping Study

Microservices have gained wide recognition and acceptance in software industries as an emerging architectural style for autonomic, scalable, and more reliable computing. The transition to microservices has been highly motivated by the need for better alignment of technical design decisions with improving value potentials of architectures. Despite microservices' popularity, research still lacks disciplined understanding of transition and consensus on the principles and activities underlying "micro-ing" architectures. In this paper, we report on a systematic mapping study that consolidates various views, approaches and activities that commonly assist in the transition to microservices. The study aims to provide a better understanding of the transition; it also contributes a working definition of the transition and technical activities underlying it. We term the transition and technical activities leading to microservice architectures as microservitization. We then shed light on a fundamental problem of microservitization: microservice granularity and reasoning about its adaptation as first-class entities. This study reviews state-of-the-art and -practice related to reasoning about microservice granularity; it reviews modelling approaches, aspects considered, guidelines and processes used to reason about microservice granularity. This study identifies opportunities for future research and development related to reasoning about microservice granularity.Comment: 36 pages including references, 6 figures, and 3 table

No more, no less - A formal model for serverless computing

Serverless computing, also known as Functions-as-a-Service, is a recent paradigm aimed at simplifying the programming of cloud applications. The idea is that developers design applications in terms of functions, which are then deployed on a cloud infrastructure. The infrastructure takes care of executing the functions whenever requested by remote clients, dealing automatically with distribution and scaling with respect to inbound traffic. While vendors already support a variety of programming languages for serverless computing (e.g. Go, Java, Javascript, Python), as far as we know there is no reference model yet to formally reason on this paradigm. In this paper, we propose the first formal programming model for serverless computing, which combines ideas from both the $\lambda$-calculus (for functions) and the $\pi$-calculus (for communication). To illustrate our proposal, we model a real-world serverless system. Thanks to our model, we are also able to capture and pinpoint the limitations of current vendor technologies, proposing possible amendments

No More, No Less - A Formal Model for Serverless Computing

Part 3: Exploring New FrontiersInternational audienceServerless computing, also known as Functions-as-a-Service, is a recent paradigm aimed at simplifying the programming of cloud applications. The idea is that developers design applications in terms of functions, which are then deployed on a cloud infrastructure. The infrastructure takes care of executing the functions whenever requested by remote clients, dealing automatically with distribution and scaling with respect to inbound traffic.While vendors already support a variety of programming languages for serverless computing (e.g. Go, Java, Javascript, Python), as far as we know there is no reference model yet to formally reason on this paradigm. In this paper, we propose the first core formal programming model for serverless computing, which combines ideas from both the lambda-calculus (for functions) and the pi-calculus (for communication). To illustrate our proposal, we model a real-world serverless system. Thanks to our model, we capture limitations of current vendors and formalise possible amendments

Ephemeral data handling in microservices

Ephemeral data handling, whereby processed data do not persist, is an emerging requirement of connected IT systems, due to storage constraints (IoT) or regulatory demands (eHealth, GDPR). We present ongoing work on TQuery, a query language for ephemeral data handling in microservices

Jolie and LEMMA: Model-Driven Engineering and Programming Languages Meet on Microservices

In microservices, Model-Driven Engineering (MDE) has emerged as a powerful methodology for architectural design. Independently, the community of programming languages has investigated new linguistic abstractions for effective microservice development. Here, we present the first preliminary study of how the two approaches can cross-pollinate, taking the LEMMA framework and the Jolie programming language as respective representatives. We establish a common ground for comparing the two technologies in terms of metamodels, discuss practical enhancements that can be derived from the comparison, and present some directions for future work that arise from our new viewpoint

Microservice Dynamic Architecture-Level Deployment Orchestration

We develop a novel approach for run-time global adaptation of microservice applications, based on synthesis of architecture-level reconfiguration orchestrations. More precisely, we devise an algorithm for automatic reconfiguration that reaches a target system Maximum Computational Load by performing optimal deployment orchestrations. To conceive and simulate our approach, we introduce a novel integrated timed architectural modeling/execution language based on an extension of the actor-based object-oriented Abstract Behavioral Specification (ABS) language. In particular, we realize a timed extension of SmartDeployer, whose ABS code annotations make it possible to express architectural properties. Our Timed SmartDeployer tool fully integrates time features of ABS and architectural annotations by generating timed deployment orchestrations. We evaluate the applicability of our approach on a realistic microservice application taken from the literature: an Email Pipeline Processing System. We prove its effectiveness by simulating such an application and by comparing architecture-level reconfiguration with traditional local scaling techniques (which detect scaling needs and enact replications at the level of single microservices). Our comparison results show that our approach avoids cascading slowdowns and consequent increased message loss and latency, which affect traditional local scaling

No more, no less: A formal model for serverless computing

Serverless computing, also known as Functions-as-a-Service, is a recent paradigm aimed at simplifying the programming of cloud applications. The idea is that developers design applications in terms of functions, which are then deployed on a cloud infrastructure. The infrastructure takes care of executing the functions whenever requested by remote clients, dealing automatically with distribution and scaling with respect to inbound traffic. While vendors already support a variety of programming languages for serverless computing (e.g. Go, Java, Javascript, Python), as far as we know there is no reference model yet to formally reason on this paradigm. In this paper, we propose the first core formal programming model for serverless computing, which combines ideas from both the λ-calculus (for functions) and the π-calculus (for communication). To illustrate our proposal, we model a real-world serverless system. Thanks to our model, we capture limitations of current vendors and formalise possible amendments