Domain Objects and Microservices for Systems Development: a roadmap

This paper discusses a roadmap to investigate Domain Objects being an adequate formalism to capture the peculiarity of microservice architecture, and to support Software development since the early stages. It provides a survey of both Microservices and Domain Objects, and it discusses plans and reflections on how to investigate whether a modeling approach suited to adaptable service-based components can also be applied with success to the microservice scenario

Measuring the modeling complexity of microservice choreography and orchestration: The case of e-commerce applications

Context: With the increasing popularity of microservices for software application development, businesses are migrating from monolithic approaches towards more scalable and independently deployable applications using microservice architectures. Each microservice is designed to perform one single task. However, these microservices need to be composed together to communicate and deliver complex system functionalities. There are two major approaches to compose microservices, namely Choreography and Orchestration. Microservice compositions are mainly built around business functionalities, therefore businesses need to choose the right composition style that best serves their needs. Hence, this research uses existing complexity metrics from the software engineering and business process modeling domains on small, mid-sized, and end-to-end e-commerce scenarios to analyze and compare the level of complexity of microservice Orchestration and Choreography using Business Process Modeling Notation (BPMN). Objective: Comparing the complexity of the two leading composition techniques on small, mid-sized, and end-to-end e-commerce scenarios, using complexity metrics from the software engineering and business process literature. More specifically, we use the metrics to assess the complexity of BPMN-based models representing the abovementioned e-commerce scenarios. Method: This research follows a five-step process for conducting a Design Science Research (DSR) methodology to define, develop and evaluate BPMN-based models for microservice compositions. Results: A series of BPMN workflows are designed as artifacts to investigate microservice Choreography and Orchestration. The results derived from the complexity evaluation of our proposed models show a higher level of complexity in orchestrating microservices for e-commerce applications given the number of services used in modeling Orchestration compared to Choreography. Conclusion: This research uncovers insights on modeling microservice Choreography and Orchestration and discusses the impacts of complexity on the modifiability and understandability of the proposed models. Keywords: Microservice, Microservice Composition, Choreography, Orchestration, Complexity Metric, BPMN

Elastic Business Process Management: State of the Art and Open Challenges for BPM in the Cloud

With the advent of cloud computing, organizations are nowadays able to react rapidly to changing demands for computational resources. Not only individual applications can be hosted on virtual cloud infrastructures, but also complete business processes. This allows the realization of so-called elastic processes, i.e., processes which are carried out using elastic cloud resources. Despite the manifold benefits of elastic processes, there is still a lack of solutions supporting them. In this paper, we identify the state of the art of elastic Business Process Management with a focus on infrastructural challenges. We conceptualize an architecture for an elastic Business Process Management System and discuss existing work on scheduling, resource allocation, monitoring, decentralized coordination, and state management for elastic processes. Furthermore, we present two representative elastic Business Process Management Systems which are intended to counter these challenges. Based on our findings, we identify open issues and outline possible research directions for the realization of elastic processes and elastic Business Process Management.Comment: Please cite as: S. Schulte, C. Janiesch, S. Venugopal, I. Weber, and P. Hoenisch (2015). Elastic Business Process Management: State of the Art and Open Challenges for BPM in the Cloud. Future Generation Computer Systems, Volume NN, Number N, NN-NN., http://dx.doi.org/10.1016/j.future.2014.09.00

Viitearkkitehtuuri tapahtumapohjaiselle mikropalveluarkkitehtuurille pilvipalveluissa

The emergence of public cloud computing platforms has had a profound effect on how software is being developed. To take advantage of many of the features of cloud platforms, software architecture of applications must aligned with the characteristics of cloud services. Where systems designed for traditional data center deployments have typically consisted of a single large application and a centralized data store, systems targeting cloud platform have become distributed applications. The microservice architecture is a software architecture style for building distributed systems that consist of autonomous services, each responsible for a single problem domain. Decomposing an application to individual components makes is possible to utilize cloud platform features such as scaling each part of the system according to load and performance. Enterprise applications are the context where the microservice architecture pattern is typically applied. These applications are large, long-lived, in state of constant change and highly integrated to other systems. But building complex enterprise applications as distributed systems poses architectural challenges on how to build a system that is evolvable, maintainable and understandable. This thesis describes patterns for building microservice systems that can scale to a large amount of services while retaining the autonomy the services and the maintainability of the system as a whole. A key factor in these patterns is the use of events for communication between the different components of the system. The thesis then presents a reference architecture on how such a system can be developed by utilizing managed services of a public cloud platform.Lisääntyvä pilvipalveluiden käyttö on vaikuttanut merkittävästi siihen, millaisia sovelluksia kehitetään. Sovelluksen arkkitehtuurin täytyy olla suunniteltu siten, että pilvipalveluiden ominaisuuksia voidaan hyödyntää. Sovellukset, jotka ovat suunniteltu ennen pilvipohjaisia arkkitehtuureja koostuvat tyypillisesti yhdestä suuresta asennettavasta komponentista ja keskitetystä tietovarastosta. Pilvipalveluiden myötä tämän mallin sijaan on ruvettu rakentamaan hajautettuja järjestelmiä. Mikropalveluarkkitehtuuri on ohjelmistoarkkitehtuuri, jossa hajautettu järjestelmä koostetaan yksittäisistä erillisistä palveluista. Jokainen palvelu vastaa järjestelmän tietystä toiminnosta tai osa-alueesta. Arkkitehtuuri, jossa sovellus on pilkottu pieniin autonomisiin komponentteihin mahdollistaa monien pilvipalveluiden ominaisuuksien (kuten kuorman mukaisen skaalauksen) käytn. Monimutkaiset yritysjärjestelmät ovat kenttä, jossa mikropalveluarkkitehtuuria tyypillisesti käytetään. Nämä järjestelmät ovat suuria, jatkuvan muutoksen alaisia ja moninaisin tavoin integroituneita useisiin muihin järjestelmiin. Monimutkaisten yritysjärjestelmien rakentaminen mikropalveluarkkitehtuurilla luo omat haasteensa siinä, miten järjestelmästä saadaan ylläpidettävä, jatkokehityskelpoinen ja ymmärrettävä. Tämä diplomityö kuvaa malleja mikropalvelujärjestelmien rakentamiseen siten, että järjestelmän kasvaessa yksittäiset mikropalvelut pysyvät erillisinä ja autonomisina sekä järjestelmä kokonaisuutena pystyy ylläpidettävänä. Avainrakenne näiden tavoitteiden saavuttamisessa on tapahtumien käyttö tiedon välittämisessä palveluiden välillä. Diplomityössä esitetään sitten viitearkkitehtuuri miten nämä mallit voidaan ottaa käyttöön julkisessa pilvipalvelussa

Extending Swarm Communication to Unify Choreography and Long-lived Processes

The usual way of doing message passing is to have relatively intelligent processes, objects or actors sending and receiving dumb messages. Swarm communication presents the inverted approach of thinking to messages as relatively smart beings, visiting relatively non intelligent places, to produce better code and a new path for integrating complex applications. Swarm communication can be used as software architecture for an Enterprise Service Bus. This paper extends the swarm communication to support long-lived processes, providing an alternative approach to the standard techniques for executable Business Process Management. The ubiquity of connected devices is a fertile ground for new approaches to application development and systems integration based on complex business processes

Algebraic service composition for user-centric IoT applications

The Internet of Things (IoT) requires a shift in our way of building applications, as it is aimed at providing many services to society in general. Non-developer people require increasingly complex IoT applications and support for their ever changing run-time requirements. Although service composition allows the combination of functionality into more complex behaviours, current approaches provide support for dealing with one IoT scenario at a time, as they allow the definition of only one workflow. In this paper, we present DX-MAN, an algebraic model for static service composition that allows the definition of composite services that encompass multiple workflows for run-time scenarios. We evaluate our proposal on an example in the domain of smart homes

RESTful Service Composition

The Service-Oriented Architecture (SOA) has become one of the most popular approaches to building large-scale network applications. The web service technologies are de facto the default implementation for SOA. Simple Object Access Protocol (SOAP) is the key and fundamental technology of web services. Service composition is a way to deliver complex services based on existing partner services. Service orchestration with the support of Web Services Business Process Execution Language (WSBPEL) is the dominant approach of web service composition. WSBPEL-based service orchestration inherited the issue of interoperability from SOAP, and it was furthermore challenged for performance, scalability, reliability and modifiability. I present an architectural approach for service composition in this thesis to address these challenges. An architectural solution is so generic that it can be applied to a large spectrum of problems. I name the architectural style RESTful Service Composition (RSC), because many of its elements and constraints are derived from Representational State Transfer (REST). REST is an architectural style developed to describe the architectural style of the Web. The Web has demonstrated outstanding interoperability, performance, scalability, reliability and modifiability. RSC is designed for service composition on the Internet. The RSC style is composed on specific element types, including RESTful service composition client, RESTful partner proxy, composite resource, resource client, functional computation and relaying service. A service composition is partitioned into stages; each stage is represented as a computation that has a uniform identifier and a set of uniform access methods; and the transitions between stages are driven by computational batons. RSC is supplemented by a programming model that emphasizes on-demand function, map-reduce and continuation passing. An RSC-style composition does not depend on either a central conductor service or a common choreography specification, which makes it different from service orchestration or service choreography. Four scenarios are used to evaluate the performance, scalability, reliability and modifiability improvement of the RSC approach compared to orchestration. An RSC-style solution and an orchestration solution are compared side by side in every scenario. The first scenario evaluates the performance improvement of the X-Ray Diffraction (XRD) application in ScienceStudio; the second scenario evaluates the scalability improvement of the Process Variable (PV) snapshot application; the third scenario evaluates the reliability improvement of a notification application by simulation; and the fourth scenario evaluates the modifiability improvement of the XRD application in order to fulfil emerging requirements. The results show that the RSC approach outperforms the orchestration approach in every aspect

On the construction of decentralised service-oriented orchestration systems

Modern science relies on workflow technology to capture, process, and analyse data obtained from scientific instruments. Scientific workflows are precise descriptions of experiments in which multiple computational tasks are coordinated based on the dataflows between them. Orchestrating scientific workflows presents a significant research challenge: they are typically executed in a manner such that all data pass through a centralised computer server known as the engine, which causes unnecessary network traffic that leads to a performance bottleneck. These workflows are commonly composed of services that perform computation over geographically distributed resources, and involve the management of dataflows between them. Centralised orchestration is clearly not a scalable approach for coordinating services dispersed across distant geographical locations. This thesis presents a scalable decentralised service-oriented orchestration system that relies on a high-level data coordination language for the specification and execution of workflows. This system’s architecture consists of distributed engines, each of which is responsible for executing part of the overall workflow. It exploits parallelism in the workflow by decomposing it into smaller sub-workflows, and determines the most appropriate engines to execute them using computation placement analysis. This permits the workflow logic to be distributed closer to the services providing the data for execution, which reduces the overall data transfer in the workflow and improves its execution time. This thesis provides an evaluation of the presented system which concludes that decentralised orchestration provides scalability benefits over centralised orchestration, and improves the overall performance of executing a service-oriented workflow