Components Interoperability through Mediating Connector Patterns

A key objective for ubiquitous environments is to enable system interoperability between system's components that are highly heterogeneous. In particular, the challenge is to embed in the system architecture the necessary support to cope with behavioral diversity in order to allow components to coordinate and communicate. The continuously evolving environment further asks for an automated and on-the-fly approach. In this paper we present the design building blocks for the dynamic and on-the-fly interoperability between heterogeneous components. Specifically, we describe an Architectural Pattern called Mediating Connector, that is the key enabler for communication. In addition, we present a set of Basic Mediator Patterns, that describe the basic mismatches which can occur when components try to interact, and their corresponding solutions.Comment: In Proceedings WCSI 2010, arXiv:1010.233

Towards a Formalization of Mediating Connectors for on the Fly Interoperability

International audienceMediators stand as a core architectural paradigm for today's and future systems that increasingly need to be connected. The mediator concept has been used to cope with many heterogeneity dimensions. Still, a key challenge for today's systems architectures is to embed the necessary support for automated mediation, i.e., the connector concept needs to evolve towards the one of mediating connector. In this paper, we introduce a framework to formalize mediating connectors. The proposed characterization paves the way for automated reasoning about protocol matching and mapping, and thus for the dynamic synthesis of mediating connectors to enable eternal networked systems, which we investigate as part of the CONNECT European projec

Methodology for Detection of Cloud Interoperability Problems

Interoperability problems between cloud providers are one of the most serious issues of this new computing paradigm. A methodology is needed to systematically and effectively find and solve interoperability problems. For these reasons, a new methodology with detailed steps to find and solve interoperability problems is proposed here. This new methodology is focused and implemented on the platform as a service model, but it can be used in any of the three main models of cloud computing. The methodology uses an iterative approach, because platform as a service offers and their application programming interfaces evolve and change very often. The focus of the methodology is to use remote cloud application programming interfaces to solve interoperability problems on technical, storage and services levels, respectively. Finally, we show the application of the methodology to achieve service-level interoperability among different providers of platform as a service

A Formalization of Mediating Connectors: Towards on the fly Interoperability

Mediators stand as a core architectural paradigm for today's and future systems that increasingly need be connected. The mediator concept has been used to cope with many heterogeneity dimensions spanning: terminology, representation format, transfer protocols, functionality, and application-layer protocols. Still, a key challenge for today's systems architectures is to embed the necessary support for automated mediation, i.e., the connector concept needs to evolve towards the one of mediating connectors. In this paper, we concentrate on the issue of enabling automated protocol mediation. Building upon tremendous research work in the area over the past few years we introduce a formalization of mediating connectors. The proposed formalization paves the way for automated reasoning about protocol matching and mapping, and thus for the dynamic synthesis of mediating connectors to enable eternal networked systems, which we investigate as part of the CONNECT European project

DL.org Digital Library Technology & Methodology Cookbook

The needs for ‘building by re-use’ and ‘sharing’ have grown out of the demand for powerful and rich Digital Libraries supporting a large variety of interdisciplinary activities coupled with the data deluge which the information society is now facing. Interoperability at a technical, semantic and organisational level is a central issue to satisfy these needs. Interoperable systems broaden choice and open up new perspectives for researchers, governments and citizens across a spectrum of disciplines and domains. Interoperability is key to improve Digital Libraries, enabling wider collaborations and ensuring that a broader spectrum of resources are available to a wider range of people whether for simple consumption or to enhance research activities. Although the importance of interoperability is well known and many attempts have been made in the past to give solutions to interoperability problems, there still is a lack of systematic approaches, and, on average, a scarce knowledge of existing solutions which remain confined to the systems they have been designed for. The need for interoperability goes actually well beyond the digital library domain. Interoperability is among the most critical issues to be faced when building systems as “collections” of independently developed constituents (systems on their own) that should co-operate and rely on each other to accomplish larger tasks. The “Digital Agenda for Europe” (European Commission, May 2010), one of the seven flagship initiatives of Europe’s 2020 Strategy, outlines seven priority areas for actions; the second one concerns “improving the framework conditions for interoperability between ICT products and services”. This key priority foresees that it is essential to enhance interoperability between devices, applications, data repositories, services and networks inside a framework where the conditions for interoperability can be improved in various ways. One important means to that end is to ensure that good ICT standards are available and used, notably in public procurement and legislation. Interoperability is actually a multi-layered and context-specific concept, which encompasses different levels along a multi-dimensional spectrum ranging from organisational to semantic and technological aspects. DL.org has investigated interoperability from multiple perspectives: content, user, functionality, policy, quality, and architecture. It has also examined interoperability at technical, semantic and organisational levels, all central to powerful Digital Libraries needed in today’s context. DL.org is the first initiative to examine interoperability from an all-encompassing perspective by harnessing leading figures in the Digital Library space globally. The output is an innovative Digital Library Technological and Methodological Cookbook with a portfolio of best practices and pattern solutions to common issues faced when developing interoperable digital library systems. A key facet of the Cookbook is the interoperability framework that can be used to systematically characterise diverse facets linked to the interoperability challenge as well as current and emerging solutions and approaches. The Cookbook is designed to facilitate the assessment and selection of the solutions presented, enabling professionals working towards interoperability to define and pursue the different steps involved. This publication presents the Interoperability Framework and discusses interoperability from the perspectives of the content, user, functionality, policy, quality and architecture domains

Application-Layer Connector Synthesis

International audienceThe heterogeneity characterizing the systems populating the Ubiquitous Computing environment prevents their seamless interoperability. Heterogeneous protocols may be willing to cooperate in order to reach some common goal even though they meet dynamically and do not have a priori knowledge of each other. Despite numerous e orts have been done in the literature, the automated and run-time interoperability is still an open challenge for such environment. We consider interoperability as the ability for two Networked Systems (NSs) to communicate and correctly coordinate to achieve their goal(s). In this chapter we report the main outcomes of our past and recent research on automatically achieving protocol interoperability via connector synthesis. We consider application-layer connectors by referring to two conceptually distinct notions of connector: coordinator and mediator. The former is used when the NSs to be connected are already able to communicate but they need to be speci cally coordinated in order to reach their goal(s). The latter goes a step forward representing a solution for both achieving correct coordination and enabling communication between highly heterogeneous NSs. In the past, most of the works in the literature described e orts to the automatic synthesis of coordinators while, in recent years the focus moved also to the automatic synthesis of mediators. Within the Connect project, by considering our past experience on automatic coordinator synthesis as a baseline, we propose a formal theory of mediators and a related method for automatically eliciting a way for the protocols to interoperate. The solution we propose is the automated synthesis of emerging mediating connectors (i.e., mediators for short)

Dynamic connector synthesis: revised prototype implementation

The CONNECT Integrated Project aims at enabling continuous composition of Networked Systems (NSs) to respond to the evolution of functionalities provided to and required from the networked environment. CONNECT aims at dropping the interoperability barrier by adopting a revolutionary approach to the seamless networking of digital systems, that is, synthesizing on-the-fly the connectors via which networked systems communicate. The resulting emergent connectors are effectively synthesized according to the behavioral semantics of application- down to middleware-layer protocols run by the interacting parties

Modeling of application- and middleware-layer interaction protocols

The CONNECT Integrated Project aims at enabling continuous composition of networked systems to respond to the evolution of functionalities provided to and required from the networked environment. CONNECT aims at dropping the interoperability barrier by adopting a revolutionary approach to the seamless networking of digital systems, that is, synthesizing on-the-fly the connectors via which networked systems communicate. The resulting emergent connectors are effectively synthesized according to the behavioral semantics of application- down to middleware-layer protocols run by the interacting parties. The role of work package WP3 is to devise automated and compositional approaches to connector synthesis, which can be performed at run-time. Given the respective interaction behavior of networked systems, we want to synthesize the behavior of the connector(s) needed for them to interact. These connectors serve as mediators of the networked systems' interaction at both application and middleware layers. In this deliverable, we set the scene for a formal theory of the automated synthesis of application- and middleware-layer protocol mediators. We formally characterize mediating connectors between mismatching application-layer protocols by rigorously defining the necessary conditions that must hold for protocols to be mediated. The outcome of this formalization is the definition of two relationships between heterogenous protocols: matching and mapping. The former is concerned with checking whether a mediator letting two protocols interoperate exists or not. The latter concerns the algorithm that should be executed to synthesize the required mediator. Furthermore, we analyze the different dimensions of interoperability at the middleware layer and exploit this analysis to formalize existing solutions to middleware-layer interoperability. Since the work on application-layer mediator synthesis is based on the assumption that a model of the interaction protocol for a networked system is dynamically discovered, we finally present an approach, based on data-flow analysis and testing, for the automated elicitation of application-layer protocols from software implementations. This approach presents similarities, but also several differences, with the work of work package WP4 (protocol learning). Furthermore, it allowed us to proceed in parallel with the work of WP4 and to state the requirements that the learning approaches have to satisfy to enable mediator synthesis. For this reason, we keep this work separate from the work on protocol learning and discuss it in this deliverable. All the approaches mentioned above are applied to several examples and scenarios

Reasoning about and Harmonizing the Interaction Behavior of Networked Systems at Application- and Middleware- Layer

The CONNECT Integrated Project aims at enabling continuous composition of networked systems to respond to the evolution of functionalities provided to and required from the networked environment. CONNECT aims at dropping the interoperability barrier by adopting a revolutionary approach to the seamless networking of digital systems, that is, synthesizing on-the-fly the connectors via which networked systems communicate. The resulting emergent connectors are effectively synthesized according to the behavioral semantics of application- down to middleware-layer protocols run by the interacting parties. The role of work package WP3 is to devise automated and compositional approaches to connector synthesis, which can be performed at run-time. Given the respective interaction behavior of networked systems, we want to synthesize the behavior of the connector(s) needed for them to interact. These connectors serve as mediators of the networked systems' interaction at both application and middleware layers. During the project's first year, the work of WP3 led us to achieve the following preliminary results: the formalization of matching and mapping relationships for application-layer interaction protocols; the definition of the corresponding mediator generation algorithm; the analysis of the interoperability problems, and related solutions, that can occur at middleware-layer; and a model-driven approach to the automated elicitation of application-layer protocols from software implementations. All these achievements have been reported in Deliverable D3.1: "Modeling of application- and middleware-layer interaction protocols". In this deliverable, we go a step forward with respect to some of the previous achievements by delivering a unified process, and related artefacts, for the automated synthesis of mediators at both application and middleware layers, code-generation techniques to generate the actual code that implements a synthesized mediator, and a preliminary integration of QoS management in the synthesis process. During year 2, all the work has been validated through its application to several scenarios, in particular as part of WP1 and WP6. By selecting one of them as common scenario, in this deliverable, we also show the different methods/techniques at work on the scenario. All the steps of the devised synthesis process are described in detail and applied to the selected common scenario