Carlos E. Cuesta

Modelling of Service-Oriented Architectures with UML

Nowadays, service-oriented architectures are becoming gradually more important. The vast diversity of implementation and support platforms for this kind of architectures (such as Web, Grid or even CORBA) increases the complexity of the development process of service-based systems. With the aim of facilitating the development of service oriented solutions, we propose the specification of an architecture centric model driven development method. To achieve this, we study the architectural properties of the SOA paradigm and follow a development approach based on the MDA proposal. MDA proposes a separation of the development process in abstraction levels. This makes MDA suitable to tackle the development of service-oriented systems. This paper describes a UML profile for the PIM-level service-oriented architectural modelling, as well as its corresponding metamodel. PIM (Platform Independent Model) level is chosen because it does not reflect constraints about any specific platform or implementation technology. To exemplify and validate the profile, a case study is presented in which the proposed profile is used.

Architectural aspects of architectural aspects

This document studies in some detail the recently developed concept of aspect at the architecture level. This concept introduces a novel kind of modularization and composition in software, and therefore it defines new structures which must be studied by Software Architecture, determining the architectural features of aspects. However the opposite strategy can also be considered; namely, a new conceptual model can be defined, including an architecture-level notion of aspect. This would provide a new abstraction to describe software structures, thus effectively providing an additional dimension in architecture description, and would enable the study of the specific compositional problems in this dimension. The document starts by addressing the relevance of this kind of study, and continues by discussing why the new notions are necessary. Then it continues by including a brief enumeration of the more relevant notions derived from this aspectual framework, with particular emphasis on their relationship with software components. Next the document explores the different forms in which these notions could be incorporated into the context of Software Architecture, revealing a rather extensive variety of approaches, and also the relationships and partial equivalences between them.The paper concludes by noting a number or open questions and futures areas of research within this context.

UML Automatic Verification Tool with Formal Methods

The use of the UML specification language is very widespread due to some of its features. However, the ever more complex systems of today require modeling methods that allow errors to be detected in the initial phases of development. The use of formal methods make such error detection possible but the learning cost is high.This paper presents a tool which avoids this learning cost, enabling the active behavior of a system expressed in UML to be verified in a completely automatic way by means of formal method techniques. It incorporates an assistant for the verification that acts as a user guide for writing properties so that she/he needs no knowledge of either temporal logic or the form of the specification obtained.

Integrating software architecture into a MDA framework

Model Driven Development (MDD) is one of the main trends in Software Engineering nowadays. Its main feature is to consider models as first-class concepts. Model Driven Architecture (MDA), the MDD proposal by the OMG, defines an infrastructure which considers models at three different levels of abstraction, namely Computer-Independent Model (CIM), Platform-Independent Model (PIM) and Platform-Specific Model (PSM). Although it is becoming ever more important, the MDA approach has still some gaps. In our opinion, the lack of an adequate support for architectural design has been, ironically, one of its main drawbacks. MIDAS is an specific Model Driven Architecture for Web Information Systems (WIS) Development. It proposes to model a WIS by considering three different viewpoints, namely Content, Hypertext and Behaviour Viewpoints, which are orthogonal to MDA abstraction levels. In this paper, we propose to extend MIDAS by integrating architectural design aspects. Software architecture is therefore conceived as an crosscutting perspective, which is in turn orthogonal to those three viewpoints. MDA abstraction levels are still considered, and therefore both Platform-Independent Architecture and Platform-Specific Architecture models are defined. This approach, named Architecture-Centric Model-Driven Architecture (ACMDA), has several advantages, as it allows architectural design to benefit from the adaptability and flexibility of an MDD process; and on the other hand it extends MDA philosophy by integrating true architectural concerns, effectively turning it into an Architecture-Centric Model-Driven Development (ACMDD) process.

The Solid architecture for real-time management of big semantic data

Big Data?management has become a critical task in many application systems, which usually rely on heavyweight batch processes to manage such large amounts of data. However, batch architectures are not an adequate choice for designing real-time systems in which data updates and reads must be satisfied with very low latency. Thus, gathering and consuming high volumes of data at high velocities is an emerging challenge which we specifically address in the scope of innovative scenarios based on semantic data (RDF) management. The Linked Open Data initiative or emergent projects in the Internet of Things are examples of such scenarios. This paper describes a new architecture (referred to as Solid) which separates the complexities of Big Semantic Data?storage and indexing from real-time data acquisition and consumption. This decision relies on the use of two optimized datastores which respectively store historical (big) data and run-time data. It ensures efficient volume management and high processing velocity, but adds the need of coordinating both datastores. Solid ?proposes a 3-tiered architecture in which each responsibility is specifically addressed. Besides its theoretical description, we also propose and evaluate a Solid ?prototype built on top of binary RDF and state-of-the-art triplestores. Our experimental numbers report that Solid ?achieves large savings in data storage (it uses up to 5 times less space than the compared triplestores), while provides efficient SPARQL resolution over the Big Semantic Data?(in the order of 10-20?ms for the studied queries). These experiments also show that Solid ?ensures low-latency operations because data effectively managed in real-time remain small, so do not suffer Big Data?issues. We propose an architecture (Solid) for managing big semantic data in real-time.Specific big data and real-time responsibilities are isolated in dedicated layers.A dynamic pipe-filter solution is introduced for addressing query responsibilities.Solid ?leverages Rdf/Hdt ?features to obtain the most compressed representations.The Solid ?prototype performs competitive respect to the most prominent triplestores.

Defining Service-Oriented Software Architecture Models for a MDA-based Development Process at the PIM level

Although the development of service-based software has evolved greatly in the last years, there is still a lack of accurate development methodologies applied to service orientation. To solve this, we focus on the model- driven development approach, and more specifically in MDA, the proposal by the OMG, as it is one of the main trends in nowadays software engineering. Accordingly, we propose to define a service-oriented software architecture (SOSA) model within a model-driven methodological framework called MIDAS, for the adaptable and flexible development of modern systems. In the present work we study the concepts and elements that need to be defined at a platform independent and neutral abstraction level. This paper reflects our proposal of PIM-level architecture model for service-oriented software architectures within MIDAS.

Automating the Trace of Architectural Design Decisions and Rationales Using a MDD Approach

The impact of architecture is not only significant in the final structure of software, but also in the development process. Architecture itself is assembled by a network of design decisions (DD) composing a design rationale. Such rationale has often been neglected; however it is essential to deal with future change. This is also the role of traceability, the crosscutting relationship describing the evolution of software. The methodology ATRIUM provides the method to manage traceability, by using a Model-Driven Development (MDD) approach where every model element maintains links to related elements in previous and further stages. This proposal defines how these links have been exploited to support the tracing of DDs and their accompanying design rationales (DRs), and study their propagation. We also present how ATRIUM tools support this proposal by introducing DD/DRs and their traceability links from requirements to the target architectural model. These are automatically generated by M2M transformations, avoiding the error-prone task of managing them by hand.

Reflection-Based, Aspect-Oriented Software Architecture

The Software Architecture discipline is devoted to the study and description of structures, created by the composition of software modules. At the same time, the most important merit of Aspect Orientation is the fact that it introduces a new kind of modularization, deployed in a range of new dimensions, orthogonally to traditional models. These fields are able not only to combine, but also to complement and extend each other. They show also remarkable coincidences in some of their key concepts, such as multiple viewpoints and connectors. This paper explores their relationship, in particular from the point of view of the specification of “aspect-oriented architectures” in terms of existing Architecture Description Languages (Adls). Specifically, we consider the language \(\mathcal {PIL}\)ar: a reflective, process-algebraic Adl conceived for the description of dynamic architectures. It has three conceptual foundations which have also been proposed as a basis for aspect-orientation, namely reflection, superimposition and process algebras. We show how, due to the semantics of its reification relationship, \(\mathcal {PIL}\)ar is capable to directly describe “architectural aspects” with no need for syntactic extensions. At the same time, we suggest that the addition of these extensions could be very useful anyway. The discussion is supported by an example of a coordination aspect in \(\mathcal {PIL}\)ar, based on the classical Paxos Consensus algorithm.

Coordination in a Reflective Architecture Description Language

Software Architecture studies the structure of software systems, as described by Architecture Description Languages (Adls). When these capture structures of change, they are comparable to Coordination Languages. Previous work suggests that the combination with Reflection concepts renders a general framework for the description of such evolving structures. This paper describes a reflective Adl named PiLar designed to provide such a framework. It consists of a structural part, which describes the static skeleton, and a dynamic part, which defines patterns of change. The major novelty is the reification relationship, which structures a description in several meta-layers, such that the architecture is able to reason and act upon itself. The paper includes a complete PiLar example, to show the languages use and some of its most relevant features. It describes a Tuple Space model, illustrating the analogy with existing Coordination Models. We conclude by emphasizing PiLars generality and applicability.

Towards an architecture for managing big semantic data in real-time

Big Data Management has become a critical task in many application systems, which usually rely on heavyweight batch processes to process large amounts of data. However, batch architectures are not an adequate choice for the design of real-time systems, where expected response times are several orders of magnitude underneath. This paper outlines the foundations for defining an architecture able to deal with such an scenario, fulfilling the specific needs of real-time systems which expose big RDF datasets. Our proposal (Solid) is a tiered architecture which separates the complexities of Big Data management from their real-time data generation and consumption. Big semantic data are stored and indexed in a compressed way following the Rdf/Hdt proposal; while at the same time, real-time requirements are addressed using NoSQL technology. Both are efficient layers, but their approaches are quite different and their combination is not easy. Two additional layers are required to achieve an overall high performance, satisfying real-time needs, and able to work even in a mobile context.