Component-based Architecture Research Articles

Framework testing of web applications using TTCN-3

Functional testing of web applications has become increasingly complex. Browser-based interfaces incorporate rich, client-side scripting that is increasingly independent of server-side application logic. At the same time, the server side application logic interacts with reusable components for key elements (security, shopping cart, product catalog, order processing) within the framework of a component-based architecture, using beans and web services. In this paper, we illustrate how a test specification approach using a language like TTCN-3 can be used to define test cases at different levels of abstraction that are more robust in the face of volatile presentation and implementation details. A case study of a shopping cart scenario with order processing is used as an illustration. Features of TTCN-3 are demonstrated, including a powerful matching mechanism that allows a separation between behavior and the conditions governing behavior. As well, TTCN-3’s data types and set-based operations allow one to track and verify the information management done by a web application, independent of implementation details. These features allow a tester to take a systematic approach to testing web applications but requires more sophistication and skills. The advantages and challenges of a test specification approach are characterized in comparison to approaches based on unit testing and test automation tools.

Failure-free coordinators synthesis for component-based architectures

One of the main problems in component assembly is how to establish properties on the assembly code by only assuming a limited knowledge of the single component properties. Our answer to this problem is an architectural approach in which the software architecture imposed on the assembly prevents black-box integration anomalies. The basic idea is to build applications by assuming a “coordinator-based” architectural style. We, then, operate on the coordinating part of the system architecture to obtain an equivalent version of the system which is failure-free. A failure-free system is a deadlock-free one and it does not violate any specified coordination policy. A coordination policy models those interactions of components that are actually needed for the overall purpose of the system. We illustrate our approach by means of an explanatory example and validate it on an industrial case study that concerns the development of systems for safeguarding, fruiting, and supporting the Cultural Heritage.

Shared Content Management in Replicated Web Systems: A Design Framework Using Problem Decomposition, Controlled Simulation, and Feedback Learning

Replication is one of the primary techniques used to improve the quality of distributed content service. It generally reduces user latencies and increases a site's availability. However, to our knowledge, there is no systematic framework that combines the structure of both content and service components of a Web application to design effective replica hosting architectures. Recent advances in interconnected and multiple content distribution network (CDN) architectures render this problem even more complex. In this study, we develop a systematic framework for designing and evaluating large-scale, component-based replication architectures for Web systems that are driven by both the quality and effectiveness of service provisioning on the service network. The proposed framework employs a combination of problem decomposition, configuration evaluation through controlled system simulations, and a neural-network-based feedback learning mechanism in the exploration of the design space. A case study demonstrates the viability of the framework. The framework can be an effective decision support tool for a system designer to systematically explore design options and select an appropriate design configuration that best meets the desired design objectives.

Object-Oriented Hypermedia Design and J2EE Technology for Web-based Applications

Introduction Nowadays, the web is one of the most important communication channels which can be accessed on various platforms around the clock all over the world. The internet encompasses more than 10 trillion pages and has about 1 billion users. While the nineteenth century was the pinnacle of industrial revolution, the beginning of the current century is characterized by the information revolution, and the web is the principal engine of this revolution. Noting the ubiquity of the web, many information systems are accessible via the web, and they are called Web Information Systems (WIS). Modern WIS applications present the information in meticulously crafted, multimedia-enabled texts. This system is not sufficient for the ever-growing need of publishing high volumes of information over the web. Information-intensive web features, like electronic cities, organizational portals, social engineering sites, e-shopping centers, digital libraries, and the like, are present in many web-based applications. Operational Terminology Navigation: guiding the users from one place to another. Even though the web is not a physical space, navigational procedures are necessary, so that the users can move in the information space. Context: a set of navigational nodes with a common property. Container: a place on the server where application components are situated and are executed therein. Containers provide middle-tier services for the components. Problem Description Web information systems allow a user to search in the plethora of information in the internet and perform tasks like research and updating. Some of the specific features in these programs are as follows: 1- They must be developed with high confidence in a short period of time, because the time to market is a critical factor in the success of web-based applications. 2- They must be able to guide the users in the application space in a satisfactory manner. 3- They must be able to respond to large numbers of users. 4-They must integrate with modern telecommunication technologies, in order to support access through mobile devices. 5- They must support a high degree of reusability. Therefore, in this article, we are going to find a suitable solution for designing applications with these features. Theoretical Background We use the component-based architecture of J2EE (Java 2 Enterprise Edition) to present solutions for reusability, rapid development, multi-user service, and rely on the object-oriented hypermedia design paradigm for navigation, graphical interface design, and reusability. We believe that the combination of these two methodologies maximizes the capabilities for reusability and rapid development for web-based applications. Objective Separation of various parts of web development paves the way for reusability and parallel development, effectively shortening the application development time. However, in most cases these benefits are lost in the implementation phase, mostly because the current implementation methodologies have a meager support for mechanisms of abstraction and composition. For this reason, our major objective is a mapping from the design artifacts to implementation components, and adding navigational capability to applications. Historical Background The earliest WIS applications delivered hypermedia content to users in the form of static web pages. Today, with the growing acceptance of the web, users can access up-to-date information presented by dynamic pages and interact with the web sites using the form functionality. The next generation of applications, called Semantic Web Information Systems, can obtain information from one or many sources and provide the user with an integrated version of that information. The design of WIS applications is a very difficult task due to the high volume of information, customization, large number of users, and the need for automatic creation of programs. …

Generating CAM aspect-oriented architectures using Model-Driven Development

Aspect-Oriented Software Development promotes the separation of those concerns that cut across several components and/or are tangled with the base functionality of a component, through all phases of the software lifecycle. The benefit of identifying these crosscutting concerns ( aspects) at the architectural level in particular is to improve the architecture design and its subsequent evolution, before moving onto detailed design and implementation. However, software architects are not usually experts on using specific AO architecture notations. Therefore, the aim of this paper is to provide support to define and specify aspect-oriented (AO) architectures using non-AO ones as the source. We will use the Model-Driven Development approach to transform a component-based architecture model into an AO architecture model. The CAM (component and aspect model) model and the DAOP–ADL language are the proposals used for modelling and specifying AO architectures. We will show how we automated part of the process and the tool support.

Editorial: Special Issue on Serving and Managing Users in a Heterogeneous B3G Wireless World—Requirements, New Research Challenges, Emerging Solutions

Enormous research, standardization and development efforts continue to be allocated in all areas related to wireless communications. These efforts result to a powerful, high-speed infrastructure that offers several wireless/mobile connectivity solutions to the digital information society. Currently, thewireless landscape includes several RadioAccess Technologies (RATs), e.g., 2.5G/3G/4G mobile infrastructures, the suite of IEEE 802 wireless technologies, Digital Audio/Video Broadcasting (DAB/DVB). Moreover, significant research effort is dedicated to the elaboration of the era of wireless communications, Beyond the 3rd Generation (B3G), in which the available RATs will form an heterogeneous infrastructure that will have to exist in an environment also characterized by the advance of the Internet, the need for broadband everywhere, the convergence of digital industries, the advance of e-commerce, deregulation and globalization, and above all the fact that services and applications are key: the end user is interested in services and applications, and should be served and managed in a way that the underlying infrastructure complexity is abstracted. Moreover, future systems should be sufficiently flexible to match the unpredictable operator and user expectations from a service and economic perspective. In response to the characteristics above, future wireless systems shall respond to versatile requirements, such as the fact that users shall be in control through intuitive interactions with applications, services, and devices. Those services and applications will be personalized, ambient-aware, and adaptive, provided ubiquitously from the user viewpoint. In addition, machines (autonomously communicating devices) shall operate irrespective of place and network, and with agreed quality-of-service (QoS). Those issues allow users, application developers, service and content providers, network operators, and manufactures to efficiently and flexibly create new services and business models based on the component-based architecture of the wireless world. In the light of the aspects above, the goal of this special issue is to present advances in various research areas related to the B3G wireless world, relevant applications, services, and infrastructure technologies. In this respect, a great variety of interesting issues are tackled,

APPLYING MDE TO THE DEVELOPMENT OF FLEXIBLE AND REUSABLE WIRELESS SENSOR NETWORKS

Wireless Sensor Networks (WSN) are a very promising research field since they are applicable in many different areas. Current proposals for WSN system development are mainly focused on implementation issues and rarely use a Software Engineering methodology to support their development life cycle. The Model-Driven Engineering (MDE) approach can be used as a solution to this by allowing designers to model their systems at different abstraction levels, providing them with automatic model transformations to incrementally refine abstract models into more concrete ones. In this vein, this paper presents an MDE approach to WSN application development. Three levels of abstraction have been defined which allow designers to build: (1) domain-specific models, (2) component-based architecture descriptions, and (3) platform-specific models. Automatic model transformations between these three abstraction levels have been designed and, in order to demonstrate the viability of the proposal, a real WSN application has been developed using the implemented tools.

The Image-Guided Surgery Toolkit IGSTK: An Open Source C++ Software Toolkit

This paper presents an overview of the image-guided surgery toolkit (IGSTK). IGSTK is an open source C++ software library that provides the basic components needed to develop image-guided surgery applications. It is intended for fast prototyping and development of image-guided surgery applications. The toolkit was developed through a collaboration between academic and industry partners. Because IGSTK was designed for safety-critical applications, the development team has adopted lightweight software processes that emphasizes safety and robustness while, at the same time, supporting geographically separated developers. A software process that is philosophically similar to agile software methods was adopted emphasizing iterative, incremental, and test-driven development principles. The guiding principle in the architecture design of IGSTK is patient safety. The IGSTK team implemented a component-based architecture and used state machine software design methodologies to improve the reliability and safety of the components. Every IGSTK component has a well-defined set of features that are governed by state machines. The state machine ensures that the component is always in a valid state and that all state transitions are valid and meaningful. Realizing that the continued success and viability of an open source toolkit depends on a strong user community, the IGSTK team is following several key strategies to build an active user community. These include maintaining a users and developers’ mailing list, providing documentation (application programming interface reference document and book), presenting demonstration applications, and delivering tutorial sessions at relevant scientific conferences.

Multimodal signal processing and interaction for a driving simulator: Component-based architecture

In this paper we focus on the software design of a multimodal driving simulator that is based on both multimodal driver’s focus of attention detection as well as driver’s fatigue state detection and prediction. Capturing and interpreting the driver’s focus of attention and fatigue state is based on video data (e.g., facial expression, head movement, eye tracking). While the input multimodal interface relies on passive modalities only (also called attentive user interface), the output multimodal user interface includes several active output modalities for presenting alert messages including graphics and text on a mini-screen and in the windshield, sounds, speech and vibration (vibration wheel). Active input modalities are added in the meta-User Interface to let the user dynamically select the output modalities. The driving simulator is used as a case study for studying its software architecture based on multimodal signal processing and multimodal interaction components considering two software platforms, OpenInterface and ICARE.

Reconfigurable modular automation systems for automotive power-train manufacture

This paper describes research towards the realization of reconfigurable modular automated machines and the associated engineering methods and tools necessary to support their lifecycle needs. UK-based research, in collaboration with the Ford Motor Company and several machine builders, has resulted in the development of full-scale prototype reconfigurable modular automation systems for both engine assembly and machining applications. The implementation of an assembly system is featured in this paper. An engineering environment and associated reconfigurable component-based control system architecture have been created aimed at supporting the lifecycle needs of a new generation of agile automated systems, i.e., providing reconfigurable, easily scalable automated machinery. This approach has the potential to fit within a wider collaborative automation strategy where manufacturing systems are implemented as a conglomerate of distributed, autonomous, and reusable units.

VERIFICATION AND PREDICTION OF TIMED PROBABILISTIC PROPERTIES OVER THE DMTF CIM

Understanding nonfunctional aspects of system behavior is an essential component of practical software development and maintenance. Many nonfunctional system properties, such as reliability and availability, involve time and probabilities. In this paper, we present a framework for runtime verification and prediction of timed and probabilistic nonfunctional properties of component-based architectures, built using the Meta-Object Facility and the Distributed Management Task Force's Common Information Model (CIM) standard. We describe a Microsoft .NET-based implementation of our framework. We define a language for describing timed probabilistic behavior based on Probabilistic Computational Tree Logic (PCTL). We provide a formal semantics for this language in terms of observed application execution traces. The semantics is interesting in that it permits checking of required timing behavior both over the overall average of traces and also over local "trends" in traces. The latter aspect of the semantics is achieved by incorporating exponential smoothing prediction techniques into the truth function for statements of our language. The semantics is generic over the aspects of an application that are represented by states and state transitions. This enables the language to be used to describe a wide range of nonfunctional properties for runtime verification and prediction purposes. We explain how statements of our language are used to define precise contracts for system monitoring, through relating the semantics to an extended CIM monitoring infrastructure.

Implementing security in a distributed web-based EHCR

Purpose In many countries there are initiatives for building an integrated patient-centric electronic health record. There are also initiatives for transnational integrations. These growing demands for integration result from the fact that it can provide improving healthcare treatments and reducing the cost of healthcare services. While in European highly developed countries computerisation in healthcare sector began in the 1970s and reached a high level, some developing countries, and Serbia among them, have started computerisation recently. This is why MEDIS (MEDical Information System) is aimed at integration itself from the very beginning instead of integration of heterogeneous information systems on a middle layer or using HL7 protocol. Approach The implementation of a national healthcare information system requires using standards as integrated and widely accepted solutions. Therefore, we have started building MEDIS to meet the requirements of CEN ENV 13606 and CEN ENV 13729 standards. The prototype version has a distributed component-based architecture with modern security solutions applied. MEDIS has been implemented as a federated system where the central server hosts basic EHCR information about a patient, and clinical servers contain their own part of patients’ EHCR. Results At present, there is an initial version of prototype planned to be deployed at first in a small community. In particular, open source API for X.509 authentication and authorisation has been developed. Our project meets the requirements for education in health informatics, including appropriate knowledge and skills on EHCR. The points included in this article have been presented on several national conferences and widely discussed. Conclusion MEDIS has explored a federated, component-based EHCR architecture and related security aspects. In its initial version it shows acceptable performances and administrative simplicity. It emphasizes the importance of using standards in building EHCR in our country, in order to prepare it for future integrations.

Early quality prediction of component-based systems – A generic framework

Component-based software engineering is currently an emerging technology used to develop complex embedded systems. These embedded systems need to fulfil requirements regarding quality attributes such as safety, reliability, availability, maintainability, performance, security and temporal correctness. Since quality problems should be identified and tackled early in the development process, there is a rising need to predict and evaluate these properties in the architecture design phase. This paper describes a generic framework for predicting quality properties based on component-based architectures, which is derived from a comprehensive study of recent architecture evaluation methods. This generic framework defines common aspects between the different evaluation methods and enables the improvement of evaluation methods for specific quality properties, by transferring knowledge from one quality domain to the other. Thus, this paper can help to create better evaluation methods in the future.

A modular and evolutive component oriented software architecture for patient modeling

This paper deals with the design aspect of a software aiming at modeling the anatomical and pathological structures of patients from medical images, for diagnosis purposes. In terms of functionalities, it allows to combine image processing algorithms, and to visualize and manipulate 3D models and images. The proposed software uses specific extensible and reusable components and a system managing their combination, thanks to a formal XML-based description of their interfaces. This architecture facilitates the dynamic integration of new functionalities, in particular in terms of image processing algorithms. We describe the structural and behavioral aspects of the proposed reusable component-based architecture. We also discuss the potential of this work for developing other softwares in the field of computer aided surgery.

A digital library framework for biodiversity information systems

Biodiversity Information Systems (BISs) involve all kinds of heterogeneous data, which include ecological and geographical features. However, available information systems offer very limited support for managing these kinds of data in an integrated fashion. Furthermore, such systems do not fully support image content (e.g., photos of landscapes or living organisms) management, a requirement of many BIS end-users. In order to meet their needs, these users—e.g., biologists, environmental experts—often have to alternate between separate biodiversity and image information systems to combine information extracted from them. This hampers the addition of new data sources, as well as cooperation among scientists. The approach provided in this paper to meet these issues is based on taking advantage of advances in digital library innovations to integrate networked collections of heterogeneous data. It focuses on creating the basis for a next-generation BIS, combining new techniques of content-based image retrieval and database query processing mechanisms. This paper shows the use of this component-based architecture to support the creation of two tailored BIS systems dealing with fish specimen identification using search techniques. Experimental results suggest that this new approach improves the effectiveness of the fish identification process, when compared to the traditional key-based method.

A component-based architecture for parallel multi-physics PDE simulation

We describe the Uintah Computational Framework (UCF), a set of software components and libraries that facilitate the simulation of partial differential equations on structured adaptive mesh refinem...

Component-Based Distributed Virtual Reality Application System

This paper presents an approach of constructing the application system in Distributed Virtual Reality. Based on a component model of application system in which three types of the basic components are discussed, this paper first focuses on the “semantic” interoperability among components, and presents a Primitive-Semantic component constructing method through a semantic model to deal with the semantic interoperability while the communication protocol among components doesn’t exist. It then presents a composable Distributed Virtual Reality Component-Based Architecture, including its key mechanism and algorithms. Finally the experimental result demonstrates the usability of this architecture.

The digital pen and paper technology: implementation and use in an existing clinical information system

Evaluation of the technical feasibility of tight integration of the digital pen and paper technology in an existing computerized patient record.Technology: The digital pen is a normal pen able to record all actions of the user and to analyze a micro pattern printed on the paper. The digital paper is a normal paper printed with an almost invisible micro pattern of small dots encoding information such as position and identifiers. We report our experience in the implementation and the use of this technology in an existing large clinical information system for acquiring clinical information.It is possible to print uniquely identified forms using the digital paper technology. These forms can be pre-filled with clinical readable information about the patient. When care providers complete these forms using the digital pen, it is possible to acquire the data in a structured computerized patient record. The technology is easy to integrate in a component-based architecture based on Web Services.The digital pen and paper is a cost-effective technology that can be integrated in an existing clinical information system and allows fast and easy bedside clinical information acquisition without the need for an expensive infrastructure based on traditional portable devices or wireless devices.

CCPA: Component-Based Communication Protocol Architecture for embedded systems

For increased and various communication requirements of modern applications on embedded systems, general purpose protocol stacks and protocol models are not efficient because they are fixed to execute in the static mode. We present the Component-Based Communication Protocol Architecture (CCPA) to make communication dynamic and configurable. It can develop, test and store the customized components for flexible reuse. The protocols are implemented by component assembly and support by configurable environments. This leads to smaller memory, more flexibility, more reconfiguration ability, better concurrency, and multiple data channel support.

Design and Implementation of Components in the Earth System Modeling Framework

The Earth System Modeling Framework is a component-based architecture for developing and assembling climate and related models. A virtual machine underlies the component-level constructs in ESMF, providing both a foundation for performance portability and mechanisms for resource allocation and component sequencing.