Using real options to select stable Middleware-induced software architectures

The requirements that force decisions towards building distributed system architectures are usually of a non-functional nature. Scalability, openness, heterogeneity, and fault-tolerance are examples of such non-functional requirements. The current trend is to build distributed systems with middleware, which provide the application developer with primitives for managing the complexity of distribution, system resources, and for realising many of the non-functional requirements. As non-functional requirements evolve, the `coupling' between the middleware and architecture becomes the focal point for understanding the stability of the distributed software system architecture in the face of change. It is hypothesised that the choice of a stable distributed software architecture depends on the choice of the underlying middleware and its flexibility in responding to future changes in non-functional requirements. Drawing on a case study that adequately represents a medium-size component-based distributed architecture, it is reported how a likely future change in scalability could impact the architectural structure of two versions, each induced with a distinct middleware: one with CORBA and the other with J2EE. An option-based model is derived to value the flexibility of the induced-architectures and to guide the selection. The hypothesis is verified to be true for the given change. The paper concludes with some observations that could stimulate future research in the area of relating requirements to software architectures

Automatic performance optimisation of component-based enterprise systems via redundancy

Component technologies, such as J2EE and .NET have been extensively adopted for building complex enterprise applications. These technologies help address complex functionality and flexibility problems and reduce development and maintenance costs. Nonetheless, current component technologies provide little support for predicting and controlling the emerging performance of software systems that are assembled from distinct components. Static component testing and tuning procedures provide insufficient performance guarantees for components deployed and run in diverse assemblies, under unpredictable workloads and on different platforms. Often, there is no single component implementation or deployment configuration that can yield optimal performance in all possible conditions under which a component may run. Manually optimising and adapting complex applications to changes in their running environment is a costly and error-prone management task. The thesis presents a solution for automatically optimising the performance of component-based enterprise systems. The proposed approach is based on the alternate usage of multiple component variants with equivalent functional characteristics, each one optimized for a different execution environment. A management framework automatically administers the available redundant variants and adapts the system to external changes. The framework uses runtime monitoring data to detect performance anomalies and significant variations in the application's execution environment. It automatically adapts the application so as to use the optimal component configuration under the current running conditions. An automatic clustering mechanism analyses monitoring data and infers information on the components' performance characteristics. System administrators use decision policies to state high-level performance goals and configure system management processes. A framework prototype has been implemented and tested for automatically managing a J2EE application. Obtained results prove the framework's capability to successfully manage a software system without human intervention. The management overhead induced during normal system execution and through management operations indicate the framework's feasibility

A Framework for Secure Management of Web Services (SMaWS) in Enterprise Application Integration

This dissertation addresses challenges currently faced by enterprises that have embraced the new technology called Web Service in order to reduce the cost of enterprise application integration (EAI) as well as improve operational efficiency of their mission-critical business processes. The nature of Web Service introduces new challenges such as dependency among applications, and a failure in one application can lead to a failure in other dependent applications. Such challenges have led to a growing need for enterprises to confront Web Service monitoring and management issues as a priority. As a solution, this dissertation proposes a SMaWS (Secure Management of Web Services) infrastructure for secure monitoring and management of Web Services. Its goals are to provide deeper visibility into Web Service runtime activities as compared to currently Web Service management tools; access to information about the Quality of Service (QoS) of these Web Services; and a unified monitoring environment for Web Services deployed across enterprise business units. This enables an earlier detection of poor performance problem in each interdependent Web Service, which would lead to a faster diagnose and fixing of possible performance issue, and thus maximize availability. This dissertation describes the requirements analysis for monitoring and management of Web Services across an enterprise environment. It describes the architecture and design of the SMaWS infrastructure proposed for secure monitoring and management of Web Service. The proposed SMaWS framework enables the instrumentation of existing and newly developed Web Service applications, and extracts Web Service performance statistics. It determines Web Service identity, reliability, availability, security, usage, and license used by Web Service consumers to access a given service. This dissertation describes the SMaWS Repository and Security concepts that are proposed to address the challenges faced by most distributed architectures to enable the client applications determine the location of the server (“bootstrapping problem”), and at the same time ensuring both the integrity and confidentiality of parties involved. Finally, this dissertation presents a prototype implementation of SMaWS Manager Application and Sample SMaWS Web Service applications. The experimental results obtained, in terms of overhead induced by the SMaWS framework on the monitored Web Service applications, demonstrate the feasibility of the SMaWS infrastructure

Fault management of web services

The use of service-oriented (SO) distributed systems is increasing. Within service orientation web services (WS) are the de facto standard for implementing service-oriented systems. The consumers of WS want to get uninterrupted and reliable service from the service providers. But WS providers cannot always provide services in the expected level due to faults and failures in the system. As a result the fault management of these systems is becoming crucial. This work presents a distributed event-driven architecture for fault management of Web Services. According to the architecture the managed WS report different events to the event databases. From event databases these events are sent to the event processors. The event processors are distributed over the network. They process the events, detect fault scenarios in the event stream and manage faults in the WS

04511 Abstracts Collection -- Architecting Systems with Trustworthy Components

From 12.12.04 to 17.12.04, the Dagstuhl Seminar 04511 ``Architecting Systems with Trustworthy Components\u27\u27 was held in the International Conference and Research Center (IBFI), Schloss Dagstuhl. During the seminar, several participants presented their current research, and ongoing work and open problems were discussed. Abstracts of the presentations given during the seminar as well as abstracts of seminar results and ideas are put together in this paper. The first section describes the seminar topics and goals in general. Links to extended abstracts or full papers are provided, if available

Service Quality and Profit Control in Utility Computing Service Life Cycles

Utility Computing is one of the most discussed business models in the context of Cloud Computing. Service providers are more and more pushed into the role of utilities by their customer's expectations. Subsequently, the demand for predictable service availability and pay-per-use pricing models increases. Furthermore, for providers, a new opportunity to optimise resource usage offers arises, resulting from new virtualisation techniques. In this context, the control of service quality and profit depends on a deep understanding of the representation of the relationship between business and technique. This research analyses the relationship between the business model of Utility Computing and Service-oriented Computing architectures hosted in Cloud environments. The relations are clarified in detail for the entire service life cycle and throughout all architectural layers. Based on the elaborated relations, an approach to a delivery framework is evolved, in order to enable the optimisation of the relation attributes, while the service implementation passes through business planning, development, and operations. Related work from academic literature does not cover the collected requirements on service offers in this context. This finding is revealed by a critical review of approaches in the fields of Cloud Computing, Grid Computing, and Application Clusters. The related work is analysed regarding appropriate provision architectures and quality assurance approaches. The main concepts of the delivery framework are evaluated based on a simulation model. To demonstrate the ability of the framework to model complex pay-per-use service cascades in Cloud environments, several experiments have been conducted. First outcomes proof that the contributions of this research undoubtedly enable the optimisation of service quality and profit in Cloud-based Service-oriented Computing architectures

Towards an Enhanced Protocol for Improving Transactional Support in Interoperable Service Oriented Application-Based (SOA-Based) Systems

When using a shared database for distributed transactions, it is often difficult to connect business processes and softwarecomponents running on disparate platforms into a single transaction. For instance, one platform may add or update data, and thenanother platform later access the changed or added data. This severely limits transactional capabilities across platforms. Thissituation becomes more acute when concurrent transactions with interleaving operations spans across different applications andresources. Addressing this problem in an open, dynamic and distributed environment of web services poses special challenges,and still remains an open issue. Following the broad adoption and use of the standard Web Services Transaction Protocols,requirements have grown for the addition of extended protocols to handle problems that exist within the context of interoperableservice-oriented applications. Most extensions to the current standard WS-Transaction Protocols still lack proper mechanisms forerror-handling, concurrency control, transaction recovery, consolidation of multiple transaction calls into a single call, and securereporting and tracing for suspicious activities. In this research, we will first extend the current standard WS-TransactionFramework, and then propose an enhanced protocol (that can be deployed within the extended framework) to improvetransactional and security support for asynchronous applications in a distributed environment. A hybrid methodology whichincorporates service-oriented engineering and rapid application development will be used to develop a procurement system(which represents an interoperable service-oriented application) that integrates our proposed protocol. We will empiricallyevaluate and compare the performance of the enhanced protocol with other conventional distributed protocols (such as 2PL) interms of QoS parameters (throughput, response time, and resource utilization), availability of the application, databaseconsistency, and effect of locking on latency, among other factors.Keywords: Database, interoperability, security, concurrent transaction, web services, protocol, service-oriente

Towards Middleware for Fault-tolerance in Distributed Real-time and Embedded Systems

Abstract. Distributed real-time and embedded (DRE) systems often require support for multiple simultaneous quality of service (QoS) properties, such as real-timeliness and fault tolerance, that operate within resource constrained environments. These resource constraints motivate the need for a lightweight middleware infrastructure, while the need for simultaneous QoS properties require the middleware to provide fault tolerance capabilities that respect time-critical needs of DRE systems. Conventional middleware solutions, such as Fault-tolerant CORBA (FT-CORBA) and Continuous Availability API for J2EE, have limited utility for DRE systems because they are heavyweight (e.g., the complexity of their feature-rich fault tolerance capabilities consumes excessive runtime resources), yet incomplete (e.g., they lack mechanisms that enable fault tolerance while maintaining real-time predictability). This paper provides three contributions to the development and standardization of lightweight real-time and fault-tolerant middleware for DRE systems. First, we discuss the challenges in realizing real-time faulttolerant solutions for DRE systems using contemporary middleware. Second, we describe recent progress towards standardizing a CORBA lightweight fault-tolerance specification for DRE systems. Third, we present the architecture of FLARe, which is a prototype based on the OMG real-time fault-tolerant CORBA middleware standardization efforts that is lightweight (e.g., leverages only those server-and client-side mechanisms required for real-time systems) and predictable (e.g., provides fault-tolerant mechanisms that respect time-critical performance needs of DRE systems)

A model-based approach for automatic recovery from memory leaks in enterprise applications

Large-scale distributed computing systems such as data centers are hosted on heterogeneous and networked servers that execute in a dynamic and uncertain operating environment, caused by factors such as time-varying user workload and various failures. Therefore, achieving stringent quality-of-service goals is a challenging task, requiring a comprehensive approach to performance control, fault diagnosis, and failure recovery. This work presents a model-based approach for fault management, which integrates limited lookahead control (LLC), diagnosis, and fault-tolerance concepts that: (1) enables systems to adapt to environment variations, (2) maintains the availability and reliability of the system, (3) facilitates system recovery from failures. We focused on memory leak errors in this thesis. A characterization function is designed to detect memory leaks. Then, a LLC is applied to enable the computing system to adapt efficiently to variations in the workload, and to enable the system recover from memory leaks and maintain functionality

Middleware Technologies for Cloud of Things - a survey

The next wave of communication and applications rely on the new services provided by Internet of Things which is becoming an important aspect in human and machines future. The IoT services are a key solution for providing smart environments in homes, buildings and cities. In the era of a massive number of connected things and objects with a high grow rate, several challenges have been raised such as management, aggregation and storage for big produced data. In order to tackle some of these issues, cloud computing emerged to IoT as Cloud of Things (CoT) which provides virtually unlimited cloud services to enhance the large scale IoT platforms. There are several factors to be considered in design and implementation of a CoT platform. One of the most important and challenging problems is the heterogeneity of different objects. This problem can be addressed by deploying suitable "Middleware". Middleware sits between things and applications that make a reliable platform for communication among things with different interfaces, operating systems, and architectures. The main aim of this paper is to study the middleware technologies for CoT. Toward this end, we first present the main features and characteristics of middlewares. Next we study different architecture styles and service domains. Then we presents several middlewares that are suitable for CoT based platforms and lastly a list of current challenges and issues in design of CoT based middlewares is discussed.Comment: http://www.sciencedirect.com/science/article/pii/S2352864817301268, Digital Communications and Networks, Elsevier (2017