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

Integration, management and communication of heterogeneous design resources with WWW technologies

Recently, advanced information technologies have opened new pos-sibilities for collaborative designs. In this paper, a Web-based collaborative de-sign environment is proposed, where heterogeneous design applications can be integrated with a common interface, managed dynamically for publishing and searching, and communicated with each other for integrated multi-objective de-sign. The CORBA (Common Object Request Broker Architecture) is employed as an implementation tool to enable integration and communication of design application programs; and the XML (eXtensible Markup Language) is used as a common data descriptive language for data exchange between heterogeneous applications and for resource description and recording. This paper also intro-duces the implementation of the system and the encapsulating issues of existing legacy applications. At last, an example of gear design based on the system is il-lustrated to identify the methods and procedure developed by this research

A Generic Deployment Framework for Grid Computing and Distributed Applications

Deployment of distributed applications on large systems, and especially on grid infrastructures, becomes a more and more complex task. Grid users spend a lot of time to prepare, install and configure middleware and application binaries on nodes, and eventually start their applications. The problem is that the deployment process is composed of many heterogeneous tasks that have to be orchestrated in a specific correct order. As a consequence, the automatization of the deployment process is currently very difficult to reach. To address this problem, we propose in this paper a generic deployment framework allowing to automatize the execution of heterogeneous tasks composing the whole deployment process. Our approach is based on a reification as software components of all required deployment mechanisms or existing tools. Grid users only have to describe the configuration to deploy in a simple natural language instead of programming or scripting how the deployment process is executed. As a toy example, this framework is used to deploy CORBA component-based applications and OpenCCM middleware on one thousand nodes of the French Grid5000 infrastructure.Comment: The original publication is available at http://www.springerlink.co

Performance Evaluation and Comparison of CORBA Implementations for the Java Platform

Middleware is a software layer between the applications, services and the operating system that provides an abstraction to the application programmer. It masks the heterogeneous nature of the network and provides such services as remote calls, naming service, transaction process abilities, and security services. Common Object Request Broker Architecture (CORBA) is a middleware design that is implemented through the use of Object Request Broker (ORB), which is a software component that,allows communication between the remote objects and applications that use them in a distributed environment. CORBA applications can run on almost any platform, operating system, and support different languages. There are many types of distributed object middleware on the market such as Sun\u27s Java 2 ORB, Inprises\u27s VisiBroker for Java, IONA\u27s ORBacus for Java, and IONA\u27s Orbix 2000 for Java. Because of these various products, it is difficult to select the product that will provide the specific requirements for one\u27s application. The goal of this project is to evaluate the above-mentioned implementations of the CORBA standards and, additionally, CORBA was compared to LAMIMPI for efficiency. The results of this project should provide developers and novices studying distributed systems the necessary data to evaluate and select the most efficient CORBA product to meet their specific design requirements, and provide a methodology for further evaluation

Context-aware, ontology-based, service discovery

Service discovery is a process of locating, or discovering, one or more documents, that describe a particular service. Most of the current service discovery approaches perform syntactic matching, that is, they retrieve services descriptions that contain particular keywords from the user’s query. This often leads to poor discovery results, because the keywords in the query can be semantically similar but syntactically different, or syntactically similar but semantically different from the terms in a service description. Another drawback of the existing service discovery mechanisms is that the query-service matching score is calculated taking into account only the keywords from the user’s query and the terms in the service descriptions. Thus, regardless of the context of the service user and the context of the services providers, the same list of results is returned in response to a particular query. This paper presents a novel approach for service discovery that uses ontologies to capture the semantics of the user’s query, of the services and of the contextual information that is considered relevant in the matching process

Applications of CORBA in the ATLAS prototype DAQ

This paper presents the experience of using the Common Object Request Broker Architecture (CORBA) in the ATLAS prototype DAQ project. Many communication links in the DAQ system have been designed and implemented using the CORBA standard. A public domain package, called Inter-Language Unification (ILU) has been used to implement CORBA based communications between DAQ components in a local area network (LAN) of heterogeneous computers. The CORBA Naming Service provides the principal mechanism through which most clients of an ORE-based system locate objects that they intend to use. In our project, conventions are employed that meaningfully partition the name space of the Naming Service according to divisions in the DAQ system itself. The Inter Process Communication (IPC) package, implemented in C++ on the top of CORBA/ILU, incorporates this facility and hides the details of the naming schema is described. The development procedure and environment for remote database access using IPC is described. Various end-user interfaces have been implemented using the Java language that communicate with C++ servers via CORBA/ILU. To support such interfaces, a second implementation of IPC in Java has been developed. The design and implementation of such connections are described. An alternative CORBA implementation, ORBacus, has been evaluated and compared with ILU. (24 refs)

Monitoring extensions for component-based distributed software

This paper defines a generic class of monitoring extensions to component-based distributed enterprise software. Introducing a monitoring extension to a legacy application system can be very costly. In this paper, we identify the minimum support for application monitoring within the generic components of a distributed system, necessary for rapid development of new monitoring extensions. Furthermore, this paper offers an approach for design and implementation of monitoring extensions at reduced cost. A framework of basic facilities supporting the monitoring extensions is presented. These facilities handle different aspects critical to the monitoring process, such as ordering of the generated monitoring events, decoupling of the application components from the components of the monitoring extensions, delivery of the monitoring events to multiple consumers, etc.\ud The work presented in this paper is being validated in the prototype of a large distributed system, where a specific monitoring extension is built as a tool for debugging and testing the application behaviour.\u