Roland Balter

Architecturing and configuring distributed application with Olan

Middleware platforms are today solutions to the problem of designing and implementing distributed applications. They provide facilities for heterogeneous software components to communicate remotely, according to various interaction model, for example client server communication or asynchronous message passing. However, middleware platforms, like message busses or object request brokers, hardly provide tools for the design, configuration and installation of complex software architectures. This paper presents the Olan environment which primary objective is the description of complex architecture, their configuration according to application requirements and the deployment on heterogeneous distributed environments. The Olan environment is based on an Architecture Description Language where the application is considered as a hierarchy of interconnected software components. A set of software engineering tools assist the application designer in his task of wrapping existing software modules into components which are in turned interconnected through various communication models and finally assembled together according to specific configuration criteria. At run time, a set of system services in charge of automating the installation of the components and their communication channels on a given middleware platform, thus facilitating the overall deployment process of the global application.

Asynchronous, Hierarchical, and Scalable Deployment of Component-Based Applications

The deployment of distributed component-based applications is a complex task. Proposed solutions are often centralized, which excludes their use for the deployment of large-scale applications. Besides, these solutions do often not take into account the functional constraints, i.e. the dependences between component activations. Finally, most of them are not fault-tolerant. In this paper, we propose a deployment application that deals with these three problems. It is hierarchical, which is a necessary feature to guarantee scalability. Moreover, it is designed as a distributed workflow decomposed into tasks executing asynchronously, which allows an “as soon as possible” activation of deployed components. Finally, the proposed deployment application is fault-tolerant. This is achieved by the use of persistent agents with atomic execution. This deployment application has been tested and performance measurements show that it is scalable.

The Guide Language

The Guide language is an object-oriented language dedicated for programming distributed applications on top of the Comandos platform. This language faithfully reflects all the capabilities of the Comandos model. It combines the facilities of a strongly typed object model with a powerful computational model. Key features of the language are: separation between types and classes, conformant subtyping, distribution transparency, concurrent activities, synchronization mechanism for shared objects, and exception handling. This paper presents the design choices for the Guide language and discusses programming experience gained from the use of the language for the construction of distributed applications.

Experience with object-based distributed computation in the GUIDE operating system

A brief description is given of how the issues of access to (possibly remote) services and cooperative distributed computing are treated in GUIDE (Grenoble universities integrated distributed environment), a distributed operating system under development at Grenoble on a local network of workstations. An overview of the project is given, and the computational model of the system is described. Remote computation is discussed. The current implementation status and experience with the system are examined.<<ETX>>

Assemblons les pièces inexistantes d un immense puzzle

The invention concerns extruded sealing strips of a resilient material with a center core or reinforcement in the form of gripping means. Such sealing strips are typically used around automobile doors or door frames. The body of the sealing strip has at least a partial fabric covering which is of a light and economical structure. This material is coated with a vinyl plastisol which advantageously is microporous. The coated material is then embossed and finally adhesively bonded, with an adhesive based on saturated polyurethane, which is not reactive in solution. Flocking may be applied prior to or after the bonding to further improve the esthetic appearance of the assembly.

Object-based distributed computation in the Guide operating system

This paper briefly describes how the issues of access to (possibly remote) services and cooperative distributed computing are treated in Guide, a distributed operating system under development at Grenoble. Section 1 is an overview of the project. Section 2 describes the computational model of the system. Section 3 is a discussion of remote computation. Section 4 describes the current implementation status.