Middleware Platform Management based on Portable Interceptors

Object middleware is an enabling technology for distributed applications that are required to operate in heterogeneous computing and communication environments. Although hiding distribution aspects to application designers proves beneficial, in an operational environment system managers may need detailed information on information flows and the locality of objects in order to track problems or tune the system. Therefore, hooks are required inside the processing core of the middleware to obtain inside-information and to influence the processing of information flows. We present the use of portable interceptors for the management of CORBA as well as COM/DCOM middleware. Management information is structured in a middleware technology independent way, using XML for representation. Our approach shows two aspects of “management transparency”: application designers are not burdened with designing management functionality, and system managers can manage CORBA and (D)COM from a single set of management tools

Quality of Service and Service Provisioning on a Competitive Market

The objective of this paper is to provide an economic and commercial context for QoS research in open distributed environments. The analyses are based on a telecommunications value chain model. The model is used to define possible roles for telecommunications companies, migrating from traditional telephony network operators towards privatised ICT companies in a new economy. Based on these developments, we advocate R&D activities aiming at standardised concepts and engineering principles to establish and control QoS in open distributed environments

OCI-Based Group Communication Support in CORBA

Group communication is a useful mechanism guaranteeing consistency among replicated objects. The existing approaches do not allow transparent plug-in of group communication protocols into CORBA. They either require modification of CORBA or OS, or provide no room for incorporating group communication transport protocols into CORBA. We thus propose a generic group communication framework that allows transparent plug-in of various group communication protocols with no modification of existing CORBA. We extend the open communications interface (OCI) to support interoperability, reusability of existing group communication, and independency on ORB and OS. We also define the group communication inter-ORB protocol (GCIOP) as a group communication instantiation of the general inter-ORB protocol (GIOP) that encapsulates underlying group communication protocols. The proposed scheme can be exploited for fault-tolerant CORBA (FT CORBA)

OCI-Based Group Communication Support in CORBA

Group communication is a useful mechanism guaranteeing consistency among replicated objects. The existing approaches do not allow transparent plug-in of group communication protocols into CORBA. They either require modification of CORBA or OS, or provide no room for incorporating group communication transport protocols into CORBA. We thus propose a generic group communication framework that allows transparent plug-in of various group communication protocols with no modification of existing CORBA. We extend the open communications interface (OCI) to support interoperability, reusability of existing group communication, and independency on ORB and OS. We also define the group communication inter-ORB protocol (GCIOP) as a group communication instantiation of the general inter-ORB protocol (GIOP) that encapsulates underlying group communication protocols. The proposed scheme can be exploited for fault-tolerant CORBA (FT CORBA)

Extending CORBA with specialised protocols for QoS provisioning

The CORBA layer in a distributed system hides the heterogeneity of the underlying computer network. The interactions of objects located at different computing systems are described in terms of IDL specifications and the ORB takes care of the actual transfer of messages along the wire. In fact, an object interaction is translated into the transfer of GIOP messages over TCP/IP networks (IIOP). The advantages in terms of interoperability and portability are obvious. Currently, OMG is in the process of standardising the Open Communication Interface (OCI). Through OCI, a protocol module can be plugged into any ORB and hence, the distributed application including the ORB can be put on top of any network without changing the application’s code, thus implementing network transparency. Obviously, the QoS of distributed applications depends on the QoS of the underlying network protocols, e.g., best effort versus guaranteed bandwidth. Through OCI we are able to use the network protocol that is needed to satisfy the QoS requirements of a specific distributed application. In this paper, we propose to extend CORBA with specialised protocols for QoS provisioning using OCI. We have prototyped protocol plug-in’s, including a plug-in that exploits IP Multicast. The IP Multicast plug-in can be used in situations where one client communicates with a group of replicated servers. In fact, we have used this mechanism to implement replication transparency in CORBA. We have shown that the OCI interface can be used for QoS provisioning in CORBA. Based on our hands-on experience, we also have identified some shortcomings in the proposed OCI specification

Utilizando reflexão computacional no desenvolvimento de aplicações distribuídas

Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico. Programa de Pós-Graduação em Ciência da Computação.O desenvolvimento de aplicações distribuídas exige o uso de algum mecanismo que possibilite a comunicação entre os processos cliente e servidor. Tecnologias de distribuição como RMI, CORBA e XML-RPC/SOAP disponibilizam serviços que facilitam esta atividade. Todavia, a implementação baseada nas interfaces de programação destas especificações acaba por misturar o código necessário à distribuição com a funcionalidade da aplicação, tornando-a dependente do mecanismo escolhido. Minimizar o impacto diante de uma troca de tecnologia e, simultaneamente, permitir que o desenvolvedor do software esteja focado em requisitos funcionais, constitui o principal problema desta pesquisa. De forma a possibilitar o desenvolvimento de aplicações distribuídas independentemente da plataforma de distribuição, esta dissertação propõe um framework que isola as especificidades de cada padrão dos componentes funcionais. Técnicas de reflexão computacional são aplicadas na implementação, de maneira a eliminar a codificação de adaptadores e proxies exigida em outras abordagens. Ao separar os elementos necessários à distribuição dos elementos funcionais, o framework possibilita a substituição dos mecanismos através de uma configuração externa ao software, dispensando, desta maneira, alterações no código fonte