Trong những gì sau, chúng tôi mô tả vấn đề thiết kế chính để được giải quyết trong mỗi tả các thành phần chính của hệ thống thông tin liên lạc sẽ được sử dụng để thông qua điều khiển và thông tin giữa các tài nguyên hệ thống phân phối. Lớp này bị phân hủy thành ba sublayers: loại hình mạng, giao thức truyền thông, | DISTRIBUTED SYSTEM DESIGN FRAMEWORK 7 tions. Based on this notion of the design process the distributed system design framework can be described in terms of three layers Figure 1 network protocol and interface NPI layer 2 system architecture and services SAS layer and 3 distributed computing paradigms DCP layer. In what follows we describe the main design issues to be addressed in each layer. Communication network protocol and interface layer. This layer describes the main components of the communication system that will be used for passing control and information among the distributed system resources. This layer is decomposed into three sublayers network type communication protocols and network interfaces. Distributed system architecture and services layer. This layer represents the designer s and system manager s view of the system. SAS layer defines the structure and architecture and the system services distributed file system concurrency control redundancy management load sharing and balancing security service etc. that must be supported by the distributed system in order to provide a single-image computing system. Distributed computing paradigms layer. This layer represents the programmer user perception of the distributed system. This layer focuses on the programming paradigms that can be used to develop distributed applications. Distributed computing paradigms can be broadly characterized based on the computation and communication models. Parallel and distributed computations can be described in terms of two paradigms functional parallel and data parallel paradigms. In functional parallel paradigm the computations are divided into distinct functions which are then assigned to different computers. In data parallel paradigm all Distributed Computing Paradigms Computation Models Communication Models Functional Parallel Data Parallel Message Passing Shared Memory System Architecture and Services SAS Architecture Models System-Level Services Computer Network
