体系结构讲义.pptx

第五讲 Automated Guided Vehicle 软件体系结构 Software Architecture Outline ? Concurrent and Real-time Software Architectures ? Problem Description ? Use Case Modeling ? Static Modeling ? Object and Class Structuring ? Dynamic Modeling ? Design Modeling 2 Concurrent and Real-time SA ? Real-time systems ? are concurrent systems with timing constraints ? refer to the whole system, including the real time application , real-time operating system, and the real-time I/O subsystem, with special-purpose device drivers to interface to the various sensors and actuators ? are plex because they have to deal with multiple independent streams of input events and produce multiple independent outputs ? the order of ing events is not predictable ? the input load might vary significantly and unpredictably with time 3 Concurrent and Real-time SA ? Real-time systems ? hard real-time systems ? has time-critical deadlines that must be met to prevent a catastrophic system failure ? soft real-time systems ? missing deadlines occasionally is considered undesirable but not catastrophic, so it can be tolerated 4 Concurrent and Real-time SA 5 Concurrent and Real-time SA ? Control Pattern for Real-time SA ? Centralized Control Architectural Pattern ? one ponent ? executes a statechart and provides the overall control and sequencing of the system ? receives events from ponents with which it interacts ? An input event to a ponent usually causes a state transition on its statechart , which results in one or more state- dependent actions ? uses these actions to control ponents ? Entity objects 6 Concurrent and Real-time SA ? Control Pattern for Real-time SA ? Distributed Control Architectural Pattern ? several ponents ? Each controls a given part of the system by conceptually executing a statechart ? No ponent in overall control ? Communicate through peer-to-munication between each other ? Interact with the external environment as in the Centralized Control pattern 7 Concurrent and Real