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1、Ch6.3 Another Example of Software Architectures Design,Ding Er-Yu Software Institute, Nanjing University,Software System Design and Architecture,Case study IS2000,A image acquisition and processing system 基本功能是用探测器上的相机捕获图像，图像源可以是光，也可以是来自热量或者其它发射源的电磁光谱。传感器需要预存控制数据。IS2000需要采集原始数据，转换成传感器数据，以及适于显示的图像 IS
2、2000用户希望获得照相机从固定或移动角度得到的一个、一组或者运动中的图像。用户可以定义采集过程 用户可以监测和调整图像生成，还可以把图像传输到远程图像系统以用于远程处理或显示,Main function,Global analysis: Issue and strategies,Factors: Aggressive schedule Reuse components Buy rather than build Make it easy to add or remove feature Skill deficiencies Avoid the user of multiple threads
3、 Encapsulate multi-process support facilities Changes in general purpose and domain-specific hardware Encapsulate domain-specific hardware Encapsulate general-purpose hardware,Global analysis: Issue and strategies,Factors: Changes in software technology Use standards Develop product-specific interfa
4、ces to external components Resource limitations Limit the number of active processes Use dynamic inter-process communication Use shared memory to communicate Easy addition and removal of feathers Separate components and modules along dimensions of concerns Encapsulate features into separate componen
5、ts Decouple the user interaction model,Global analysis: Issue and strategies,Factors: Easy addition and removal of acquisition procedures and processing algorithms Use a flexible pipeline model for image processing Introduce components for acquisition and image processing Encapsulate domain-specific
6、 image data High throughput Map independent threads of control to processes Use an additional CPU,Global analysis: Issue and strategies,Factors: Real-time acquisition performance Separate time-critical from nontime-critical components Use flexible allocation of modules to processes Implementation of
7、 recovery Introduces a recovery mode of operation Make all data at the point of recovery persistent and accessible Implementation of diagnostics Define an error-handling policy Encapsulate diagnostic component Use standard logging services,Global analysis: Issue and strategies,Factors: Multiple deve
8、lopment and target platform Separate and encapsulate code dependent on the target platform Concurrent development tasks Use phased development Release layers through static libraries Limited availability of Probe Prototypes Develop an off-line probe simulator with an appropriate abstraction Use a fl
9、exible build procedure,The initial framework,From the use cases,Changes in general purpose and domain-specific hardware Encapsulate domain-specific hardware,Easy addition and removal of feathers Decouple the user interaction model,Real-time acquisition performance Separate time-critical from nontime
10、-critical components,Easy addition and removal of acquisition procedures and processing algorithms Encapsulate domain-specific image data,The initial component view,Map each part of logical view to a component,Separate the components into layers,Concurrent development tasks Use phased development Ar
11、chitectural integrity,Adjusts layers,Changes in general purpose and domain-specific hardware Encapsulate general-purpose hardware Implementation of diagnostics Define an error-handling policy Encapsulate diagnostic component Use standard logging services Implementation of recovery Introduces a recov
12、ery mode of operation Make all data at the point of recovery persistent and accessible,Logical view should be adjusts according to these!,Allocation of modules to processes,Skill deficiencies Avoid the user of multiple threads Encapsulate multi-process support facilities Resource limitations Limit t
13、he number of active processes Use dynamic inter-process communication Use shared memory to communicate High throughput Map independent threads of control to processes Real-time acquisition performance Use flexible allocation of modules to processes However, the cost of creating/destroying operating
14、system processes is low,Process view,Allocates each module to a process,Deployment of processes,High throughput Use an additional CPU Real-time acquisition performance Separate time-critical from nontime-critical components Deploy processes between two CPU Communications influenced by deployment sho
15、uld be dealt with,Real-Time CPU,UNIX CPU,Deployment of components,Concurrent development tasks Release layers through static libraries Codes are deployed with unit on layer, such as GUI.lib, etc. Multiple development and target platform Separate and encapsulate code dependent on the target platform
16、Organize compiled files into a separate sub-package for each target platform Limited availability of Probe Prototypes Develop an off-line probe simulator with an appropriate abstraction Use a flexible build procedure Develop an off-line probe simulator, provides two libraries for ProbeService layer (ProbeService.lib, ProbeSimulatorService.lib),
