2 - SSZG 653 Software Architectures : 2 Quality Attributes...

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SS ZG653 Software Architecture - 1 SSZG 653 Software Architectures : 2 Quality Attributes General Quality Scenarios Achieving Quality : Tactics A case
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SS ZG653 Software Architecture - 2 Case Study : A-7E Avionics System The case study is included in the textbook to show which structures emerge in a case, depending on system qualities emphasized by the architect. Summary : Real time system, limited computing power, stringent performance requirements (from the domain), no compilers available for the processor Architect’s emphasis : to build a systems that can easily accommodate changes of various kinds. Modifiable Architect’s strategies, tactics: to use information hiding where ever possible and to use a sequence of processes.
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SS ZG653 Software Architecture - 3 Higher level goal : to demonstrate the relevance of principles like information hiding in a real time system with constraints. Requirements, briefly: The aircraft uses several sensors to measure its current acceleration and velocity, and altitude. Target location on the ground can be pointed at using radar pointer. The system displays the location pointed at, on a map, and allows the aircraft to navigate to that point, or fire a weapon directed at that location, there being several kinds of weapons onboard, and each has its own set of parameters, and computation algorithms.
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SS ZG653 Software Architecture - 4 The structures that emerge in the architecture: Decomposition : modules Uses Process Decomposition structure: Encapsulate system details that are likely to change independently in different modules. Modules interact only through stable interfaces.
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SS ZG653 Software Architecture - 5 Module Decomposition Hardware Hiding Module : provide virtual hardware Hide details of the processor sub-module : Device Interface : Control, drive devices Radar Altimeter module Flight Information Display module Weapon Release System module sub module : Extended Computer module input-output module timer module
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SS ZG653 Software Architecture - 6 Behaviour Hiding module : Function Driving Module Doppler Radar Set Module Inter Navigation System module Shared Services Module Mode Determination Module Panel I/O Support Module
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SS ZG653 Software Architecture - 7 Software Decision Module : Hides design decisions based on mathematical theorems, physical facts, programming considerations such as algorithmic efficiency, accuracy Application Data Type module Data Banker Module : allows maintainence of most recent values of data Filter Module : how signals should be filtered, handle noise Physical module: computing physical dynamical values System Generation Module: Regarding the compiler that will be used to generate the code for the avionics processor, etc
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SS ZG653 Software Architecture - 8 Process Structure It was important to pay attention to the process structure: the structure could be used to replace the single processor system with a multi-processor Software implemented as a set of cooperating sequential processes that synchronize with each other to use shared
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2 - SSZG 653 Software Architectures : 2 Quality Attributes...

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