Software Architecture unit 2

1. What is KWIC? 

The KWIC (Key Word In Context) index system accepts an ordered set of lines; each line is an ordered set of words, and each word is an ordered set of characters. Any line may be “circularly shifted” by repeatedly removing the first word and appending it at the end of the line. The KWIC index system outputs a listing of all circular shifts of all lines in alphabetical order. 

2. What are the software design changes proposed by Parnas? 

• Changes in the processing algorithm 

• Changes in the data representation 

3. What are the considerations given by Garlan, Kaiser, and Notkin? 

The considerations given by Garlan, Kaiser, and Notkin are as follows: 

. Enhancement to system function 

. Performance 

. Reuse 

4. Give reasons, why Main Program/Subroutine with shared data style is not suitable for KWIC? 

A change in data storage format will affect almost all of the modules. Also changes in the overall processing algorithm and enhancements to system function are not easily accommodated. Finally this decomposition is not particularly supportive of reuse. 

5. Why Abstract data type style is more suitable for KWIC? 

Abstract data type style is more suitable for KWIC, because both the algorithms  and data representations can be changed in individual modules without affecting others. Also reuse is better supported, because modules make fewer assumptions about the others with which they interact. 

6. Is the Software design changes proposed by Parnas support for KWIC using implicit 

invocation? Give reason. 

The software design changes proposed by Parnas can be obtained in KWIC using implicit invocation. Since the additional modules can be attached to the system by registering them to be invoked on data-changing events. Thus the solution obtains functional enhancement. Also the solution insulates computations from changes in data representation. 

7. What is an Oscilloscope? 

An Oscilloscope is an instrumentation system that samples electrical signals and displays pictures of them on a screen. Oscilloscopes also perform measurements on the signals, and display them on the screen. 

8. Give the reason for moving from Pipe-and filter architecture to modified pipe-andfilter 

architecture in Oscilloscope. 

The Pipe-and-filter architecture was not clear how the user should interact with it. In modified pipe-and-filter architecture the introduction of a control interface solves a large part of the user interface problem. 

9. What are the basic requirements for a mobile robot’s architecture? 

• Deliberative and reactive behavior 

• Uncertainty 

• Account for dangers 

• Flexibility 

10. What are all the requirements supported by the control loop architecture in Mobile 

Robotics? 

Account for dangers can be reduced, since simplicity makes duplication easy and reduces the chance of errors creeping into the system. The major components of robot architecture such as supervisor, sensors, motors are separated from each other and can be replaced independently. Thus it satisfies the flexibility requirement.