CMU CS 15-675 Architectures for Software Systems Spring 1997

Formal Models for Data Flow

Garlan & Shaw Questions on Readings for Lecture 7

Due: Monday, February 3, 1997

The papers:

[SG96]: Sec 6.1 - 6.3, 6.7

[Spi89]: pp 40-44

Hints:

This is our first assignment involving architectural formalisms and analysis. Many of you may already be familiar with the Z specification language. If not, [Spi89] is included to give you a quick introduction. To learn more about Z consult one of the several books about Z on reserve in the library. Overall, you do not need to become an expert in formal specification, but you should gain enough facility with the formal notations of the course that you can read others' specifications, and create simple ones of your own.

In the readings of [SG96], you need not follow all of the formal details, but you should attempt to see if the formal models match your intuition about what a Pipe & Filter architecture is. Consider issues such as: How are schemas used? What is the essence of the model? You should also consider how the two formal models differ.

Questions:

1. Contrasting the formal model of Section 6.2 with the one of 6.3, what is the essential difference between the two?
2. How does the formal model of an oscilloscope in 6.2 handle the ability for the user to configure what function an oscilloscope performs.
3. List two ways in which the formal model of Pipes & Filters in 6.3 abstracts from reality.
4. List two constraints that the model of Pipes & Filters in 6.3 places on the use of data flow?

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Modified: 01/31/97