Software Engineering Exam #2

The steps of dynamic data flow analysis

1. Restate the problem as data flow graph

2. Identify the afferent and efferent data elements

3. First-level factoring

4. Factoring of afferent, efferent, and transform branches.

How to produce a factored system for a DDFA problem

-provide detailed data dictionaries for each interface including identifying inputs and outputs.

-Modules should have high cohesion and low coupling

Data Flow Graph Example:

How data flow graphs work

-Design concentrate on identifying what is required, the necessary inputs and desired outputs.

-Label the data elements carefully with descriptive names and leave a transform bubble.

-use ‘and’ and ‘or’ operators where appropriate in diagrams

-make sure the data flow is correct for the level of detail being modeled.

Which metrics to use to evaluate a design

specified all input/output parameters and their types for each module.

1. Meet Miller’s Law?

2. Meet Graicunuas Law (Relations or Interactions?)

3. Minimized Data and Control Coupling

4. Are the modules Functionally Cohesive with Sequential Cohesion between them?

5. Highly Factored - upper modules mostly command/control with details implemented in lower level?

6. Identifiable Afferent, Central Transform and Efferent Branches?

7. Meet Scope-Of-Effect subset of Scope-Of-Control goals?

The steps of using the Jackson technique

Design:

1.Evaluate the problem environment and record our understanding of it by defining structures for the data to be processed

2.Develop a program structure based on data structure

Implementation:

3.Define the tasks to be performed in terms of elementary operations, any order.

4.Allocate each of the elementary operations to suitable components of the program structure

How to solve problems with the Jackson technique

1. Define the data structure (Design)

2. Develop the program structure (Design)

3. List the tasks (Implementation)

4. Allocate each operation (Implementation)

The philosophy of the Jackson

Programs process datum, not control!

The structure of a program should reflect the structure of the data it processes.

The types of structures allowed in Jackson approach to design

Sequential

Iteration

Selection

Sequential (type of structure in Jackson)

The notation indicates that the DATA consists of a structure of Type -1 followed by a structure of Type-2.

Iteration (type of structure in Jackson)

The structure indicates that the DATA consists of an iteration of structures of Type-1 (by the *)

Selection (type of structure in Jackson)

The structure (DATA) consists of a structure of TYPE-1 or TYPE-2

The difference between macro and micro flow charts

Macro - Gods Eye View (Overview of what is to be accomplished)

Micro - Detailed implementation of Gods eye view.

How to draw a flow chart

1. Define purpose and scope

2. List Steps in Order

3. Choose Standard Shapes

4. Draw and Connect the Shapes

5. Review and Refine

What is Inversion of control?

Where are you likely to encounter it ?

-code being called by another program, got modules separated they work separated

What is a CASE tool?

What it does for you?

Computer Aided Software Engineering

automates and supports design and development activities

What is an audit trail?

What is it used for?

-A record of every transaction made against the system

-Used for system recovery

What are the effects from excessive or unpaid overtime?

results in poor work attitudes, your best employees will eventually leave

The replacement costs for employees

approximately 1.5 to 2 months salary to advertise, interview and hire

The results of the DeMarco and Lister performance studies

A few good employees are better than an army of average employees.

What is flow and why is it important

a deep, nearly meditative involvement with work attained during single-minded work with no interruptions.

IT IS MOST CREATIVE PERIOD

The cost related to having a poor work environment

Ways of measuring quality

When in a project you must build quality