CSE 5306-2

Lab Insights

Rapid Prototyping

• Agile software designers do the hardest parts of their projects first.

• Software analysts very quickly develop a series of simple models (rapid prototypes) of a customer’s concepts to elicit her requirements.

• Nontechnical customers cannot clearly verbalize technical requirements to software designers. (Nor can software designers paint portraits.)

• But customers know what they like, when they see it. And they can conceptually verbalize what is wrong with each prototype demonstration.

MATLAB Simulations• Start with those parts of each performance

demonstration that are 1) easiest to code and 2) the customer feels are most important.

• Lab 1 example:– A simple script (not a function) with fprintf (or disp)

functions would earn you about 80%.– disp(‘myBalance yourBalance myChex’)– disp(‘100 0’)– disp(’40 0 150’)– disp(‘Overdraft!’)– disp(’20 20 20’)

Bridge to the Software Designer• The designer says, “But you have only written a test case and its

correct results. …How does the system work?”• Answer: rapidly prototype the logic in function(s), most of which

already appear in MATLAB’s very extensive library. (Thinkers always should browse “Help” diligently!)

• Lab 1 example—repeatedly invoke the following function in the Command Window to earn a 85% grade:– function [ myAcct urAcct ] = banksvr( myChex )– urAcct = urAcct + myChex % your deposit…– myAcct = myAcct – myChex % …matches my withdrawal– If myAcct < 0 % transaction failure!– urAcct = urAcct – myChex % back out the deposit– myAcct = myAcct + myChex – 60 % back out the withdrawal– end– end

Software Reuse

• MATLAB is the rapid prototypers’ Wikipedia…! (Every part of your next system simulation already has been implemented by other systems analysts hundreds of times.)

• Lab 1 example:– One of MATLAB’s GUI templates already includes

two labeled textboxes and two buttons. (You need only one more button, exactly like the others.)

– Make a few cosmetic changes, and press the green triangle “GO” button to automatically generate your GUI’s code and earn a 90%.

Put It All Together

• Integrate all of your lightly-adapted MATLAB stock functions to achieve the customer’s desired performance, in a way that also informs the software designer.

• Lab 1 example—insert function invocations directly into the GUI code to earn a 95%:– % “100” button paragraph:– myAcct = 100 – urAcct = 0– % “20” button paragraph:– [ myAcct urAcct ] = banksvr( 20 )– Etc.

Make the Customer Smile

• Clean up the GUI, clarify the Command Window test report, fully test the function(s), etc. (See MATLAB’s extensive library of very professional demonstrations on your computer and at www.Mathworks.com .)

• Ensure that every known requirement is demonstrated.• Lab 1 example, which earns 100%:

– Transactions’ classic ACID features are clear here.– You and I perceive this collection of independent computers

(i.e., the distributed system of two GUI clients and bank server) as a single coherent system.

– Several distributed system transparencies are clearly apparent.

Summary

Take these 5 steps in your next rapid prototyping effort:0. (Doing absolutely nothing earns 70% by default.)1. A MATLAB script that simply uses fprintf instructions to print a

demonstration of the prototype's required performance in the Command Window earns ~80%.

2. Also allocating those fprintf statements to a collection of interacting functions helps out your software developers and earns ~85%.

3. Also integrating those functions with any necessary MATLAB functions earns ~90%.

4. Also tidying up your code and making its nontechnical customer demonstration abundantly clear earns ~95%.

5. Also making the demo clearly describe the textbook concepts, for which the lab was created, earns ~100%.