Software Engineering Lab Session 1 Introduction to the

Software Engineering Lab Session 1 – Introduction to the practicum © Jorge Aranda, 2005

Overview p What is it about? p Why are we doing this? p How to get a good grade p The Personal Software Process p Assignment 1

What is it about? p Based on Watts Humphrey’s Personal Software Process n Outlined in A Discipline for Software Engineering p n You should have finished reading Chapters 1 -4 already! Six relatively easy programming assignments On C p Focus on learning and understanding the process p Assignments map to Humphrey’s 1 A-6 A exercises p

What is it about? p You’ll be submitting one assignment per week n n p Except on Thanksgiving and the midterm week There’ll also be weekly reading assignments The process will be increasingly elaborated as we go along…

Why are we doing this? p Hardly surprising facts: n n n 1 – Most software projects go wrong 2 – Most software projects do not follow *any* development process 3 – Software projects that do follow some process have a much better chance of survival It really can be almost any process p Extreme Programming and other Agile styles p Cleanroom p Capability Maturity Model (CMM) p

Why are we doing this? p But software engineers are frequently too busy to learn software processes p The best time for you to learn them is now p We chose the Personal Software Process (PSP) n n Will help you think about software development in a disciplined way Will help you to know your own strengths and weaknesses, and to improve them It’s a personal activity, but it can be extended to teams and organizations It’ll look good on your resume

Why are we doing this? p Think about the term ‘Software Engineer’ n What defines an engineer? n What do engineers measure/control/plan? n Do software developers really do engineering?

Why are we doing this? p Software engineering: n Management of resources Main resource is the engineer’s own time and what she does with it! p Estimation p Progress tracking p n Quality Assurance Defects injected into product p Conformance of product to requirements p

Why are we doing this? p Would you be able to respond accurately to these questions? n On average, how many defects do you inject in the code you write (per 1, 000 lines of code)? n How many of those defects are coding errors, and how many are design or requirements errors? n What percentage of your time goes into coding? What percentage goes into fixing defects? n How many lines of code have you written in the past year? How many classes, methods or routines? Of what kind? n By what percentage are your estimates normally off? n Developers are all different –what are your weaknesses and strengths as a developer? (Fast coder, high quality, good architecture…? )

Why are we doing this? p This practicum will help you find answers to those questions p It’s harder than it sounds! n n n You need to be disciplined about your own work Use a structured process Keep track of a lot of little details Little by little you’ll get used to it If you like it, great! You’ll have an important skill for your professional career. And if you don’t like it, remember you only have to do it this term…

How to get a good grade p Short story: n p It’s very easy, really. Just follow the process thoroughly and you’ll do great. Longer story: n Read ‘A Discipline for Software Engineering’ conscientiously. p n Stick to the process while doing the exercises p n Reflections on your performance and on the process Work on two levels p n Use the forms appropriately Extract insights from your own work, and report them p n Warning: Humphrey is not especially fun or concise Quality of your code, quality of your process Submit your assignments on time

The Personal Software Process p Basic idea #1: Measure yourself n n n Know how much time you spend in programming tasks Know how many defects your code has Know how well you estimate your effort p You can’t control what you can’t measure p Basic idea #2: Control yourself n n Improve your estimates Improve the quality of your software

The Personal Software Process p PSP is incremental: n PSP 0 p n Whatever you’re currently doing, plus some measurements PSP 0. 1 -> PSP 1. 1 Increasingly detailed estimates, controls p You start to apply regression to your estimates p You start getting efficiency and other quality metrics p This is as far as we’ll go p n PSP 2 -> PSP 3 We won’t have the time to go there… p I admit it does get hairy at this point… p

The Personal Software Process p PSP 0 n You’ll be using three forms: p p p Project Plan Summary Time Recording Log Defect Recording Log n Refer to Humphrey’s book for correct usage of these forms n Project Plan Summary p p p After understanding the requirements, estimate how many minutes will the assignment take After finishing the assignment, write down how much time it actually took, and how many defects you found It is OK to be absolutely wrong in your initial estimates…

The Personal Software Process p PSP 0 n Time Recording Log Have it handy when you work on your assignments p Record everything p § If you get up from your desk, get a call, read email… make sure your log has the corresponding ‘Interruption Time’ entries § Some details will feel embarrassing (two hours fixing a bug, for example…). Record them anyway Use minutes, not hours p Low-tech works better than hi-tech at this point p Use Humphrey’s classification of activities: p § Planning, Design, Code, Compile, Test, Postmortem

The Personal Software Process p PSP 0 n Defect Recording Log p Again, record every defect § If you designed your routines incorrectly, write the defect in the log § If you made an off-by-one error, write it in the log § If your automated tests were wrong, write it in the log § …you get the idea… p If unsure as to what ‘defect type’ each defect belongs to, write your assumptions in the defect description

The Personal Software Process p The three forms of PSP 0 will become the foundation of later assignments n It will feel weird at the beginning p n With time, you will be recording your time and defects naturally p n Give it some time Appreciating the advantages of this process will take a while It shouldn’t interfere with your creative processes!

Assignment 1 p Write a program to calculate the mean and standard deviation of a sample of n real numbers. p Hints n n n n Remember we’re interested in that you learn a process, not in that you know how to program a standard deviation routine! Your report on insights and impressions is important – it will show us if your brain is engaged in the exercise or not Make sure you understand the requirements before you start coding Document all assumptions Automated tests are (almost) always better than manual tests Be nice to the TA that will mark your work and that of 150 other persons Although it shouldn’t take too long, start soon. We can tell if you’re rushing to finish your assignment

Am I missing something? p Questions?