Trivadis TechEvent 2017 Secrets of creation of reliable + maintainable (=cost effective) software by Jonatan Kazmierczak

BASEL BERN BRUGG DÜSSELDORF FRANKFURT A.M. FREIBURG I.BR. GENF HAMBURG KOPENHAGEN LAUSANNE MÜNCHEN STUTTGART WIEN ZÜRICH

Secrets of creation of Secrets of creation of reliable + maintainable (= cost effective) reliable + maintainable (= cost effective) softwaresoftware

Jonatan KazmierczakJonatan Kazmierczak

Cost effective software – Jonatan Kazmierczak – TechEvent 2017

Why is it important?

we and our customers want to be cost effective

we want to create reliable and maintainable software we want to help our customers to do the same

We want to avoid expensive failuresWe want to avoid expensive failures


About author

senior consultant at Trivadis creator of Class Visualizer creates software for 28 years top rated participant in contests

in programming and data science:HackerRank, TopCoder, Code Jam

conference speaker fan of Atari XL/XE demos

https://www.trivadis.com/

http://class-visualizer.net/

https://www.hackerrank.com/jonatan_k

https://www.topcoder.com/members/jonatan-k/

https://www.go-hero.net/jam/17/multilang


About author – cont.www.hackerrank.com/jonatan_k

1st rank in Java 1st rank in JavaScript Top 1% in functional programming in Scala Top 1% in SQL Medalist in algorithmic contests

https://www.hackerrank.com/jonatan_k


Agenda

Stable ground Clear boundaries Solid foundation Proper construction Quality assurance Summary Questions / Comments


Mottos

"80% of the lifetime cost of a piece of software goes to maintenance" – Java Code Conventions (12.09.1997, Sun Microsystems)

“Everything should be made as simple as possible”– Albert Einstein (probably)

Stable groundStable ground


Stable ground

Clear purpose of the software


Stable ground

Clear requirements classified as

mandatory (must have) desired (should have) optional (nice to have)


Stable ground

Requirements – challenges usually incomplete and not clear enough at the beginning will be extended afterwards some may be changed or removed


Stable ground – checkpoint

Is there an existing product fulfilling the purpose and most of requirements ?

Usually it is cheaper and safer to buy it →than to create the own one

Clear boundariesClear boundaries


Clear boundaries

Clear constraints

cannot change dramatically afterwards→


Clear boundaries

Defined input and output – how to interact with the software

will be extended and maybe changed in the future→


Clear boundaries – checkpoint

Do we have a clear picture of input, output and constrainsof the new software?

Solid foundationSolid foundation


Architecture

allowing to fulfill requirements in the simplest way allowing the software to be:

easily extended possible to change

with limited dependencies on external libraries and tools each dependency can become a project killer→


Design

easy to maintain and to extend clear picture of flows (what, not necessarily how) interfaces (UI, REST, API)

UI mockups highly recommended →

Proper constructionProper construction


Implementation

starting with mockups of exposed interfaces– for easy integration and verification


Implementation

correct syntactically, logically, functionally easy to maintain and to extend


Implementationeasy to maintain and to extend

as simple as possible + clean = easy to understand– with meaningful, descriptive names

with logging tested (discussed later) boilerplate code should be generated

– regeneration should be possible with constants and enums representing:

magic numbers, strings, sets of allowed values



best choice of used classes/interfaces first - language API next - existing external libraries last - eventual new libraries

stateless and immutable whenever possible minimal needed visibility/scope no useless/unused code and comments



no redundancy/duplications proper exception handling/throwing formatted properly to ensure maximal readability following (language-specific) coding rules and conventions


Implementation– easy to (re)build

built by execution of one simple command (not only from IDE) fast build for developers long-running build for automated verification outcome: distributable package


Implementation

documented

– especially public APIs / interfaces

Quality assuranceQuality assurance


Quality assurance– involving people

working in pairs review of everything:

requirements, architecture, design, implementation


Quality assurance– automated

sending notifications in case of new problem(s) build unit tests

at least partially written not by author of tested code→

verification of coding rules and conventions


Quality assurance– automated

smoke test integration tests static code analysis system / end-to-end tests

SummarySummary


What do you need to be successful

Stable ground Clear boundaries Solid foundation Proper construction Quality assurance

Questions / CommentsQuestions / Comments


Session Feedback – now

Please use the Trivadis Events mobile app to give feedback on each session

Use "My schedule" if you have registered for a session;

Otherwise use "Agenda" and the search function

If the mobile app does not work, use the web browser URL: http://trivadis.quickmobileplatform.eu/ User name: <your_loginname> (such as "svv") Password: sent by e-mail...

Thank you!Thank you!Jonatan KazmierczakJonatan Kazmierczak

Technology

Trivadis TechEvent 2017 Secrets of creation of reliable + maintainable (=cost effective) software by Jonatan Kazmierczak