The document discusses software evolution decisions made by Taavet Tamm, highlighting real-world examples of application development choices like using Ruby on Rails and Java. It emphasizes the importance of app evolution with company growth, the challenges of maintaining infrastructure, and the influence of the work environment on applications. The decisions are framed within the context of performance, scalability, and technological ecosystem maturity.

2. Decisions of Software
Evolution

3. Taavet Tamm, a developer,
nice to meet you.

4. Let’s get right into the following
● Couple of real-world examples
● The abstract of software decisions

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We need to make some decisions

6. Lets build the second application
● RubyOnRails
○ it fits the team
○ matches what we’ve built before
○ can we deliver fast
● Mongo
○ Fits the features of the app

7. Lets build an app number xx
● NodeJS
○ Fits the features
○ Performs well
○ Encourages modular approaches
● DynamoDB
○ Easy to scale
○ Performance

8. Differences
● Old app is easy to kill and compicated to recover
● New app is happily serving 2000 request/second

9. Microservices
● RabbitMq
● Java

10. RabbitMq - A message queue
● Asynchronous communication
● Event based communication
● Persistent communication
● Configurability for future
● Proven track record
● Clients for several languages

11. We chose Java over Ruby
● Can it fit on a cheapest amazon node
● Can it provide fast response time
● Is the ecosystem mature
● Can we build apis in it
● Is it evolving or revolutionary

12. ● JVM - predictable, performant
● Fundamentals - threads, objects, annotations
● Tooling - IDE, javadoc, debugging, code generation
● Lightweight enough (jetty)
● Easy to abstract and extract libraries
● Load tests are good enough

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The evolution

14. Less building more maintaining
● Scaling
● Maintaining infrastructure
● Reworking previous features
● Working around past mistakes

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Conway’s law

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Application continuum

17. Conclusion
● App evolves with the company
● Rewriting and maintaining things takes time
● Day to day environment influences applications
more than features

18. Questions?