iOS Application Architecture

Zalando teck talk held at October 29, 2015

Transcript

1. Modular iOS Application Architecture 1 — © Zalando SE, 2015
2. Modules To be adaptable to evolving needs it is desirable to build complex system by assembling highly cohesive loosely coupled modules, where cost of redesigning each of such adoptable modules (or replacing by a better modules) must be minimized.CBSE CBSE Loosely based on Wikipedia, Component-based software engineering 2 — © Zalando SE, 2015
3. Modules should be - Developed independently - Build independently - Tested independently - Changed or replaced independently 3 — © Zalando SE, 2015
4. Building Blocks Part 1 How can we assemble an App out of independent modules? 4 — © Zalando SE, 2015
5. Building Blocks Part 1 → The Dependency Inversion PrincipleDIP (It’s the D in the SOLIDOOD principles) OOD Robert C. Martin ‘05, Principles of OOD DIP Robert C. Martin ‘96, objectmentor.com/resources/articles/dip.pdf 5 — © Zalando SE, 2015
6. The Dependency Inversion Principle High level modules should not depend upon low level modules. Both should depend upon abstractions.Abs Abs Abstractions: Interfaces, Protocols 6 — © Zalando SE, 2015
7. The Dependency Inversion Principle Abstractions should not depend upon details.Det Details should depend upon abstractions. Det Details: Implementation details 7 — © Zalando SE, 2015
8. Building Blocks Part 2 → Inversion of ControlIoC IoC Martin Fowler ‘04, martinfowler.com/articles/injection.html 8 — © Zalando SE, 2015
9. Inversion of Control Just declare static dependencies, leave object graph composition to the framework 9 — © Zalando SE, 2015
10. Case Study We use a Service Locator as an IoC container → But Address the Common Problems of a Service Locator 10 — © Zalando SE, 2015
11. Case Study Sample App: How do we do it? 11 — © Zalando SE, 2015
12. Inversion of Control → No need for Mocking → Decorators for AOP-style cross-cutting concerns → Configuration changes in deployed apps → Feature Flags 12 — © Zalando SE, 2015
13. Case Study Sample App: Decorate me. 13 — © Zalando SE, 2015
14. Is It Any Good? Yes! 14 — © Zalando SE, 2015
15. Is It Any Good? Yes! → Proven: Used over the last two years → First Use: Monolithic Objective-C legacy App 15 — © Zalando SE, 2015
16. Is It Any Good? Yes! → Makes development fast, modules testable → Plays well with Continuous Integration 16 — © Zalando SE, 2015
17. Buzzword compliance In object-oriented programming, the use of interfaces as an architectural pattern to construct modules is known as API-First Design. 17 — © Zalando SE, 2015
18. Buzzword compliance Microservices is a software architecture style in which complex applications are composed of small, independent modules communicating with each other. These services are small, highly decoupled and focus on doing a small task, facilitating a modular approach to system-building. 18 — © Zalando SE, 2015
19. Thank You! Questions?A A The Answer is Yes, now what's Your Question? 19 — © Zalando SE, 2015