Chapter 12 The Koala Component Model

1. Chapter 12 The Koala Component Model Building Reliable Component-based SystemsChapter 12 - The Koala Component Model

2. Overview • Requirements for Koala • Koala Interfaces • Binding, Gluing and Switches • The Product Line Architecture • Managing Versions and Variants • Subtyping • Summary Building Reliable Component-based SystemsChapter 12 - The Koala Component Model

3. Koala • Koala is • architectural description language • component model for development of embedded software for consumer electronics products. • Is used to build a large diversity of products from a repository of components. Building Reliable Component-based SystemsChapter 12 - The Koala Component Model

4. Requirements for Koala • Original requirements: • Devise a technique with which components can be ‘freely’ composed into products. • The technique must work in resource-constrained environments. • Make the product architectures as explicit as possible. • Additional requirements: • Let components make as few assumptions as possible about their environment. • Allow for parameterized components that are as efficient as dedicated components. • Allow for various ways of connecting components. Building Reliable Component-based SystemsChapter 12 - The Koala Component Model

5. Koala Interfaces • Provide: • Like interfaces in COM and java. • Require: • Communication with components environment. • Multiple: • Handle evolution and diversity. • Optional: • Fine tune. Building Reliable Component-based SystemsChapter 12 - The Koala Component Model

6. Binding and Bind Time in Koala • Basic binding scheme: • Usage of symbolic names. • Architectural description language. • Compiler generates #define. • Can be used as long as we build closed systems. Building Reliable Component-based SystemsChapter 12 - The Koala Component Model

7. Principle of Binding P P’ A A B B’ Building Reliable Component-based SystemsChapter 12 - The Koala Component Model

8. Koala Components • Koala component: • Implementation in C. • Component definition. • Koala configuration: • List of components. • Top-level component. • Koala component definition: • Describes template for instantiating component. • Resembles a class in java. Building Reliable Component-based SystemsChapter 12 - The Koala Component Model

9. A Koala Component Subcomponent Interfaces A switch CC C1 s m C3 C2 A module Building Reliable Component-based SystemsChapter 12 - The Koala Component Model

10. Composing Koala Components • Connect: • Requires interfaces to provides interfaces; • Provides interfaces to provides interfaces; • Requires interfaces to requires interfaces. • Does not fit? • Connect a wider type. • ’Normal’ glue code. • Switch. Building Reliable Component-based SystemsChapter 12 - The Koala Component Model

11. Architectural Rules • Initialization • Initialization interface • Multithreading • Pumps • Notifications • Large number of asynchronous activities Building Reliable Component-based SystemsChapter 12 - The Koala Component Model

12. Overall Architecture • Separated into three layers: • Computing platform • Audio/video/data platform • Service and application • Layer contains a set of subsystems • Subsystems contain may components Building Reliable Component-based SystemsChapter 12 - The Koala Component Model

13. Product Line Architecture Computing Platform API uims apps Applications & Services epg tvsvc fact deal Computing Platform Computing Hardware infra A/V Platform API txt tvplf A/V and Data Platform Audio / Video Hardware Building Reliable Component-based SystemsChapter 12 - The Koala Component Model

14. Managing Versions and Variants • Diversity in a product line should not be handled by a CM system, because: • It keeps diversity outside scope of the architects and, • CM systems only handle compile-time variation. • CM used for: • Maintaining full version history. • Temporary branches. • Safeguarding product in final testing phase. • Koala used for permanent diversity. Building Reliable Component-based SystemsChapter 12 - The Koala Component Model

15. Summary • Interfaces • Binding and bindtimes • Components composition • Architectural rules • Overall architecture • Version management Building Reliable Component-based SystemsChapter 12 - The Koala Component Model