The document discusses modularity patterns using OSGi, focusing on microservices architecture, patterns such as the whiteboard and extender patterns, and real-world examples. It emphasizes the importance of service registries, managing service configurations, and the need for maintainability and extensibility in modular architectures. Additionally, it critiques the overuse of certain patterns and suggests best practices for utilizing OSGi effectively.

1. Modularity
patterns
with OSGi

2. Paul Bakker
@pbakker

3. Agenda
μServices architecture
Whiteboard pattern
Reusable and configurable
services
Extender pattern
Real world example

4. Classes https://www.flickr.com/photos/crdot/

5. https://www.flickr.com/photos/128326674@N06/
Modules
http://www.carpartsireland.ie/uploads/Reardriftspoiler144cm003.jpg

6. Module
Service contract
Implementation
classes

7. Hide
implementation
details

8. Make imports and
exports explicit
Export only public interfaces
Import public interfaces
provided by others Export-Package:
example.api;version=“1.0.0"
Import-Package:
some.otherapi;version=“[1.0,2)"

10. OSGi Service Registry
Service
Registry
Bundle registering a
service
Bundle using a
service
Publish
MyInterface
Lookup
MyInterface

11. Demo

12. Components only communicate
using service APIs
Implementation should
be replaceable!
A simple example
Results
REST
Results
Storage
Stats
REST
Stats
Aggregator
Tracks
REST
Tracks
Storage
Services may use
multiple other services

13. Demo

14. Always
be
prepared
for
dynamics

15. Services must
contain their own
data
Results
Storage
Tracks
Storage

16. Examples
MongoDB
Each service owns a
collection
Relational
Each service owns a
set of tables
Results
Storage
Tracks
Storage
...
...
Ta b l e A
...
...
Ta b le B
...
...
Ta b l e C
...
...
Ta b le D
...
...
Ta b le F
...
...
Ta bl e E
...
...
Ta b le G

17. Whiteboard
Pattern

18. Plugin
Registry
Plugin Plugin Plugin
Whiteboard
Use multiple services
with the same inter face

19. Demo

20. Real life examples
Amdatu REST
Apache Felix HTTP Whiteboard
Amdatu Scheduling
Amdatu Bootstrap plugins
Apache Felix Gogo commands

21. Configuration

22. What if
all services
do the same thing
with different config?

23. Managed
Service
Factory
Config
Config
Config
Component
Component
Component
Managed Service Factor y

24. Extender
Pattern

25. Real life examples
Providing static web resources
Amdatu JPA (weaving)
Templates in Amdatu
Bootstrap
What if
my bundles don’t
really “do” anything?

26. Resource
bundle A
Resource
bundle B
Extender
Component
Component
Component
Extender pattern

27. Demo

28. Do NOT overuse
Adding extenders is like
adding a DSL:
Powerful and confusing.

29. Bootstrap
Core
Amdatu
Plugin
Dependency
Manager
Plugin
Project
Plugin
Workspace
Plugin
Baselining
Plugin
Bootstrap
Web backend
Bootstrap
Shell
Template
Extender
Project
templates
Workspace
templates
Bootstrap
Web UI
bnd
Plugin Whiteboard
...
Plugin
R eal world
example
Bootstrap

30. Wrap up
A modular architecture gives us:
Maintainability
Extensibility
Freedom to change

31. But what if I want
Spring
EJB
…?
Just don’t… You really don’t need to.

32. Eclipse OSGi plugin
http://bndtools.org/
Open source
OSGi components
http://www.amdatu.org/
Amdatu
That’s us
http://luminis-technologies.
com
Paul Bakker
paul.bakker@luminis.eu
@pbakker