Modularity with osgi

1. Modular Java EE
in the cloud
A practical guide to mixing java EE and OSGi
Jfokus 2013

2. Practical Guide to
Modularity in the
Cloud Age
Jfokus 2013

3. Bert Ertman
Fellow at Luminis in the Netherlands
JUG Leader for NLJUG and a Java Champion
Paul Bakker
Architect at Luminis Technologies
@bertertman
@pbakker
A presentation for

4. Trend
Applications tend to grow bigger and
more complex
Agile development and refactoring
have become more common

5. This leads to a number of challenges :
Maintenance
(long term)
Versioning
Dependency
Management
Deployment

6. Cloud challenges require non-
trivial non-functional
requirements
Zero-downtime deployments
Modular deployments
Customer specific extensions
(SaaS)
Apps are moving to the cloud

7. Modularity
is the answer

8. But... what exactly is
modularity?

9. Prevent
(tight)
coupling
What we learned about OO design in university :
Promote
cohesion
coupling
cohesion

10. How to prevent
coupling in a code
base?

11. How to prevent
coupling in a code
base?
interfaces

12. But how to make
sure nobody
accidentally uses
implementation
classes?

13. But how to make
sure nobody
accidentally uses
implementation
classes?
imp lemen tation
hi di ng

14. Modules

15. Ok, but how to create an
instance of a hidden
class?
MyInterface myI = new
MyImplementation();

16. Service Lookups

17. Design time
modularity
Divide and conquer
Forces separation of concerns
Prevents spaghetti

18. The jar file is the unit of
runtime modularity
on the Java platform
What about
classpath
hell?

19. Runtime dynamics
Module versioning
Updating single modules
Intra-module dependency
management
How to deal with

20. W
h
a
t
d
o
w
e
n
e
e
d
?
design
consequences
High-level
enterprise APIs
Architectural
focus on
modularity
Runtime
dynamic
module
framework
Right now,
OSGi is the
only option
let’s not
reinvent the
wheel

21. OSGi is the de-facto
standard module
system for Java
OSGi != modularity
What about Jigsaw?

22. OSGi is the de-facto
standard module
system for Java
OSGi != modularity
What about Jigsaw?
remember!
Modularity is
an architectural
principle

23. OSGi is the de-facto
standard module
system for Java
OSGi != modularity
What about Jigsaw?
remember!
Modularity is
an architectural
principle
Modularity
does not come
for free with a
framework

24. Demo

25. OSGi vs. Java EE

26. Java EE:
high level
APIs
OSGi vs. Java EE : opposite ends?
OSGi:
low-level, mix
and match
yourself

27. Java EE:
high level
APIs
OSGi vs. Java EE : opposite ends?
OSGi:
low-level, mix
and match
yourself
They don’t
have to be
either / or

28. How? - 3 options
OSGi a la carte
#3
Hybrid solution
using an
injection bridge
OSGi as core
architecture with
EE APIs published
as services
#1
#2

29. Option 1 - OSGi in Java EE App Servers
Java EE APIs
available from
within bundles
OSGi bundles as
your core
programming
model
use app server
capabilities like
clustering, data
sources, etc.
the
(near)
future!

30. Web Application Bundle (WAB)
WAR with a
manifest
Easy
registration
of Servlets
and JAX-RS
components
Enterprise
OSGi
standard

31. Web Application Bundle (WAB)
/myweb/index.html
/myweb/agenda
manifest.mf
Bundle-Name: agenda.web.ui
Web-ContextPath: /myweb
Import-Package: javax.servlet
mywab.jar
META-INF/manifest.mf
index.html
WEB-INF/classes/
MyResource.class
WEB-INF/faces-config.xml
WEB-INF/web.xml

32. EJB Bundles
Not a standard yet!
Publish EJBs
as OSGi
services
Use transactions
and JPA like you
normally would

33. EJB Bundles
manifest.mf
Export-EJB: ALL
Bundle-Name:
agenda.storage.ejb

34. Use CDI
within
bundles
OSGi CDI integration
Prototyped in
WELD
RFP 146
Use CDI to
produce /
consume
services

35. How are the app servers doing?
App server
Deploy
bundles
WAB support
EJB/JPA
support
Glassfish
WebSphere
WebLogic
JBoss AS

36. Option 2 : Hybrid solution
Best of both worlds?
Your app is effectively split into two parts:
‘Adminstrative’ enterprise part -> Java EE
‘Dynamic’ part where services can be replaced
without downtime -> OSGi
Glue the two together using an ‘injection bridge’

37. Example

38. Option 3 - OSGi a la carte
Demo

39. What about
deployment?

40. What about
deployment?
Apache
Ace
- demo -

41. Apache ACE

43. Wrap up

44. What have we learned?
You’ve seen the future of enterprise development ;-)
Why modularity is important (in the cloud)
Practical solution for doing modularity now

45. Recommended reading

46. Cloud provisioning
http://ace.apache.org/
Eclipse OSGi plugin
http://bndtools.org/
That’s us
http://luminis.eu/
Bert Ertman
bert.ertman@luminis.eu
@BertErtman
Cloud OSGi services
http://www.amdatu.org/
Amdatu
Paul Bakker
paul.bakker@luminis.eu
@pbakker