This document summarizes Bertrand Delacrétaz's presentation on Adobe's experience using OSGi as the foundation for its CQ5 content management system. Some key points included: - OSGi provided strong modularity and dynamic loading/unloading of bundles that enabled many plugins and extensions. Declarative services and clean OSGi APIs made development easier. - Testing and unpredictable bundle startup order presented challenges. Integration between many bundles was difficult to test. - While OSGi enabled many benefits, it also brought complexity due to its asynchronous nature and requirement for strict version management between bundles. Tooling has improved but OSGi concepts remain unfamiliar to many.

1. OSGi Alliance Community Event 2012
Bertrand DelacrétazOSGiTales from the trenches
Senior Developer, R&D, Adobe Digital Marketing Systems
Apache Software Foundation Member and (current) Director
http://grep.codeconsult.ch - @bdelacretaz - bdelacretaz@apache.org
OSGi Alliance Community Event, Ludwigsburg, October 2012
slides revision: 2012-10-22
Bertrand Delacrétaz
OSGi
Ta l e s f r o m t h e
t r e n c h e s
Adobe CQ5: a real-life OSGi case study

2. OSGi Alliance Community Event 2012
Bertrand DelacrétazOSGiTales from the trenches
What?
Share our experience using OSGi
(Apache Felix) as the foundation
of Adobe CQ5.
More than five years working with OSGi, very
high impact on developers, customers, service
people, mostly in a positive way.
OSGi is no silver bullet either.
silver

3. OSGi Alliance Community Event 2012
Bertrand DelacrétazOSGiTales from the trenches
What?
the
GOODthe
BADthe
UGLY
symbols by ppdigital , o0o0xmods0o0oon and clarita, on morguefile.com
Just my own,
personal
opinion as a
software
developer...

4. OSGi Alliance Community Event 2012
Bertrand DelacrétazOSGiTales from the trenches
Trenches?
Web Content Management
and Digital Marketing system.
Includes its own JCR content store.
About 200 OSGi bundles.
Install instructions fit in a tweet.
Built on Apache Sling, Apache
Felix and Apache Jackrabbit
www.adobe.com/products/cq.html
http://jackrabbit.apache.org
http://felix.apache.org
http://sling.apache.org
BTW...wearehiring!
jobs-basel@adobe.com

5. OSGi Alliance Community Event 2012
Bertrand DelacrétazOSGiTales from the trenches
What we use from OSGi
Bundles (using Maven plugins)
Lifecycle, Service Tracker
Configurations and Felix Web Console
Declarative Services (using Maven plugins)
Sling’s installer module (like fileinstall, using JCR)
Log, HTTP, Event services, JMX

6. OSGi Alliance Community Event 2012
Bertrand DelacrétazOSGiTales from the trenches
Famous quotesthe short version

7. OSGi Alliance Community Event 2012
Bertrand DelacrétazOSGiTales from the trenches
Famous Quotes, #2
“Each (OSGi) bundle can serve as a micro
application, having it's own lifecycle,
having it's own citizens and each bundle
can carefully decide which objects to
expose to the outside world”
Peter Rietzler
http://peterrietzler.blogspot.com/2008/12/is-osgi-going-
to-become-next-ejb-bubble.html

8. OSGi Alliance Community Event 2012
Bertrand DelacrétazOSGiTales from the trenches
Famous Quotes, #4
“The lifecycle model of OSGi makes life
complicated. Actually, tracking services
and managing all the aspects of what to
do when services come and go is nasty”
Peter Rietzler
http://peterrietzler.blogspot.com/2008/12/is-osgi-going-
to-become-next-ejb-bubble.html

9. OSGi Alliance Community Event 2012
Bertrand DelacrétazOSGiTales from the trenches
Famous Quotes, #6
“OSGi makes "impossible" things easy:
hot deploy/upgrade, service discovery, ...
and trivial things hard: hibernate, tag
libraries, even deploying a simple war!”
But, for the first time in my
career, I see software reusability
that works: service reusability.
Filippo Diotalevi

10. OSGi Alliance Community Event 2012
Bertrand DelacrétazOSGiTales from the trenches
The Good

11. OSGi Alliance Community Event 2012
Bertrand DelacrétazOSGiTales from the trenches
Modularity
Classloading
distinct from
class visibility.
Public packages
Metadata
OSGi bundle
Private packages
Matchless picture: Alvimann on morguefile.com
OSGi bundles as reusable components.
Dynamic setup and updates that work.
At last!

12. OSGi Alliance Community Event 2012
Bertrand DelacrétazOSGiTales from the trenches
Declarative Services

13. OSGi Alliance Community Event 2012
Bertrand DelacrétazOSGiTales from the trenches
Clean OSGi APIs
Just a few
basic examples...

14. OSGi Alliance Community Event 2012
Bertrand DelacrétazOSGiTales from the trenches
Dynamic load/unload
Just copy bundle jar
to Sling’s JCR
repository (WebDAV)
Bundle activated
and started.
(using Sling’s installer module)

15. OSGi Alliance Community Event 2012
Bertrand DelacrétazOSGiTales from the trenches
Plugins for everything
Servlets
Mime-type based handlers
Content editors based on
JCR node properties
Content renderers and decorators
Debugging/monitoring tools
Mail and messaging services
etc, etc...
Legacy integration gateways

16. OSGi Alliance Community Event 2012
Bertrand DelacrétazOSGiTales from the trenches
The Bad

17. OSGi Alliance Community Event 2012
Bertrand DelacrétazOSGiTales from the trenches
Granularity?
How many bundles? Services?
CQ5: about 200 bundles, 1000 services
How to handle “implementation
details” libraries.
Extra bundles or private packages?
Strict version management required.
Are we there yet?

18. OSGi Alliance Community Event 2012
Bertrand DelacrétazOSGiTales from the trenches
Integration testing...
V5.3
V6.54
V4.2
V5.11
V1.03
V4.22
V3.22
V2.13
V3.2
V3.2
V6.4
V1.03
V3.21
V1.11
V1.05
V6.4
V5.6
V2.4
V3.4
V5.43
In-system
testing?
but when done!

19. OSGi Alliance Community Event 2012
Bertrand DelacrétazOSGiTales from the trenches
Testing options
Unit testing In-framework
testing
Integration
testing
Necessary
but usually
not sufficient.
Mocks can
be painful
Relatively new
tools, can
be slow
Much slower
but ok for actual
integration testing
JUnit,
TestNG,
Mocks,
etc..
Pax Exam,
Sling testing tools,
etc.
Start application
and test it “from
the outside”.
See Apache Sling’s
launchpad/testing
module

20. OSGi Alliance Community Event 2012
Bertrand DelacrétazOSGiTales from the trenches
I want my...
Spring
J2EE
App Server
Guice
do you really need it?

21. OSGi Alliance Community Event 2012
Bertrand DelacrétazOSGiTales from the trenches
The Ugly

22. OSGi Alliance Community Event 2012
Bertrand DelacrétazOSGiTales from the trenches
Asynchronicity...
V5.3
V6.54
V4.2
V5.11
V1.03
V4.22
V3.22
V4.5 V7.4
V2.13
V3.2
V3.2
V6.4
V1.03
V3.21
V1.11
V1.05
V6.4
V5.6
V2.4
V3.4
V5.43
“unpredictable”
startup order
1
19
7
11 15
14 17
10
3
16
18
9
8
4
6
2
11
5
13
12
19
20
Is the system ready now?
Threading
issues?
Mostly from Declarative Services, not OSGi itself.

23. OSGi Alliance Community Event 2012
Bertrand DelacrétazOSGiTales from the trenches
Unpredictable assemblies
V5.3
V6.54
V4.2
V5.11
V1.03
V4.22
V3.22
V4.5
V2.13
V3.2
V3.2
V6.4
V1.03
V3.21
V1.11
V1.05
V6.4
V5.6
V2.4
V3.4
V5.43
Spot the monsters!
Discipline (and semantic versioning) help.
Integration (and in-system) testing required.

24. OSGi Alliance Community Event 2012
Bertrand DelacrétazOSGiTales from the trenches
The Summary

25. OSGi Alliance Community Event 2012
Bertrand DelacrétazOSGiTales from the trenches
My vision back in 2009...
Developers got used to it (and
read the book).
Frameworks and tools improved.
Distributed OSGi? Maybe.
Customers understand OSGi and like it..
Apache Sling paved the way.
√
√
√
√

26. OSGi Alliance Community Event 2012
Bertrand DelacrétazOSGiTales from the trenches
Conclusions
Modularity. modularity. modularity.
OSGi fosters better structured code
Dynamic services and plugins FTW!
Tooling ... getting better all the time
OSGi is often unfamiliar / unusual
Asynchronous behavior can be
problematic (declarative services)
BTW...wearehiring!
jobs-basel@adobe.com