Presentation by Graham Charters at OSGi Users' Forum UK meeting on Nov 16, 2011 in London. Abstract: For those in the thick of OSGi, it is easy to forget what it was like to get started, and what benefits are achieved at each stage. Drawing inspiration from the various SOA maturity models, I thought it would be an interesting exercise to try to put together a modularity equivalent, and so the Modularity Maturity Model (M3) was born. The title says "Towards" because this is an initial proposal and so input from the audience (rocks, rotten vegetables, and maybe even faint praise) would be welcome.

1. © 2011 IBM Corporation

2. A Maturity Model
Source: Wikipedia
 A set of structured levels describing how well an organization can reliably
and sustainably produce required outcomes
 May provide
– a place to start
– benefit of prior experiences
– common language and shared vision
– framework for prioritizing actions
– define what improvement means
 Can be used as a benchmark for
comparison and an aid to understanding
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3. Modularity Maturity Model
 A Maturity Model for Modularity 
 Focus on organisational capability
 Modularity technology agnostic
 Drawn from observations from a number of projects and customers
 An 80:20 guide, not a 100% law
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4. Level 1: Ad Hoc
Characteristics Benefits
• No formal modularity focus • Cheap to get started
• Bunch of classes with no structure
• Flat class path
• Library Jars
• Monolithic application
• Archives of archives
.../A_v1.jar
.../Bv2.jar
.../C.jar
© 2011 IBM Corporation

5. Level 2: Modules
Characteristics Benefits
• Formal module identities • Decouple module from artefact
• In artifact or catalogue • Clearer view of module assembly
• Identities can be versioned • Enables version awareness
• Dependencies based on identities • Build
• Build • Development
• Development • Operations
• Operations • Enables module catalogues
• Examples: Maven, Ivy, RPM, OSGi,
etc…
B v2 Identity Artifact
A v1 A v1 .../B_v1.jar
B v2 …/Bv2.jar
C v1.1
C v1.1 …/C.jar
© 2011 IBM Corporation

6. Segue Module Identity != Modularity
Modularity
“(Desirable) property of a system,
such that individual components can
be examined, modified and
maintained independently of the
remainder of the system. Objective PCIe x16
is that changes in one part of a
system should not lead to
unexpected behavior in other parts.” VGA
www.maths.bath.ac.uk/~jap/MATH0 DVI
015/glossary.html
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7. Level 3: Modularity
Characteristics Benefits
• Declared module contracts • System structure awareness
(capabilities and requirements) • Client/Provider independence
• Private parts are implementation • Requirement-based dependency
detail checking
• Dependency resolution first,
module identity second
B v2
A v1
C v1.1
© 2011 IBM Corporation

8. Level 4: Loose-Coupling
Characteristics Benefits
• Separation of interface from • Implementation client/provider
implementation with independence
implementation used indirectly • Fine-grained impact awareness
• No factories • Bug fix
• No ‘new’ • Implementer breaking change
• Services-based module • Client breaking change
collaboration
• Dependencies semantically
versioned
B v2
A v1
C v1.1
D v1
© 2011 IBM Corporation

9. Level 5: Devolution
Characteristics Benefits
• Artifact ownerships devolved to • Greater awareness of existing
modularity-aware repositories modules
• Repositories may support • Reduced duplication, increases
• Collaboration (commenting, quality
ratings, forums) • Collaboration/empowerment
• Governance (approvals, life- around modules
cycle) • Quality/operational control
B v2
A v1 C v1.1
D v1
© 2011 IBM Corporation

10. Level 6: Dynamism
Characteristics Benefits
• Dynamic module life-cycle • No brittle ordering dependencies
• Modules fully life-cycle aware • Ability to dynamically update a
• Operational support for module running system
addition, removal, replacement, • Extend capabilities
without loss of state • Apply fixes
B v2
A v1
C v1.1
D v1
© 2011 IBM Corporation

11. Simple Summary
Level Name Summary
1 Ad Hoc Nothing
2 Modules Formal identity, decoupled from artifact
3 Modularity Formal module contracts, decoupled from identity
4 Loose-Coupling Services, semantic versioning, decoupled from
implementation
5 Devolution Modularity-aware repositories, collaboration,
governance, decoupled from ownership
6 Dynamism Life-cycle awareness and independence, decoupled
from time
© 2011 IBM Corporation

12. Time to apply...
 How do your projects and organization fair?
 How do some well-known projects fair?
 How are we doing as an industry?
 In answering these questions we can better
understand the tasks and benefits ahead
© 2011 IBM Corporation

13. Level 7: Peter Kriens
Characteristics Benefits
• Sees the modularity in anything • Can address all modularity problems
and everything
• A higher state of modularity
enlightenment
• 10+ years eating and breathing
modularity
© 2011 IBM Corporation

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