dci - data, context and interaction @ jug genova april 2011
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DCIData, Context and
InteractionFabrizio Giudici, Senior Java Architect
Tidalwave s.a.s - fabrizio.giudici@tidalwave.it
1Wednesday, April 20, 2011
DCI
About the speaker
2
2Wednesday, April 20, 2011
DCI
About the speaker
• Senior Software Architect, Mentor, Technical Writer
• Fourteen years of Java experience (JSE, JEE, JME, etc...)
• Sun partner since 1998, Oracle consultant since 2010
• Author of a number of open source projects
• Speaker at JavaOne, Devoxx, Jazoon, JAX and other events
• Member of the NetBeans Dream Team
• Co-leader of JUG Milano
• Java.Net blogger at http://www.java.net/blogs/fabriziogiudici
2
2Wednesday, April 20, 2011
DCI
Agenda
3
3Wednesday, April 20, 2011
DCI
Agenda
• Two real world examples
3
3Wednesday, April 20, 2011
DCI
Agenda
• Two real world examples
• DCI - Basic concepts
3
3Wednesday, April 20, 2011
DCI
Agenda
• Two real world examples
• DCI - Basic concepts
• DCI - How to implement?
3
3Wednesday, April 20, 2011
DCI
Agenda
• Two real world examples
• DCI - Basic concepts
• DCI - How to implement?
• Some simple examples
3
3Wednesday, April 20, 2011
DCI
Agenda
• Two real world examples
• DCI - Basic concepts
• DCI - How to implement?
• Some simple examples
• Abstracting and sweetening
3
3Wednesday, April 20, 2011
Two real world examples
4Wednesday, April 20, 2011
DCI
Shameless Plug
5
5Wednesday, April 20, 2011
DCI
Shameless Plug
• Exercises of Design - my design book...
5
5Wednesday, April 20, 2011
DCI
Shameless Plug
• Exercises of Design - my design book...
• Just started!
5
5Wednesday, April 20, 2011
DCI
Shameless Plug
• Exercises of Design - my design book...
• Just started!
• http://exercisesofdesign.java.net
5
5Wednesday, April 20, 2011
DCI
The Observation API
• A core component of blueBill Mobile
• An application about recording bird observations
• Designed with a high degree of abstraction
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6Wednesday, April 20, 2011
DCI
The Observation API
• A core component of blueBill Mobile
• An application about recording bird observations
• Designed with a high degree of abstraction
6
6Wednesday, April 20, 2011
DCI
The Observation API
• A core component of blueBill Mobile
• An application about recording bird observations
• Designed with a high degree of abstraction
6
6Wednesday, April 20, 2011
DCI 7
7Wednesday, April 20, 2011
DCI
The Taxonomy API
• Models the taxonomy of a philogenetic tree
• The standard way of biology for representing living beings species
8
8Wednesday, April 20, 2011
DCI 9
9Wednesday, April 20, 2011
DCI - Basic Concepts
10Wednesday, April 20, 2011
DCI
Data, Context and Interaction
11
11Wednesday, April 20, 2011
DCI
Data, Context and Interaction
• OOD best practice invented by Trygve Reenskaug
11
11Wednesday, April 20, 2011
DCI
Data, Context and Interaction
• OOD best practice invented by Trygve Reenskaug
• The formalizer of MVC
11
11Wednesday, April 20, 2011
DCI
Data, Context and Interaction
• OOD best practice invented by Trygve Reenskaug
• The formalizer of MVC
• Seen as an evolution of MVC
11
11Wednesday, April 20, 2011
DCI
Data, Context and Interaction
• OOD best practice invented by Trygve Reenskaug
• The formalizer of MVC
• Seen as an evolution of MVC
• But it doesn’t replace it
11
11Wednesday, April 20, 2011
DCI
Data, Context and Interaction
• OOD best practice invented by Trygve Reenskaug
• The formalizer of MVC
• Seen as an evolution of MVC
• But it doesn’t replace it
• It rather broadens the analysis scope
11
11Wednesday, April 20, 2011
DCI
Data, Context and Interaction
• OOD best practice invented by Trygve Reenskaug
• The formalizer of MVC
• Seen as an evolution of MVC
• But it doesn’t replace it
• It rather broadens the analysis scope
• http://www.artima.com/articles/dci_vision.html
11
11Wednesday, April 20, 2011
DCI
DCI - aims
12
12Wednesday, April 20, 2011
DCI
DCI - aims
• Improve readability of a OO system
12
12Wednesday, April 20, 2011
DCI
DCI - aims
• Improve readability of a OO system
• Give system behaviour first-class status
12
12Wednesday, April 20, 2011
DCI
DCI - aims
• Improve readability of a OO system
• Give system behaviour first-class status
• Recover readability of system properties on the whole
12
12Wednesday, April 20, 2011
DCI
DCI - aims
• Improve readability of a OO system
• Give system behaviour first-class status
• Recover readability of system properties on the whole
• Separate responsibilities for behaviour and domain
12
12Wednesday, April 20, 2011
DCI
DCI - aims
• Improve readability of a OO system
• Give system behaviour first-class status
• Recover readability of system properties on the whole
• Separate responsibilities for behaviour and domain
• Behaviour: what the system does
12
12Wednesday, April 20, 2011
DCI
DCI - aims
• Improve readability of a OO system
• Give system behaviour first-class status
• Recover readability of system properties on the whole
• Separate responsibilities for behaviour and domain
• Behaviour: what the system does
• Domain: what the system is
12
12Wednesday, April 20, 2011
DCI
DCI - aims
• Improve readability of a OO system
• Give system behaviour first-class status
• Recover readability of system properties on the whole
• Separate responsibilities for behaviour and domain
• Behaviour: what the system does
• Domain: what the system is
• Be close to people’s mental model
12
12Wednesday, April 20, 2011
DCI
DCI - Data
13
13Wednesday, April 20, 2011
DCI
DCI - Data
• What the system is
13
13Wednesday, April 20, 2011
DCI
DCI - Data
• What the system is
• Relatively static with relations
13
13Wednesday, April 20, 2011
DCI
DCI - Data
• What the system is
• Relatively static with relations
• Domain structure implemented with “conventional” classes
13
13Wednesday, April 20, 2011
DCI
DCI - Data
• What the system is
• Relatively static with relations
• Domain structure implemented with “conventional” classes
• Typically it includes persistence
13
13Wednesday, April 20, 2011
DCI
DCI - Data
• What the system is
• Relatively static with relations
• Domain structure implemented with “conventional” classes
• Typically it includes persistence
• Comes from the mental model of system stakeholders
13
13Wednesday, April 20, 2011
DCI
DCI - Data
• What the system is
• Relatively static with relations
• Domain structure implemented with “conventional” classes
• Typically it includes persistence
• Comes from the mental model of system stakeholders
• Close to the “model” in MVC
13
13Wednesday, April 20, 2011
DCI
DCI - Data
• What the system is
• Relatively static with relations
• Domain structure implemented with “conventional” classes
• Typically it includes persistence
• Comes from the mental model of system stakeholders
• Close to the “model” in MVC
• Example: BankAccount with increase(), decrease(); no deposit()
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13Wednesday, April 20, 2011
DCI
DCI - Context (and Roles)
14
14Wednesday, April 20, 2011
DCI
DCI - Context (and Roles)
• Associated to a use case, user story, scenario, or algorithm
14
14Wednesday, April 20, 2011
DCI
DCI - Context (and Roles)
• Associated to a use case, user story, scenario, or algorithm
• Identifies objects participating in a scenario
14
14Wednesday, April 20, 2011
DCI
DCI - Context (and Roles)
• Associated to a use case, user story, scenario, or algorithm
• Identifies objects participating in a scenario
• Assign to each object one or more stateless roles
14
14Wednesday, April 20, 2011
DCI
DCI - Context (and Roles)
• Associated to a use case, user story, scenario, or algorithm
• Identifies objects participating in a scenario
• Assign to each object one or more stateless roles
• Objects can have multiple roles at the same time
14
14Wednesday, April 20, 2011
DCI
DCI - Context (and Roles)
• Associated to a use case, user story, scenario, or algorithm
• Identifies objects participating in a scenario
• Assign to each object one or more stateless roles
• Objects can have multiple roles at the same time
• Decompose the use case (etc...) into roles, not objects
14
14Wednesday, April 20, 2011
DCI
DCI - Context (and Roles)
• Associated to a use case, user story, scenario, or algorithm
• Identifies objects participating in a scenario
• Assign to each object one or more stateless roles
• Objects can have multiple roles at the same time
• Decompose the use case (etc...) into roles, not objects
• Contrast this with polymorphism and classic OO decomposition
14
14Wednesday, April 20, 2011
DCI
DCI - Context (and Roles)
• Associated to a use case, user story, scenario, or algorithm
• Identifies objects participating in a scenario
• Assign to each object one or more stateless roles
• Objects can have multiple roles at the same time
• Decompose the use case (etc...) into roles, not objects
• Contrast this with polymorphism and classic OO decomposition
• Example: MoneyTransfer with SrcAccount and DestAccount
14
14Wednesday, April 20, 2011
DCI
Quick terminology note
15
15Wednesday, April 20, 2011
DCI
Quick terminology note
• Methodless role: abstract role
15
15Wednesday, April 20, 2011
DCI
Quick terminology note
• Methodless role: abstract role
• Interface, abstract class
15
15Wednesday, April 20, 2011
DCI
Quick terminology note
• Methodless role: abstract role
• Interface, abstract class
• Methodful role: concrete role
15
15Wednesday, April 20, 2011
DCI
Quick terminology note
• Methodless role: abstract role
• Interface, abstract class
• Methodful role: concrete role
• Regular class
15
15Wednesday, April 20, 2011
DCI
DCI - Interaction
16
16Wednesday, April 20, 2011
DCI
DCI - Interaction
• What the system does
16
16Wednesday, April 20, 2011
DCI
DCI - Interaction
• What the system does
• Occurs among roles, which act as adapters to objects
16
16Wednesday, April 20, 2011
DCI
DCI - Interaction
• What the system does
• Occurs among roles, which act as adapters to objects
• Roles are bound in different ways for each context
16
16Wednesday, April 20, 2011
DCI
DCI - Interaction
• What the system does
• Occurs among roles, which act as adapters to objects
• Roles are bound in different ways for each context
• Roles should be generic
16
16Wednesday, April 20, 2011
DCI
DCI - Interaction
• What the system does
• Occurs among roles, which act as adapters to objects
• Roles are bound in different ways for each context
• Roles should be generic
• Roles life cycle is likely to be bound to a given interaction
16
16Wednesday, April 20, 2011
DCI
DCI - Interaction
• What the system does
• Occurs among roles, which act as adapters to objects
• Roles are bound in different ways for each context
• Roles should be generic
• Roles life cycle is likely to be bound to a given interaction
• Interaction should be explicit given role nature, rather than emergent as in (agile) OOD
16
16Wednesday, April 20, 2011
DCI
DCI - Execution Model
17
17Wednesday, April 20, 2011
DCI
DCI - Execution Model
• The Context finds object participants
17
17Wednesday, April 20, 2011
DCI
DCI - Execution Model
• The Context finds object participants
• Then, it assigns (injects?) roles to them
17
17Wednesday, April 20, 2011
DCI
DCI - Execution Model
• The Context finds object participants
• Then, it assigns (injects?) roles to them
• Roles find each other by type (methodless)
17
17Wednesday, April 20, 2011
DCI
DCI - Execution Model
• The Context finds object participants
• Then, it assigns (injects?) roles to them
• Roles find each other by type (methodless)
• What about static languages and designs?
17
17Wednesday, April 20, 2011
DCI
DCI - Execution Model
• The Context finds object participants
• Then, it assigns (injects?) roles to them
• Roles find each other by type (methodless)
• What about static languages and designs?
• Then, it invokes a method on the first role
17
17Wednesday, April 20, 2011
DCI
DCI - Execution Model
• The Context finds object participants
• Then, it assigns (injects?) roles to them
• Roles find each other by type (methodless)
• What about static languages and designs?
• Then, it invokes a method on the first role
• Interaction goes on among other roles
17
17Wednesday, April 20, 2011
DCI - How to implement?
18Wednesday, April 20, 2011
DCI
Some design issues
19
19Wednesday, April 20, 2011
DCI
Some design issues
• Static vs dynamic
19
19Wednesday, April 20, 2011
DCI
Some design issues
• Static vs dynamic
• Traits, Mix-ins
19
19Wednesday, April 20, 2011
DCI
Some design issues
• Static vs dynamic
• Traits, Mix-ins
• AOP, annotations (e.g. Qi4J)
19
19Wednesday, April 20, 2011
DCI
Some design issues
• Static vs dynamic
• Traits, Mix-ins
• AOP, annotations (e.g. Qi4J)
• Problems: schizophrenia
19
19Wednesday, April 20, 2011
DCI
Some design issues
• Static vs dynamic
• Traits, Mix-ins
• AOP, annotations (e.g. Qi4J)
• Problems: schizophrenia
• Which is the identity of an object that becomes a cluster of roles
19
19Wednesday, April 20, 2011
DCI
Some design issues
• Static vs dynamic
• Traits, Mix-ins
• AOP, annotations (e.g. Qi4J)
• Problems: schizophrenia
• Which is the identity of an object that becomes a cluster of roles
• Partly solved by the clear separation object (stateful) / role (stateless)
19
19Wednesday, April 20, 2011
DCI
Some design issues
• Static vs dynamic
• Traits, Mix-ins
• AOP, annotations (e.g. Qi4J)
• Problems: schizophrenia
• Which is the identity of an object that becomes a cluster of roles
• Partly solved by the clear separation object (stateful) / role (stateless)
• What about equals() / hashcode()?
19
19Wednesday, April 20, 2011
DCI
Some design issues
• Static vs dynamic
• Traits, Mix-ins
• AOP, annotations (e.g. Qi4J)
• Problems: schizophrenia
• Which is the identity of an object that becomes a cluster of roles
• Partly solved by the clear separation object (stateful) / role (stateless)
• What about equals() / hashcode()?
• Problem: anemic objects
19
19Wednesday, April 20, 2011
DCI
Some design issues
• Static vs dynamic
• Traits, Mix-ins
• AOP, annotations (e.g. Qi4J)
• Problems: schizophrenia
• Which is the identity of an object that becomes a cluster of roles
• Partly solved by the clear separation object (stateful) / role (stateless)
• What about equals() / hashcode()?
• Problem: anemic objects
• Really a problem in this perspective?19
19Wednesday, April 20, 2011
DCI
Designing with DCI
20
20Wednesday, April 20, 2011
DCI
Designing with DCI
• First, acknowledge that DCI is a best practice
20
20Wednesday, April 20, 2011
DCI
Designing with DCI
• First, acknowledge that DCI is a best practice
• Some languages can fit better than others
20
20Wednesday, April 20, 2011
DCI
Designing with DCI
• First, acknowledge that DCI is a best practice
• Some languages can fit better than others
• Frameworks might help... but they force a new nature
20
20Wednesday, April 20, 2011
DCI
Designing with DCI
• First, acknowledge that DCI is a best practice
• Some languages can fit better than others
• Frameworks might help... but they force a new nature
• My point: DCI must be addressed in design
20
20Wednesday, April 20, 2011
Some UI-oriented examples
21Wednesday, April 20, 2011
DCI
NodesExample 1
• Static role implementation
• Introduce some generic, (G)UI oriented roles
• NetBeans Platform’s Lookup based implementation
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22Wednesday, April 20, 2011
DCI
NodesExample 2
• Dynamically replacing roles with decorators
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23Wednesday, April 20, 2011
DCI
NodesExample 4
• Adding contextual Actions and ToolTips
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24Wednesday, April 20, 2011
DCI
NodesExample 5
• Removing UI dependencied
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25Wednesday, April 20, 2011
DCI
NodesExample 6
• Injecting roles from the Context
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26Wednesday, April 20, 2011
DCI
NodesExample 7
• Injecting Roles in function of the Context
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27Wednesday, April 20, 2011
Abstracting and sweetening
28Wednesday, April 20, 2011
DCI
Abstracting and sweetening
• Would be nice to be technology independent
• Would be nice to have some syntactic sugar
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29Wednesday, April 20, 2011
DCI
as()
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30Wednesday, April 20, 2011
DCI
as()
• From Role role = object.getLookup().lookup(Role.class) ...
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30Wednesday, April 20, 2011
DCI
as()
• From Role role = object.getLookup().lookup(Role.class) ...
• ... to Role role = object.as(Role);
30
30Wednesday, April 20, 2011
DCI
as()
• From Role role = object.getLookup().lookup(Role.class) ...
• ... to Role role = object.as(Role);
• As a wrapper around Lookup
30
30Wednesday, April 20, 2011
DCI
as()
• From Role role = object.getLookup().lookup(Role.class) ...
• ... to Role role = object.as(Role);
• As a wrapper around Lookup
• With annotations and Lombok
30
30Wednesday, April 20, 2011
DCI
as()
• From Role role = object.getLookup().lookup(Role.class) ...
• ... to Role role = object.as(Role);
• As a wrapper around Lookup
• With annotations and Lombok
30
@AsCapablepublic class MyObject { @Role private Role1 r1 = new Role1();
@Role // lazy private Provider<Role> r2 = ...; }
30Wednesday, April 20, 2011
DCI
Q & A
• Question Time
31
31Wednesday, April 20, 2011
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