Comparing%20Architecture%20Description%20Languages%20for%20Mobile%20Software%20Systems

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Comparing Architecture Description Languages for
Mobile Software Systems
Nour Ali Politecnico di Milano ali_at_elet.polimi.it
Carlos Solís, Isidro Ramos Universidad
Politecnica de Valencia csolis,
iramos_at_dsic.upv.es
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Content

• Introduction
• Features and ADLs used in the comparison
• Comparison
• Conclusions and Further Work

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Introduction

• How current ADLs deal with distribution and
  mobility?
• No consensus on how ADLs should support
  distributed and mobile software systems.

?
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Mobility

• ltltCode Mobility is the capability to reconfigure
  dynamically, at runtime, the binding between the
  software components of the application and their
  physical location within a computer network.gtgt
• Carzaniga et al. in Car97

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Software Architecture

• Building blocks of software architecture Med00
• Components
• Connectors
• Configurations

Coordination
Computation
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Content

• Introduction
• Features and ADLs used in the comparison
• Comparison
• Conclusions and Further Work

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Features used for comparing ADLs

• Features of a Mobile Model Roman00
• Notion of Location
• Location-awareness
• Mobility Support
• Unit of Mobility
• Migration Decision
• Coordination
• Formalism
• Middleware
• Other features considered such as in Med00
• Graphical Support
• Tool support

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ADLs Compared

• ADLs that that have described distribution and
  mobility are
• Darwin (Magee et al., 1995)
• C2Sadel (Medvidovic et al., 2001)
• Community (Lopes et al., 2002)
• MobiS (Ciancarini et al., 1998)
• LAM Model (Xu et al., 2003)
• ?-ADL (Oquendo et al., 2004)
• Con-Moto (Gruhn et al., 2005)

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Content

• Introduction
• Features and ADLs used in the comparison
• Comparison
• Conclusions and Further Work

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Notion of Location

• Locations represent the different positions where
  a mobile entity can move in space.
• Locations have to be explicitly dealt as
  first-class entities and be distinguished from
  other entities of a model.

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Notion of Location

• Representation Variable
• Darwin

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Notion of Location

• Implicitly as a composite component
• ?-ADL

Composite Component
Component located in Client
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Notion of Location

• Explicitly, as a physical components
• Con Moto

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Notion of Location

• Explicitly, as a connector
• Ambient-PRISMA

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Notion of Location
Representation Type
Darwin Integer value Flat
C2Sadel Explicitly, a border connector Flat
Community Explicitly, a value of an abstract data type Flat
MobiS Implicitly, composite component Hierarchical
LAM model Implicitly, composite component Flat
?-ADL Implicitly,composite component Flat
Con Moto Explicitly, physical components Flat
Ambient-PRISMA Explicitly, an ambient connector Hierarchical
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Location-Awareness

• This feature determines whether an entity can be
  aware of its current location or not.
• This feature is important because it allows an
  entity to take decisions depending on its current
  location.

Location-Awareness
Darwin Implicit
C2Sadel Implicit
Community Explicit
MobiS Implicit
LAM model Implicit
?-ADL Implicit
Con Moto Implicit
Ambient-PRISMA Explicit
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Location-Awareness

• Implicit
• Darwin
• Explicit
• Ambient-PRISMA

Distribution Aspect Bidder using IMobility,
ICapability Attributes Variable location
Ambient NOT NULL End_Distribution
Aspect BidderDist
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Mobility Support

• How a model supports the movement of an entity?
• Unit of mobility
• What is the smallest entity of a model that is
  allowed to move?
• Migration Decision
• When and what causes an entity to move?
• Objective or subjective moves?

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Mobility Support
Support Unit of Mobility Migration Decision
Darwin X X X
C2Sadel reconfiguration Components objective moves
Community Change in a value Fine-grained components connectors objective and subjective
MobiS reconfiguration Components, locations, channels objective and subjective
LAM model reconfiguration subcomponents objective and subjective
?-ADL reconfiguration subcomponents objective and subjective
Con Moto reconfiguration Logical components objective and subjective
Ambient-PRISMA reconfiguration Components, connectors, ambients and composite components objective and subjective
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Mobility Support

• Reconfiguration
• Ambient-PRISMA

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Mobility Support

• Reconfiguration
• Ambient-PRISMA

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Mobility Support

• Reconfiguration
• Ambient-PRISMA

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Coordination

• Do ADLs provide special coordination mechanisms
  for distribution and mobility?

Coordination
Darwin Bindings
C2Sadel border, communication,, connectors
Community Distribution connectors for mobility
MobiS Implicit coordination model
LAM model Connectors for mobility
?-ADL First class connectors
Con Moto Physical connections
Ambient-PRISMA A connector for mobility, communication, security
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Formalism

• Models need to enable a precise description of
  the distribution and mobility properties.
• The formalism used to formalize an ADL needs to
  provide explicit mobility primitives.

Formalism
Darwin ?-calculus
C2Sadel First-order logic
Community Category theory, Mobile Unity
MobiS multiple tuple-space
LAM model Predicate/Transition nets (a variant of Petri Nets)
?-ADL ?-calculus
Con Moto ?-calculus
Ambient-PRISMA Channel Ambient Calculus, etc
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Graphical, Middleware and Tool Support

• Graphical Notation
• A graphical notation allows a model to be more
  usable and understandable.
• Which ADLs provide a graphical notation for
  distribution and mobility?
• Middleware
• Have ADLs been used for implementing executable
  distributed and mobile applications?
• Tool support
• What facilities do ADL tools provide for
  distribution and mobility?

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Graphical, Middleware and Tool Support
Graphical Middleware Tool
Darwin Implicit RMI Graphical modelling, Automatic compiler, Automatic distributed configuration
C2Sadel Implicit RMI, code-on-demand mobility Textual and graphical modelling, skeletons generation
Community Implicit X Textual and graphical modelling, simulation
MobiS Implicit X X
LAM model Implicit X X
?-ADL Implicit X Code generation to Java,modelling verification
Con Moto Explicit X Simulation tool
Ambient-PRISMA Explicit RMI, agent weak mobility, distributed transactions, etc Graphical modelling, verification, Automatic distributed configuration
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Content

• Introduction
• Features and ADLs used in the comparison
• Comparison
• Conclusions and Further Work

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Conclusions

• Notion of location has been provided explicitly
  as components, connectors or as a variable.
• Mobility has been supported either by
  reconfiguration or change of value
• Components are the only unit of mobility in most
  ADLs.
• Explicit coordination mechanisms for distribution
  and mobility have been supported by different
  kinds of connectors.
• Formal methods used have not supported explicit
  notions for mobility
• Graphical notation, middleware and tool support
  for ADLs for distribution and mobility are
  limited

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Further Work

• Extend the comparison for including new features
  such as non-functional requirements, QoS,
  physical mobility, etc.,
• Necessity to empirically demonstrate the
  usability, understability and expressiveness of
  ADLs for distribution and mobility

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Questions?
Nour Ali Politecnico di Milano ali_at_elet.polimi.it
Carlos Solís, Isidro Ramos Universidad
Politecnica de Valencia csolis,
iramos_at_dsic.upv.es