specification and refinement of domain-specific eca policiescaise11/dse2011_p5.pdf · programming...
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Specification and Refinement of Domain-Specific ECA Policies
Raphael Romeikat, University of Augsburg
Bernhard Bauer, University of Augsburg
Programming Distributed Systems Lab
Outline
Motivation › Mobile networks
› Coverage and capacity optimization
Basics › Policy-based management
Approach › Policy development phases
› Policy specification
› Policy refinement
Conclusion
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Mobile Networks
Mobile network › Cellular network layout
› Coverage and capacity
Increasing management complexity › Time-consuming, expensive, error-prone
› Self-organization is required
Management automation approach › SON functions
› ECA policies
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Coverage and Capacity Optimization
Modification of cell sizes to › Provide full coverage
› Balance load and optimize per cell capacity
Two SON functions realize CCO
› CCO(TXP) Changes transmission power
› CCO(RET) Changes antenna tilt
Both functions influence cell size › Should not be executed concurrently at the same cell
› Requires coordination to avoid negative impacts
Policy-based coordination › Example policy: “Reschedule a tilt change at a cell
if a power change is already active at that cell.”
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Policy-Based Management
Policies › Rules to manage the states of entities
and to accomplish decisions
› Event-Condition-Action (ECA) model
› Abstraction level ranges from very abstract to very technical
› Benefits » Automation
» Abstraction
» Flexibility
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Policies are derived from management goals
and define the desired behavior of a system.
A policy is a set of declarative constraints
on the possible behaviors of a system
to define its acceptable behaviors.
Ponder2
PolicyEvent
Policy
PolicyAction
TriggeredBy
HasActions
1..n 1..n
1..n 1..n
PolicyCondition
HasConditions1..n
1..n
Programming Distributed Systems Lab
Policy Development Phases
Policy specification › Formalization of guidelines and constraints on the system behavior
› Focus on business and functional aspects at a high level of abstraction
› “If a power change is active at a cell…"
Policy refinement › Addition of information for a detailed view on the system behavior
› Focus on technical aspects at a low level of abstraction
› “If a reconfiguration of type TXP is active at a cell with property…“
Policy implementation › Preparation for enforcement in a particular system
› Creation of a fully machine-executable representation
› Code in a policy language
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High level of abstraction
Separation of domain and policy aspects into different models
Graphical modeling and formal specification
Metamodels
Policy Specification
Layer i
Domain
Metamodel
Policy
Metamodel
Domain
Modeli
Policy
Modeli
Linking
Modeli
Linking
Metamodel
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Policy Specification
“Reschedule a tilt change at a cell if a power change is already active at that cell.”
Policy specification
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Policy Refinement
Low level of abstraction
Automation › Manual refinement
of the domain
› Automated generation of refined policies
Formal semantics
Mapping patterns
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Layer i
Layer j
e1
undef e2
undefe1
e2ne21
Split Erasure Appearance
e
e
e1
e2
Identity Replacement Merge
e2
e1ne11
Layer j
Layer i
Domain
Modelj
Policy
Modelj
Linking
Modelj
Domain
Metamodel
Policy
Metamodel
Domain
Modeli
Policy
Modeli
Linking
Modeli
Linking
Metamodel
Mapping
Modeli→j
Refinement
Rulesi→j
Mapping
Metamodel
Programming Distributed Systems Lab
Policy Refinement
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“Reschedule a tilt change at a cell if a power change is already active at that cell.”
Policy specification
Policy refinement
Programming Distributed Systems Lab
Conclusion
Benefits › Policy modeling at an abstract level
› Automated refinement and code generation
› Generic wrt. domain and number of abstraction layers
Future work › Evaluation
› Tool chain
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Questions
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