specification and refinement of domain-specific eca policiescaise11/dse2011_p5.pdf · programming...

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


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


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


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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