Jae-Yoon Jung

1
WS-ECA An ECA Rule Description Language for
Ubiquitous Services Computing

• Jae-Yoon Jung
• ASRI
• Seoul National University, Korea
• jjyjung_at_gmail.com

Seung-Kyun Han Digital Interactions Lab. Seoul
National University, Korea jackleg83_at_gmail.com
Jonghun Park Digital Interactions Lab. Seoul
National University, Korea jonghun_at_snu.ac.kr
Kang Chan Lee Protocol Eng. Center ETRI,
Korea chan_at_etri.re.kr
2
Contents
1. Introduction
2. WS-ECA Language
3. The Framework of WS-ECA
4. Example
5. Rule Conflict Detection
6. Conclusions
3
Introduction Ubiquitous Computing Environments
How to coordinate ?
Source ETRI (Electronics and Telecommunications
Research Institute), 2006
4
Introduction Ubiquitous Computing Environments
Source ETRI (Electronics and Telecommunications
Research Institute), 2006
5
Introduction limitations
Focus on device ONLY
Define their own protocol device description
standard
No support coordination
6
Introduction Requirements of New Language
Adopt Event-Condition-Action Mechanism
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WS-ECA Language ECA Overview

• General structure of ECA Rule
• Examples of ECA Rules
• (conditional response)
• on e1 if c1 do a1
• on e1 if c2 do a2
• (transitive property) on e1 if c1 doon
  e2 if c2 do a2
• Rule 1 on e1 if c1 do a1 (?e1)
• cf. action a1 generate internal event e1
• Rule 2 on e1e2 if c2 do a2
• (logical operation)
• Event on (e1e2) e3 if c1 do a1
• Condition on e1 if c1(c2c3) do a1
• Action on e1 if c1 do a1(a2a3)

on event if condition do action
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WS-ECA Language WS-ECA

• WS-ECA Rules
• Variables
• Event
• primitive composite events
• Condition
• Action
• primitive composite actions

WS-ECA Rules
Variables
Device variables
Event variables
ECA Rule
Events
Time events
Event
Service events
External events
Condition
Internal events
Action
Actions
Generate intEvent
Generate extEvent
Invoke Service
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WS-ECA Language Event

• Event
• triggers a rule

lteventsgt lttimeEvent typeonce namexsNCNamegt xsdateTime lt/timeEventgt lttimeEvent typeperiodic namexsNCName unitxsduration issuedxsdateTime? expiredxsdateTime?gtxsdateTime lt/timeEventgt lttimeEvent typerelative namexsNCName baseEventxsNCName intervalxsduration/gt ltintEvent namexsNCName/gt ltextEvent namexsNCName eventIDxsanyURI/gt ltsvcEvent typebefore namexsNCName servicexsQName/gt ltsvcEvent typeafter namexsNCName servicexsQName/gt ltcompositeEvent typeOR namexsNCNamegt event lt/compositeEventgt ltcompositeEvent typeAND namexsNCName TTLxsdurationgt event lt/eventgt ltcompositeEvent typeSEQ namexsNCName TTLxsdurationgt event lt/eventgt ltcompositeEvent typeNOT namexsNCNamegt event lt/compositeEventgt lt/eventsgt
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WS-ECA Language Condition

• Condition
• boolean statement
• XPath expression
• Variables
• specific elements of an event
• state of device
• Extension functions
• getVariable
• getDateTime

ltcondition expression"/alarm/today/_at_holiday'no'"
/gt
Variable
device variable
event variable
Functions Return type Return value
ecagetVariable(event QName, path PathExpr) xsany Specific values from event variables
ecagetDateTime(event Qname) xsdateTime Date and time information of the system
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WS-ECA Language Action

• Actions
• instructions executed when a triggered rule is
  activated

ltactionsgt ltinvokeService namexsNCName serviceQNamegt xsany lt/invokeServicegt ltcreateIntEvent namexsNCName intEventxsNCNamegt xsany lt/createIntEventgt ltcreateExtEvent namexsNCName extEventxsanyURIgt xsany lt/createExtEventgt ltcompositeAction namexsNCName operatorAND transactionxsanyURIgt action lt/compositeActiongt ltcompositeAction namexsNCName operatorOR sequencexsbooleangt action lt/compositeActiongt lt/actionsgt
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The Framework of WS-ECA

• WS-Eventing SOAP
• Use XML-Family standards
• Web services in devices

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Example morning cook service

• A user set the get-up time to 700 AM on the
  alarm clock before sleeping.
• The clock informs the rice cooker of 20 minutes
  before get-up.
• The cooker starts to cook, and if rice is not
  enough, it alerts to the user at his/her get-up
  time.
• When the cook is completed, the cooker informs
  the coffee maker, and the coffee maker will start
  to prepare a morning coffee after 10 minutes.

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Example morning cook service
get-up time700AM
alarm.xml
ltrulesgt ltrule name"alarm-before-get-up-rule"gt ltevent name"before-get-up-time"/gt ltcondition expression"/alarm/today/_at_holiday'no'"/gt ltaction name"pre-alarm"/gt lt/rulegt ltrule name"alarm-on-get-up-rule"gt ltevent name"get-up-time"/gt ltcondition expression"/alarm/today/_at_holiday'no'"/gt ltaction name"get-up-alarm"/gt lt/rulegt lt/rulesgt
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Rule Conflict Detection

• ECA Rules in Ubiquitous Service Devices
• WS-ECA rules can be defined by multiple users and
  registered to distributed devices.
• Some rules may have discrepancies with each other
  and they may cause conflicts.
• Service Constraints
• a set of service invocation actions that are not
  allowed to occur at the same time.
• e.g. 1) radio.turnUp() radio.turnDown()
• e.g. 2) heater.trunOn() air conditioner.turnOn()
  
• Global Rule Manager (GRM)
• analyzing the defined rules for devices at
  build-time
• resolving any rule conflicts at run-time

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Rule Conflict Detection

• Static Conflict
• triggering rules cause a conflict
• detect resolve at build-time
• e.g.)
• rule 1 on e1 if c1 do radio.turnOn()
• rule2 on e1 if c1 do radio.turnOff()
• Dynamic Conflict
• triggering rules MAY cause a conflict
• detect resolve at run-time
• e.g.)
• rule 1 on e1?e2 if c1 do radio.turnOn()
• rule 2 on e1?e3 if c1 do radio.turnDown()

Flowchart of rule generation and execution
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Conclusions

• ECA Rules in Ubiquitous Service Computing
• WS-ECA Rule description Language
• Advantages of WS-ECA in Ubiquitous Computing
• Active functionality of service devices
• Stateless and light interaction
• Decentralized rule processing based on ECA rules
• Future Work
• Develop conflict detection and resolution
  algorithm
• Make language standard

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Thank You !

• Jae-Yoon Jung
• ASRI
• Seoul National University, Korea
• jjyjung_at_gmail.com

Seung-Kyun Han Digital Interactions Lab. Seoul
National University, Korea jackleg83_at_gmail.com
Jonghun Park Digital Interactions Lab. Seoul
National University, Korea jonghun_at_snu.ac.kr
Kang Chan Lee Protocol Eng. Center ETRI,
Korea chan_at_etri.re.kr