Visual Dataflow Coordination2010

A Hybrid Visual Dataflow Language For Coordination in Mobile Ad Hoc Networks

Andoni Lombide Carreton and Theo D’Hondt

Department of Computer ScienceVrije Universiteit Brussel

12th International Conference on Coordination Models and LanguagesJune 7-10 2010Amsterdam, the Netherlands 1

Wednesday 9 June 2010

Mobile Reactive Applications

2



Mobile devices

2



Mobile devices

Intermittent connectivity

2



Mobile devices


2

Spontaneous interactions



Mobile devices


2

Scarce infrastructure




Mobile devices


2


Representation of physical objects



Distributed Event-driven Architecture






Mobile devices

3








Mobile devices

Ad Hoc Discovery

3








Mobile devices

Decentralized

Ad Hoc Discovery

3








Mobile devices

Decentralized

Resilient

Ad Hoc Discovery

3








Mobile devices

Event streams

Decentralized

Resilient

Ad Hoc Discovery

3








Mobile devices

Event streams

Decentralized

Resilient

Ad Hoc Discovery Broadcasting

3


AmbientTalk

whenever: Product discovered: { |product|

}

4



AmbientTalk

def future := product<-getSerial(); when: future becomes: { |serial| println(“Product discovered: ” + serial);

}


}

4



AmbientTalk


}


}

whenever: product disconnected: { println("Product disconnected: " + serial); }; whenever: product reconnected: { println("Product reconnected: " + serial); };

4



AmbientTalk


}


}


Decentralized discovery based on UDP broadcasting

4



AmbientTalk


}


}



Resilient asynchronous

messages

4



AmbientTalk


}


}



Resilient asynchronous

messages

Control flow driven by events, but specified by textual, sequential blocks

4



Dataflow Programming

f(x,y,z)

x y z

5


The Ambient Vinyl Store

6


7

ListeningStation -> rfidTags.map: { |t| t.getProduct() };

productsInBag

products

1

1

1

1


UserDatabase -> DB.getRecommendationsWithProducts(products);

7


productsInBag

products

1

1

1

1



Shelf -> filterOutPresentProducts(recommendToUser);

7


productsInBag

products recommendToUser

1

1

1

1 1

*




7


productsInBag

products

recommendations

recommendToUser

1

1

1

1 1

1

1

*




7


productsInBag

products

recommendations

nearbyRecommendations

recommendToUser

1

1

1

1 1

1 1

1

1

*


Customer -> GUI.showProductsInBag(productsInBag); GUI.showRecommendations(recommendations); GUI.showRecommendationsInShop(nearbyRecommendations);



7


productsInBag

products

recommendations


recommendToUser

1

1

1

1 1

1 1

1

1

*


A Visual Dataflow Language For Coordination in Mobile Ad Hoc Networks

Role -> << par1, par2, par3 << code

dependency1

dependency4dependen

cy2

dependen

cy31

1

*

1

1

1

1

*

JVM

AmbientTalk VMJVM

AmbientTalk VM

8

Role- method1- method2- method3

Role- method1- method2- method3


Executing Mobile AmbientTalk Code Resilient


productsInBag recommendations nearbyRecommendations

1 1 1

[ record1, record2, record3, record4 ]

[ record1, record2, record4 ]

[ record2, record4 ]

def customer := extend: OperatorHostInterface with: { // ... Private fields ... def GUI := extend: JFrame with: { def showProductsInBag(products) { ... }; def showRecommendations(products) { ... }; def showRecommendationsInShop(products) { ... }; } }

JVM

AmbientTalk VM9


Propagating and Reacting to EventsEvent streams

Resilient



recommendToUser

1

*



filterOutPresentProducts( )

>> system.println(recommendToUser) [ record1, record2 ]

10



Resilient



recommendToUser

1

*





10

[ record1, record2, record3 ]



Resilient



recommendToUser

1

*





10

[ record1, record2, record3 ][ ]



Resilient



recommendToUser

1

*





10

[ record1, record2, record3 ][ ][ record4 ]


Discovering NodesAd Hoc Discovery

Decentralized




productsInBag

products

1

1

1

1

Resilient

11



Decentralized




productsInBag

products

1

1

1

1

[ record1, record2, ... recordN ]

Resilient

11



Decentralized




productsInBag

products

1

1

1

1

Resilient

11



Decentralized




productsInBag

products

1

1

1

1

[ record1, record2, ... recordN ]

Resilient

11



Decentralized




productsInBag

products

1

1

1

1

Resilient

11



Decentralized



productsInBag

1

1


products

1

1

Resilient

11


Dependency Arities





recommendToUser

1

1

1

*

incoming 1 incoming *

outgoing 1send one

recommendationbroadcast one

recommendation

outgoing * send list of recommendations

broadcast list of recommendations

12

Broadcasting


Dependency Arities





recommendToUser

1

*

incoming 1 incoming *

outgoing 1send one

recommendationbroadcast one

recommendation

outgoing * send list of recommendations

broadcast list of recommendations

1

*

send list of recommendations

12

Broadcasting


Remembering State

Averager -> << buffer << if: (buffer == nil) then: { buffer := Buffer.new(5); }; buffer.put(value); def accumulated := 0; buffer.each: { |val| accumulated := accumulated + val }; accumulated / 5;

value

1

1

average

1

1

Event streams

13


Editing Dataflow Graphs

14


Limitations and Future Work

• Node discovery based on role names may cause name clashes: look into more advanced publish/subscribe mechanisms?

• Security: build a secure environment to execute mobile AmbientTalk code.

• Current editor prototype is still very rudimentary.

• Dataflow debugging support.

15


Conclusion

• Hybrid visual dataflow language to coordinate distributed AmbientTalk components.

• Coarse grained control flow encoded in dataflow graph and separated from fine grained control flow (AmbientTalk statement level).

• Dynamically reconfiguring dataflow graph when mobile network topology changes.

• Based on reactive programming.

• Extends basic dataflow coordination model with broadcasting primitives by means of dependency arities.

16

Ad Hoc Discovery

Decentralized

Resilient

Event streams

http://soft.vub.ac.be/soft/research/amopcop

Broadcasting




Visual Dataflow Coordination2010

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