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 Science
Vrije Universiteit Brussel

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

Wednesday 9 June 2010

Mobile Reactive Applications

2



Mobile devices

2



Mobile devices

Intermittent connectivity

2



Mobile devices

Spontaneous interactions


2


Scarce infrastructure
Mobile devices



2


Mobile devices

Representation of physical objects



2



Mobile devices


Distributed
Event-driven Architecture



3



Mobile devices


overy
o c Disc
Ad H Distributed



3



Mobile devices


overy
o c Disc
Ad H Distributed


ecent ralized
D Intermittent connectivity

3



Mobile devices


overy
o c Disc
Ad H Distributed

Res
ilien
Scarce infrastructure t
ecent ralized

3



Mobile devices

Event streams

overy
o c Disc
Ad H Distributed

Res
ilien
ecent ralized

3



Mobile devices

Event streams
as ting
adc
overy Bro
o c Disc
Ad H Distributed

Res
ilien
ecent ralized

3


AmbientTalk Distributed
Event-driven
Architecture

whenever: Product discovered: { |product|

}

4

Event-driven
Architecture

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

}
}

4

Event-driven
Architecture

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

4

Event-driven
Architecture
Decentralized discovery
based on UDP broadcasting

};
};
}
}

4

Event-driven
Architecture

whenever: Product discovered: { |product| Resilient
def future := product<-getSerial(); asynchronous
when: future becomes: { |serial| messages
};
};
}
}

4

Event-driven
Architecture

whenever: Product discovered: { |product| Resilient
def future := product<-getSerial(); asynchronous
when: future becomes: { |serial| messages
};
};
}
}
Control ﬂow driven by events, but
speciﬁed by textual, sequential blocks
4

Dataﬂow Programming

x y z

f(x,y,z)

5


The Ambient Vinyl Store

6


1

productsInBag

1

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

1

products

1

7


1

productsInBag

1

ListeningStation ->

1

products

1

UserDatabase ->
DB.getRecommendationsWithProducts(products);

7


1

productsInBag

1

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

1 *

products recommendToUser

1 1

UserDatabase ->

7


1 1

productsInBag

recommendations
1


1 *


1 1 1

UserDatabase ->

7


1 1 1

productsInBag nearbyRecommendations

recommendations
1 1


1 *


1 1 1

UserDatabase ->

7


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

1 1 1

productsInBag nearbyRecommendations

recommendations
1 1


1 *


1 1 1

UserDatabase ->

7


A Visual Dataﬂow Language For Coordination in
Mobile Ad Hoc Networks
1
de 1
pe
nd y3
en e nc
cy nd
1 pe
de
1 1
Role ->
<< par1, par2, par3 <<
1 code 1
2 dep
e ncy end
end enc
dep y4
* *
Role
Role
- method1
- method1
- method2
- method2
- method3
- method3
AmbientTalk VM
AmbientTalk VM
JVM
JVM

8


Res
Executing Mobile AmbientTalk Code ilien
t

Customer ->

1 1 1

productsInBag recommendations nearbyRecommendations

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

def customer := extend: OperatorHostInterface with: {
// ... Private fields ...
def GUI := extend: JFrame with: {
def showProductsInBag(products) { ... };
def showRecommendations(products) { ... };
def showRecommendationsInShop(products) { ... };
}
} AmbientTalk VM
9
JVM

Propagating and Reacting to Events ms
strea
Ev ent Res
ilien
t

[ record2,
record4 ] nearbyRecommendations

1

Shelf ->
filterOutPresentProducts( ) filterOutPresentProducts(recommendToUser);

*

[ record1, recommendToUser
record2, >> system.println(recommendToUser)
record3, [ record1, record2 ]
record4 ]

10


strea
Ev ent Res
ilien
t

[ record2,

1

Shelf ->

*

record4 ] [ record1, record2, record3 ]

10


strea
Ev ent Res
ilien
t

[ record2,

1

Shelf ->

*

[ ]

10


strea
Ev ent Res
ilien
t

[ record2,

1

Shelf ->

*

[ ]
[ record4 ]

10


Discovering Nodes covery Res
H oc Dis ralized
ilien
t
Ad D ecent
Customer ->

1

productsInBag

1

ListeningStation ->

1

products

1

UserDatabase ->
DB.getRecommendationsWithProducts(products); 11


H oc Dis ralized
ilien
t
Ad D ecent
Customer ->

1
[ record1,
record2,
productsInBag ...
recordN ]

1

ListeningStation ->

1

products

1

UserDatabase ->


H oc Dis ralized
ilien
t
Ad D ecent
Customer ->

1

productsInBag

1

ListeningStation ->

1

[ record1,
record2,
products
...
recordN ]

1

UserDatabase ->


H oc Dis ralized
ilien
t
Ad D ecent
Customer ->

1

productsInBag

1

ListeningStation ->
rfidTags.map: { |t| t.getProduct() }; 1

products

1

UserDatabase ->

11


as ting
Dependency Arities roa
dc
B
Customer ->

1

nearbyRecommendations

incoming 1 incoming * 1

send one broadcast one Shelf ->
outgoing 1 recommendation recommendation filterOutPresentProducts(recommendToUser);

send list of broadcast list of *
outgoing * recommendations recommendations

recommendToUser

1

UserDatabase ->


as ting
Dependency Arities roa
dc
B
Customer ->

1

nearbyRecommendations

incoming 1 incoming * *

send one broadcast one Shelf ->
outgoing 1 recommendation recommendation filterOutPresentProducts(recommendToUser);

send list of broadcast list of *
outgoing * recommendations recommendations

recommendToUser

1

UserDatabase ->


ms
trea
Remembering State ent
s
Ev
1

value

1

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

1

average

13
1

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


Res
ilien
t
overy ms ting
Conclusion d Ho c Disc tralize
d st rea dc as
A D ecen ent B roa
Ev
• 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.

http://soft.vub.ac.be/soft/research/amopcop 16


Visual Dataflow Coordination2010

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