browser-based enforcement of interface contracts in web applications with beepbeep (talk @ cav 2009)

Sylvain Hallé

Sylvain Hallé, Roger Villemaire

Browser-based Enforcement ofInterface Contracts in Web Applications

with BeepBeep

University of CaliforniaSanta Barbara, USA

Université du Québec à MontréalMontréal, CANADA

Sylvain Hallé

Some web services

E-Commerce ServiceCompute Cloud

PayPal API: billing, express checkout

Shopping: like AmazonGoogle Search, Google Maps, GMail, ...

Sylvain Hallé

MyApplication.com

Using web applications

Sylvain Hallé

MyApplication.comi ?


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MyApplication.com

1.

2.

...

i ?


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<ListItems>

</ListItems> birds<title> </title>

<Items>

</Items>

1

abc

<Item> </ID> <Title> </Title> </Item> ...

<ID>

MyApplication.com

XML request

XMLresponse


Sylvain Hallé


MyApplication.com

2

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MyApplication.com

c

2

Sylvain Hallé

<cart>

</cart>

<id> </id><items>

</items>

c

2 <item> </item>

<cartCreate>

</cartCreate> 2<item> </item>

XML request

MyApplication.com

XMLresponse


Sylvain Hallé


MyApplication.com

2

c

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Constraints on the message trace

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i ?


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i ?

1.

2.

...


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i ?

1.

2.

...

2

c


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i ?

1.

2.

...

2

c

2

c


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i ?

1.

2.

...

2

c

2

c

You cannot add the same item twiceto the shopping cart


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i ?

1.

2.

...

2

c

2

c



???

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???

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2 2

c


! Atoms are properties over messages...


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2 2

cG F( (Þ Ø


! Atoms are properties over messages...! + LTL operators...


Sylvain Hallé

i i

cG( (Þ"i FØ


! Atoms are properties over messages...! + LTL operators...! + quantification on elements


Sylvain Hallé

i i

cG( (Þ"i FØ


! Atoms are properties over messages...! + LTL operators...! + quantification on elements } LTL-FO+


Sylvain Hallé

Enter BeepBeep

MyApplication.com

Sylvain Hallé

MyApplication.com

Enter BeepBeep

Sylvain Hallé

MyApplication.com

ii ii

ccGG(( ((ÞÞ""ii FFØØ

Enter BeepBeep

Sylvain Hallé

Enter BeepBeep

MyApplication.com

2

Sylvain Hallé

MyApplication.com

Enter BeepBeep

Sylvain Hallé

Enter BeepBeep

MyApplication.com

2

Sylvain Hallé

MyApplication.com

Enter BeepBeep

Sylvain Hallé

Adding BeepBeep to a real application

Sylvain Hallé


Copy BeepBeep to application folderhttp://beepbeep.sourceforge.net

�

Sylvain Hallé



Include BeepBeep

�

�

Sylvain Hallé


myapplication.html

<html><head><title></title><script type=" " href=" "/>

</head><body>

</body></html>

My Application

...

text/javascriptmyapplication.js


Include BeepBeep

�

�

Sylvain Hallé


myapplication.html


</head><body>

</body></html>

My Application

...


<script type="text/javascript" href="beepbeep.js"/>


Include BeepBeep

�

�

Sylvain Hallé


myapplication.html myapplication.js


</head><body>

</body></html>

My Application

...



// Initializations

= ();

(){

( );}

...

req XMLHttpRequest

...

abc

... req. some_message

new

function

send


Include BeepBeep

�

�

Sylvain Hallé


myapplication.html myapplication.js


</head><body>

</body></html>

My Application

...



// Initializations

= ();

(){

( );}

...

req

...

abc

... req. some_message

new

function

send

XMLHttpRequestBB


Include BeepBeep

�

�

Sylvain Hallé

Obtain (or create) a with LTL-FO+ formulaecontract file�


# ---------------------------------------------------------------# BeepBeep contract file for the Amazon ECS# ---------------------------------------------------------------

% To create a cart, you must put at least one item

% You can only create a cart once

% No CartAdd can occur before a CartCreate

% You cannot add the same item twice to the shopping cart

; G ([x1 /CartCreate/Operation] (((x1) = ({CartCreate})) -> (<x2 /CartCreate/Items/Item/ASIN> ({TRUE}))))

; G ([x1 /CartCreate/Operation] (((x1) = ({CartCreate})) -> (X (G (!(<x2 /CartCreate/Operation> ((x2) = ({CartCreate}))))))))

; (!(<x1 /CartAdd/Operation> ((x1) = ({CartAdd})))) U (<x2 /CartCreate/Operation> ((x2) = ({CartCreate})))

; G ([i /CartCreate/Items/Item/ASIN] (X (G ([j /CartAdd/Items/Item/ASIN] (!((i) = (j)))))))

Sylvain Hallé

Quick demo

Sylvain Hallé

Sample property: "each car entering in a parking lot must exit before entering again"

Tim

e pe

r m

essa

ge (

ms)

Trace length

Experimental results

Hallé & Villemaire, EDOC 2008

< 5 ms/msg.

Sylvain Hallé

Simultaneous monitoring of 11 properties (Amazon example)


-20

0 20 40 60 80 100 120 140 160 180 200

-10

0

10

20

Moyenne

Tim

e d

iffe

ren

ce (

%)

< 5%

Trace length

Sylvain Hallé

Simultaneous monitoring of 11 properties (Amazon example)


Tim

e pe

r m

essa

ge (

ms)

Trace length

Data domain

00 20 40 60 80 100 120 140 160

2

4

14

6

8

10

12

200

25

Sylvain Hallé

Take-home points

Sylvain Hallé

1. Constraints involving operators and on message contents arise naturally in web applications

temporal quantificationreal

Take-home points

Sylvain Hallé


2. An extension of LTL can formalize them:


LTL-FO+

Take-home points

Sylvain Hallé



3. of these constraints can be doneefficiently, even with quantification


LTL-FO+

Runtime monitoring

Take-home points

Sylvain Hallé



3. of these constraints can be doneefficiently, even with quantification

4. BeepBeep is a tool that allows it with on real applications


LTL-FO+

Runtime monitoring

minimal modifications

http://beepbeep.sourceforge.net/

Take-home points

browser-based enforcement of interface contracts in web applications with beepbeep (talk @ cav 2009)

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