Using interface grammars to model the interface contract of a web service, we can automatically generate stubs and drivers to test and verify a web service client.

1. Generating Interface Grammars
from WSDL for Automated
Verification of Web Services
Sylvain Hallé, Graham Hughes,
Tevfik Bultan, Muath Alkhalaf
University of California
Santa Barbara, USA
Hallé, Hughes, Bultan, Alkhalaf

2. A motivating scenario
Hallé, Hughes, Bultan, Alkhalaf

3. A motivating scenario
Hallé, Hughes, Bultan, Alkhalaf

4. A motivating scenario
$
Hallé, Hughes, Bultan, Alkhalaf

5. A motivating scenario
?
Hallé, Hughes, Bultan, Alkhalaf

6. A motivating scenario
?
express checkout
Hallé, Hughes, Bultan, Alkhalaf

7. A motivating scenario
!
express checkout
Hallé, Hughes, Bultan, Alkhalaf

8. A motivating scenario
?
!
express checkout
Hallé, Hughes, Bultan, Alkhalaf

9. A motivating scenario
express checkout
Hallé, Hughes, Bultan, Alkhalaf

10. A motivating scenario
express checkout
Hallé, Hughes, Bultan, Alkhalaf

11. A motivating scenario
express checkout
Hallé, Hughes, Bultan, Alkhalaf

12. More concretely
Hallé, Hughes, Bultan, Alkhalaf

13. More concretely
PP
Hallé, Hughes, Bultan, Alkhalaf

14. More concretely
PP
<SetExpressCheckoutRequest>
<PaymentDetails>
<Token>1234</Token>
<OrderTotal>50</OrderTotal>
<PaymentDetailsItem>
<Number>456</Number>
<Quantity>1</Quantity>
</PaymentDetailsItem>
<PaymentAction>Sale</PaymentAction>
</PaymentDetails>
</SetExpressCheckoutRequest>
Hallé, Hughes, Bultan, Alkhalaf

15. More concretely
PP
<SetExpressCheckoutRequest>
<PaymentDetails>
<Token>1234</Token>
<OrderTotal>50</OrderTotal>
<PaymentDetailsItem>
<Number>456</Number>
<Quantity>1</Quantity>
</PaymentDetailsItem>
<PaymentAction>Sale</PaymentAction>
</PaymentDetails>
</SetExpressCheckoutRequest>
<SetExpressCheckoutResponse>
<Token>1234</Token>
</SetExpressCheckoutResponse>
Hallé, Hughes, Bultan, Alkhalaf

16. More concretely
PP
<SetExpressCheckoutRequest>
<PaymentDetails>
<Token>1234</Token>
<OrderTotal>50</OrderTotal>
<PaymentDetailsItem>
<Number>456</Number>
<Quantity>1</Quantity>
</PaymentDetailsItem>
<PaymentAction>Sale</PaymentAction>
</PaymentDetails>
</SetExpressCheckoutRequest>
<SetExpressCheckoutResponse>
<Token>1234</Token>
</SetExpressCheckoutResponse>
<GetExpressCheckoutDetails>
<Token>1234</Token>
<PayerID>abcd</PayerId>
</GetExpressCheckoutDetails>
Hallé, Hughes, Bultan, Alkhalaf

17. More concretely
PP
<SetExpressCheckoutRequest>
<PaymentDetails>
<Token>1234</Token>
<OrderTotal>50</OrderTotal>
<PaymentDetailsItem>
<Number>456</Number>
<Quantity>1</Quantity>
</PaymentDetailsItem>
<PaymentAction>Sale</PaymentAction>
</PaymentDetails>
</SetExpressCheckoutRequest>
<SetExpressCheckoutResponse>
<Token>1234</Token>
</SetExpressCheckoutResponse>
<GetExpressCheckoutDetails>
<Token>1234</Token>
<PayerID>abcd</PayerId>
</GetExpressCheckoutDetails>
<GetExpressCheckoutDetailsResponse>
<Token>1234</Token>
<PayerID>abcd</PayerId>
<PaymentDetails>...</PaymentDetails>
</GetExpressCheckoutDetailsResponse>
Hallé, Hughes, Bultan, Alkhalaf

18. More concretely
PP
<SetExpressCheckoutRequest>
<PaymentDetails>
<Token>1234</Token>
<OrderTotal>50</OrderTotal>
<PaymentDetailsItem>
<Number>456</Number>
<Quantity>1</Quantity>
</PaymentDetailsItem>
<PaymentAction>Sale</PaymentAction>
</PaymentDetails>
</SetExpressCheckoutRequest>
<SetExpressCheckoutResponse>
<Token>1234</Token>
</SetExpressCheckoutResponse>
<GetExpressCheckoutDetails>
<Token>1234</Token>
<PayerID>abcd</PayerId>
</GetExpressCheckoutDetails>
<GetExpressCheckoutDetailsResponse>
<Token>1234</Token>
<PayerID>abcd</PayerId>
<PaymentDetails>...</PaymentDetails>
</GetExpressCheckoutDetailsResponse>
<DoExpressCheckoutPaymentRequest>
<Token>1234</Token>
<PayerID>abcd</PayerId>
<PaymentAction>Sale</PaymentAction>
</DoExpressCheckoutPaymentRequest>
Hallé, Hughes, Bultan, Alkhalaf

19. More concretely
PP
<SetExpressCheckoutRequest>
<PaymentDetails>
<Token>1234</Token>
<OrderTotal>50</OrderTotal>
<PaymentDetailsItem>
<Number>456</Number>
<Quantity>1</Quantity>
</PaymentDetailsItem>
<PaymentAction>Sale</PaymentAction>
</PaymentDetails>
</SetExpressCheckoutRequest>
<SetExpressCheckoutResponse>
<Token>1234</Token>
</SetExpressCheckoutResponse>
<GetExpressCheckoutDetails>
<Token>1234</Token>
<PayerID>abcd</PayerId>
</GetExpressCheckoutDetails>
<GetExpressCheckoutDetailsResponse>
<Token>1234</Token>
<PayerID>abcd</PayerId>
<PaymentDetails>...</PaymentDetails>
</GetExpressCheckoutDetailsResponse>
<DoExpressCheckoutPaymentRequest>
<Token>1234</Token>
<PayerID>abcd</PayerId>
<PaymentAction>Sale</PaymentAction>
</DoExpressCheckoutPaymentRequest>
<DoExpressCheckoutPaymentResponse>
<Token>1234</Token>
<PaymentInfo>
<TransactionID>7890</TransactionId>
</PaymentInfo>
</DoExpressCheckoutPaymentResponse>
Hallé, Hughes, Bultan, Alkhalaf

20. More concretely
PP
<SetExpressCheckoutRequest>
<PaymentDetails>
Many ways to
<Token>1234</Token>
<OrderTotal>50</OrderTotal>
<PaymentDetailsItem>
<Number>456</Number>
make the
<Quantity>1</Quantity>
</PaymentDetailsItem>
<PaymentAction>Sale</PaymentAction>
exchange fail
</PaymentDetails>
</SetExpressCheckoutRequest>
<SetExpressCheckoutResponse>
<Token>1234</Token>
</SetExpressCheckoutResponse>
<GetExpressCheckoutDetails>
<Token>1234</Token>
<PayerID>abcd</PayerId>
</GetExpressCheckoutDetails>
<GetExpressCheckoutDetailsResponse>
<Token>1234</Token>
<PayerID>abcd</PayerId>
<PaymentDetails>...</PaymentDetails>
</GetExpressCheckoutDetailsResponse>
<DoExpressCheckoutPaymentRequest>
<Token>1234</Token>
<PayerID>abcd</PayerId>
<PaymentAction>Sale</PaymentAction>
</DoExpressCheckoutPaymentRequest>
<DoExpressCheckoutPaymentResponse>
<Token>1234</Token>
<PaymentInfo>
<TransactionID>7890</TransactionId>
</PaymentInfo>
</DoExpressCheckoutPaymentResponse>
Hallé, Hughes, Bultan, Alkhalaf

21. More concretely
PP
Many ways to
make the
exchange fail
Hallé, Hughes, Bultan, Alkhalaf

22. More concretely
PP
<SetExpressCheckoutRequest>
<PaymentDetails>
Many ways to
<Token>1234</Token>
<OrderTotal>50</OrderTotal>
<CustomerAddress>
<Name>John Doe</Name>
make the
...
</CustomerAddress>
<FooBar>bazbaz</FooBar>
exchange fail
</PaymentDetails>
</SetExpressCheckoutRequest>
Hallé, Hughes, Bultan, Alkhalaf

23. More concretely
PP
<SetExpressCheckoutRequest>
<PaymentDetails>
Many ways to
<Token>1234</Token>
<OrderTotal>50</OrderTotal>
<CustomerAddress>
<Name>John Doe</Name>
make the
...
</CustomerAddress>
<FooBar>bazbaz</FooBar>
exchange fail
</PaymentDetails>
</SetExpressCheckoutRequest>
Hallé, Hughes, Bultan, Alkhalaf

24. More concretely
PP
<SetExpressCheckoutRequest>
<PaymentDetails>
Many ways to
<Token>1234</Token>
<OrderTotal>50</OrderTotal>
<CustomerAddress>
<Name>John Doe</Name>
make the
...
</CustomerAddress>
<FooBar>bazbaz</FooBar>
exchange fail
</PaymentDetails>
</SetExpressCheckoutRequest>
Hallé, Hughes, Bultan, Alkhalaf

25. More concretely
PP
<SetExpressCheckoutRequest>
<PaymentDetails>
Many ways to
<Token>1234</Token>
<OrderTotal>50</OrderTotal>
<CustomerAddress>
<Name>John Doe</Name>
make the
...
</CustomerAddress>
<FooBar>bazbaz</FooBar>
exchange fail
</PaymentDetails>
</SetExpressCheckoutRequest>
unexpected
element
Hallé, Hughes, Bultan, Alkhalaf

26. More concretely
PP
<SetExpressCheckoutRequest>
<PaymentDetails>
Many ways to
<Token>1234</Token>
<OrderTotal>50</OrderTotal>
<CustomerAddress>
<Name>John Doe</Name>
make the
...
</CustomerAddress>
<FooBar>bazbaz</FooBar>
exchange fail
</PaymentDetails>
</SetExpressCheckoutRequest>
PaymentAction
missing
Hallé, Hughes, Bultan, Alkhalaf

27. More concretely
PP
<SetExpressCheckoutRequest>
<PaymentDetails>
Many ways to
<Token>1234</Token>
<OrderTotal>50</OrderTotal>
<CustomerAddress>
<Name>John Doe</Name>
make the
...
</CustomerAddress>
<FooBar>bazbaz</FooBar>
exchange fail
</PaymentDetails>
</SetExpressCheckoutRequest>
PaymentAction
missing
1. Message
with wrong
structure
Hallé, Hughes, Bultan, Alkhalaf

28. More concretely
PP
Many ways to
make the
exchange fail
Hallé, Hughes, Bultan, Alkhalaf

29. More concretely
PP
<SetExpressCheckoutRequest>
<PaymentDetails>
Many ways to
<Token>1234</Token>
<OrderTotal>50</OrderTotal>
<PaymentDetailsItem>
<Number>456</Number>
make the
<Quantity>1</Quantity>
</PaymentDetailsItem>
<PaymentAction>Sale</PaymentAction>
exchange fail
</PaymentDetails>
</SetExpressCheckoutRequest>
Hallé, Hughes, Bultan, Alkhalaf

30. More concretely
PP
<SetExpressCheckoutRequest>
<PaymentDetails>
Many ways to
<Token>1234</Token>
<OrderTotal>50</OrderTotal>
<PaymentDetailsItem>
<Number>456</Number>
make the
<Quantity>1</Quantity>
</PaymentDetailsItem>
<PaymentAction>Sale</PaymentAction>
exchange fail
</PaymentDetails>
</SetExpressCheckoutRequest>
<SetExpressCheckoutResponse>
<Token>5678</Token>
</SetExpressCheckoutResponse>
Hallé, Hughes, Bultan, Alkhalaf

31. More concretely
PP
<SetExpressCheckoutRequest>
<PaymentDetails>
Many ways to
<Token>1234</Token>
<OrderTotal>50</OrderTotal>
<PaymentDetailsItem>
<Number>456</Number>
make the
<Quantity>1</Quantity>
</PaymentDetailsItem>
<PaymentAction>Sale</PaymentAction>
exchange fail
</PaymentDetails>
</SetExpressCheckoutRequest>
<SetExpressCheckoutResponse>
<Token>5678</Token>
</SetExpressCheckoutResponse>
Hallé, Hughes, Bultan, Alkhalaf

32. More concretely
PP
<SetExpressCheckoutRequest>
<PaymentDetails>
Many ways to
<Token>1234</Token>
<OrderTotal>50</OrderTotal>
<PaymentDetailsItem>
<Number>456</Number>
make the
<Quantity>1</Quantity>
</PaymentDetailsItem>
<PaymentAction>Sale</PaymentAction>
exchange fail
</PaymentDetails>
</SetExpressCheckoutRequest>
<SetExpressCheckoutResponse>
<Token>5678</Token>
</SetExpressCheckoutResponse>
Hallé, Hughes, Bultan, Alkhalaf

33. More concretely
PP
<SetExpressCheckoutRequest>
<PaymentDetails>
Many ways to
<Token>1234</Token>
should be
<OrderTotal>50</OrderTotal>
<PaymentDetailsItem>
<Number>456</Number>
equal make the
<Quantity>1</Quantity>
</PaymentDetailsItem>
<PaymentAction>Sale</PaymentAction>
exchange fail
</PaymentDetails>
</SetExpressCheckoutRequest>
<SetExpressCheckoutResponse>
<Token>5678</Token>
</SetExpressCheckoutResponse>
Hallé, Hughes, Bultan, Alkhalaf

34. More concretely
PP
<SetExpressCheckoutRequest>
<PaymentDetails>
Many ways to
<Token>1234</Token>
should be
<OrderTotal>50</OrderTotal>
<PaymentDetailsItem>
<Number>456</Number>
equal make the
<Quantity>1</Quantity>
</PaymentDetailsItem>
<PaymentAction>Sale</PaymentAction>
exchange fail
</PaymentDetails>
</SetExpressCheckoutRequest>
<SetExpressCheckoutResponse>
<Token>5678</Token>
</SetExpressCheckoutResponse>
2. Message
with good
structure
Hallé, Hughes, Bultan, Alkhalaf

35. More concretely
PP
<SetExpressCheckoutRequest>
<PaymentDetails>
Many ways to
<Token>1234</Token>
should be
<OrderTotal>50</OrderTotal>
<PaymentDetailsItem>
<Number>456</Number>
equal make the
<Quantity>1</Quantity>
</PaymentDetailsItem>
<PaymentAction>Sale</PaymentAction>
exchange fail
</PaymentDetails>
</SetExpressCheckoutRequest>
<SetExpressCheckoutResponse>
<Token>5678</Token>
</SetExpressCheckoutResponse>
2. Message
with good
structure but
wrong values
Hallé, Hughes, Bultan, Alkhalaf

36. More concretely
PP
Many ways to
make the
exchange fail
Hallé, Hughes, Bultan, Alkhalaf

37. More concretely
PP
Many ways to
<DoExpressCheckoutPaymentRequest>
<Token>1234</Token>
<PayerID>abcd</PayerId>
make the
<PaymentAction>Sale</PaymentAction>
</DoExpressCheckoutPaymentRequest> exchange fail
Hallé, Hughes, Bultan, Alkhalaf

38. More concretely
PP
Many ways to
<DoExpressCheckoutPaymentRequest>
<Token>1234</Token>
<PayerID>abcd</PayerId>
make the
<PaymentAction>Sale</PaymentAction>
</DoExpressCheckoutPaymentRequest> exchange fail
Hallé, Hughes, Bultan, Alkhalaf

39. More concretely
PP
Many ways to
<DoExpressCheckoutPaymentRequest>
<Token>1234</Token>
<PayerID>abcd</PayerId>
make the
<PaymentAction>Sale</PaymentAction>
</DoExpressCheckoutPaymentRequest> exchange fail
Hallé, Hughes, Bultan, Alkhalaf

40. More concretely
PP
Many ways to
<DoExpressCheckoutPaymentRequest>
<Token>1234</Token>
<PayerID>abcd</PayerId>
make the
<PaymentAction>Sale</PaymentAction>
</DoExpressCheckoutPaymentRequest> exchange fail
the first occurrence
of a token must be in
a SetExpressCheckout
request
Hallé, Hughes, Bultan, Alkhalaf

41. More concretely
PP
Many ways to
<DoExpressCheckoutPaymentRequest>
<Token>1234</Token>
<PayerID>abcd</PayerId>
make the
<PaymentAction>Sale</PaymentAction>
</DoExpressCheckoutPaymentRequest> exchange fail
the first occurrence 3. Message
of a token must be in
a SetExpressCheckout with good
request
structure and
good values
Hallé, Hughes, Bultan, Alkhalaf

42. More concretely
PP
Many ways to
<DoExpressCheckoutPaymentRequest>
<Token>1234</Token>
<PayerID>abcd</PayerId>
make the
<PaymentAction>Sale</PaymentAction>
</DoExpressCheckoutPaymentRequest> exchange fail
the first occurrence 3. Message
of a token must be in
a SetExpressCheckout with good
request
structure and
good values
in the wrong
sequence
Hallé, Hughes, Bultan, Alkhalaf

43. More concretely
PP
Many ways to
<DoExpressCheckoutPaymentRequest>
<Token>1234</Token>
<PayerID>abcd</PayerId>
make the
<PaymentAction>Sale</PaymentAction>
</DoExpressCheckoutPaymentRequest> exchange fail
the first occurrence 3. Message
of a token must be in
a SetExpressCheckout with good
request
???
structure and
good values
in the wrong
sequence
Hallé, Hughes, Bultan, Alkhalaf

44. More concretely
???
Hallé, Hughes, Bultan, Alkhalaf

45. More concretely
???
Hallé, Hughes, Bultan, Alkhalaf

46. Proposed solution
We want to do, as automatically as possible...
Hallé, Hughes, Bultan, Alkhalaf

47. Proposed solution
We want to do, as automatically as possible...
Œ
Hallé, Hughes, Bultan, Alkhalaf

48. Proposed solution
We want to do, as automatically as possible...
Œ
...impersonate the client, send
test sequences to the service
Hallé, Hughes, Bultan, Alkhalaf

49. Proposed solution
We want to do, as automatically as possible...
Œ
DRIVER
...impersonate the client, send
test sequences to the service
Hallé, Hughes, Bultan, Alkhalaf

50. Proposed solution
We want to do, as automatically as possible...
Œ
DRIVER
...impersonate the client, send
test sequences to the service
! Check if service does what
we expect/understand
Hallé, Hughes, Bultan, Alkhalaf

51. Proposed solution
We want to do, as automatically as possible...
Œ 
DRIVER
...impersonate the client, send
test sequences to the service
! Check if service does what
we expect/understand
Hallé, Hughes, Bultan, Alkhalaf

52. Proposed solution
We want to do, as automatically as possible...
Œ 
DRIVER
...impersonate the client, send ...impersonate the service,
test sequences to the service generate responses to the client
! Check if service does what
we expect/understand
Hallé, Hughes, Bultan, Alkhalaf

53. Proposed solution
We want to do, as automatically as possible...
Œ 
DRIVER STUB
...impersonate the client, send ...impersonate the service,
test sequences to the service generate responses to the client
! Check if service does what
we expect/understand
Hallé, Hughes, Bultan, Alkhalaf

54. Proposed solution
We want to do, as automatically as possible...
Œ 
DRIVER STUB
...impersonate the client, send ...impersonate the service,
test sequences to the service generate responses to the client
! Check if service does what ! Environment closed
we expect/understand Þ model checking possible
Hallé, Hughes, Bultan, Alkhalaf

55. Related work
Hallé, Hughes, Bultan, Alkhalaf

56. Related work
Stub/
driver
Hallé, Hughes, Bultan, Alkhalaf

57. Related work
Stub/
driver
Constraints
Structure
Values
Sequence
Hallé, Hughes, Bultan, Alkhalaf

58. Related work
Stub/
driver
Constraints
Structure
Values
Sequence
Hallé, Hughes, Bultan, Alkhalaf

59. Related work
Stub/
driver
Constraints
Structure
Values
Sequence
soapUI with "mock web services"
Hallé, Hughes, Bultan, Alkhalaf

60. Related work
Stub/
driver
Constraints
Structure
Values
Sequence
Java API for XML Web Services; IBM Web Service Validation
Tool (validation only)
Hallé, Hughes, Bultan, Alkhalaf

61. Related work
Stub/
driver
Constraints
Structure
Values
Sequence
Cacciagrano et al., WS-FM 2006
(validation only)
Hallé, Hughes, Bultan, Alkhalaf

62. Related work
Stub/
driver
Constraints
Structure
Values
Sequence
Bai et al., SOSE 2005
Bartolini et al., ICSOC 2008
Hallé, Hughes, Bultan, Alkhalaf

63. Related work
Stub/
driver
Constraints
Structure
Values
Sequence
Hallé & Villemaire, CAV 2009
(validation only)
Hallé, Hughes, Bultan, Alkhalaf

64. Related work
Stub/
driver
Constraints
Structure
Values
Sequence
Hughes & Bultan, ISSTA 2007
Hallé, Hughes, Bultan, Alkhalaf

65. Related work
Stub/
driver
Constraints
Structure
Values
Sequence
Hughes & Bultan, AFM 2007
Hallé, Hughes, Bultan, Alkhalaf

66. Related work
Stub/
driver
Constraints
Structure
Values
Sequence
Hughes & Bultan, TAV-WEB 2008
Hallé, Hughes, Bultan, Alkhalaf

67. Related work
Stub/
driver
Constraints
Structure
Values
Sequence
The present paper
Hallé, Hughes, Bultan, Alkhalaf

68. Tool architecture
Hallé, Hughes, Bultan, Alkhalaf

69. Tool architecture
Control-flow
constraints
Hallé, Hughes, Bultan, Alkhalaf

70. Tool architecture
Interface
grammar
Control-flow
G constraints
Hallé, Hughes, Bultan, Alkhalaf

71. Tool architecture
Interface
grammar
Control-flow
G constraints
WSDL
Hallé, Hughes, Bultan, Alkhalaf

72. Tool architecture
Interface
grammar
Translator Control-flow
G constraints
WSDL
Hallé, Hughes, Bultan, Alkhalaf

73. Tool architecture
Interface
grammar
Control-flow
Translator G constraints
WSDL
Hallé, Hughes, Bultan, Alkhalaf

74. Tool architecture
Interface
grammar
Control-flow
Translator G constraints
WSDL
Interface
compiler
Hallé, Hughes, Bultan, Alkhalaf

75. Tool architecture
Interface
grammar
Control-flow
Translator G constraints
WSDL
Interface
compiler
Service
driver
Hallé, Hughes, Bultan, Alkhalaf

76. Tool architecture
Interface
grammar
Control-flow
Translator G constraints
WSDL
Interface
compiler
Service
driver
Hallé, Hughes, Bultan, Alkhalaf

77. Tool architecture
Interface
grammar
Control-flow
Translator G constraints
WSDL
Interface
compiler
Service Server
driver stub
Hallé, Hughes, Bultan, Alkhalaf

78. Tool architecture
Interface
grammar
Control-flow
Translator G constraints
WSDL
Interface
compiler
Service Server
driver stub
Hallé, Hughes, Bultan, Alkhalaf

79. Tool architecture
Interface
grammar
Control-flow
Translator G constraints
WSDL
Interface
compiler
automated
Service Server
driver stub
Hallé, Hughes, Bultan, Alkhalaf

80. Tool architecture
Interface
grammar
Control-flow
Translator G constraints
WSDL
Interface
compiler
automated
Service Server
driver stub
Hallé, Hughes, Bultan, Alkhalaf

81. Interface grammar
Recall: grammar
Hallé, Hughes, Bultan, Alkhalaf

82. Interface grammar
Recall: grammar
S ® AB|e
A ® login S | S login
B ® logout S | S logout
Hallé, Hughes, Bultan, Alkhalaf

83. Interface grammar
Recall: grammar
S ® AB|e
A ® login S | S login
B ® logout S | S logout
production rule
Hallé, Hughes, Bultan, Alkhalaf

84. Interface grammar
Recall: grammar
start symbol
S ® AB|e
A ® login S | S login
B ® logout S | S logout
production rule
Hallé, Hughes, Bultan, Alkhalaf

85. Interface grammar
Recall: grammar
nonterminal
start symbol
S ® AB|e
A ® login S | S login
B ® logout S | S logout
production rule
Hallé, Hughes, Bultan, Alkhalaf

86. Interface grammar
Recall: grammar
nonterminal
start symbol
S ® AB|e
A ® login S | S login
B ® logout S | S logout
production rule terminal
Hallé, Hughes, Bultan, Alkhalaf

87. Interface grammar
Recall: grammar
nonterminal
start symbol
empty symbol
S ® AB|e
A ® login S | S login
B ® logout S | S logout
production rule terminal
Hallé, Hughes, Bultan, Alkhalaf

88. Interface grammar
Recall: grammar
nonterminal
start symbol
empty symbol
S ® AB|e
A ® login S | S login
B ® logout S | S logout
production rule terminal
Sufficient to express control-flow
constraints: "every login can be matched
to exactly one logout in the future"
Hallé, Hughes, Bultan, Alkhalaf

89. Interface grammar
Two uses for the grammar:
1. Check that a given sequence belongs to that grammar
S ® AB|e
A ® login S | S login
B ® logout S | S logout
What about login login logout logout ?
S
AB
login S B
login A B B
...
login login logout logout
Hallé, Hughes, Bultan, Alkhalaf

90. Interface grammar
Two uses for the grammar:
2. Generate sequences belonging to that grammar
S ® AB|e
A ® login S | S login
B ® logout S | S logout
S
AB
login S B
login B
...
login logout
Hallé, Hughes, Bultan, Alkhalaf

91. Interface grammar
DRIVER
Hallé, Hughes, Bultan, Alkhalaf

92. Interface grammar
G
DRIVER
Hallé, Hughes, Bultan, Alkhalaf

93. Interface grammar
G
?
DRIVER
Hallé, Hughes, Bultan, Alkhalaf

94. Interface grammar
G
1
DRIVER
Hallé, Hughes, Bultan, Alkhalaf

95. Interface grammar
G
1
DRIVER
Hallé, Hughes, Bultan, Alkhalaf

96. Interface grammar
G
2
DRIVER
Hallé, Hughes, Bultan, Alkhalaf

97. Interface grammar
G
2 ÎG ?
2
DRIVER
Hallé, Hughes, Bultan, Alkhalaf

98. Interface grammar
G
üû
/
2
DRIVER
Hallé, Hughes, Bultan, Alkhalaf

99. Interface grammar
G
STUB
Hallé, Hughes, Bultan, Alkhalaf

100. Interface grammar
G
1
STUB
Hallé, Hughes, Bultan, Alkhalaf

101. Interface grammar
G
1 ÎG ?
1
STUB
Hallé, Hughes, Bultan, Alkhalaf

102. Interface grammar
G
üû
/
1
STUB
Hallé, Hughes, Bultan, Alkhalaf

103. Interface grammar
G
?
1
STUB
Hallé, Hughes, Bultan, Alkhalaf

104. Interface grammar
G
2
1
STUB
Hallé, Hughes, Bultan, Alkhalaf

105. Interface grammar
G
2
2
STUB
Hallé, Hughes, Bultan, Alkhalaf

106. Interface grammar
Interesting consequence:
G
We use the same grammar G for:
! Checking messages
! Generating messages
Both to produce:
! A stub
! A driver
Hallé, Hughes, Bultan, Alkhalaf

107. Interface grammar
S ® AB|e
A ® login S | S login
B ® logout S | S logout
Sufficient to express control-flow
constraints: "every login can be matched
to exactly one logout in the future"
Hallé, Hughes, Bultan, Alkhalaf

108. Interface grammar
S ® AB|e
A ® login S | S login
B ® logout S | S logout
Sufficient to express control-flow
constraints: "every login can be matched
to exactly one logout in the future"
Hallé, Hughes, Bultan, Alkhalaf

109. Interface grammar
Extensions to classical grammar
S ® AB|e
A ® login S | S login
B ® logout S | S logout
Hallé, Hughes, Bultan, Alkhalaf

110. Interface grammar
Extensions to classical grammar
S ® int(x) A(x) B(x) | e
A(x) ® !login(x) S | S !login(x)
B(x) ® !logout(x) S | S !logout(x)
int(x) ® ááx=0ññ | ááx=1ññ | ...
Hallé, Hughes, Bultan, Alkhalaf

111. Interface grammar
Extensions to classical grammar
S ® int(x) A(x) B(x) | e
A(x) ® !login(x) S | S !login(x)
B(x) ® !logout(x) S | S !logout(x)
int(x) ® ááx=0ññ | ááx=1ññ | ...
argument
Hallé, Hughes, Bultan, Alkhalaf

112. Interface grammar
Extensions to classical grammar
the same x
S ® int(x) A(x) B(x) | e
A(x) ® !login(x) S | S !login(x)
B(x) ® !logout(x) S | S !logout(x)
int(x) ® ááx=0ññ | ááx=1ññ | ...
argument
Hallé, Hughes, Bultan, Alkhalaf

113. Interface grammar
Extensions to classical grammar
checks that x is an int the same x
generates an int x
S ® int(x) A(x) B(x) | e
A(x) ® !login(x) S | S !login(x)
B(x) ® !logout(x) S | S !logout(x)
int(x) ® ááx=0ññ | ááx=1ññ | ...
argument
Hallé, Hughes, Bultan, Alkhalaf

114. Interface grammar
Extensions to classical grammar
checks that x is an int the same x
generates an int x
S ® int(x) A(x) B(x) | e
A(x) ® !login(x) S | S !login(x)
B(x) ® !logout(x) S | S !logout(x)
int(x) ® ááx=0ññ | ááx=1ññ | ...
argument
semantic predicate
semantic action
Hallé, Hughes, Bultan, Alkhalaf

115. Interface grammar
Extensions to classical grammar
checks that x is an int the same x
generates an int x
S ® int(x) A(x) B(x) | e
A(x) ® !login(x) S | S !login(x)
B(x) ® !logout(x) S | S !logout(x)
int(x) ® ááx=0ññ | ááx=1ññ | ...
argument
semantic predicate
semantic action
Sufficient to express control-flow and value
constraints: "every login with argument x
can be matched to exactly one logout with
argument x in the future"
Hallé, Hughes, Bultan, Alkhalaf

116. Interface grammar
Example: generate a sequence
S ® int(x) A(x) B(x) | e
A(x) ® !login(x) S | S !login(x)
B(x) ® !logout(x) S | S !logout(x)
int(x) ® ááx=0ññ | ááx=1ññ | ...
S
int(x) A(x) B(x)
A(1) B(1)
!login(1) S B(1)
!login(1) S !logout(1)
!login(1) int(x) A(x) B(x) !logout(1)
Hallé, Hughes, Bultan, Alkhalaf

117. Interface grammar
Example: generate a sequence
S ® int(x) A(x) B(x) | e
A(x) ® !login(x) S | S !login(x)
B(x) ® !logout(x) S | S !logout(x)
int(x) ® ááx=0ññ | ááx=1ññ | ...
S
int(x) A(x) B(x)
A(1) B(1)
!login(1) S B(1)
!login(1) S !logout(1)
!login(1) int(x) A(x) B(x) !logout(1)
Hallé, Hughes, Bultan, Alkhalaf

118. Interface grammar
Interface
grammar
Control-flow
G constraints
Interface
compiler
Service Server
driver stub
Hallé, Hughes, Bultan, Alkhalaf

119. Interface grammar
Interface
grammar
Control-flow
G constraints
Interface
compiler
Service Server
driver stub
Hallé, Hughes, Bultan, Alkhalaf

120. Interface grammar
Interface
grammar
Control-flow
G constraints
still missing
message structure
Interface
compiler
Service Server
driver stub
Hallé, Hughes, Bultan, Alkhalaf

121. Interface grammar
S ® int(x) A(x) B(x) | e
A(x) ® !login(x) S | S !login(x)
B(x) ® !logout(x) S | S !logout(x)
int(x) ® ááx=0ññ | ááx=1ññ | ...
We have production rules to check/generate primitive data
types...
Hallé, Hughes, Bultan, Alkhalaf

122. Interface grammar
S ® int(x) A(x) B(x) | e
A(x) ® !login(x) S | S !login(x)
B(x) ® !logout(x) S | S !logout(x)
int(x) ® ááx=0ññ | ááx=1ññ | ...
!login(x) ® áá???ññ
We have production rules to check/generate primitive data
types...
How can we get similar rules for composite data types?
Hallé, Hughes, Bultan, Alkhalaf

123. Interface grammar
S ® int(x) A(x) B(x) | e
A(x) ® !login(x) S | S !login(x)
B(x) ® !logout(x) S | S !logout(x)
int(x) ® ááx=0ññ | ááx=1ññ | ...
!login(x) ® WSDL
áá???ññ
We have production rules to check/generate primitive data
types...
How can we get similar rules for composite data types?
Hallé, Hughes, Bultan, Alkhalaf

124. From WSDL to interface grammar rules
WSDL provides a (machine-readable) definition of a message's
structure
Hallé, Hughes, Bultan, Alkhalaf

125. From WSDL to interface grammar rules
WSDL provides a (machine-readable) definition of a message's
structure
Short-hand notation: Model Schema Language (MSL; Brown
et al., WWW 2001)
SetExpressCheckoutRequest[
Token[string]{0,1},
PaymentDetails[
OrderTotal[int],
PaymentDetailsItem[
Number[int],
Quantity[int]
]{1,8}
]{0,8}
]
Hallé, Hughes, Bultan, Alkhalaf

126. From WSDL to interface grammar rules
WSDL provides a (machine-readable) definition of a message's
structure
Short-hand notation: Model Schema Language (MSL; Brown
et al., WWW 2001)
SetExpressCheckoutRequest[
Token[string]{0,1}, <SetExpressCheckoutRequest>
<PaymentDetails>
PaymentDetails[ <Token>1234</Token>
OrderTotal[int], <OrderTotal>50</OrderTotal>
<PaymentDetailsItem>
PaymentDetailsItem[ <Number>456</Number>
<Quantity>1</Quantity>
Number[int], </PaymentDetailsItem>
Quantity[int] <PaymentAction>Sale</PaymentAction>
</PaymentDetails>
]{1,8} </SetExpressCheckoutRequest>
]{0,8}
]
Hallé, Hughes, Bultan, Alkhalaf

127. From WSDL to interface grammar rules
We build a (recursive) mapping p from MSL constructs to sets
of production rules
Example:
p[[Element[e]{0,1}]] =
Element(x) ® ááx=nullññ |
{ ááx=new Element();ññ } È p[[e(x)]]
Mapping for other MSL constructs: see the paper
(straightforward)
Hallé, Hughes, Bultan, Alkhalaf

128. From WSDL to interface grammar rules
Interface
grammar
Control-flow
G constraints
S ® int(x) A(x) B(x) | e
A(x) ® !login(x) S | S !login(x)
B(x) ® !logout(x) S | S !logout(x)
int(x) ® ááx=0ññ | ááx=1ññ | ...
Hallé, Hughes, Bultan, Alkhalaf

129. From WSDL to interface grammar rules
Interface
grammar
Control-flow
G constraints
WSDL
S ® int(x) A(x) B(x) | e
A(x) ® !login(x) S | S !login(x)
B(x) ® !logout(x) S | S !logout(x)
int(x) ® ááx=0ññ | ááx=1ññ | ...
Hallé, Hughes, Bultan, Alkhalaf

130. From WSDL to interface grammar rules
Interface
grammar
Control-flow
G constraints
WSDL
(MSL)
S ® int(x) A(x) B(x) | e
A(x) ® !login(x) S | S !login(x)
B(x) ® !logout(x) S | S !logout(x)
int(x) ® ááx=0ññ | ááx=1ññ | ...
Hallé, Hughes, Bultan, Alkhalaf

131. From WSDL to interface grammar rules
Interface
grammar
Translator Control-flow
G constraints
WSDL
(MSL)
S ® int(x) A(x) B(x) | e
A(x) ® !login(x) S | S !login(x)
B(x) ® !logout(x) S | S !logout(x)
int(x) ® ááx=0ññ | ááx=1ññ | ...
Hallé, Hughes, Bultan, Alkhalaf

132. From WSDL to interface grammar rules
Interface
grammar
Control-flow
Translator G constraints
WSDL
(MSL)
S ® int(x) A(x) B(x) | e
A(x) ® !login(x) S | S !login(x)
B(x) ® !logout(x) S | S !logout(x)
int(x) ® ááx=0ññ | ááx=1ññ | ...
!login(x) ® ááx=new Login();ññ logininside(x,y)
logininside(x,y) ® ááy=new UserId(); x.userId=y;ññ
...
Hallé, Hughes, Bultan, Alkhalaf

133. From WSDL to interface grammar rules
Interface
grammar
Control-flow
Translator G constraints
WSDL
(MSL)
S ® int(x) A(x) B(x) | e
A(x) ® !login(x) S | S !login(x)
B(x) ® !logout(x) S | S !logout(x)
int(x) ® ááx=0ññ | ááx=1ññ | ...
!login(x) ® ááx=new Login();ññ logininside(x,y)
logininside(x,y) ® ááy=new UserId(); x.userId=y;ññ
...
Hallé, Hughes, Bultan, Alkhalaf

134. From WSDL to interface grammar rules
Java code, classes
provided by Apache Axis
!login(x) ® ááx=new Login();ññ logininside(x,y)
Hallé, Hughes, Bultan, Alkhalaf

135. Experimental results
We extracted interface grammars for two real-world web
services:
Express Checkout E-Commerce Service
Hallé, Hughes, Bultan, Alkhalaf

136. Experimental results
We extracted interface grammars for two real-world web
services:
Express Checkout E-Commerce Service
Java/Axis driver generated test
Πsequences to the actual service
Hallé, Hughes, Bultan, Alkhalaf

137. Experimental results
We extracted interface grammars for two real-world web
services:
Express Checkout E-Commerce Service
Java/Axis driver generated test
Πsequences to the actual service
Pair Java client/Java stub model
 checked with Java Pathfinder
Hallé, Hughes, Bultan, Alkhalaf

138. Experimental results
! Driver message generation time: 1 sec./message
! Typical test sequence: 5 seconds
! Found 2 mismatches between implementation and
documentation
! Multiple contract violations found in sample client using
Java Pathfinder
! Maximum checking time: 20 sec. / 43 MB memory
! Found 2 mismatches between impl. and doc. with driver
Hallé, Hughes, Bultan, Alkhalaf

139. Take-home points
1. Long-running WS interactions involve constraints over
message structure, values and sequence
2. We developed interface grammars to model these constraints
in a uniform notation
3. Using the same IG, we can automatically generate a service
stub and a client driver to perform model checking / test
generation
4. We tested the approach with two real-world
WS and found mismatches between
documentation and implementation
Hallé, Hughes, Bultan, Alkhalaf