1) The document describes a middleware architecture for instantiating and executing workflows at runtime based on quality of service constraints. 2) The middleware selects appropriate services for each workflow activity based on offers published to a registry and binds them to generate a concrete workflow execution plan. 3) Workflow execution is decentralized by distributing workflow instance information to participating services, which invoke each other to continue execution in a self-coordinated manner.

1. ServiceWave 2010 A Chemical Based Middleware for Workflow Instantiation and Execution Chen WANG1, Jean-Louis PAZAT1, Claudia DI NAPOLI2, Maurizio GIORDANO2 1Université Européenne de Bretagne, INSA/INRIA/IRISA, F-35708 Rennes, France 2Istituto di Cibernetica CNR, Via Campi Flegrei 34, 80078 Pozzuoli, Naples, Italy 15th December 2010 @ Gent, Belgium ServiceWave 2010 13-15 December 2010

3. Middleware Architecture

4. Workflow Instantiation & Execution

5. Implementation

6. Conclusion & Future WorkServiceWave 2010 13-15 December 2010

7. Introduction ServiceWave 2010 13-15 December 2010

9. A concept of large distributed system;

10. A paradigm/concept/perspective

11. Purpose: realize and maintain business processes that span large distributed systems;

12. Web Service

13. A way to realize the technical aspects of SOA;

14. Definition (W3C): a software system designed to support interoperable machine-to-machine interaction over a network.

15. A Web Services architecture then requires three fundamental operations: publish, find, and bind. Service providers publish services to a service broker. Service requesters find required services using a service broker and bind to them. These ideas are shown in the following figure.Bind Web services architecture. 13-15 December 2010 ServiceWave 2010

17. Service Selection:

18. All the partner services are selected at run-time;

19. The selection is based on the global QoS constraints;

20. Workflow Execution*:

21. The execution is decentralized;

22. Proposed by IRISA/INRIA (H. FERNANDEZ, C.TEDESCHI and T.PRIOL);

23. Integrated into our system;

24. Distribute the Implementation using Chemical Computing:

25. Unconventional computing paradigm;

26. Automated/parallel/self-coordinated computing 13-15 December 2010 ServiceWave 2010

27. Global Architecture Middleware Layer Abstract Business Process Registry AS1 AS3 Workflow Instantiation AS2 Abstract Service Web Service Grid Service Grid Service Concrete Service Business Process 13-15 December 2010 ServiceWave 2010

28. Middleware Architecture ServiceWave 2010 13-15 December 2010

29. Middleware Architecture Middleware Layer Web Service Execution Level Registry Publish Information of all offers provided by Abstract Services Monitoring/Rating Module Workflow Instantiation The 3rd party component, exposed as a service, to monitor the execution process of a workflow. - Input: an Abstract workflow - Output: a Concrete Workflow (Execution Plan) Web Service Representation Level Abstract WSn Abstract WS1 … … Abstract Business Processm Abstract Business Process1 WSn_Invoker WS1_Invoker Definition of Abstract WF Definition of Abstract WF … Concrete WS1 Concrete WSn 13-15 December 2010 ServiceWave 2010

31. Description of functional interface;

32. Middleware level role: service provider;

33. Connect to a concrete service in order to forward the invocation message;

34. Act as the representative of a concrete service in the middleware;

35. Invoker

36. Connector between the abstract service and the concrete one;

37. Forward the invocation message to the concrete service;

38. Retrieve the calculation result from the concrete service;

39. Concrete Web Service

40. Implementation of functional interfaces;

41. Atomic service (Java)/composite service (WS-BPEL) Abstract WS1 WS1_Invoker Concrete WS1 13-15 December 2010 ServiceWave 2010

43. Description of workflow topology using a directed graph;

44. Node: activity/task, edge: dependency

45. Collection of interrelated activities/tasks to achieve the ultimate business goal;

46. Each workflow activity/task specifies only functional requirement, but no binding information;

47. Middleware level role: service provider & consumer

48. QoS Constraints Over the Entire Workflow

49. Global Non-functional parameters can be aggregated (aggregated price can be added and the aggregated availability can be multiplied)

50. The same abstract workflow + different global QoS Constraints = different concrete workflow (Instantiation process: coming slide) Abstract Business Processm Definition of Abstract WF 13-15 December 2010 ServiceWave 2010

52. Abstract workflow definition;

53. Global QoS constraints (total price & execution time);

54. Output:

55. Concrete/Instantiated workflow: Abstract workflow + endpoint reference bindings;

56. Instantiation Process:

57. Coming section.Workflow Instantiation - Input: an Abstract workflow - Output: a Concrete Workflow (Execution Plan) 13-15 December 2010 ServiceWave 2010

59. offer: simple contract between service provider and requester;

60. Offer specifies 4 aspects:

61. ID of service provider;

62. Offer name;

63. Functional and

64. Non-functional characteristics of a service delivery

65. Example:

66. “inter_flight_reservation” offer is provided by “Air France” for reserving international airline tickets, the average response time is 5 seconds, the availability is 99%.13-15 December 2010 ServiceWave 2010

67. Workflow Instantiation & Execution Process 13-15 December 2010 ServiceWave 2010

68. Web Service Invocation Middleware Layer Service Invocation Message (with parameters) Abstract BP (SPA) P Q s1 s2 s3 s4 s5 13-15 December 2010 ServiceWave 2010

69. Forward Abstract WF to Instantiation Middleware Layer Workflow Instantiation Abstract BP (SPA) Send Workflow P Q s1 s1 s2 s2 Execution time: within 8 time units s3 s3 Complete Instantiation s4 s4 s5 s5 13-15 December 2010 ServiceWave 2010

70. Look For Appropriate Offers Middleware Layer Workflow Instantiation Demand Offers I look for the service providers that deliver the functionalities s1, s2, s3, s4 and s5. Registry Publish Information of all Abstract Web Services Abstract BP (SPA) P Q s1 s1 s2 s2 Execution time: within 8 time units s3 s3 Complete Instantiation s4 s4 s5 s5 13-15 December 2010 ServiceWave 2010

71. Return Qualified Offers Middleware Layer Workflow Instantiation Qualified Offers Registry Publish Information of all Abstract Web Services Abstract BP (SPA) P Q s1 s1 s2 s2 Execution time: within 8 time units s3 s3 Complete Instantiation s4 s4 s5 s5 13-15 December 2010 ServiceWave 2010

72. Associate Offers to Activities Middleware Layer Workflow Instantiation (0,3) (0,3) (0,2) (1,5) (2,4) (1,6) (4,5) Registry (4,6) (5,7) Publish Information of all Abstract Web Services (6,7) (3,8) (5,9) Abstract BP (SPA) P Q s1 s1 s2 s2 Execution time: within 8 time units s3 s3 Complete Instantiation s4 s4 s5 s5 13-15 December 2010 ServiceWave 2010

73. Non-functional Property Middleware Layer Workflow Instantiation (0,3) (0,3) (0,2) (1,5) (2,4) (1,6) (4,5) Registry (4,6) (5,7) Publish Information of all Abstract Web Services (6,7) (3,8) (5,9) Abstract BP (SPA) P Q s1 s1 s2 s2 Execution time: within 8 time units s3 s3 Complete Instantiation s4 s4 s5 s5 13-15 December 2010 ServiceWave 2010

74. Workflow Fragment Middleware Layer Workflow Instantiation (0,3) (0,3) (0,2) (2,4) (1,5) (1,6) (4,5) Registry (4,6) (5,7) Publish Information of all Abstract Web Services (6,7) (3,8) (5,9) Abstract BP (SPA) P Q s1 s1 s2 s2 Execution time: within 8 time units s3 s3 Complete Instantiation s4 s4 s5 s5 13-15 December 2010 ServiceWave 2010

75. QoS Constraints Middleware Layer Workflow Instantiation (0,3) (0,3) (0,2) (2,4) (1,5) (1,6) (4,5) Registry (4,6) (5,7) Publish Information of all Abstract Web Services (6,7) (3,8) (5,9) Abstract BP (SPA) P Q Constraint: The execution duration of two consecutive nodes has no Intersection. s1 s1 s2 s2 Execution time: within 8 time units s3 s3 Complete Instantiation s4 s4 s5 s5 13-15 December 2010 ServiceWave 2010

76. Branch Instantiation Middleware Layer Workflow Instantiation (0,3) (0,3) (0,2) (1,6) (4,5) Registry Publish Information of all Abstract Web Services (6,7) (3,8) (5,9) Abstract BP (SPA) (2,6) (1,7) P Q Constraint: The execution duration of two consecutive nodes has no Intersection. s1 s1 s2 s2 Execution time: within 8 time units s3 s3 Complete Instantiation s4 s4 s5 s5 13-15 December 2010 ServiceWave 2010

77. Connect fragments Middleware Layer Workflow Instantiation (0,3) (0,3) (0,7) (1,6) Registry Publish Information of all Abstract Web Services (3,8) (5,9) Abstract BP (SPA) (1,7) P Q Constraint: The execution duration of two consecutive nodes has no Intersection. s1 s1 s2 s2 Execution time: within 8 time units s3 s3 Complete Instantiation s4 s4 s5 s5 13-15 December 2010 ServiceWave 2010

78. Find A Feasible Solution Middleware Layer Workflow Instantiation (0,3) (0,3) (1,6) Registry Publish Information of all Abstract Web Services (3,8) (5,9) Abstract BP (SPA) (1,7) P Q s1 s1 s2 s2 Execution time: within 8 time units s3 s3 Complete Instantiation s4 s4 s5 s5 (0,7) 13-15 December 2010 ServiceWave 2010

79. Return Instantiation Result Middleware Layer Workflow Instantiation (0,3) (0,3) (1,6) Registry Publish Information of all Abstract Web Services (3,8) (5,9) Abstract BP (SPA) (1,7) P Q Return Instantiation s1 s1 s2 s2 Execution time: within 8 time units s3 s3 Complete Instantiation s4 s4 s5 s5 (0,7) 13-15 December 2010 ServiceWave 2010

80. Ready For Execution Middleware Layer Workflow Instantiation (0,3) (0,3) (1,6) Registry Publish Information of all Abstract Web Services (3,8) (5,9) Abstract BP (SPA) (1,7) P Q Return Instantiation s1 s1 sp2 s2 s2 Execution time: within 8 time units sp6 s3 s3 sp3 Complete Instantiation s4 s4 sp5 s5 s5 sp1 13-15 December 2010 ServiceWave 2010

82. Next:<?>

83. Previous:<?>s1 sp2 Abstract WS (SP2) Abstract WS (SP6) Abstract WS (SP5) Abstract WS (SP1) Abstract BP (SP3) s2 sp6 s3 sp3 s4 SP2_Invoker SP2_Invoker SP2_Invoker SP2_Invoker sp5 s5 sp1 * The decentralized execution is proposed by H. FERNANDEZ, C.TEDESCHI and T.PRIOL, IRISA, Rennes, France 13-15 December 2010 ServiceWave 2010

85. Next:<SP6, SP3>

86. Previous:<SPA>s1 sp2 Abstract WS (SP2) Abstract WS (SP6) Abstract WS (SP5) Abstract WS (SP1) Abstract BP (SP3) s2 sp6 s3 sp3 s4 SP2_Invoker SP2_Invoker SP2_Invoker SP2_Invoker sp5 s5 sp1 13-15 December 2010 ServiceWave 2010

88. Next:<SP1>

89. Previous:<SP2>s1 sp2 Abstract WS (SP2) Abstract WS (SP6) Abstract WS (SP5) Abstract WS (SP1) Abstract BP (SP3) s2 sp6 s3 sp3 s4 SP2_Invoker SP2_Invoker SP2_Invoker SP2_Invoker sp5 s5 sp1 13-15 December 2010 ServiceWave 2010

91. Next:<SPA>

92. Previous:<SP5, SP3>s1 sp2 Abstract WS (SP2) Abstract WS (SP6) Abstract WS (SP5) Abstract WS (SP1) Abstract BP (SP3) s2 sp6 s3 sp3 s4 SP2_Invoker SP2_Invoker SP2_Invoker SP2_Invoker sp5 s5 sp1 13-15 December 2010 ServiceWave 2010

94. Input:s1 sp2 Abstract WS (SP2) Abstract WS (SP6) Abstract BP (SP3) Abstract WS (SP5) Abstract WS (SP1) s2 sp6 s3 sp3 s4 SP2_Invoker SP2_Invoker SP2_Invoker SP2_Invoker sp5 s5 sp1 13-15 December 2010 ServiceWave 2010

96. Input:

97. ID:CWSA001

98. Input:s1 sp2 Abstract WS (SP2) Abstract WS (SP6) Abstract WS (SP5) Abstract WS (SP1) Abstract BP (SP3) s2 sp6 s3 sp3 s4 SP2_Invoker SP2_Invoker SP2_Invoker SP2_Invoker sp5 s5 sp1 13-15 December 2010 ServiceWave 2010

100. Input:s1 sp2 Abstract WS (SP2) Abstract WS (SP6) Abstract WS (SP5) Abstract WS (SP1) Abstract BP (SP3) s2 sp6 s3 sp3 s4 SP2_Invoker SP2_Invoker SP2_Invoker SP2_Invoker sp5 s5 sp1 13-15 December 2010 ServiceWave 2010

102. Input:

103. ID:CWSA001

104. Input:s1 sp2 Abstract WS (SP2) Abstract WS (SP6) Abstract WS (SP5) Abstract WS (SP1) Abstract BP (SP3) s2 sp6 s3 sp3 s4 SP2_Invoker SP2_Invoker SP2_Invoker SP2_Invoker sp5 s5 sp1 13-15 December 2010 ServiceWave 2010

106. Input:s1 sp2 Abstract WS (SP2) Abstract WS (SP6) Abstract WS (SP5) Abstract WS (SP1) Abstract BP (SP3) s2 sp6 s3 sp3 s4 SP2_Invoker SP2_Invoker SP2_Invoker SP2_Invoker sp5 s5 sp1 13-15 December 2010 ServiceWave 2010

107. Implementation 13-15 December 2010 ServiceWave 2010

109. Computation = Chemical Reactions;

110. Computing Resources = Molecules;

111. Control = A Set of Rules;

112. HOCL: Higher Order Chemical Language

113. Multi-set/Solution (what to put in the chemical container);

114. Rules definition

115. Replace … by … if (See the example later on.)13-15 December 2010 ServiceWave 2010

116. 1 16 6 5 9 12 Example: Calculate Maximum Number <1, 6, 16, 5, 9, 12> Multi-set 13-15 December 2010 ServiceWave 2010

117. 1 16 6 5 9 12 Example: Calculate Maximum Number Max letmax = replacex::int, y::intbyxifx >= yin<max, 1, 6, 16, 5, 9, 12> Multi-set 13-15 December 2010 ServiceWave 2010

118. Example: Calculate Maximum Number Max letmax = replacex::int, y::intbyxifx >= yin<max, 1, 6, 16, 5, 9, 12> Multi-set 1 16 6 5 9 12 13-15 December 2010 ServiceWave 2010

119. Example: Calculate Maximum Number Max letmax = replacex::int, y::intbyxifx >= yin<max, 1, 6, 16, 5, 9, 12> Multi-set 16 6 12 13-15 December 2010 ServiceWave 2010

120. Example: Calculate Maximum Number Max letmax = replacex::int, y::intbyxifx >= yin<max, 1, 6, 16, 5, 9, 12> Multi-set 6 16 12 13-15 December 2010 ServiceWave 2010

121. Example: Calculate Maximum Number Max letmax = replacex::int, y::intbyxifx >= yin<max, 1, 6, 16, 5, 9, 12> Multi-set 6 16 13-15 December 2010 ServiceWave 2010

122. Example: Calculate Maximum Number Max letmax = replacex::int, y::intbyxifx >= yin<max, 1, 6, 16, 5, 9, 12> Multi-set 6 16 13-15 December 2010 ServiceWave 2010

123. Example: Calculate Maximum Number Max letmax = replacex::int, y::intbyxifx >= yin<max, 1, 6, 16, 5, 9, 12> Multi-set 16 13-15 December 2010 ServiceWave 2010

125. Dynamic, elements are chosen non-predefined;

126. Reaction rule can do everything: computing, coordinating, fault-handling, etc.

127. Add/Remove Elements

128. User interface: add new element (data as well as reaction rules);

129. Remove the incorrect elements from the multi-set;

130. Reactivate the reaction: when a multi-set reaches the inert state, new elements can reactivate the reaction;

131. Communication

132. Pass the elements/commands to a remote multi-set

133. Either from the user interface or can be performed automatically by reaction rules (once a certain type of element is produced, it will be sent to a specified remote multi-set)13-15 December 2010 ServiceWave 2010

135. Each component is implemented by a multi-set (chemical reaction container);

136. Service related elements can be seen as molecules (a workflow can be seen as a composed molecule);

137. Rules are created to perform different actions

138. Reaction rules operate on the elements (such as workflow definition);

139. Computation can be seen as perpetual motion that never need to stop;

140. Ability to adapt to the dynamic environment;

141. Distributed Implementation

142. Different multi-set can be implemented on different machines;

143. The component works independently and concurrently to the others; 13-15 December 2010 ServiceWave 2010

144. Conclusions & Future Work 13-15 December 2010 ServiceWave 2010

146. Partner services are selected and bound during run-time;

147. The selection process is based on both functional and non-functional requirement over the entire workflow;

148. The execution of workflow is decentralized;

149. Chemical Computing Based Implementation:

150. Each middleware component is implemented by a multi-set as an autonomic system;

151. Capable to adapt to the fast changing execution environment;

152. New elements and rules can be added to the middleware on-demand to meet the new requirements;

153. Distributed implementation: each component is running independently and concurrently to each other;13-15 December 2010 ServiceWave 2010

155. Parallel, conditional, loops, etc.

156. Multiple real QoS constraints:

157. Work on the more realistic QoS constraints (price & execution time)

158. Service Adaptation:

159. Service Monitoring: monitor the execution of a workflow, detect the unpredictable problems (such as node crash etc.);

160. Adaptation process: replace the crashed part with new offers and continue the execution;13-15 December 2010 ServiceWave 2010

161. ICSOC-ServiceWave 2009 Thanks For Your Attention! * The research leading to these results has received funding from the European Community’s Seventh Framework Programme [FP7/2007-2013] under grant agreement 215483 (S-CUBE).