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Thesis Report: Composition and Evaluation of Trustworthy Web Services James S.F. Hsieh, nomad_libral@gmail.com SOA Team, K...
Outline <ul><li>Introduction </li></ul><ul><li>Motivation </li></ul><ul><li>Our Proposed Architecture </li></ul><ul><li>Pa...
Introduction <ul><li>SOA   could   </li></ul><ul><ul><li>seamlessly integrate existing services to  fulfill  dynamic reque...
Motivation (1/2) <ul><li>What is our motivation:  (specify, evolve and  use  trust) </li></ul><ul><li>Important problems a...
Motivation (2/2) <ul><li>Define:  I defined trust between requester and provider is that anything of suitable trustworthy ...
Our Proposed Architecture (1/2) Based on CMU Framework Evaluate trust of a signal web service. Evaluate trust of a composi...
Our Proposed Architecture (2/2)
Part 1: Single Service Trustworthy Evaluation <ul><li>Specifications of Trustworthy   Experience  </li></ul><ul><li>Trustw...
Specifications of Trustworthy Experience  (1/3) Description of trustworthy experience of bookstore services <ul><li>How lo...
Specifications of Trustworthy Experience (2/3) An example of the trustworthy aspect ontology
Specifications of Trustworthy Experience (2/3) Description of an experience instance  for bookstore service   2 Days 3 Hou...
Trustworthy  Requirement M atching Trustworthy requirements are kind of rule based policies that I can utilize to determin...
Requirement Hypothesis and Confidence <ul><li>Requirement Hypothesis  - We can utilize the  ontology instance   to specify...
Part 2: Composite Service Trustworthy Evaluation <ul><li>Composition Confidence  </li></ul><ul><li>Trustworthy Web Service...
<ul><li>In the OWL-S description language, the schedule of a service has control structures which  similar  to the followi...
Trustworthy Web Service Evaluation Petri Net (1/3) <ul><li>We proposed the  Trustworthy Web Service Evaluation Petri Net  ...
Trustworthy Web Service Evaluation Petri Net (2/3) A control flow of a general composite service can be organized by the f...
Trustworthy Web Service Evaluation Petri Net (3/3) For Example: OWL-S Each edge has a  Confidence  value in a Coverability...
Composition Confidence Evaluation (1/2) <ul><li>As we evaluate the  Composite Confidence  of a TWSEPN we must find out the...
Composition Confidence Evaluation (2/2) <ul><li>For Example: The following is a directed graph which  exists cycle. </li><...
Evaluation Algorithm Case 1 [M initial ,   M 1 , M 2 , M 34 , M 34 ’, M 5 , M 67 , M 67 ’, M final  ] Composition Confiden...
Conclusion <ul><li>Trust is one of the most important issues of SOA. The composite web service composes individual  sub-se...
The End Thanks James S.F. Hsieh, nomad_libral@gmail.com SOA Team, KS Lib,  Graduate Institute of Network Learning Technolo...
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2006 05 12 Composition And Evaluation Of Trustworthy Web Services

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2006 05 12 Composition And Evaluation Of Trustworthy Web Services

  1. 1. Thesis Report: Composition and Evaluation of Trustworthy Web Services James S.F. Hsieh, nomad_libral@gmail.com SOA Team, KS Lib, Graduate Institute of Network Learning Technology , National Central University , Taiwan
  2. 2. Outline <ul><li>Introduction </li></ul><ul><li>Motivation </li></ul><ul><li>Our Proposed Architecture </li></ul><ul><li>Part 1: Single Service Trustworthy Evaluation </li></ul><ul><ul><li>Specifications of Trustworthy Experience </li></ul></ul><ul><ul><li>Trustworthy Requirement Matching </li></ul></ul><ul><ul><li>Requirement Hypothesis and Confidence </li></ul></ul><ul><li>Part 2: Composite Service Trustworthy Evaluation </li></ul><ul><ul><li>Composition Confidence </li></ul></ul><ul><ul><li>Trustworthy Web Service Evaluation Petri Net </li></ul></ul><ul><ul><li>Composition Confidence Evaluation </li></ul></ul><ul><ul><li>Evaluation Algorithm </li></ul></ul><ul><li>Conclusion </li></ul><ul><li>References </li></ul>
  3. 3. Introduction <ul><li>SOA could </li></ul><ul><ul><li>seamlessly integrate existing services to fulfill dynamic requests in distributed platforms and </li></ul></ul><ul><ul><li>promise that service providers will offer the functionality to service requesters without exposing details of provided services. </li></ul></ul><ul><li>The web service exists a big problem : trustworthiness problem. </li></ul><ul><li>The trustworthiness solution was separated into following: </li></ul><ul><li>Infrastructure </li></ul><ul><ul><li>For example: XML Signature, XML Encryption, and P3P projects…(W3C) </li></ul></ul><ul><li>Understanding </li></ul><ul><ul><li>Abstract Behavior Model </li></ul></ul><ul><ul><li>Past Experiences Analysis </li></ul></ul><ul><li> For example: Rating Service, Reputation Mechanism, and Referral Network… </li></ul><ul><li>Policy </li></ul>
  4. 4. Motivation (1/2) <ul><li>What is our motivation: (specify, evolve and use trust) </li></ul><ul><li>Important problems are </li></ul><ul><ul><li>how do we utilize past experiences to evaluate a service and </li></ul></ul><ul><ul><li>how to utilize past experiences to compose a composite web service from a lot of sub-services. (dynamic composite) </li></ul></ul><ul><li>We will solve the following problems: </li></ul><ul><li>How do we evaluate trust of a signal web service (atomic service or simple service)? The evaluation should be a formal method. </li></ul><ul><li>How do we consider structure of a composite web service while we evaluate trust of it? We need a formal model to specify the structure. </li></ul>
  5. 5. Motivation (2/2) <ul><li>Define: I defined trust between requester and provider is that anything of suitable trustworthy requirement which be defined formally and specifically by service requester and be measured objectively and quantitatively by agreed suitable third-party is performed completely by service provider . </li></ul><ul><li>Expectation-phase </li></ul><ul><li>Contract-phase </li></ul>Expectation-phase Contract-phase
  6. 6. Our Proposed Architecture (1/2) Based on CMU Framework Evaluate trust of a signal web service. Evaluate trust of a composite web servi ce.
  7. 7. Our Proposed Architecture (2/2)
  8. 8. Part 1: Single Service Trustworthy Evaluation <ul><li>Specifications of Trustworthy Experience </li></ul><ul><li>Trustworthy Requirement Matching </li></ul><ul><li>Requirement Hypothesis and Confidence </li></ul>
  9. 9. Specifications of Trustworthy Experience (1/3) Description of trustworthy experience of bookstore services <ul><li>How long will it take to deliver the requested book in this service? </li></ul><ul><li>Does the book have been damaged during delivery in this service? </li></ul><ul><li>What is the list price of the requested book in this service? </li></ul>Bookstore Selling Domain aspect <ul><li>Does the service use RSA technology? </li></ul><ul><li>Does the service use DES technology? </li></ul>Security <ul><li>What is the response time of service in this service? </li></ul><ul><li>What is the turnaround time of service in this service? </li></ul><ul><li>What is the packet miss rate of service in this service? </li></ul>Network performance Non-Functional <ul><li>Does requester’s goal regarding this service request has been fulfilled? </li></ul>Functional General aspect
  10. 10. Specifications of Trustworthy Experience (2/3) An example of the trustworthy aspect ontology
  11. 11. Specifications of Trustworthy Experience (2/3) Description of an experience instance for bookstore service 2 Days 3 Hours False $ 53.5 Book delivery time Damage Price Bookstore True True RSA technology DES technology Security 510 ms 2100 ms 1.5 % Response time Turnaround time Packet miss rate Network performance True Reach Functional Value Property Aspect
  12. 12. Trustworthy Requirement M atching Trustworthy requirements are kind of rule based policies that I can utilize to determine whether described trustworthy experiences are acceptable and meet service requester’s trustworthy requirement. Trustworthy requirements are similar to sentences appeared in propositional logic. 0
  13. 13. Requirement Hypothesis and Confidence <ul><li>Requirement Hypothesis - We can utilize the ontology instance to specify a trust requirement of a requester. </li></ul><ul><li>Confidence - We utilize “Large-Sample of Hypothesis for a Binomial Proportion” to evaluate the simple error and true error of the hypothesis. </li></ul>, ,
  14. 14. Part 2: Composite Service Trustworthy Evaluation <ul><li>Composition Confidence </li></ul><ul><li>Trustworthy Web Service Evaluation Petri Net </li></ul><ul><li>Composition Confidence Evaluation </li></ul><ul><li>Evaluation Algorithm </li></ul>
  15. 15. <ul><li>In the OWL-S description language, the schedule of a service has control structures which similar to the following structures . We can compose separate Confidence to a Composition Confidence. </li></ul><ul><li>Composition Confidence </li></ul>Composition Confidence Sub-service 1 Sub-service 2 confidence 1 confidence 2 Sequence Pattern Concurrent Pattern confidence of the composite service = confidence 1 × confidence 1 Sub-service 1 Sub-service 2 confidence 1 confidence 2 Switch and IF-Then-Else Pattern Sub-service 1 Sub-service 2 confidence 1 confidence 2 confidence of the composite service = min{ confidence 1 , confidence 1 }
  16. 16. Trustworthy Web Service Evaluation Petri Net (1/3) <ul><li>We proposed the Trustworthy Web Service Evaluation Petri Net to specify structure of a OWL-S in following. </li></ul><ul><li>is a finite set of places, each place represents a control-structure. </li></ul><ul><li>is a finite set of transitions, each transition represents a sub-service. </li></ul><ul><li>is a finite set of transitions, each transition represents a schedule-control. </li></ul><ul><li>is a set of arcs, each arc represent the control flow between sub-service. </li></ul><ul><li>is a set of all sub-services. </li></ul><ul><li>is a mapping function, it maps the transitions of the Petri nets to the sub-services of a composite web service. </li></ul><ul><li>is a mapping function, it maps the sub-services to these confidences, and we can use the Requirement Hypothesis to compute the of sub-services </li></ul>
  17. 17. Trustworthy Web Service Evaluation Petri Net (2/3) A control flow of a general composite service can be organized by the following control patterns .
  18. 18. Trustworthy Web Service Evaluation Petri Net (3/3) For Example: OWL-S Each edge has a Confidence value in a Coverability Graph. The Coverability Graph is a special case of the Markov Process. <process:CompositeProcess rdf:ID=&quot;CompositionService&quot;> <process:composedOf> <process:If-Then-Else> <process:ifCondition>…</process:ifCondition> <process:then>… <process:AtomicProcess rdf:about=&quot;#Ser1&quot;/> </process:then> <process:else>… <process:SplitJoin>… <process:AtomicProcess rdf:about=&quot;#Ser2&quot;/> <process:Repeat-Until> <process:untilCondition>…</process:untilCondition> <process:untilProcess>… <process:AtomicProcess rdf:about=&quot;# Ser3&quot;/> </process:untilProcess> </process:Repeat-Until> </process:SplitJoin> </process:else> </process:If-Then-Else> </process:composedOf> </process:CompositeProcess>
  19. 19. Composition Confidence Evaluation (1/2) <ul><li>As we evaluate the Composite Confidence of a TWSEPN we must find out the minimum confidence product of the firing sequences between the M initial and M final the in the Coverability Graph. </li></ul><ul><li>Case 1: If coverability graph is a directed acyclic graph, </li></ul><ul><li>we propose a algorithm which is based on the AOE and the BFS to calculate the Composite Confidence. </li></ul><ul><li>Case 2: Otherwise, we find the Strongly Connected Components out, and we compress that into two vertexes and one edge so the directed graph can be converted to a DAG (Case 1). </li></ul>
  20. 20. Composition Confidence Evaluation (2/2) <ul><li>For Example: The following is a directed graph which exists cycle. </li></ul>Case 2 Case 1 SCC Compress the cycle into case 1.
  21. 21. Evaluation Algorithm Case 1 [M initial , M 1 , M 2 , M 34 , M 34 ’, M 5 , M 67 , M 67 ’, M final ] Composition Confidence = min{a, b × c δ } Step 1 [1, 1, 1, 1, 1, 1, 1, 1, a] 1 Step 2 [1, 1, 1, 1, 1, 1, 1, 1, a] 2 3 Step 3 [1, 1, b, 1, 1, 1, 1, 1, a] 4 Step 4 [1, 1, b, b, 1, 1, 1, 1, a] 5 Step 5 [1, 1, b, b, 1, 1, c δ , 1, a] 6 Step 6 [1, 1, b, b, b ×c δ , 1, c δ , 1, a] 7 Step 7 [1, 1, b, b, b ×c δ , 1, b×c δ , 1, a] 8 Step 8 [1, 1, b, b, b ×c δ , 1, b×c δ , 1, a] 9 Step 9 [1, 1, b, b, b ×c δ , 1, b×c δ , 1, min{a, b×c δ }]
  22. 22. Conclusion <ul><li>Trust is one of the most important issues of SOA. The composite web service composes individual sub-services to reach requester‘s objective. Our proposition bases on the understanding which is nature of trust, to analyze the past experience. </li></ul><ul><ul><li>The Inquiry module use statistics to evaluate the Confidence of the individual sub-service according to the trust requirement. </li></ul></ul><ul><ul><li>The Evaluate module use TWSEPN to model the schedule of the Composite Web Service, and it analyzes Coverability Graph which is deduced from TWSEPN to evaluate the Composite Confidence . </li></ul></ul><ul><ul><li>In the last, the Choice module import policies to decide the best plan and the best schedule of the composite web service and perform that. </li></ul></ul>
  23. 23. The End Thanks James S.F. Hsieh, nomad_libral@gmail.com SOA Team, KS Lib, Graduate Institute of Network Learning Technology , National Central University , Taiwan

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