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AMPol-Q : A daptive M iddleware Pol icy to support Q oS

AMPol-Q : A daptive M iddleware Pol icy to support Q oS. Raja Afandi , Jianqing Zhang, Carl A. Gunter Computer Science Department, University of Illinois Urbana-Champaign. QoS Based Discovery. Services are discovered and selected on the basis of functional properties (IOPE)

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AMPol-Q : A daptive M iddleware Pol icy to support Q oS

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  1. AMPol-Q: Adaptive Middleware Policy to support QoS Raja Afandi, Jianqing Zhang, Carl A. Gunter Computer Science Department, University of Illinois Urbana-Champaign

  2. QoS Based Discovery • Services are discovered and selected on the basis of functional properties (IOPE) • Difficult to discover and compose services on the basis of non-functional features (QoS) • Complex to model QoS features • Global nature of QoS • QoS composition requires complex calculations of aggregate and global QoS values

  3. Global QoS • Client policies constraining Service A & B • Message Sender requires the message to be confidential • Business client needs its loan request to be processed with in a week • End service policies constraining Client • Bank requires applicant credit score to be fair • RMTA requires that a message from a sender must not be greater than 10KB • Global QoS • End-to-End QoS • Two-way QoS constraints Service A Service B Client • Client & Service A • Sender MUA and SMTA • Business Client and Loan Agency • Service A & Service B • SMTA and RMTA • Loan Agency & Bank

  4. Global QoS: Discovery • Discovery approaches: • Limited to discovering first-level immediate services • Each individual service is responsible for discovering other services independently • Global QoS evaluation requires global information of all the entities (Global View) Service B3 ? Service A Service B2 Client Service B1

  5. QoS Policies • Supporting QoS also requires monitoring and enforcing QoS behavior and policies • Support for non-functional features such as security and reliability breaks the interoperability of the system • Diverse Policies • Constraints may change

  6. Main Objectives… • Global QoS and dynamic discovery • QoS Policies and Interoperability

  7. Strategy • End-to-End (E2E) integrated approach • Description: Semantic modeling of QoS capabilities and constraints (policy rules) • Global Discovery: Global service discovery and QoS analysis • Distribute Monitoring: Semantic model and distributed enforcement • Two-Way-Specialization: entities can dynamically adapt to the advertised requirements of each other • Basic architecture based on three frameworks • Description framework defines QoS model and describes declarative domain-specific policy rules • Discovery framework governs how to publish, find, and select services on the basis of QoS • Monitoring framework provides means to adhere to and enforce published QoS requirements and constraints

  8. Case Study: Messaging System • WSEmail • Internet messaging based on web services SS RS SS: Sender Mail Server RS: Recipient Mail Server SC RC

  9. Description Framework • Includes semantic models for describing QoS capabilities, constraints and requirements of different entities in the system: • QoS Model • Policy Model • Entity Profile Model • Messaging Domain Model

  10. Description Framework: QoS Model APES QoS Domain Ontology QoS Base Ontology QoS Monitoring Ontology

  11. Description Framework : Policy Model • Semantic language of constraints and requirements • Rules are defined using QoS ontology and SWRL rule format: ampol:Encryption(?a) ∧ ampol:algoType(?a, ?b) ∧ ampol:stringValue(?b, "IBE2.3") → ampol:verified(RC_Enc_Rule1, true) ampol:Attachment(?a) ∧ ampol:attachmentSize(?a, ?b) ∧ ampol:intValue(?b, ?c) ∧ swrlb:lessThanOrEqual(?c, 1000) ∧ ampol:unit(?b, "KB") → ampol:verified(RS_Att_Rule1, true) • Supports • Delegation of policy enforcement • Rule prioritization to resolve conflicts • Public vs. private rules

  12. Description Framework : Policy Model

  13. Description Framework : Entity Profile Model • Type of service description profile • Associated with a system entity and can be advertised with OWL-S service profile • Profiles represent entity : • Domain vocabulary • Capabilities • Constraints • Extension constraints • Service dependencies • OWL-S request templates • Clients uses it to discover desired services • Supports global discovery better than current approaches (based on pure OWL-S, UDDI and IOPE) Sample Entity Profile Sample Service Request Sample Service Profile

  14. Discovery Framework • Discover global QoS information about all the candidate services • Select best matched services • Binding selected parties in a QoS contract • Consist of three components: • Service Discovery and Chaining • Global QoS Analysis • Policy Agreement and Contract Negotiation

  15. Discovery: Service Chain Graph Request Template Request Template B CR Dependency List Dependency List CR Request Template Dependency List Dependency List

  16. Global QoS Analysis CB1 CB1 FL1 FB1 FCR1 FC1 C1 L1 B1 CR1 RC1 RC1 RC1 RC1 CB1  FC1 R = Requirements C = Constraints F = Capabilities E = Extension Capabilities EP = Extension Policy CB1  E EPC1 Agreement  Agreement Value No Agreement  Penalty

  17. Monitoring Framework • Monitoring involves measuring delivered QoS, verifying QoS constraints and taking enforcement actions • QoS feature is associated with Monitoring Processes: • Measurement • Enforcement • Adherence • Policy Framework control the system QoS policies • Adapts by adding or replacing pluggable components • Policy conformance and enforcement logic as extensions • Generic enough to process any complex constraints • Monitoring processes are implemented as pluggable extensions • Extension Manager • Policies control the download and execution of extensions • Download plug-ins from secure third-party plug-in server

  18. AMPol-Q Middleware

  19. AMPol-Q Middleware Implementation

  20. Case Study: Policy Based WSEmail • WSEmail: Web services based Internet messaging • Integrated AMPol-Q middleware with WSEmail • Transparent Integration • Implemented APES features: • Payment as Puzzle • Hashcash • RTT • Encryption using Identity-Based Encryption (IBE)

  21. Case Study: Overview Server Ingress Policies • HashCash Puzzle RMTA (RS) Sandy SMTA (SS) Gary Server Egress Policies • Attachment Size Entity Profiles Registry Server Client Ingress Policies • IBE Encryption Recipient MUA (RC) afandisandy@sandy Sender MUA (SC) afandigary@gary Plugin Server

  22. AMPol-Q Contributions • End-to-end solution for supporting non-functional constraints, capabilities & requirements • Comprehensive semantic QoS Model • Global service discovery and global QoS analysis • Adaptive policy framework for QoS monitoring • Reference architecture for adaptive middleware for messaging systems • Validation of proposed approach through a case study on WSEmail • One of the most complete studies to date of a proof-of-concept QoS-aware policy system based on Web services

  23. Current and Future Work • Formal security analysis and Improved security measures • Policy conflict resolution and models for negotiation • Performance testing • Inter-Ontology relationship for heterogeneous ontologies

  24. Questions… • Thanks…

  25. Discovery: Sample Merged Policy SC adherence policy SC Enforcement policy SS Enforcement policy RS Enforcement policy Delegated Rules RC Enforcement policy

  26. Query Matching • Service query matching constraints

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