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Constraints and Capabilities Workshop Oracle Position Ashok Malhotra Greg Pavlik

Constraints and Capabilities Workshop Oracle Position Ashok Malhotra Greg Pavlik. Background. Position based on lessons learned: Product implementation experiences. Work on WSDL 2.0 Features and Properties, WS-Reliability as well as WS-Policy.

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Constraints and Capabilities Workshop Oracle Position Ashok Malhotra Greg Pavlik

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  1. Constraints and Capabilities Workshop Oracle Position Ashok Malhotra Greg Pavlik

  2. Background • Position based on lessons learned: • Product implementation experiences. • Work on WSDL 2.0 Features and Properties, WS-Reliability as well as WS-Policy. • While we agree that a declarative, assertion-based design is desirable, we think F&P and WS-Policy have shortcomings. WS-Policy allows composition of assertions from different domains. F&P needs compositors.

  3. Summary • A policy is a collection of domain expressions. • Domain functionality cannot be combined. • Two distinct varieties of domains that must be treated differently: • Domains that influence message content. • Domains that convey information about the service.

  4. Domains • A domain is an orthogonal axis of functionality. • A policy is a collection of independent domain expressions. • Functionality for a domain is expressed using domain-specific formalisms and syntax.

  5. Domain Dichotomy • Two kinds of domains… • Some domains influence message content (headers and bodies). • e.g. Security, Reliability • Other domains convey information about the service and may be in various ways e.g. used to decide whether to use the service. • Privacy (P3P) • Auditing/Logging

  6. Domains that Influence Message Content • For example: security, reliability, transactions. • Functionality expressed as assertions connected by operators (compositors) such as all, choice, exactlyOne. • Client and server must agree on/select message policy. • Domain functionality may be ‘required’ or ‘supported’.

  7. Domains that Influence Message Content (continued) • Client is configured or generated to conform to selected policy alternative. • Messages need to indicate which policy alternative is followed. • Server verifies that policy is adhered to.

  8. Informational Domains • Informational assertions do not affect message content. They convey information about the service that may be used in several ways. • Informational domains are not ‘required’ or ‘supported’. • In some cases the client may insist that some advertised policy be enforced and may verify this.

  9. Informational Domains • Several service characteristics may influence whether a client will use a policy or not: e.g. legal contract, privacy policy. • Decision could be made by man (lawyer reads legal contract) or machine (EPAL, WSPL). • Such characteristics could be used as part of the service discovery process.

  10. Policy Attachment and Access • The policy may be associated with a service in several different ways: attached to WSDL, UDDI, RDDL, WSIL, etc. • Several policies may apply to a service. • Policies may be managed as documents in a document library with change control etc. • Need a standard mechanism to: • Access the entire policy for a service endpoint. • Access the policy details for a particular domain. • This mechanism would return a policy that may be composed of policy fragments from several related sources.

  11. Policy Attachment and Access • Policies will evolve and may change during a conversation. • Messages should identify the policy they adhere to and if the policy changes during the conversation a fault should be signaled.

  12. Recapitulation • A policy is a collection of domain expressions. • A domain’s functionality is described (and combined) using a domain-specific formalism. • Functionality for different domains cannot be combined. • Domains that influence message content and domains that provide information about the service are fundamentally different and must be treated differently.

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