Policy Discovery Functional Profile
Policy discovery allows application developers to find and retrieve policies on services.
While policy and contract descriptions have much of the same architectural implications as described in Service Description, languages and mechanisms supporting policies and contracts also have the following architectural implications:
Policy and Contract language specifications will typically provide support for the following capabilities:
- expression of assertion and commitment policy constraints;
- expression of positive and negative policy constraints;
- expression of permission and obligation policy constraints;
- nesting of policy constraints allowing for abstractions and refinements of a policy constraint;
- definition of alternative policy constraints to allow for the selection of compatible policy constraints for a consumer and provider;
- composition of policies to combine one or more policies.
Policy and contract mechanisms in a SOA ecosystem will require the following capabilities:
- decision procedures which must be able to measure and render decisions on constraints;
- enforcement of decisions;
- measurement and notification of obligation constraints;
- auditability of decisions, enforcement, and obligation measurements;
- administration of policy and contract language artifacts;
- storage of policies and contracts;
- distribution of policies/contracts;
- conflict resolution or elevation of conflicts in policy rules;
- delegation of policy authority to agents acting on behalf of a client;
- decision procedures capable of incorporating roles and/or attributes for rendered decisions.
Policy Discovery has architectural implications on the Semantic Infrastructure:
Policies define conditions of use and optionally contracts representing agreement on policies and other conditions. This requires the following capabilities:
- descriptions to enable the policy modules to be visible, where the description includes a unique identifier for the service and a sufficient, and preferably a machine processible, representation of the meaning of terms used to describe the policy, its functions, and its effects;
- one or more discovery mechanisms that enable searching for policies that best meet the search criteria specified by the service participant; where the discovery mechanism will have access to the individual policy descriptions, possibly through some repository mechanism;
- accessible storage of services and service descriptions, so service participants can access, examine, and use the policies as defined.
Descriptions include references to metrics which describe the operational characteristics of the subjects being described. This requires the following capabilities:
- the infrastructure monitoring and reporting information on SOA resources;
- possible interface requirements to make accessible metrics information generated or most easily accessed by the service itself;
- mechanisms to catalog and enable discovery of which metrics are available for a described resources and information on how these metrics can be accessed;
- mechanisms to catalog and enable discovery of compliance records associated with policies and contracts that are based on these metrics.
Descriptions provide up-to-date information on what a resource is, the conditions for interacting with the resource, and the results of such interactions. As such, the description is the source of vital information in establishing willingness to interact with a resource, reachability to make interaction possible, and compliance with relevant conditions of use. This requires the existence of:
- one or more discovery mechanisms that enable searching for described resources that best meet the criteria specified by a service participant, where the discovery mechanism will have access to individual descriptions, possibly through some repository mechanism;
- tools to appropriately track users of the descriptions and notify them when a new version of the description is available.
This Functional Profile includes, but is not limited to, the following capability elaborations:
Derived From Requirements
- Semantic Infrastructure Requirements::Service Discovery and Governance::Administer Services The use of well defined service metadata promotes better discovery and reuse of services during design and run time. Service metadata includes information about service interactions and dependencies. It also includes a classification scheme for organizing services based on business objectives, domain, and usage. It also links services to all the supporting artifacts in the specification and provides a placeholder for conformance statements. This enables better reuse across the enterprise and eliminates redundancy.
- Semantic Infrastructure Requirements::caGRID 2.0 Platform and Terminology Integration::Policy and Rules Management Policy and Rules Management allow non-developer secondary users to create policies and rules and apply them to services. The scope of policies includes, but is not limited to, definition and configuration of business processing policy and related rules, compliance policies, quality of service policies, and security policies. Some key functional requirements for managing policies include capabilities to author policies and store policies, and to approve and validate policies and execute policies at runtime. The Semantic Infrastructure will provide a mechanism to specify policies, including business processing policies and related rules, compliance policies, and quality of service policies. Tools and services for creating security specific policies will be provided by the caGRID 2.0 platform and will be used by the semantic infrastructure. All other policies specified in the Semantic Infrastructure will be enforced by the platform at runtime. Link to use case satisfied from caGRID 2.0 Roadmap: Each institution has different data sharing needs, access control needs, and business rules for processing that are defined and customized. For example, policy at the pathologist's institution may state that the patient is scheduled for a visit when the review is complete.
- Semantic Infrastructure Requirements::caGRID 2.0 Platform and Terminology Integration::Service Discovery and Utilization This group of requirements focuses on enabling developers of composite services and applications to discover, compose, and invoke services. This includes the discovery of published services based on service metadata and the generation of client APIs in multiple languages to provide cross-platform access to existing services. The platform will use the semantic infrastructure service metadata to address all the service discovery requirements. The semantic infrastructure relies on metadata about services and artifacts. Link to use case satisfied from caGRID 2.0 Roadmap: As institutions share de-identified glioblastoma data sets, they are available to others via data discovery. The treatment recommendation service used by the oncologist is able to discover these new data sets and their corresponding information models, and include that data for subsequent use in recommendation of treatment. Link to use case satisfied from caGRID 2.0 Roadmap: all of the data management and access services in the use case are utilized by application developers to build the user interfaces that the clinicians use during the course of patient care.
- Semantic Infrastructure Requirements::Artifact Management::Specification Content to be done
policiesAndContractsDiscovery
The use of well defined service metadata promotes better discovery and reuse of services during design and run time. Service metadata includes information about service interactions and dependencies. It also includes a classification scheme for organizing services based on business objectives, domain, and usage. It also links services to all the supporting artifacts in the specification and provides a placeholder for conformance statements. This enables better reuse across the enterprise and eliminates redundancy.
Service policies help establish constraints on the service specifications and mandate an approach. Policies can be specified around governance, access control and other design and runtime constraints.
In the realization of policies and contracts for a SOA, there are common policy principles that will be encountered in many of the standards and/or technology choices used for the realization.
Policy Discovery provides the following capabilities
- one or more discovery mechanisms that enable searching for policies that best meet the search criteria specified by the service participant; where the discovery mechanism will have access to the individual policy descriptions through some repository mechanism;
- accessible storage of policy descriptions, so service participants can access, examine, and use the policies as defined.
- access to metrics information about policies obtained from the platform infrastructure monitoring and notification capabilities
- mechanisms to catalog and enable discovery of which metrics are available for a described policy and information on how these metrics can be accessed;
- mechanisms to catalog and enable discovery of compliance records associated with polcies that are based on these metrics.
- one or more mechanisms to capture, describe, store, discover, and retrieve interaction logs, execution contexts, and the combined interaction descriptions;
- one or more mechanisms for attaching to any results the means to identify and retrieve the interaction description under which the results were generated.
- tools to facilitate identifying description elements that are to be aggregated to assemble the composite description;
- tools to facilitate identifying the sources of information to associate with the description elements;
- tools to collect the identified description elements and their associated sources into a standard, referenceable format that can support general access and understanding;
- tools to automatically update the composite policy as the component sources change, and to consistently apply versioning schemes to identify the new description contents and the type and significance of change that occurred.
- tools to appropriately track users of the polcies and notify them when a new version of the policy is available.
