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diff --git a/docs/architecture/architecture.rst b/docs/architecture/architecture.rst index e0b40489..b1c66d16 100644 --- a/docs/architecture/architecture.rst +++ b/docs/architecture/architecture.rst @@ -4,7 +4,7 @@ Architecture ------------- +############ Abstract @@ -17,15 +17,15 @@ provide examples that illustrate how to write, deploy, and run policies of various types using the framework. .. contents:: - :depth: 4 + :depth: 6 -1. Overview +1. Overview =========== The ONAP Policy Framework is a comprehensive policy design, deployment, and execution environment. The Policy Framework is the decision making component in `an ONAP -system <https://www.onap.org/wp-content/uploads/sites/20/2017/12/ONAP_CaseSolution_Architecture_120817_FNL.pdf>`__. +system <https://www.onap.org/wp-content/uploads/sites/20/2018/11/ONAP_CaseSolution_Architecture_112918FNL.pdf>`__. It allows you to specify, deploy, and execute the governance of the features and functions in your ONAP system, be they closed loop, orchestration, or more traditional open loop use case implementations. @@ -123,7 +123,7 @@ all policies running in an ONAP installation. The diagram below shows the architecture of the ONAP Policy Framework at its highest level. -.. image:: highest.png +.. image:: images/highest.png The *PolicyDevelopment* component implements the functionality for development of policy types and policies. *PolicyAdministration* is @@ -136,10 +136,10 @@ correctly, and that the state and status of policies is monitored. *PolicyExecution* is the set of PDPs running in the ONAP system and is responsible for making policy decisions and for managing the administrative state of the PDPs as directed -by \ *PolicyAdministration.* +by \ *PolicyAdministration.* *PolicyDevelopment* creates policy artifacts and supporting information -in the policy database. \ *PolicyAdministration* reads those artifacts +in the policy database. \ *PolicyAdministration* reads those artifacts and the supporting information from the policy database whilst deploying policy artifacts. Once the policy artifacts are deployed, *PolicyAdministration* handles the run-time management of the PDPs on @@ -152,7 +152,7 @@ The diagram below shows a more detailed view of the architecture, as inspired by `RFC-2753 <https://tools.ietf.org/html/rfc2753>`__ and `RFC-3198 <https://tools.ietf.org/html/rfc3198>`__. -.. image:: detailed.png +.. image:: images/detailed.png *PolicyDevelopment* provides a `CRUD <https://en.wikipedia.org/wiki/Create,_read,_update_and_delete>`__ @@ -192,7 +192,7 @@ asynchronous messaging over DMaaP. *PolicyExecution* is the set of running PDPs that are executing policies, logically partitioned into PDP groups and subgroups. -.. image:: execution.png +.. image:: images/execution.png The figure above shows how *PolicyExecution* looks at run time with PDPs running in Kubernetes. A *PDPGroup* is a purely logical construct that @@ -202,7 +202,7 @@ running the same policies. *A PDPSubGroup* is deployed as a Kubernetes `Deployment <https://kubernetes.io/docs/concepts/workloads/controllers/deployment/>`__. PDPs are defined as Kubernetes `Pods <https://kubernetes.io/docs/concepts/workloads/pods/pod/>`__. At -run time, the actual number of PDPs in each *PDPSubGroup* is specified +run time, the actual number of PDPs in each *PDPSubGroup* is specified in the configuration of the *Deployment* of that *PDPSubGroup* in Kubernetes. This structuring of PDPs is required because, in order to simplify deployment and scaling of PDPs in Kubernetes, we gather all the @@ -236,12 +236,12 @@ concepts in the Policy Framework. This model is implemented as a common model and is used by *PolicyDevelopment*, *PolicyDeployment,* and *PolicyExecution.* -.. image:: objectmodel1.png +.. image:: images/objectmodel1.png The UML class diagram above shows the portion of the Policy Framework Object Model that applies to *PolicyDeployment* and *PolicyExecution.* -.. image:: objectmodel2.png +.. image:: images/objectmodel2.png The UML class diagram above shows the portion of the Policy Framework Object Model that applies to *PolicyDevelopment* and *PolicyDeployment.* @@ -262,7 +262,7 @@ OOF placement Models, DCAE microservice models. Policy type implementation development is done by an experienced developer. 2.2.1 Policy Type Design -~~~~~~~~~~~~~~~~~~~~~~~~ +^^^^^^^^^^^^^^^^^^^^^^^^ Policy Type Design is the task of creating policy types that capture the generic and vendor independent aspects of a policy for a particular @@ -271,7 +271,7 @@ information, rules, and tasks that a policy type requires to generate concrete policies. All policy types must implement the ONAP Policy Framework *PolicyType* -interface. This interface allows \ *PolicyDevelopment* to manage policy +interface. This interface allows \ *PolicyDevelopment* to manage policy types and to generate policies from these policy types in a uniform way regardless of the domain that the policy type is addressing or the PDP technology that will execute the policy. The interface is used by @@ -279,12 +279,12 @@ technology that will execute the policy. The interface is used by the structure, type, and definition of the model information that must be supplied to the policy type to generate a concrete policy. -A \ *PolicyTypeImpl* is developed for a certain type of PDP (for example +A \ *PolicyTypeImpl* is developed for a certain type of PDP (for example XACML oriented for decision policies or Drools rules oriented for ECA policies). The design environment and tool chain for a policy type is specific for the type of policy being designed. -The \ *PolicyTypeImpl* implementation (or raw policy) is the +The \ *PolicyTypeImpl* implementation (or raw policy) is the specification of the specific rules or tasks, the flow of the policy, its internal states and data structures and other relevant information. A *PolicyTyp*\ e\ *Impl* is specific to a PDP technology, that is XACML, @@ -299,19 +299,19 @@ which allows other components to query policy types and policy type implementations, to determine the model information, rules, or tasks that they require, to specialize policy flow, and to generate policies from policy types. This API is used by the ONAP Policy Framework and -other components such as \ *PolicyDistribution* to create policies from +other components such as \ *PolicyDistribution* to create policies from policy types. Consider a policy type created for managing faults on vCPE equipment in a vendor independent way. The policy type captures the generic logic required to manage the faults and specifies the vendor specific information that must be supplied to the type for specific vendor vCPE -VFs. The actual vCPE policy that is used for managing particular vCPE +VFs. The actual vCPE policy that is used for managing particular vCPE equipment is created by setting the parameters specified in the policy type together with the specific modeled information, rules and tasks in the policy type implementation for that vendor model of vCPE. -2.2.1 Generating Policy Types +2.2.2 Generating Policy Types ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ It is possible to generate policy types using MDD (Model Driven @@ -333,8 +333,8 @@ via the DCAE-DS (DCAE Design Studio). The GUI implementation in another ONAP component such as SDC DCAE-DS uses the *API_User* API to create and edit ONAP policy types. -2.2.1.2 Programming Policy Type Implementations -^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ +2.2.1.1 Programming Policy Type Implementations +""""""""""""""""""""""""""""""""""""""""""""""" For skilled developers, the most straightforward way to create a policy type is to program it. Programming a policy type might simply mean @@ -347,31 +347,31 @@ of implementation, a Policy Type Implementation SDK. The project is under source control in git. This Eclipse project is structured correctly for creating implementations for a specific type of PDP. It includes the correct POM files for generating the policy type -implementation and has editors and perspectives that aid programmers in +implementation and has editors and perspectives that aid programmers in their work 2.2.2 Policy Design -~~~~~~~~~~~~~~~~~~~ +^^^^^^^^^^^^^^^^^^^ The *PolicyCreation* function of *PolicyDevelopment* creates policies -from a policy type. The information expressed during policy type design +from a policy type. The information expressed during policy type design is used to parameterize a policy type to create an executable policy. A service designer and/or operations team can use tooling that reads the TOSCA Policy Type specifications to express and capture a policy at its highest abstraction level. Alternatively, the parameter for the policy can be expressed in a raw JSON or YAML file and posted over the policy -design API described on the `Model driven Control Loop +design API described on the `Model driven Control Loop Design <file://localhost/display/DW/Model+driven+Control+Loop+Design>`__ page. -A number of mechanisms for policy creation are supported in ONAP. The +A number of mechanisms for policy creation are supported in ONAP. The process in *PolicyDevelopment* for creating a policy is the same for all mechanisms. The most general mechanism for creating a policy is using the RESTful *Policy Design API*, which provides a full interface to the policy creation support of *PolicyDevelopment*. This API may be -exercised directly using utilities such as *curl*. \ *PolicyDevelopment* +exercised directly using utilities such as *curl*. \ *PolicyDevelopment* provides a command line tool that is a loose wrapper around the API. It -also provides a general purpose Policy GUI in the ONAP Portal for policy +also provides a general purpose Policy GUI in the ONAP Portal for policy creation, which again is a general purpose wrapper around the policy creation API. The Policy GUI can interpret any TOSCA Model ingested and flexibly presents a GUI for a user to create policies from. The @@ -388,7 +388,7 @@ The following subsections outline the mechanisms for policy creation and modification supported by the ONAP Policy Framework. 2.2.2.1 Policy Design in the ONAP Policy Framework -^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ +"""""""""""""""""""""""""""""""""""""""""""""""""" Policy creation in *PolicyDevelopment* follows the general sequence shown in the sequence diagram below. An *API_USER* is any component that @@ -398,26 +398,26 @@ command line tool and general purpose client that wraps the API. A *PolicyDevAPIUser* first gets a reference to and the metadata for the Policy type for the policy they want to work on from -*PolicyDevelopment*. \ *PolicyDevelopment* reads the metadata and +*PolicyDevelopment*. \ *PolicyDevelopment* reads the metadata and artifact for the policy type from the database. The *API_User* then asks -for a reference and the metadata for the policy. \ *PolicyDevelopment* +for a reference and the metadata for the policy. \ *PolicyDevelopment* looks up the policy in the database. If the policy already -exists, \ *PolicyDevelopment* reads the artifact and returns the -reference of the existing policy to the \ *PolicyDevAPIUser* with the +exists, \ *PolicyDevelopment* reads the artifact and returns the +reference of the existing policy to the \ *PolicyDevAPIUser* with the metadata for the existing policy. If the policy does not -exist, \ *PolicyDevelopment* creates and new reference and metadata and -returns that to the \ *API_User*. +exist, \ *PolicyDevelopment* creates and new reference and metadata and +returns that to the \ *API_User*. -The \ *PolicyDevAPIUser* may now proceed with a policy specification +The \ *PolicyDevAPIUser* may now proceed with a policy specification session, where the parameters are set for the policy using the policy -type specification. Once the \ *PolicyDevAPIUser* is happy that the +type specification. Once the \ *PolicyDevAPIUser* is happy that the policy is completely and correctly specified, it -requests \ *PolicyDevelopment* to create the -policy. \ *PolicyDevelopment* creates the policy, stores the created +requests \ *PolicyDevelopment* to create the +policy. \ *PolicyDevelopment* creates the policy, stores the created policy artifact and its metadata in the database. 2.2.2.2 Model Driven VF (Virtual Function) Policy Design via VNF SDK Packaging -^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ +"""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""""" VF vendors express policies such as SLA, Licenses, hardware placement, run-time metric suggestions, etc. These details are captured within the @@ -434,7 +434,7 @@ parameters to create a policy are read from a TOSCA Policy specification read from a CSAR received from SDC. *PolicyDesign* uses the *PolicyDistribution* component for managing -SDC-triggered policy creation and update requests. *PolicyDistribution* +SDC-triggered policy creation and update requests. *PolicyDistribution* is an *API_User*, it uses the Policy Design API for policy creation and update. It reads the information it needs to populate the policy type from a TOSCA specification in a CSAR received from SDC and then uses @@ -445,16 +445,16 @@ also provides a TOSCA parser. See `Policy Platform - SDC Service Distribution Software Architecture <file://localhost/display/DW/Policy+Platform+-+SDC+Service+Distribution+Software+Architecture>`__ -In Step 4 above, the \ *PolicyDesign* must download the CSAR file. If +In Step 4 above, the \ *PolicyDesign* must download the CSAR file. If the policy is to be composed from the TOSCA definition, it must also parse the TOSCA definition. -In Step 9 above, the \ *PolicyDesign* must send back/publish status +In Step 9 above, the \ *PolicyDesign* must send back/publish status events to SDC such as DOWNLOAD_OK, DOWNLOAD_ERROR, DEPLOY_OK, DEPLOY_ERROR, NOTIFIED. -2.2.2.4 Scripted Model Driven Policy Design -^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ +2.2.2.3 Scripted Model Driven Policy Design +""""""""""""""""""""""""""""""""""""""""""" Service policies such as optimization and placement policies can be specified as a TOSCA Policy at design time. These policies use a TOSCA @@ -469,7 +469,7 @@ the parameters of the directive to create a TOSCA Policy. It then uses the Policy API to create the policy. 2.2.3 Policy Design Process -~~~~~~~~~~~~~~~~~~~~~~~~~~~ +^^^^^^^^^^^^^^^^^^^^^^^^^^^ All policy types must be certified as being fit for deployment prior to run time deployment. In the case of design-time via the SDC application, @@ -520,7 +520,7 @@ page, where the mechanisms for PDP Deployment and Registration with PAP are explained. 2.3.1 Policy Framework Services -~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ The ONAP Policy Framework follows the architectural approach for micro services recommended by the `ONAP Architecture @@ -529,7 +529,7 @@ Subcommittee <https://wiki.onap.org/display/DW/Architecture+Subcommittee>`__. The ONAP Policy Framework defines `Kubernetes Services <https://kubernetes.io/docs/concepts/services-networking/service/>`__ to manage the life cycle of Policy Framework executable components at -runtime. A Kubernetes service allows, among other parameters, the +runtime. A Kubernetes service allows, among other parameters, the number of instances (pods in Kubernetes terminology) that should be deployed for a particular service to be specified and a common endpoint for that service to be defined. Once the service is started in @@ -572,7 +572,7 @@ groups in the system. There are multiple PDP services, one PDP service for each domain for which there are policies. 2.3.2 The Policy Framework Information Structure -~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ The following diagram captures the relationship between Policy Framework concepts at run time. @@ -591,31 +591,31 @@ Framework database and is administered by the PAP service. The diagram above gives an indicative structure of the run time topology information in the Policy Framework database. Note that -the \ *PDP_SUBGROUP_STATE* and \ *PDP_STATE* fields hold state +the \ *PDP_SUBGROUP_STATE* and \ *PDP_STATE* fields hold state information for life cycle management of PDP groups and PDPs. 2.3.3 Startup, Shutdown and Restart -~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ This section describes the interactions between Policy Framework components themselves and with other ONAP components at startup, shutdown and restart. 2.3.3.1 PAP Startup and Shutdown -^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ +"""""""""""""""""""""""""""""""" The sequence diagram below shows the actions of the PAP at startup. The PAP is the run time point of coordination for the ONAP Policy Framework. When it is started, it initializes itself using data from the -database. It then waits for periodic PDP status updates and for +database. It then waits for periodic PDP status updates and for administration requests. PAP shutdown is trivial. On receipt or a shutdown request, the PAP completes or aborts any ongoing operations and shuts down gracefully. 2.3.3.2 PDP Startup and Shutdown -^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ +"""""""""""""""""""""""""""""""" The sequence diagram below shows the actions of the PDP at startup. See also Section 4 of the `Policy Design and API Flow for Model Driven @@ -623,7 +623,7 @@ Control Loop <file://localhost/display/DW/Policy+Design+and+API+Flow+for+Model+Driven+Control+Loop>`__ page for the API used to implement this sequence. -At startup, the PDP initializes itself. At this point it is in PASSIVE +At startup, the PDP initializes itself. At this point it is in PASSIVE mode. The PDP begins sending periodic Status messages to the PAP. The first Status message initializes the process of loading the correct @@ -633,7 +633,7 @@ On receipt or a shutdown request, the PDP completes or aborts any ongoing policy executions and shuts down gracefully. 2.3.4 Policy Execution -~~~~~~~~~~~~~~~~~~~~~~ +^^^^^^^^^^^^^^^^^^^^^^ Policy execution is the execution of a policy in a PDP. Policy enforcement occurs in the component that receives a policy decision. @@ -661,7 +661,7 @@ TEST MODE Policy execution proceeds and changes to domain and state are ================== =========================================================================================================================================================================================================================================================================================================================== 2.3.5 Policy Lifecycle Management -~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Policy lifecycle management manages the deployment and life cycle of policies in PDP groups at run time. Policy sets can be deploy at run @@ -669,7 +669,7 @@ time without restarting PDPs or stopping policy execution. PDPs preserve state for minor/patch version upgrades and rollbacks. 2.3.5.1 Load/Update Policies on PDP -^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ +""""""""""""""""""""""""""""""""""" The sequence diagram below shows how policies are loaded or updated on a PDP. @@ -696,7 +696,7 @@ cycle mode that has been specified for it (ACTIVE/SAFE/TEST). The PDP beings to execute policies in the specified mode (see section 2.3.4). 2.3.5.2 Policy Rollout -^^^^^^^^^^^^^^^^^^^^^^ +"""""""""""""""""""""" A policy set steps through a number of life cycle modes when it is rolled out. @@ -723,7 +723,7 @@ of target operation are reported. The PDP group can be reverted to SAFE, TEST, or even PASSIVE mode at any time if problems arise. 2.3.5.3 Policy Upgrade and Rollback -^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ +""""""""""""""""""""""""""""""""""" There are a number of approaches for managing policy upgrade and rollback. @@ -736,7 +736,7 @@ policy set version. For rollback, one follows the process in section set into ACTIVE mode immediately. The advantage of this approach is that the approach is straightforward. The obvious disadvantage is that the PDP group is not executing on the target environment while the new -policy set is in PASSIVE, TEST, and SAFE mode. +policy set is in PASSIVE, TEST, and SAFE mode. A second manner to tackle upgrade and rollback is to use a spare-wheel approach. An special upgrade PDP group service is set up as a K8S @@ -756,7 +756,7 @@ active set and a standby set. However such an approach would increase the complexity of implementation in PDPs significantly. 2.3.6 Policy Monitoring -~~~~~~~~~~~~~~~~~~~~~~~ +^^^^^^^^^^^^^^^^^^^^^^^ PDPs provide a periodic report of their status to the PAP. All PDPs report using a standard reporting format that is extended to provide @@ -777,7 +777,7 @@ RealTimeInfo Real time information on running policies. ===================== =============================================================================== 2.3.7 PEP Registration and Enforcement Guidelines -~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ In ONAP there are several applications outside the Policy Framework that enforce policy decisions based on models provided to the Policy @@ -809,7 +809,7 @@ PDP_<> A specific type of PDP PDP Group A group of PDPs that execute the same set of policies Policy Development The development environment for policies Policy Type A generic prototype definition of a type of policy in TOSCA, see the `TOSCA Policy Primer <file://localhost/display/DW/TOSCA+Policy+Primer>`__ -Policy An executable policy defined in TOSCA and created using a Policy Type, see the `TOSCA Policy Primer <file://localhost/display/DW/TOSCA+Policy+Primer>`__ +Policy An executable policy defined in TOSCA and created using a Policy Type, see the `TOSCA Policy Primer <file://localhost/display/DW/TOSCA+Policy+Primer>`__ Policy Set A set of policies that are deployed on a PDP group. One and only one Policy Set is deployed on a PDP group ================================= ========================================================================================================================================================= diff --git a/docs/architecture/images/ToscaPolicyStructure.png b/docs/architecture/images/ToscaPolicyStructure.png Binary files differnew file mode 100644 index 00000000..f1e6cb47 --- /dev/null +++ b/docs/architecture/images/ToscaPolicyStructure.png diff --git a/docs/architecture/detailed.png b/docs/architecture/images/detailed.png Binary files differindex 9ac8cf30..9ac8cf30 100644 --- a/docs/architecture/detailed.png +++ b/docs/architecture/images/detailed.png diff --git a/docs/architecture/execution.png b/docs/architecture/images/execution.png Binary files differindex 4e564856..4e564856 100644 --- a/docs/architecture/execution.png +++ b/docs/architecture/images/execution.png diff --git a/docs/architecture/highest.png b/docs/architecture/images/highest.png Binary files differindex bfe07ae8..bfe07ae8 100644 --- a/docs/architecture/highest.png +++ b/docs/architecture/images/highest.png diff --git a/docs/architecture/objectmodel1.png b/docs/architecture/images/objectmodel1.png Binary files differindex ef3c7d12..ef3c7d12 100644 --- a/docs/architecture/objectmodel1.png +++ b/docs/architecture/images/objectmodel1.png diff --git a/docs/architecture/objectmodel2.png b/docs/architecture/images/objectmodel2.png Binary files differindex 44f79746..44f79746 100644 --- a/docs/architecture/objectmodel2.png +++ b/docs/architecture/images/objectmodel2.png diff --git a/docs/design/tosca-policy-primer.rst b/docs/architecture/tosca-policy-primer.rst index bc35abc7..686d3564 100644 --- a/docs/design/tosca-policy-primer.rst +++ b/docs/architecture/tosca-policy-primer.rst @@ -8,14 +8,28 @@ TOSCA Policy Primer ------------------- .. contents:: - :depth: 1 + :depth: 2 + +This page gives a short overview of how Policy is modelled in the +`TOSCA Simple Profile in YAML <http://docs.oasis-open.org/tosca/TOSCA-Simple-Profile-YAML/v1.1/TOSCA-Simple-Profile-YAML-v1.1.pdf>`__. + +TOSCA defines three concepts for Policy: Policy Type, Policy, and Trigger. + +.. image:: images/ToscaPolicyStructure.png + :width: 800 Policy Type ~~~~~~~~~~~ -A Policy Type is used to specify the types of policies that may be used in a service. The parameter definitions for a policy of this type, the entity types to which it applies, and what triggers policies of this type may be specified. +A Policy Type is used to specify the types of policies that may be used in a service. The parameter definitions +for a policy of this type, the entity types to which it applies, and what triggers policies of this type may be +specified. -The types of policies that are used in a service are defined in the policy_types section of the TOSCA service template as a Policy Type. More formally, TOSCA defines a Policy Type as an artifact that "defines a type of requirement that affects or governs an application or service’s topology at some stage of its lifecycle, but is not explicitly part of the topology itself". In the definition of a Policy Type in TOSCA, you specify: + +The types of policies that are used in a service are defined in the policy_types section of the TOSCA service template +as a Policy Type. More formally, TOSCA defines a Policy Type as an artifact that "defines a type of requirement that +affects or governs an application or service’s topology at some stage of its life cycle, but is not explicitly part of +the topology itself". In the definition of a Policy Type in TOSCA, you specify: * its properties, which define the type of configuration parameters that the policy takes * its targets, which define the node types and/or groups to which the policy type applies @@ -24,9 +38,12 @@ The types of policies that are used in a service are defined in the policy_types Policy ~~~~~~ -A Policy is used to specify the actual instances of policies that are used in a service. The parameter values of the policy and the actual entities to which it applies may be specified. +A Policy is used to specify the actual instances of policies that are used in a service. The parameter values of the +policy and the actual entities to which it applies may be specified. -The policies that are used in a service are defined in the policies section of the TOSCA topology template as a Policy. More formally, TOSCA defines a Policy as an artifact that "defines a policy that can be associated with a TOSCA topology or top-level entity definition". In the definition of a Policy in TOSCA, you specify: +The policies that are used in a service are defined in the policies section of the TOSCA topology template as a Policy. +More formally, TOSCA defines a Policy as an artifact that "defines a policy that can be associated with a TOSCA +topology or top-level entity definition". In the definition of a Policy in TOSCA, you specify: * its properties, which define the values of the configuration parameters that the policy takes * its targets, which define the node types and/or group types to which the policy type applies @@ -36,22 +53,27 @@ Note that policy triggers are specified on the Policy Type definition and are no Trigger ~~~~~~~ -A Trigger defines an event, condition, and action that is used to initiate execution of a policy associated with it. The definition of the Trigger allows specification of the type of events to trigger on, the filters on those events, conditions and constraints for trigger firing, the action to perform on triggering, and various other parameters. +A Trigger defines an event, condition, and action that is used to initiate execution of a policy associated with it. +The definition of the Trigger allows specification of the type of events to trigger on, the filters on those events, +conditions and constraints for trigger firing, the action to perform on triggering, and various other parameters. -The triggers that are used in a service are defined as reusable modules in the TOSCA service template as a Trigger. More formally, TOSCA defines a Trigger as an artifact that "defines the event, condition and action that is used to “trigger” a policy it is associated with". In the definition of a Trigger in TOSCA, you specify: +The triggers that are used in a service are defined as reusable modules in the TOSCA service template as a Trigger. +More formally, TOSCA defines a Trigger as an artifact that "defines the event, condition and action that is used to +“trigger” a policy it is associated with". In the definition of a Trigger in TOSCA, you specify: * its event_type, which defines the name of the event that fires the policy * its schedule, which defines the time interval in which the trigger is active -* its target_filter, which defines specific filters for firing such as specific characteristics of the nodes or relations for which the trigger should or should not fire +* its target_filter, which defines specific filters for firing such as specific characteristics of the nodes or +relations for which the trigger should or should not fire * its condition, which defines extra conditions on the incoming event for firing the trigger * its constraint, which defines extra conditions on the incoming event for not firing the trigger * its period, which defines the period to use for evaluating conditions and constraints -* its evaluations, which defines the number of evaluations that must be performed over the period to assert the condition or constraint exists +* its evaluations, which defines the number of evaluations that must be performed over the period to assert the +condition or constraint exists * its method, the method to use for evaluation of conditions and constraints * its action, the workflow or operation to invoke when the trigger fires Note that how a Trigger actually works with a Policy is not clear from the specification. - End of Document |
