diff options
Diffstat (limited to 'src/site-docs/adoc/fragments/apex-policy-model/concept-state.adoc')
| -rw-r--r-- | src/site-docs/adoc/fragments/apex-policy-model/concept-state.adoc | 45 |
1 files changed, 45 insertions, 0 deletions
diff --git a/src/site-docs/adoc/fragments/apex-policy-model/concept-state.adoc b/src/site-docs/adoc/fragments/apex-policy-model/concept-state.adoc new file mode 100644 index 000000000..acab55235 --- /dev/null +++ b/src/site-docs/adoc/fragments/apex-policy-model/concept-state.adoc @@ -0,0 +1,45 @@ +// +// ============LICENSE_START======================================================= +// Copyright (C) 2016-2018 Ericsson. All rights reserved. +// ================================================================================ +// This file is licensed under the CREATIVE COMMONS ATTRIBUTION 4.0 INTERNATIONAL LICENSE +// Full license text at https://creativecommons.org/licenses/by/4.0/legalcode +// +// SPDX-License-Identifier: CC-BY-4.0 +// ============LICENSE_END========================================================= +// +// @author Sven van der Meer (sven.van.der.meer@ericsson.com) +// + +== Concept: State + +The __State__ concept represents a phase or a stage in a policy, with a policy being composed of a series of states. +Each state has at least one but may have many tasks and, on each run of execution, a state executes one and only one of its tasks. +If a state has more than one task, then its task selection logic is used to select which task to execute. +Task selection logic is programmable logic provided by the state designer. +That logic can use incoming, policy, global, and external context to select which task best accomplishes the purpose of the state in a give situation if more than one task has been specified on a state. +A state calls one and only one task when it is executed. + +Each state is triggered by an event, which means that all tasks of a state must also be triggered by that same event. +The set of output events for a state is the union of all output events from all tasks for that task. +In practice at the moment, because a state can only have a single input event, a state that is not the final state of a policy +may only output a single event and all tasks of that state may also only output that single event. +In future work, the concept of having a less restrictive trigger pattern will be examined. + +A __State__ concept is keyed with a `ReferenceKey` key, which references the __Policy__ concept that owns the state. +The __LocalName__ field of the `ReferenceKey` holds the name of the state. +As a state is part of a chain of states, the __NextState__ field of a state holds the `ReferenceKey` key of the state in the policy to execute after this state. + +The __Trigger__ field of a state holds the `ArtifactKey` of the event that triggers this state. +The __OutgoingEvents__ field holds the `ArtifactKey` references of all possible events that may be output from the state. +This is a set that is the union of all output events of all tasks of the state. + +The __Task__ concepts that hold the definitions of the task for the state are held as a set of `ArtifactKey` references in the state. +The __DefaultTask__ field holds a reference to the default task for the state, a task that is executed if no task selection logic is +specified. +If the state has only one task, that task is the default task. + +The __Logic__ concept referenced by a state holds the task selection logic for a state. +The task selection logic uses the incoming context (parameters of the incoming event) and other context to determine the best task to use to execute its goals. +The state holds a set of references to __ContextItem__ and __ContextItemTemplate__ definitions for the context used by its task selection logic. + |