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diff --git a/src/site-docs/adoc/fragments/apex-policy-model/concept-contextmap.adoc b/src/site-docs/adoc/fragments/apex-policy-model/concept-contextmap.adoc new file mode 100644 index 000000000..d3276590c --- /dev/null +++ b/src/site-docs/adoc/fragments/apex-policy-model/concept-contextmap.adoc @@ -0,0 +1,52 @@ +// +// ============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: ContextMap + +The set of context that is available for use by the policies of a __PolicyModel__ is defined as __ContextMap__ concept instances. +The __PolicyModel__ holds a map of all the __ContextMap__ definitions. +A __ContextMap__ is itself a container for a group of related context items, each of which is represented by a __ContextItem__ concept instance. +__ContextMap__ concepts are keyed with an `ArtifactKey` key. +A developer can use the APEX Policy Editor to create context maps for their application domain. + +A __ContextMap__ uses a map to hold the context items. +The ContextItem concept instances in the map are indexed by the __LocalName__ of their `ReferenceKey`. + +The __ContextMapType__ field of a __ContextMap__ defines the type of a context map. +The type can have either of two values: + +* A __BAG__ context map is a context map with fixed content. + Each possible context item in the context map is defined at design time and is held in the __ContextMap__ context instance as __ContextItem__ concept definitions and only the values of the context items in the context map can be changed at run time. + The context items in a __BAG__ context map have mixed types and distinct __ContextItem__ concept instances of the same type can be defined. + A __BAG__ context map is convenient for defining a group of context items that are diverse but are related by domain, such as the characteristics of a device. + A fully defined __BAG__ context map has a fully populated __ContextItem__ map but its __ContextItemTemplate__ reference is not defined. ++ +* A __SAMETYPE__ context map is used to represent a group of __ContextItem__ instances of the same type. + Unlike a __BAG__ context map, the __ContextItem__ concept instances of a __SAMETYPE__ context map can be added, modified, and deleted at runtime. + All __ContextItem__ concept instances in a __SAMETYPE__ context map must be of the same type, and that context item is defined as a single __ContextItemTemplate__ concept instances at design time. + At run time, the __ContextItemTemplate__ definition is used to create new __ContextItem__ concept instances for the context map on demand. + A fully defined _SAMETYPE__ context map has an empty __ContextItem__ map and its __ContextItemTemplate__ reference is defined. + + +The __Scope__ of a __ContextMap__ defines the range of applicability of a context map in APEX. +The following scopes of applicability are defined: + +* __EPHEMERAL__ scope means that the context map is owned, used, and modified by a single application, but the context map only exists while that application is running +* __APPLICATION__ scope specifies that the context map is owned, used, and modified by a single application, the context map is persistent +* __GLOBAL__ scope specifies that the context map is globally owned and is used and modified by any application, the context map is persistent +* __EXTERNAL__ scope specifies that the context map is owned by an external system and may be used in a read-only manner by any application, the context map is persistent + +A much more sophisticated scoping mechanism for context maps is envisaged for +Apex in future work. In such a mechanism, the scope of a context map would work +somewhat like the way roles work in security authentication systems. + |