72 lines
2.2 KiB
ReStructuredText
72 lines
2.2 KiB
ReStructuredText
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Copyright 2018 AT&T Intellectual Property.
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All Rights Reserved.
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Licensed under the Apache License, Version 2.0 (the "License"); you may
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not use this file except in compliance with the License. You may obtain
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a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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License for the specific language governing permissions and limitations
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under the License.
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.. _rendering:
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Document Rendering
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==================
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Document rendering involves extracting all raw revision documents from
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Deckhand's database, retrieving encrypted information from `Barbican`_,
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and applying substitution, layering and replacement algorithms on the
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data.
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The following algorithms are involved during the rendering process:
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:ref:`substitution`
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-------------------
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Substitution provides an "open" data sharing model in which any source
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document can be used to substitute data into any destination document.
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Use Cases
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^^^^^^^^^
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* Sharing of data between specific documents no matter their ``schema``.
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* Data sharing using pattern matching.
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* Fine-grained sharing of specific sections of data.
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:ref:`layering`
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---------------
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Layering provides a "restricted" data inheritance model intended to help
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reduce duplication in configuration.
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Use Cases
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^^^^^^^^^
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* Sharing of data between documents with the same ``schema``.
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* Deep merging of objects and lists.
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* Layer order with multiple layers, resulting in a larger hierarchy of
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documents.
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* Source document for data sharing can be identified via labels, allowing for
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different documents to be used as the source for sharing, depending on
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:ref:`parent-selection`.
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:ref:`replacement`
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------------------
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Replacement builds on top of layering to provide yet another mechanism
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for reducing data duplication.
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Use Cases
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^^^^^^^^^
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* Same as layering, but with a need to replace higher-layer documents with
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lower-layer documents for specific site deployments.
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.. _Barbican: https://docs.openstack.org/barbican/latest/api/
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