Design document for yang2tosca patch set-4

Signed-off-by: shiva-charan <shiva-charan.m-s@hpe.com>
Change-Id: Id3b8c198d08ea71130828d941dcc16ac5b23a421
(cherry picked from commit 6a4722caccc69de6dffd96751e4832df4df96f47)

1 files changed, 56 insertions, 1 deletions

diff --git a/docs/developer/design/yang2tosca.rst b/docs/developer/design/yang2tosca.rst
index 61d31b2..9726962 100644
--- a/docs/developer/design/yang2tosca.rst
+++ b/docs/developer/design/yang2tosca.rst
@@ -1,7 +1,62 @@
-.. This work is licensed under a Creative Commons Attribution 4.0 International License.
+.. This work is licensed under a Creative Commons Attribution
+.. 4.0 International License.
 .. http://creativecommons.org/licenses/by/4.0
 
 =================
 Parser yang2tosca
 =================
 
+Problem description
+-------------------
+In NFV, various templates are utilized to describe the deployment requirements,
+the post-instantiation records or other purposes. However in order to make
+these templates adaptable and feasible for purpose like deployment
+orchestration/automation, certain tooling mechanism that provides template
+translation is necessary.When an end user needs a translation from YANG to
+TOSCA for further deployment this is where the yang2tosca module comes in as
+part of parser project.
+
+Design
+------
+The following modules are implemented in yang2tosca module.
+
+PYANG
+-----
+PYAG module is used to validate YANG templates, if the user input the YAGN
+template in YAML format we use this module to validate and convert it to XML
+format of YANG.The “yin” module under PYANG is used for the conversion from
+YAML to XML.
+Reference for PYANG:
+http://www.yang-central.org/twiki/pub/Main/YangTools/pyang.1.html
+
+LXML
+----
+lxml is another python module that we make use in our design, this module is
+used to parse the xml object, which will be the base for translational.
+The “etree” module under lxml is used for the translation to TOSCA files.
+Reference for lxml: http://lxml.de/
+
+tosca_translator
+----------------
+All the above module come under this tosca_translator function which can be
+invoked and used for translation purposes.
+
+The user inputs the YANG template in either XML or in YAML format to the
+yang2tosca module and the output is the TOSCA YAML file.
+1.The First step in the module is where the input is checked for the format.
+   If the format is YAML then a module called pyang converts this into a YANG
+   XML file.
+   If the format is XML then then the conversion process is initiated.
+2.The conversion process will be with the help of an XSLT which will be invoked
+through python scripting.
+
+Input
+-----
+The user can input either YANG XML or YANG YAML file which should be present
+where the scripts/modules are present.
+
+Output
+------
+The user will get the out TOSCA YAML file under the same directory where the
+scripts/modules are executed with same name as the input file with "_tosca"
+suffixed to it.