Add apigateway docs

Add documents for apigateway.

JIRA:PARSER-123

Change-Id: Ibe8ebd6e3a3f62d58d8da0da4d9be8ceb673fb7b
Signed-off-by: shangxdy <shang.xiaodong@zte.com.cn>

8 files changed, 50 insertions, 11 deletions

diff --git a/docs/developer/design/apigateway.rst b/docs/developer/design/apigateway.rst
new file mode 100644
index 0000000..dbeb94d
--- /dev/null
+++ b/docs/developer/design/apigateway.rst
@@ -0,0 +1,38 @@
+.. This work is licensed under a Creative Commons Attribution 4.0 International License.
+.. http://creativecommons.org/licenses/by/4.0
+
+=================
+Parser apigateway
+=================
+
+This document provides a description of apigateway, a message relay submodule for the other
+parser submodules.
+
+.. contents::
+   :depth: 3
+   :local:
+
+Overview
+--------
+Provide unified access interfaces for follow independent parser components:
+ - tosca2heat
+ - yang2tosca
+ - policy2tosca
+ - verigraph
+ - parser ui
+ The apigateway will relay message between above submodules throngh gRPC interface, in additon,
+apigateway also exposes restful api to provide parser all functions to the 3rd applications.
+
+
+Architecture
+------------
+Apigateway exploits three sub-components:
+
+- **APIGW**, the main part of apigateway, which is the message center.
+- **gRPC**, provide gRPC client and server for the other parser sub-modules, it can be devided
+into defferent pair of client/server according to the function.
+- **CLI**, command line tool for apigateway access and management .
+
+Apigateway architecture is shown below:
+
+.. image:: /images/API_gateway_architecture.png
diff --git a/docs/developer/design/images/API_gateway_architecture.png b/docs/developer/design/images/API_gateway_architecture.png
new file mode 100644
index 0000000..7fbaa74
--- /dev/null
+++ b/docs/developer/design/images/API_gateway_architecture.png
diff --git a/docs/developer/design/index.rst b/docs/developer/design/index.rst
index 0f29a8a..fa13788 100644
--- a/docs/developer/design/index.rst
+++ b/docs/developer/design/index.rst
@@ -15,3 +15,4 @@ OPNFV Parser Design Documentation
    yang2tosca.rst
    policy2tosca.rst
    verigraph.rst
+   apigateway.rst
diff --git a/docs/developer/design/policy2tosca.rst b/docs/developer/design/policy2tosca.rst
index 3753d6c..8dcedad 100644
--- a/docs/developer/design/policy2tosca.rst
+++ b/docs/developer/design/policy2tosca.rst
@@ -1,8 +1,8 @@
 .. This work is licensed under a Creative Commons Attribution 4.0 International License.
 .. http://creativecommons.org/licenses/by/4.0
 
-===================
+==================
 Parser polic2tosca
-===================
+==================
 
 
diff --git a/docs/developer/design/tosca2heat.rst b/docs/developer/design/tosca2heat.rst
index d4ead14..3fb1d26 100644
--- a/docs/developer/design/tosca2heat.rst
+++ b/docs/developer/design/tosca2heat.rst
@@ -1,7 +1,7 @@
 .. This work is licensed under a Creative Commons Attribution 4.0 International License.
 .. http://creativecommons.org/licenses/by/4.0
 
-===================
+=================
 Parser tosca2heat
-===================
+=================
 
diff --git a/docs/developer/design/verigraph.rst b/docs/developer/design/verigraph.rst
index d364091..1362e23 100644
--- a/docs/developer/design/verigraph.rst
+++ b/docs/developer/design/verigraph.rst
@@ -1,9 +1,9 @@
 .. This work is licensed under a Creative Commons Attribution 4.0 International License.
 .. http://creativecommons.org/licenses/by/4.0
 
-=================
+================
 Parser verigraph
-=================
+================
 
 This document provides a description of VeriGraph, a formal verification tool for service graphs.
 
diff --git a/docs/developer/overview/overview.rst b/docs/developer/overview/overview.rst
index 8baffdd..3ae173a 100644
--- a/docs/developer/overview/overview.rst
+++ b/docs/developer/overview/overview.rst
@@ -10,7 +10,7 @@ OPNFV Parser Danube Overview Doumentation
    :local:
 
 Introduction
----------------
+------------
 
 In NFV, various templates (such as descriptors, records and so on) are utilized
 to describe the deployment requirements (such as basic VM requirements – vCPU,
@@ -27,7 +27,7 @@ translate TOSCA/CAMP templates into certain common templates, which could be
 used in IaaS orchestration projects like OpenStack Heat.
 
 For Arno Release
-------------------------
+----------------
 Parser is not one of the Arno Release projects, however the project has established
 the code base for the later releases:
 
@@ -35,7 +35,7 @@ the code base for the later releases:
 * Initial documentation on use cases
 
 Upgrades from Arno Release
-------------------------
+--------------------------
 
 For Brahmaputra Release, Parser offers the following additional capabilities:
 
@@ -59,7 +59,7 @@ For Brahmaputra Release, Parser offers the following additional capabilities:
   scenario. See also https://wiki.opnfv.org/parser.
 
 Upgrades from Brahmaputra Release
------------------------
+---------------------------------
 
 For Colorado Release, Parser offers the following additional capabilities:
 
diff --git a/docs/developer/requirements/parser_requirement_arno_release.rst b/docs/developer/requirements/parser_requirement_arno_release.rst
index 96d1d38..67f812c 100644
--- a/docs/developer/requirements/parser_requirement_arno_release.rst
+++ b/docs/developer/requirements/parser_requirement_arno_release.rst
@@ -10,7 +10,7 @@ OPNFV Parser Requirements In Arno Release
    :local:
 
 Use Case Description
----------------
+--------------------
 
 * When Operators want to do automation on utilizing VIM to manage hypervisor
 level accelerators which VNFs don't have knowledge of, certain templates