ydk-gen is a tool which is meant to be used to generate bindings for different languages like python, C++ etc from a given set of YANG models. The input YANG models are specified in a profile file.

##System Requirements:

####Linux Ubuntu (Debian-based): The following packages must be present in your system before installing YDK-Py:

user-machine# sudo apt-get install python-pip zlib1g-dev python-lxml libxml2-dev libxslt1-dev python-dev

####Mac It is recommended to install homebrew (http://brew.sh) and Xcode command line tools on your system before installing YDK-Py:

user-machine# /usr/bin/ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)"
user-machine# xcode-select --install

user-machine# git clone https://github.com/CiscoDevNet/ydk-gen.git
user-machine# cd ydk-gen
user-machine# source install.sh

user-machine# python generate.py --help
Usage: generate.py [options]

Options:
  --version           show program's version number and exit
  -h, --help          show this help message and exit
  --profile=PROFILE   Take options from a profile file, any CLI targets
                      ignored. Profile options override CLI currently
  -p, --python        Generate Python SDK
  -c, --cpp           Generate C++ SDK
  -v, --verbose       Verbose mode
  --generate-doc      Generation documentation
  --output-directory  The output-directory . If not specified the output can be found under ydk-gen/gen-api/python

1. Construct a profile file, such as xr600-native-oc-bgp.json

2. Generate the SDK using a command of the form:

python generate.py --python --profile profiles/cisco-ios-xr/xr600-native-oc-bgp.json

The generated SDK will in ydk-gen/gen-api/python.

A sample profile file is described below.

As should be fairly obvious, the file is in a JSON format. The initial section of metadata is mostly ignored for now. It will be used later.

{
    "version": "0.1.0",
    "Author": "Cisco",
    "Copyright": "Cisco",
    "Description": "Cisco IOS-XR Native Models From Git",

The "models" section of the file describes where to source models from. There are 3 sources:

• Directories
• Specific files
• Git, within which specific relative directories and files may be referenced

The sample below shows the use of git sources only.

    "models": {
        "git": [

We have a list of git sources. Each source must specify a URL. This URL should be one that allows the repository to be cloned without requiring user intervention, so please use a public URL such as the example below. There are three further options that can be specified:

• commitid - Optional specification of a commit in string form. The files identified will be copied from the context of this commit.
• dir - List of relative directory paths within git repository. All .yang files in this directory and any sub-directories will be pulled into the generated SDK.
• file- List of relative file paths within the git repository.

Only directory examples are shown below.

            {
                "url": "https://github.com/YangModels/yang.git",
                "dir": [
                    "vendor/cisco/xr/532"
                ]
            },
            {
                "url": "https://github.com/YangModels/yang.git",
                "commitid": "f6b4e2d59d4eedf31ae8b2fa3119468e4c38259c",
                "dir": [
                    "experimental/openconfig/bgp",
                    "experimental/openconfig/policy"
                ]
            }
        ]
    },

YANG Development Kit Generator:

• Tools that auto generate different programming language binding API's (Python, Ruby, GPB, Thrift, Objective C), Developers can use these objects/APIs, to write application
• Runtime libraries which provided "services" and transport code for App to talk to network devices (runtime for: Python, Ruby, gRPCServer). These runtime libraries also have protocol plugin, currently netconf plug has been added for testing.
• The runtime libraries have three parts:
  • Entity: X object definitions for YANG model. X here is programming language (Python, Ruby, Obj-C, GPBIDL, ThriftIDL etc)
  • ServiceProvider: Provides concrete implementation that abstracts underlying protocol details
  • Services: Provides simple API interface to be used with the entity and provider

For Python entities and netconf session, CRUD service invoked on python class will:

• Encode python data objects to netconf XML payload
• Perform transport operation with device, collect the netconf response,
• Decode netconf response in python class, return result to python app.

README          - install and usage notes
install.sh      - Simple one-shot installation script 
gen-api         - source dir or autogenerated SDK 
					- python (Python SDK)

generate.py     - bootstrap script to generate SDK for yang data models
profiles        - profile files used during generation
yang            - some yang models used for testing
requirements.txt- python dependencies used during installation (refer README)
sdk             - sdk stubs
test            - test code, engineering playground

Make sure that PYTHONPATH is set properly

user-machine# cd ydk-gen 
user-machine# export PYTHONPATH=.:$PYTHONPATH

To run the sanity tests, do the following after running install.sh.

user-machine# cd ydk-gen/sdk/python 
user-machine# python test/test_sanity_types.py
user-machine# python test/test_sanity_levels.py
user-machine# python test/test_sanity_filters.py
...

To run the generator test case, do the following after running install.sh.

user-machine# cd ydk-gen 
user-machine# python test/pygen_tests.py