example-service

Example Service for CORD/XOS

This is an example implementation documentation for providing a quick walk-through on composing and on-boarding service modules onto the CORD/XOS platform.

You may contact Larry Peterson llp@onlab.us and Peter Lee peter@corenova.com to learn more about this initiative and find out how you can help.

Installation

There is no need to run a separate installation as it comes bundled as part of yang-cord project repository.

If you have cloned the repository, you should first run: npm install in order to initialize this example service package with dependencies.

Example Service Composition Tutorial

Before getting started with the Example Service tutorial, you should first take a look at Composing Services reference guide to get a high-level overview of the package assets that we'll be working with.

1. Define the Service Model
2. Define the Controller Logic
3. Define the Package Manifest
4. Build the Package
5. Test on XOS

Define the Service Model

The example-service.yang is the primary file for describing the Example Service Controller configuration data model.

As described in Composing Service guide, the primary sections of importance in creating a new Service Model is defining the container controller section as well as augment "/xos:tenant/cord/subscriber" section.

Define the Controller Logic

The example-service.coffee is the primary file for binding control logic to the Example Service data model. While this step is completely optional during prototyping, it plays an important role when this Service package is deployed into an actual runtime environment. The control logic bindings serve as the glue which provides operational mapping to perform actions via accessors, observers, and synchronizers.

Additional concrete examples and documentation for expressing control logic bindings will be coming soon...

Define the Package Manifest

The package.json is the primary file for describing the Example Service package configuration.

In general, most CORD/XOS service package will have similar configuration with minor variations in terms of service specific metadata.

The key package attributes for customization are as follows:

• name
• version
• author
• license
• description
• keywords
• dependencies
• scripts
• controller*
• models*

The dependencies section should include yang-cord dependency mapping information, such as "yang-cord": "1.3.0".

Build the Package

$ npm run build

The above command will execute the build related scripts defined inside package.json. Typically, it will compile any *.coffee files found inside the package and generate the swagger.yaml API specifications for the service controller. In the future, this step will likely be replaced with the yang-forge utility.

Testing on XOS

$ NODE_ENV=test npm start

The above command internally executes xos example-service which will basically start an instance of the XOS Controller (which uses yang-express) and dynamically load the Example Service data model into the runtime execution.

Since example-service YANG module has additional dependencies for cord-tenant and xos-slice (among others), these dependent YANG modules will be automatically resolved and loaded into the runtime instance.

The default initializer for the service will use the config module, which will look for environmental configuration data in the package's config directory. You can specify any configuration state to be used at initialization stage across all the YANG modules that the Example Service depends on. This means that you can customize the exact configuration state of the XOS Controller runtime during your testing to suit your service module's testing requirements. Another way to look at this is to consider that you're running your testing on a model-complete CORD/XOS emulation layer.