Green Button Data

Green Button Data is a Ruby gem that can consume Green Button APIs and parse the Green Button data XML schema very quickly. It uses an event-driven SAX parser which parses XML data without building an entire DOM in memory.

On a 2.3 GHz Core i7 processor, this gem is capable of parsing at a rate of ~1.7 MB/s which is fast enough to parse a 1 year 12-hour interval data in just over a second.

You may run the benchmarks by cloning this project and running rake benchmark.

Getting Started

Add the Green Button Data gem to your Gemfile:

gem 'green-button-data'

Then run Bundler:

$ bundle

Unless you have a project that auto loads all gems in the Gemfile (e.g. a Rails project), you will need to require it:

require 'green-button-data'

This will expose the GreenButtonData module namespace.

Integrating GreenButtonData Into Your Application

GreenButtonData gem provides a familiar interface to consuming API endpoints. Method names are similar to Rails' ActiveRecord models and can be easily integrated into existing applications.

Global Configuration

You can add configuration options like the following:

GreenButtonData.configure do |config|
  config.base_url = "https://api.example.com/DataCustodian/espi/1_1/resource/"
  config.application_information_path = "ApplicationInformation/"
  config.authorization_path = "Authorization/"
  config.subscription_path = "Subscription/"
  config.usage_point_path = "UsagePoint/"
end

Note that each path must end with a trailing slash.

Rails Integration

IMPORTANT: Version 0.3.0 has a bug which causes Rails not to boot correctly. Please use 0.3.1 or higher when integrating into Rails by running bundle update green-button-data.

If you are developing a Rails app, create a file at config/initializers/green_button_data.rb from your Rails project root and add the configuration there.

Green Button Data API Client

Green Button Data specification states that all API endpoints be secured with OAuth2 which means most fetch operations will require auth tokens.

Some endpoints are secured further by utilizing client SSL certificates (e.g. Pacific Gas & Electric). You may pass in ssl options in addition to the token option in this case.

DISCLAIMER: Green Button Data is NOT responsible for managing OAuth tokens to make authenticated requests. There are other gems that provide mature, production proven OAuth 2 functionalities such as OmniAuth.

Querying Data

With version 0.4.0, there are two ways to query data on a remote endpoint:

• Using a scoped client class
• Calling query methods directly on resource classes

Using API Client class

This is the recommended method to query data from multiple Data Custodians.

Each instance of GreenButtonData::Client uses scoped configuration suitable for each Data Custodians.

This allows you to make requests to different Data Custodians that have different URL path layouts.

The example below creates two clients: one for ESPI Green Button Data reference API and the other for Pacific Gas & Electric:

espi_base_url   = "https://services.greenbuttondata.org/DataCustodian/espi/" +
                  "1_1/resource/"
pge_base_url    = "https://api.pge.com/GreenButtonConnect/espi/1_1/resource/"

espi_client = GreenButtonData.connect base_url: "https://foo.com" do |client|
  # Override base_url configuration
  client.configuration.base_url = espi_base_url

  # Equivalent to passing in as an argument hash in connect method:
  # GreenButtonData.connect subscription_path: "Subscription/" do |client|
  client.configuration.subscription_path = "Subscription/"

  client.configuration.usage_point_path = "UsagePoint/"
  client.configuration.usage_summary_path = "ElectricPowerUsageSummary/"

  # Set OAuth 2.0 bearer token
  client.token = "12345678-5672-abcd-567890abcdef"
end

pge_client = GreenButtonData.connect base_url: pge_base_url do |client|
  client.configuration.subscription_path = "Subscription/"
  client.configuration.usage_point_path = "UsagePoint/"
  client.configuration.usage_summary_path = "UsageSummary/"

  client.token = "098765432-abcd-ef00-12345678900"
end

Querying a resource

The Client class provides query methods to query each resources:

• GreenButtonData::Client#application_information

  Returns a collection of GreenButtonData::ApplicationInformation instances if id is not specified. If id is specified, returns a single instance.

• GreenButtonData::Client#authorization

  Returns a collection of GreenButtonData::Authorization instances if id is not specified. If id is specified, returns a single instance.

• GreenButtonData::Client#interval_block

  Returns a collection of GreenButtonData::IntervalBlock instances if id is not specified. If id is specified, returns a single instance.

• GreenButtonData::Client#local_time_parameters

  Returns a collection of GreenButtonData::LocalTimeParameters instances if id is not specified. If id is specified, returns a single instance.

• GreenButtonData::Client#meter_reading

  Returns a collection of GreenButtonData::MeterReading instances if id is not specified. If id is specified, returns a single instance.

• GreenButtonData::Client#reading_type

  Returns a collection of GreenButtonData::ReadingType instances if id is not specified. If id is specified, returns a single instance.

• GreenButtonData::Client#usage_point

  Returns a collection of GreenButtonData::UsagePoint instances if id is not specified. If id is specified, returns a single instance.

• GreenButtonData::Client#usage_summary

  Returns a collection of GreenButtonData::UsageSummary instances if id is not specified. If id is specified, returns a single instance.

Following the example from previous section, to retrieve all entries:

# Generally, Data Custodian access token is required to do this query which you
# can override with `token` keyword argument
# Makes a request to:
# https://services.greenbuttondata.org/DataCustodian/espi/1_1/resources/UsagePoint
espi_all_usage_points = espi_client.usage_point

To retrieve a specific entry, specify the resource ID:

# Get a Usage Point 2
# Makes a request to:
# https://services.greenbuttondata.org/DataCustodian/espi/1_1/resources/UsagePoint/2
espi_usage_point = espi_client.usage_point 2, token: data_custodian_access_token

# Get a UsagePoint 1234 for subscription 3401
# Makes a request to:
# https://api.pge.com/GreenButtonConnect/espi/1_1/resources/Subscription/3401/UsagePoint/1234
pge_usage_point = pge_client.usage_point 1234, subscription_id: 3401

You can query for related resources as well. There are couple ways you can do this:

# Gets all meter readings for this instance of UsagePoint
meter_readings_1 = pge_usage_point.meter_readings

# Same as above but requires knowledge of UsagePoint and Subscription ids
meter_readings_2 = pge_client.meter_reading usage_point_id: 1234, subscription_id: 3401

Using resource classes

This method allows you to query for data using the global configuration. This has limitations as you can only query data from one Data Custodian at a time unless you override the global configuration per method call.

The resource classes are as follows:

• GreenButtonData::ApplicationInformation
• GreenButtonData::Authorization
• GreenButtonData::IntervalBlock
• GreenButtonData::LocalTimeParameters
• GreenButtonData::MeterReading
• GreenButtonData::ReadingType
• GreenButtonData::UsagePoint
• GreenButtonData::UsageSummary

List all entries

By default, the .all method attempts to use the URL path set by configuration:

require 'green-button-data'

# Ideally obtained from OmniAuth gem
access_token = "12345678-1024-2048-abcdef001234"

# Return all usage points; URL is specified in GreenButtonData.configuration.usage_point_url
usage_points = UsagePoint.all token: access_token

You may override the global configuration by specifying the URL in the method:

usage_points = UsagePoint.all "https://someotherapi.org/espi/Authorization",
                              token: access_token

Find an entry by ID

If you have URL defined in configuration, the .find method appends the ID to the URL:

GreenButtonData.configure do |config|
  config.base_url = "https://services.greenbuttondata.org/"
  config.usage_point_path = "DataCustodian/espi/1_1/resource/UsagePoint/"
end

# GET request to https://services.greenbuttondata.org/DataCustodian/espi/1_1/resource/UsagePoint/2
usage_point = GreenButtonData::UsagePoint.find 2, token: access_token

As with .all method, URL can be overridden per request in .find:

usage_point = GreenButtonData::UsagePoint.find "https://someotherapi.org/espi/UsagePoint/1",
                                               token: access_token

Parsing

Almost all of the functionality for parsing data is wrapped in the GreenButtonData::Feed class.

To parse a Green Button Atom feed, simply call the parse method and pass in the entire XML document:

require 'green-button-data'

xml_text = File.read "#{File.dirname __FILE__}/gb_example_interval_block.xml"
data = GreenButtonData::Feed.parse xml_text

You can then access the data like this:

# Print all the interval readings from the feed
data.entries.each do |entry|
  p "Entry: #{entry.title}"
  entry.content.interval_block.interval_readings.each do |reading|
    time_period = reading.time_period
    p "[#{time_period.starts_at} - #{time_period.ends_at}]: #{reading.value}"
  end
end

Contributing

1. Fork this project
2. Create a feature branch: git checkout -b my-awesome-feature
3. Make changes and commit: git commit -am "Add awesome feature"
4. Push the branch: git push origin my-awesome-feature
5. Submit a pull request

Versioning

Green Button Data gem follows Semantic Versioning 2.0. As such, you can specify a pessimistic version constraint on this gem with two digits of precision and be guaranteed latest features and bug fixes without backwards breaking changes:

gem 'green-button-data', '~> 0.1'

Exception to this rule as per the SemVer specification is major version zero for initial development. This gem's API should NOT be considered stable until 1.0 release.

License

This software is distributed AS IS WITHOUT WARRANTY under Simplified BSD license.

Verdigris Technologies Inc. assumes NO RESPONSIBILITY OR LIABILITY UNDER ANY CIRCUMSTANCES for usage of this software. See the LICENSE.txt file for detailed legal information.

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