Content Gateway

An easy way to get external content with two cache levels. The first is a performance cache and second is the stale.

Content Gateway lets you set a timeout for any request. If the configured timeout is reached without response, it searches for cached data. If cache is unavailable or expired, it returns the stale cache data. Only then, if stale cache is also unavailable or expired, it raises an exception

Dependencies

• Ruby >= 1.9
• ActiveSupport (for cache store)

Installation

Add this line to your application's Gemfile:

gem 'content_gateway'

And then execute:

$ bundle

Or install it yourself as:

$ gem install content_gateway

Configuration

ContentGateway::Gateway class accepts a configuration object with the following parameters:

• timeout: request timeout in seconds
• cache_expires_in: cache data expiration time, in seconds
• cache_stale_expires_in: stale cache data expiration time, in seconds
• stale_on_error: if true, returns value from cache stale (if available) after a server error. Default value: true
• cache: cache store instance. This may be an instance of ActiveSupport::Cache
• proxy: proxy address, if needed

Configuration object example:

config = OpenStruct.new(
  timeout: 2,
  cache_expires_in: 1800,
  cache_stale_expires_in: 86400,
  stale_on_error: false,
  cache: ActiveSupport::Cache.lookup_store(:memory_store),
  proxy: "http://proxy.example.com:3128"
)

Usage

ContentGateway::Gateway expects four parameters:

• a label, which is used in the log messages
• a config object, just as described above
• (optional) an URL Generator object. This may be any object that responds to a generate method, like this:
• (optional) a hash with default params. Currently, it only supports default headers

class UrlGenerator
  def generate(resource_path, params = {})
    args = "?#{params.map {|k, v| "#{k}=#{v}"}.join("&")}" if params.any?
    "http://example.com/#{resource_path}#{args}"
  end
end

default_params = { headers: { Accept: "application/json" } }

gateway = ContentGateway::Gateway.new("My API", config, UrlGenerator.new, default_params)

If ommited, the default URL Generator adds the method call params as query string parameters. Every param may be overrided on each request.

This Gateway object supports the following methods:

GET

To do a GET request, you may use the get or get_json methods. The second one parses the response as JSON. Optional parameters are supported:

• timeout: overwrites the default timeout
• expires_in: overwrites the default cache expiration time
• stale_expires_in: overwrites the default stale cache expiration time
• skip_cache: if set to true, ignores cache and stale cache
• headers: a hash with request headers
• ssl_certificate: a hash with ssl cert, key, ssl version (see ssl support section below)

Every other parameter is passed to URLGenerator generate method (like query string parameters).

Examples:

gateway.get("/path", timeout: 3)

gateway.get_json("/path.json", skip_cache: true)

POST, PUT and DELETE

POST, PUT and DELETE verbs are also supported, but ignore cache and stale cache. The gateway object offers the equivalent methods for these verbs (post, post_json, put, put_json, delete and delete_json). The only optional parameters supported by these methods are payload and ssl_certificate. Every other parameter is passed to URLGenerator generate method (like query string parameters).

Examples:

gateway.post("/api/post_example", payload: { param1: "value" })

gateway.put_json("/api/put_example.json", query_string_param: "value")

gateway.delete("/api/delete_example", id: "100")

SSL Support

You can use ssl certificates to run all supported requests (get, post, put, delete).

Just pass the path of cert file (x509 certificate) and key file (rsa key) to the request method. See exemple below:

ssl = {
  ssl_client_cert: "path/client.cert",
  ssl_client_key: "path/client.key"
}

gateway.get("/path", timeout: 3, ssl_certificate: ssl)

gateway.get_json("/path.json", skip_cache: true, ssl_certificate: ssl)

gateway.post("/api/post_example", payload: { param1: "value" }, ssl_certificate: ssl)

You can use ssl_version to specify which version you need. (You can use with client cert and key or use it alone) See example below:

ssl = {
  ssl_version: "SSLv23"
}

gateway.get("/path", timeout: 3, ssl_certificate: ssl)

gateway.get_json("/path.json", skip_cache: true, ssl_certificate: ssl)

gateway.post("/api/post_example", payload: { param1: "value" }, ssl_certificate: ssl)

Authors

• Túlio Ornelas
• Roberto Soares
• Emerson Macedo
• Guilherme Garnier
• Daniel Martins
• Rafael Biriba
• Célio Latorraca

Contributing

1. Fork it
2. Create your feature branch (git checkout -b my-new-feature)
3. Commit your changes (git commit -am 'Add some feature')
4. Push to the branch (git push origin my-new-feature)
5. Create new Pull Request

License

Copyright (c) 2016 Globo.com - Webmedia. See LICENSE.txt for more details.