EM HTTP Request

EM HTTP Request allows multiple simultaneous asynchronous requests. (The other HTTP libraries are synchronous). The scenarios below demonstrate how VCR can be used with asynchronous em-http requests.

Background

Given a file named "vcr_setup.rb" with:

ruby

require 'em-http-request'

$server = start_sinatra_app do
  %w[ foo bar bazz ].each_with_index do |path, index|
    get "/#{path}" do
      sleep index * 0.1 # ensure the async callbacks are invoked in order
      ARGV[0] + ' ' + path
    end
  end
end

require 'vcr'

VCR.configure do |c|
  c.hook_into :webmock
  c.cassette_library_dir = 'cassettes'
  c.before_record do |i|
    i.request.uri.sub!(/:\d+/, ':7777')
  end
end

multiple simultaneous HttpRequest objects

Given a file named "make_requests.rb" with:

ruby

require 'vcr_setup'

VCR.use_cassette('em_http') do
  EventMachine.run do
    http_array = %w[ foo bar bazz ].map do |p|
      # Several request options are required to prevent em-http-request from inserting headers
      request_options = {
        compressed: false,
        head: {"user-agent" => nil},
        keepalive: true
      }
      EventMachine::HttpRequest.new("http://localhost:#{$server.port}/#{p}").get(**request_options)
    end

    http_array.each do |http|
      http.callback do
        puts http.response

        if http_array.all? { |h| h.response.to_s != '' }
          EventMachine.stop
        end
      end
    end
  end
end

When I run ruby make_requests.rb Hello

Then the output should contain:

Hello foo
Hello bar
Hello bazz

And the file "cassettes/em_http.yml" should contain YAML like:

--- 
http_interactions: 
- request: 
    method: get
    uri: http://localhost:7777/foo
    body: 
      encoding: UTF-8
      string: ""
    headers: {}
  response: 
    status: 
      code: 200
      message: OK
    headers: 
      Content-Type: 
      - text/html;charset=utf-8
      Content-Length: 
      - "9"
    body: 
      encoding: UTF-8
      string: Hello foo
  recorded_at: Tue, 01 Nov 2011 04:58:44 GMT
- request: 
    method: get
    uri: http://localhost:7777/bar
    body: 
      encoding: UTF-8
      string: ""
    headers: {}
  response: 
    status: 
      code: 200
      message: OK
    headers: 
      Content-Type: 
      - text/html;charset=utf-8
      Content-Length: 
      - "9"
    body: 
      encoding: UTF-8
      string: Hello bar
  recorded_at: Tue, 01 Nov 2011 04:58:44 GMT
- request: 
    method: get
    uri: http://localhost:7777/bazz
    body: 
      encoding: UTF-8
      string: ""
    headers: {}
  response: 
    status: 
      code: 200
      message: OK
    headers: 
      Content-Type: 
      - text/html;charset=utf-8
      Content-Length: 
      - "10"
    body: 
      encoding: UTF-8
      string: Hello bazz
  recorded_at: Tue, 01 Nov 2011 04:58:44 GMT
recorded_with: VCR 2.0.0

When I run ruby make_requests.rb Goodbye

Then the output should contain:

Hello foo
Hello bar
Hello bazz

MultiRequest

Given a file named "make_requests.rb" with:

ruby

require 'vcr_setup'

VCR.use_cassette('em_http') do
  EventMachine.run do
    multi = EventMachine::MultiRequest.new

    %w[ foo bar bazz ].each do |path|
      # Several request options are required to prevent em-http-request from inserting headers
      request_options = {
        compressed: false,
        head: {"user-agent" => nil},
        keepalive: true
      }
      multi.add(path, EventMachine::HttpRequest.new("http://localhost:#{$server.port}/#{path}").get(**request_options))
    end

    multi.callback do
      responses = Hash[multi.responses[:callback]]

      %w[ foo bar bazz ].each do |path|
        puts responses[path].response
      end

      EventMachine.stop
    end
  end
end

When I run ruby make_requests.rb Hello

Then the output should contain:

Hello foo
Hello bar
Hello bazz

And the file "cassettes/em_http.yml" should contain YAML like:

--- 
http_interactions: 
- request: 
    method: get
    uri: http://localhost:7777/foo
    body: 
      encoding: UTF-8
      string: ""
    headers: {}
  response: 
    status: 
      code: 200
      message: OK
    headers: 
      Content-Type: 
      - text/html;charset=utf-8
      Content-Length: 
      - "9"
    body: 
      encoding: UTF-8
      string: Hello foo
  recorded_at: Tue, 01 Nov 2011 04:58:44 GMT
- request: 
    method: get
    uri: http://localhost:7777/bar
    body: 
      encoding: UTF-8
      string: ""
    headers: {}
  response: 
    status: 
      code: 200
      message: OK
    headers: 
      Content-Type: 
      - text/html;charset=utf-8
      Content-Length: 
      - "9"
    body: 
      encoding: UTF-8
      string: Hello bar
  recorded_at: Tue, 01 Nov 2011 04:58:44 GMT
- request: 
    method: get
    uri: http://localhost:7777/bazz
    body: 
      encoding: UTF-8
      string: ""
    headers: {}
  response: 
    status: 
      code: 200
      message: OK
    headers: 
      Content-Type: 
      - text/html;charset=utf-8
      Content-Length: 
      - "10"
    body: 
      encoding: UTF-8
      string: Hello bazz
  recorded_at: Tue, 01 Nov 2011 04:58:44 GMT
recorded_with: VCR 2.0.0

When I run ruby make_requests.rb Goodbye

Then the output should contain:

Hello foo
Hello bar
Hello bazz