Class: OpenC3::WebSocketApi

Inherits:
Object show all
Defined in:
lib/openc3/script/web_socket_api.rb

Overview

Base class - Do not use directly

Direct Known Subclasses

CmdTlmWebSocketApi, ScriptWebSocketApi

Constant Summary collapse

USER_AGENT = 
'OpenC3 / v7 (ruby/openc3/lib/io/web_socket_api)'.freeze
DEFAULT_OPTIONS =

Options every websocket api accepts, and their defaults. Subclasses forward **options rather than restating these.

{
  write_timeout: 10.0,
  read_timeout: 10.0,
  connect_timeout: 5.0,
  authentication: nil,
}.freeze

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(url:, scope: $openc3_scope, **options, &block) ⇒ WebSocketApi

Create the WebsocketApi object. If a block is given will automatically connect/disconnect

Parameters:

  • The cable URL to connect to

  • (defaults to: $openc3_scope)

    The scope to connect with

  • See DEFAULT_OPTIONS

Raises:



51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
 
# File 'lib/openc3/script/web_socket_api.rb', line 51

def initialize(url:, scope: $openc3_scope, **options, &block)
  # Restore the arity checking that explicit keyword arguments used to give
  # us, so a typo'd option is an error rather than a silently ignored value
  unknown = options.keys - DEFAULT_OPTIONS.keys
  raise ArgumentError, "unknown keyword#{'s' if unknown.length > 1}: #{unknown.join(', ')}" unless unknown.empty?

  options = DEFAULT_OPTIONS.merge(options)
  # $openc3_scope is only set inside the Script Runner / microservice
  # environment. Fall back to OPENC3_SCOPE (mirrors the Python client) so a
  # bare `ruby script.rb` doesn't send a nil scope that the server rejects.
  @scope = scope || ENV.fetch('OPENC3_SCOPE', 'DEFAULT')
  @authentication = options[:authentication] || generate_auth()
  @url = url
  @write_timeout = options[:write_timeout]
  @read_timeout = options[:read_timeout]
  @connect_timeout = options[:connect_timeout]
  @subscribed = false
  if block_given?
    begin
      connect()
      yield self
    ensure
      disconnect()
    end
  end
end

Class Method Details

.cable_url(env_prefix:, default_hostname:, default_port:, path:) ⇒ Object

Build a cable URL from the standard OPENC3 environment variable quartet: _SCHEMA, _HOSTNAME, _CABLE_PORT, _PORT



34
35
36
37
38
39
40
41
42
43
44
 
# File 'lib/openc3/script/web_socket_api.rb', line 34

def self.cable_url(env_prefix:, default_hostname:, default_port:, path:)
  schema = ENV.fetch("#{env_prefix}_SCHEMA", 'http')
  # Normalize to the websocket schemes (mirrors the Python client). The
  # websocket gem accepts http/https too, but ws/wss is what the URL
  # actually is and Python's websockets library rejects anything else.
  schema = 'ws' if schema == 'http'
  schema = 'wss' if schema == 'https'
  hostname = ENV.fetch("#{env_prefix}_HOSTNAME", nil) || (ENV['OPENC3_DEVEL'] ? '127.0.0.1' : default_hostname)
  port = (ENV.fetch("#{env_prefix}_CABLE_PORT", nil) || ENV.fetch("#{env_prefix}_PORT", default_port)).to_i
  return "#{schema}://#{hostname}:#{port}#{path}"
end

Instance Method Details

#check_protocol_frame(json_hash) ⇒ Object

Apply the protocol rules shared by #read and #wait_for_subscribed



233
234
235
236
237
238
239
240
241
242
243
244
245
 
# File 'lib/openc3/script/web_socket_api.rb', line 233

def check_protocol_frame(json_hash)
  case json_hash['type']
  when 'reject_subscription'
    raise "Subscription Rejected"
  when 'disconnect'
    # Any other disconnect reason is not fatal; the caller keeps reading
    raise "Unauthorized" if json_hash['reason'] == 'unauthorized'
  else
    # ping, welcome, confirm_subscription and anything new the server adds
    # are informational only
    nil
  end
end

#connect ⇒ Object

Connect to the websocket with authorization in query params



176
177
178
179
180
181
182
183
184
185
 
# File 'lib/openc3/script/web_socket_api.rb', line 176

def connect
  disconnect()
  final_url = @url + "?scope=#{@scope}"
  @stream = WebSocketClientStream.new(final_url, @write_timeout, @read_timeout, @connect_timeout)
  @stream.headers = {
    'Sec-WebSocket-Protocol' => 'actioncable-v1-json, actioncable-unsupported',
    'User-Agent' => USER_AGENT
  }
  @stream.connect
end

#connected? ⇒ Boolean

Are we connected?

Returns:



188
189
190
191
192
193
194
 
# File 'lib/openc3/script/web_socket_api.rb', line 188

def connected?
  if @stream
    @stream.connected?
  else
    false
  end
end

#disconnect ⇒ Object

Disconnect from the websocket and attempt to send unsubscribe message



197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
 
# File 'lib/openc3/script/web_socket_api.rb', line 197

def disconnect
  if connected?()
    begin
      unsubscribe()
    rescue
      # Oh well, we tried
    end
    # unsubscribe only clears this after a successful write. The stream is
    # being closed regardless, so it cannot remain subscribed.
    @subscribed = false
    @stream.disconnect
  else
    @subscribed = false
  end
end

#generate_auth ⇒ Object

Generate the appropriate token for OpenC3



248
249
250
251
252
253
254
255
256
257
258
 
# File 'lib/openc3/script/web_socket_api.rb', line 248

def generate_auth
  if ENV['OPENC3_API_TOKEN'].nil? and ENV['OPENC3_API_USER'].nil?
    if ENV['OPENC3_API_PASSWORD']
      return OpenC3Authentication.new()
    else
      raise "Environment Variables Not Set for Authentication"
    end
  else
    return OpenC3KeycloakAuthentication.new(ENV['OPENC3_KEYCLOAK_URL'])
  end
end

#parse_message(message) ⇒ Object

Parse a server frame. Kept in one place so the JSON options cannot drift between the two readers.



228
229
230
 
# File 'lib/openc3/script/web_socket_api.rb', line 228

def parse_message(message)
  return JSON.parse(message, allow_nan: true, create_additions: true)
end

#read(ignore_protocol_messages: true, timeout: nil) ⇒ Object

Read the next message with json parsing, filtering, and timeout support



85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
 
# File 'lib/openc3/script/web_socket_api.rb', line 85

def read(ignore_protocol_messages: true, timeout: nil)
  start_time = Time.now
  while true
    message = read_message()
    # Empty string is a normal end-of-stream signal when ActionCable / anycable-go
    # closes the WS. Treat it the same as nil so consumer `while (resp = api.read)`
    # loops exit cleanly instead of hitting JSON::ParserError on JSON.parse("").
    return nil if message.nil? || message.empty?

    json_hash = parse_message(message)
    if ignore_protocol_messages
      type = json_hash['type']
      if type # ping, welcome, confirm_subscription, reject_subscription, disconnect
        check_protocol_frame(json_hash)
        if timeout
          end_time = Time.now
          if (end_time - start_time) > timeout
            raise Timeout::Error, "No Data Timeout"
          end
        end
        if defined? RunningScript and RunningScript.instance
          raise StopScript if RunningScript.instance.stop?
        end
        next
      end
    end
    return json_hash['message']
  end
end

#read_message ⇒ Object

Read the next message without filtering / parsing



79
80
81
82
 
# File 'lib/openc3/script/web_socket_api.rb', line 79

def read_message
  subscribe()
  return @stream.read
end

#subscribe ⇒ Object

Will subscribe to the channel based on @identifier



116
117
118
119
120
121
122
123
124
125
126
 
# File 'lib/openc3/script/web_socket_api.rb', line 116

def subscribe
  unless @subscribed
    # Token is part of the identifier so it surfaces as params[:token] in
    # ApplicationCable::Channel#authenticate_subscription! — ActionCable
    # ignores `data` on `subscribe` commands.
    @identifier['token'] = @authentication.token(include_bearer: false)
    write_command('subscribe')
    @subscribed = true
    wait_for_subscribed()
  end
end

#unsubscribe ⇒ Object

Will unsubscribe to the channel based on @identifier



150
151
152
153
154
155
 
# File 'lib/openc3/script/web_socket_api.rb', line 150

def unsubscribe
  if @subscribed
    write_command('unsubscribe')
    @subscribed = false
  end
end

#wait_for_subscribed ⇒ Object

Block until the server confirms the subscription. ActionCable / anycable-go process 'subscribe' and 'message' commands as independent RPCs, so an action (add/remove) written immediately after subscribe can reach StreamingChannel#add before the subscription's broadcaster exists, where it is silently dropped (a no-op) and no data ever streams. Waiting for confirm_subscription guarantees the broadcaster is ready before any action is written.



135
136
137
138
139
140
141
142
143
144
145
146
147
 
# File 'lib/openc3/script/web_socket_api.rb', line 135

def wait_for_subscribed
  while true
    message = @stream.read
    # Unlike #read, end-of-stream is fatal here rather than a nil return:
    # a socket that closes mid-handshake leaves nothing to carry on with.
    raise "WebSocket closed before subscription was confirmed" if message.nil? || message.empty?

    json_hash = parse_message(message)
    check_protocol_frame(json_hash)
    # Ignore welcome / ping and keep waiting for confirmation
    return if json_hash['type'] == 'confirm_subscription'
  end
end

#write(data) ⇒ Object

General write to the websocket



170
171
172
173
 
# File 'lib/openc3/script/web_socket_api.rb', line 170

def write(data)
  subscribe()
  @stream.write(data)
end

#write_action(data_hash) ⇒ Object

Send an ActionCable command



158
159
160
161
162
163
164
165
166
167
 
# File 'lib/openc3/script/web_socket_api.rb', line 158

def write_action(data_hash)
  # Subscribe first so the token is present in @identifier before we
  # serialize it below. ActionCable matches a 'message' command to its
  # subscription by the exact identifier string; if subscribe() injected the
  # token only afterward, the message identifier (no token) would not match
  # the subscription identifier (with token) and the server would silently
  # ignore the action.
  subscribe()
  write_command('message', data_hash)
end

#write_command(command, data_hash = nil) ⇒ Object

Write an ActionCable command frame for the current @identifier. Writes straight to the stream because the callers have already subscribed (and subscribe itself must not recurse through write).



218
219
220
221
222
223
224
 
# File 'lib/openc3/script/web_socket_api.rb', line 218

def write_command(command, data_hash = nil)
  json_hash = {}
  json_hash['command'] = command
  json_hash['identifier'] = JSON.generate(@identifier, allow_nan: true)
  json_hash['data'] = JSON.generate(data_hash, allow_nan: true) if data_hash
  @stream.write(JSON.generate(json_hash, allow_nan: true))
end