Class: RJR::Nodes::Web

Inherits:
RJR::Node show all
Defined in:
lib/rjr/nodes/web.rb

Overview

Web node definition, listen for and invoke json-rpc requests via web requests

Clients should specify the hostname / port when listening for requests and when invoking them.

note the RJR javascript client also supports sending / receiving json-rpc messages over http

Examples:

Listening for json-rpc requests over tcp

# initialize node
server = RJR::Nodes::Web.new :node_id => 'server', :host => 'localhost', :port => '7777'

# register rjr dispatchers (see RJR::Dispatcher)
server.dispatcher.handle('hello') do |name|
  "Hello #{name}!"
end

# listen, and block
server.listen
server.join

Invoking json-rpc requests over http using rjr

client = RJR::Nodes::Web.new :node_id => 'client'
puts client.invoke('http://localhost:7777', 'hello', 'mo')

Invoking json-rpc requests over http using curl

$ curl -X POST http://localhost:7777 -d '{"jsonrpc":"2.0","method":"hello","params":["mo"],"id":"123"}'
> {"jsonrpc":"2.0","id":"123","result":"Hello mo!"}

Constant Summary collapse

RJR_NODE_TYPE = 
:web
PERSISTENT_NODE = 
false

Instance Attribute Summary

Attributes inherited from RJR::Node

#dispatcher, #message_headers, #node_id

Instance Method Summary collapse

Methods inherited from RJR::Node

#clear_event_handlers, em, #halt, #join, #node_type, #on, #persistent?, persistent?, tp

Constructor Details

#initialize(args = {}) ⇒ Web

Web initializer

Parameters:

  • args (Hash) (defaults to: {}) —

    the options to create the tcp node with

Options Hash (args):

  • :host (String) —

    the hostname/ip which to listen on

  • :port (Integer) —

    the port which to listen on



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# File 'lib/rjr/nodes/web.rb', line 104

def initialize(args = {})
   super(args)
   @host      = args[:host]
   @port      = args[:port]
end

Instance Method Details

#invoke(uri, rpc_method, *args) ⇒ Object

Instructs node to send rpc request, and wait for / return response

Implementation of RJR::Node#invoke

Do not invoke directly from em event loop or callback as will block the message subscription used to receive responses

Parameters:

  • uri (String) —

    location of node to send request to, should be in format of hostname:port

  • rpc_method (String) —

    json-rpc method to invoke on destination

  • args (Array) —

    array of arguments to convert to json and invoke remote method wtih



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# File 'lib/rjr/nodes/web.rb', line 153

def invoke(uri, rpc_method, *args)
  message = RequestMessage.new :method => rpc_method,
                               :args   => args,
                               :headers => @message_headers
  cb = lambda { |http|
    # TODO handle errors
    handle_message(http.response, http)
  }

  @@em.schedule do
    http = EventMachine::HttpRequest.new(uri).post :body => message.to_s,
                                                   :head => {'content-type' => 'application/json'}
    http.errback  &cb
    http.callback &cb
  end

  # will block until response message is received
  # TODO optional timeout for response ?
  result = wait_for_result(message)
  if result.size > 2
    raise Exception, result[2]
  end
  return result[1]
end

#listen ⇒ Object

Instruct Node to start listening for and dispatching rpc requests

Implementation of RJR::Node#listen



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# File 'lib/rjr/nodes/web.rb', line 135

def listen
  @@em.schedule do
    EventMachine::start_server(@host, @port, WebConnection, :rjr_node => self)
  end
  self
end

#notify(uri, rpc_method, *args) ⇒ Object

Instructs node to send rpc notification (immadiately returns / no response is generated)

Implementation of RJR::Node#notify

Parameters:

  • uri (String) —

    location of node to send request to, should be in format of hostname:port

  • rpc_method (String) —

    json-rpc method to invoke on destination

  • args (Array) —

    array of arguments to convert to json and invoke remote method wtih



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# File 'lib/rjr/nodes/web.rb', line 186

def notify(uri, rpc_method, *args)
  # will block until message is published
  published_l = Mutex.new
  published_c = ConditionVariable.new

  invoked = false
  message = NotificationMessage.new :method => rpc_method,
                                    :args   => args,
                                    :headers => @message_headers
  cb = lambda { |arg| published_l.synchronize { invoked = true ; published_c.signal }}
  @@em.schedule do
    http = EventMachine::HttpRequest.new(uri).post :body => message.to_s,
                                                   :head => {'content-type' => 'application/json'}
    http.errback  &cb
    http.callback &cb
  end
  published_l.synchronize { published_c.wait published_l unless invoked }
  nil
end

#send_msg(data, connection) ⇒ Object

Send data using specified http connection

Implementation of RJR::Node#send_msg



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# File 'lib/rjr/nodes/web.rb', line 117

def send_msg(data, connection)
  # we are assuming that since http connections
  # are not persistant, we should be sending a
  # response message here

  @@em.schedule  do
    resp = EventMachine::DelegatedHttpResponse.new(connection)
    #resp.status  = response.result.success ? 200 : 500
    resp.status = 200
    resp.content = data.to_s
    resp.content_type "application/json"
    resp.send_response
  end
end

#to_s ⇒ Object 



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# File 'lib/rjr/nodes/web.rb', line 110

def to_s
  "RJR::Nodes::Web<#{@node_id},#{@host},#{@port}>"
end