Class: DripDrop::Node

Inherits:
Object
  • Object
show all
Defined in:
lib/dripdrop/node.rb,
lib/dripdrop/node/nodelet.rb

Defined Under Namespace

Classes: Nodelet

Constant Summary

ZCTX =
ZMQ::Context.new 1

Instance Attribute Summary (collapse)

Class Method Summary (collapse)

Instance Method Summary (collapse)

Constructor Details

- (Node) initialize(opts = {}, &block)

Returns a new instance of Node



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# File 'lib/dripdrop/node.rb', line 29

def initialize(opts={},&block)
  @block      = block
  @thread     = nil # Thread containing the reactors
  @routing    = {}  # Routing table
  @run_list   = opts['run_list'] || opts[:run_list] || nil  #List of nodelets to run
  @run_list   = @run_list.map(&:to_sym) if @run_list
  @debug      = opts[:debug]
  @recipients_for       = {}
  @handler_default_opts = {:debug => @debug}
  @nodelets   = {}  # Cache of registered nodelets
  @zctx = ZCTX
end

Instance Attribute Details

- (Object) debug

Returns the value of attribute debug



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# File 'lib/dripdrop/node.rb', line 27

def debug
  @debug
end

- (Object) nodelets (readonly)

Returns the value of attribute nodelets



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# File 'lib/dripdrop/node.rb', line 26

def nodelets
  @nodelets
end

- (Object) routing (readonly)

Returns the value of attribute routing



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# File 'lib/dripdrop/node.rb', line 26

def routing
  @routing
end

- (Object) run_list (readonly)

Returns the value of attribute run_list



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# File 'lib/dripdrop/node.rb', line 26

def run_list
  @run_list
end

- (Object) zm_reactor (readonly)

Returns the value of attribute zm_reactor



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# File 'lib/dripdrop/node.rb', line 26

def zm_reactor
  @zm_reactor
end

Class Method Details

+ (Object) error_handler(e)

Catch all error handler Global to all DripDrop Nodes



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# File 'lib/dripdrop/node.rb', line 310

def self.error_handler(e)
  $stderr.write "#{e.class}: #{e.message}\n\t#{e.backtrace.join("\n\t")}"
end

Instance Method Details

- (Object) action

When subclassing DripDrop::Node you probably want to define this method Otherwise it will attempt to run the @block passed into DripDrop::Node.new



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# File 'lib/dripdrop/node.rb', line 64

def action
  if @block
    self.instance_eval(&@block)
  else
    raise "Could not start, no block or action specified"
  end
end

- (Object) http_client(address, opts = {})

An EM HTTP client. Example:

client = http_client(addr)
client.send_message(:name => 'name', :body => 'hi') do |resp_msg|
  puts resp_msg.inspect
end


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# File 'lib/dripdrop/node.rb', line 266

def http_client(address,opts={})
  uri     = URI.parse(address)
  h_opts  = handler_opts_given(opts)
  DripDrop::HTTPClientHandler.new(uri, h_opts)
end

- (Object) http_server(address, opts = {}, &block)

Starts a new Thin HTTP server listening on address. Can have an on_receive handler that gets passed msg and response args.

http_server(addr) {|msg,response| response.send_message(msg)}


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# File 'lib/dripdrop/node.rb', line 254

def http_server(address,opts={},&block)
  uri     = URI.parse(address)
  h_opts  = handler_opts_given(opts)
  DripDrop::HTTPServerHandler.new(uri, h_opts,&block)
end

- (Object) join

If the reactor has started, this blocks until the thread running the reactor joins. This should block forever unless stop is called.



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# File 'lib/dripdrop/node.rb', line 75

def join
  if @thread
    @thread.join
  else
    raise "Can't join on a node that isn't yet started"
  end
end

- (Object) nodelet(name, klass = Nodelet, *configure_args, &block)

Nodelets are a way of segmenting a DripDrop::Node. This can be used for both organization and deployment. One might want the production deployment of an app to be broken across multiple servers or processes for instance:

nodelet :heartbeat do |nlet|
  nlet.route :ticker, :zmq_publish, 'tcp://127.0.0.1', :bind
  EM::PeriodicalTimer.new(1) do
    nlet.ticker.send_message(:name => 'tick')
  end
end

Nodelets can also be subclassed, for instance:

class SpecialNodelet < DripDrop::Node::Nodelet
  def action
    nlet.route :ticker, :zmq_publish, 'tcp://127.0.0.1', :bind
    EM::PeriodicalTimer.new(1) do
      nlet.ticker.send_message(:name => 'tick')
    end
  end
end

nodelet :heartbeat, SpecialNodelet

If you specify a block, Nodelet#action will be ignored and the block will be run

Nodelets are made available as instance methods on the current DripDrop::Nodelet Object, so the following works as well:

nodelet :mynodelet

mynodelet.route :route_name, :zmq_xreq, 'tcp://127.0.0.1:2000', ;bind


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# File 'lib/dripdrop/node.rb', line 157

def nodelet(name,klass=Nodelet,*configure_args,&block)
  # If there's a run list, only run nodes in that list
  return nil if @run_list && !@run_list.include?(name.to_sym)
   
  nlet = @nodelets[name] ||= klass.new(self,name,*configure_args)
  
  # Define a method returning the nodelet in the current node
  unless respond_to?(name)
   (class << self; self; end).class_eval do
      define_method(name) { nlet }
    end
  end
   
  if block
    block.call(nlet)
  else
    nlet.action
  end
  nlet
end

- (Object) recv_internal(dest, identifier, &block)

Defines a subscriber to the channel dest, to receive messages from send_internal. identifier is a unique identifier for this receiver. The identifier can be used by remove_recv_internal



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# File 'lib/dripdrop/node.rb', line 293

def recv_internal(dest,identifier,&block)
  if @recipients_for[dest]
    @recipients_for[dest][identifier] =  block
  else
    @recipients_for[dest] = {identifier => block}
  end
end

- (Object) remove_recv_internal(dest, identifier)

Deletes a subscriber to the channel dest previously identified by a reciever created with recv_internal



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# File 'lib/dripdrop/node.rb', line 303

def remove_recv_internal(dest,identifier)
  return false unless @recipients_for[dest]
  @recipients_for[dest].delete(identifier)
end

- (Object) route(name, handler_type, *handler_args)

Defines a new route. Routes are the recommended way to instantiate handlers. For example:

route :stats_pub, :zmq_publish, 'tcp://127.0.0.1:2200', :bind
route :stats_sub, :zmq_subscribe, stats_pub.address, :connect

Will make the following methods available within the reactor block:

stats_pub  # A regular zmq_publish handler
:stats_sub # A regular zmq_subscribe handler

See the docs for routes_for for more info in grouping routes for nodelets and maintaining sanity in larger apps



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# File 'lib/dripdrop/node.rb', line 95

def route(name,handler_type,*handler_args)
  route_full(nil, name, handler_type, *handler_args)
end

- (Object) route_full(nodelet, name, handler_type, *handler_args)

Probably not useful for most, apps. This is used internally to create a route for a given nodelet.



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# File 'lib/dripdrop/node.rb', line 101

def route_full(nodelet, name, handler_type, *handler_args)
  # If we're in a route_for block, prepend appropriately
  full_name = (nodelet && nodelet.name) ? "#{nodelet.name}_#{name}".to_sym : name
  
  handler = self.send(handler_type, *handler_args)
  @routing[full_name] = handler
  
  # Define the route name as a singleton method
  (class << self; self; end).class_eval do
    define_method(full_name) { handler }
  end
  
  handler
end

- (Object) routes_for(nodelet_name, &block)

DEPRECATED, will be deleted in 0.8



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# File 'lib/dripdrop/node.rb', line 117

def routes_for(nodelet_name,&block)
  $stderr.write "routes_for is now deprecated, use nodelet instead"
  nlet = nodelet(nodelet_name,&block)
  block.call(nlet)
end

- (Object) send_internal(dest, data)

An inprocess pub/sub queue that works similarly to EM::Channel, but has manually specified identifiers for subscribers letting you more easily delete subscribers without crazy id tracking.

This is useful for situations where you want to broadcast messages across your app, but need a way to properly delete listeners.

dest is the name of the pub/sub channel. data is any type of ruby var you'd like to send.



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# File 'lib/dripdrop/node.rb', line 281

def send_internal(dest,data)
  return false unless @recipients_for[dest]
  blocks = @recipients_for[dest].values
  return false unless blocks
  blocks.each do |block|
    block.call(data)
  end
end

- (Object) start

Starts the reactors and runs the block passed to initialize. This is non-blocking.



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# File 'lib/dripdrop/node.rb', line 44

def start
  @thread = Thread.new do
    EM.error_handler {|e| self.class.error_handler e}
    EM.run { action }
  end
end

- (Object) start!

Blocking version of start, equivalent to start then join



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# File 'lib/dripdrop/node.rb', line 52

def start!
  self.start
  self.join
end

- (Object) stop

Stops the reactors. If you were blocked on #join, that will unblock.



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# File 'lib/dripdrop/node.rb', line 58

def stop
  EM.stop
end

- (Object) websocket(*args)

DEPRECATED: Use websocket_server



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# File 'lib/dripdrop/node.rb', line 246

def websocket(*args)
  $stderr.write "DripDrop#websocket handler is deprecated, use DripDrop#websocket_server"
  websocket_server(*args)
end

- (Object) websocket_server(address, opts = {})

Binds an EM websocket server connection to address. takes blocks for on_open, on_receive, on_close and on_error.

For example on_receive could be used to echo incoming messages thusly:

websocket_server(addr).on_open {|conn|
  ws.send_message(:name => 'ws_open_ack')
}.on_receive {|msg,conn|
  conn.send(msg)
}.on_close {|conn|
}.on_error {|reason,conn|
}

The ws object that's passed into the handlers is not the DripDrop::WebSocketHandler object, but an em-websocket object.



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# File 'lib/dripdrop/node.rb', line 239

def websocket_server(address,opts={})
  uri     = URI.parse(address)
  h_opts  = handler_opts_given(opts)
  DripDrop::WebSocketHandler.new(uri,h_opts)
end

- (Object) zmq_m2(addresses, opts = {}, &block)



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# File 'lib/dripdrop/node.rb', line 178

def zmq_m2(addresses, opts={}, &block)
  zmq_handler(DripDrop::Mongrel2Handler, [ZMQ::PULL, ZMQ::PUB], addresses, [:connect, :connect], opts)
end

- (Object) zmq_publish(address, socket_ctype, opts = {})

Creates a ZMQ::PUB type socket, can only send messages via send_message



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# File 'lib/dripdrop/node.rb', line 190

def zmq_publish(address,socket_ctype,opts={})
  zmq_handler(DripDrop::ZMQPubHandler,ZMQ::PUB,address,socket_ctype,opts)
end

- (Object) zmq_pull(address, socket_ctype, opts = {}, &block)

Creates a ZMQ::PULL type socket. Can only receive messages via on_receive



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# File 'lib/dripdrop/node.rb', line 195

def zmq_pull(address,socket_ctype,opts={},&block)
  zmq_handler(DripDrop::ZMQPullHandler,ZMQ::PULL,address,socket_ctype,opts)
end

- (Object) zmq_push(address, socket_ctype, opts = {})

Creates a ZMQ::PUSH type socket, can only send messages via send_message



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# File 'lib/dripdrop/node.rb', line 200

def zmq_push(address,socket_ctype,opts={})
  zmq_handler(DripDrop::ZMQPushHandler,ZMQ::PUSH,address,socket_ctype,opts)
end

- (Object) zmq_subscribe(address, socket_ctype, opts = {}, &block)

Creates a ZMQ::SUB type socket. Can only receive messages via on_receive. zmq_subscribe sockets have a topic_filter option, which restricts which messages they can receive. It takes a regexp as an option.



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# File 'lib/dripdrop/node.rb', line 185

def zmq_subscribe(address,socket_ctype,opts={},&block)
  zmq_handler(DripDrop::ZMQSubHandler,ZMQ::SUB,address,socket_ctype,opts)
end

- (Object) zmq_xrep(address, socket_ctype, opts = {})

Creates a ZMQ::XREP type socket, both sends and receivesc XREP sockets are extremely powerful, so their functionality is currently limited. XREP sockets in DripDrop can reply to the original source of the message.

Receiving with XREP sockets in DripDrop is different than other types of sockets, on_receive passes 2 arguments to its callback, message, and response. A minimal example is shown below:

zmq_xrep(z_addr, :bind).on_receive do |message,response|
  response.send_message(message)
end


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# File 'lib/dripdrop/node.rb', line 216

def zmq_xrep(address,socket_ctype,opts={})
  zmq_handler(DripDrop::ZMQXRepHandler,ZMQ::XREP,address,socket_ctype,opts)
end

- (Object) zmq_xreq(address, socket_ctype, opts = {})

See the documentation for zmq_xrep for more info



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# File 'lib/dripdrop/node.rb', line 221

def zmq_xreq(address,socket_ctype,opts={})
  zmq_handler(DripDrop::ZMQXReqHandler,ZMQ::XREQ,address,socket_ctype,opts)
end