Class: NatsMessaging::NatsService

Inherits:
Object
  • Object
show all
Defined in:
lib/nats_messaging/nats_service.rb

Instance Method Summary collapse

Constructor Details

#initialize(nats_url, stream_name: nil, subjects: []) ⇒ NatsService

Returns a new instance of NatsService.



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# File 'lib/nats_messaging/nats_service.rb', line 6

def initialize(nats_url, stream_name: nil, subjects: [])
  @nats = NATS.connect(nats_url)
  if stream_name
    @js = @nats.jetstream
    create_stream(stream_name, subjects)
  end
  @subscriptions = {} # Store active subscriptions
end

Instance Method Details

#create_stream(stream_name, subjects) ⇒ Object

Create a stream



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# File 'lib/nats_messaging/nats_service.rb', line 16

def create_stream(stream_name, subjects)
  begin
    stream = @js.stream_info(stream_name)
    puts "NATS: Stream #{stream_name} already exists"
  rescue NATS::JetStream::Error::NotFound
    @js.add_stream(name: stream_name, subjects: subjects)
    puts "NATS: Stream #{stream_name} created"
  rescue => e
    puts "NATS: Failed to create stream: #{e.message}"
  end
end

#listen_and_reply(subject, reply_message) ⇒ Object

Listen to a subject and reply with a message using MessagePack



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# File 'lib/nats_messaging/nats_service.rb', line 101

def listen_and_reply(subject, reply_message)
  # Cancel active subscription if it already exists for this subject
  if @subscriptions[subject]
    @subscriptions[subject].unsubscribe
  end
  unpacked_data = nil
  begin
    # Create a new subscription
    puts "NATS: Listening on #{subject} with reply message: #{reply_message}"
    @subscriptions[subject] = @nats.subscribe(subject) do |msg|
      begin
        unpacked_data = MessagePack.unpack(msg.data) # Deserializar mensaje recibido
        puts "NATS: Received request on #{subject}: #{unpacked_data}"
        packed_reply = reply_message.to_msgpack # Serializar respuesta
        # Asegurar que msg.reply existe antes de responder
        if msg.reply
          @nats.publish(msg.reply, packed_reply)
          puts "NATS: Replied to #{subject} with message: #{reply_message}"
        else
          puts "NATS: No reply subject for #{subject}, cannot respond"
        end
        yield(msg.subject, unpacked_data) if block_given?
        unpacked_data
      rescue => e
        puts "NATS: Error while processing message: #{e.message}"
      end
    end
  rescue => e
    puts "NATS: Error while replying: #{e.message}"
  end
end

#process_received_message(msg, subject) ⇒ Object

Process received message



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# File 'lib/nats_messaging/nats_service.rb', line 71

def process_received_message(msg, subject)
  begin
    unpacked_data = MessagePack.unpack(msg.data)
    puts "NATS: Message received on #{subject}: #{unpacked_data}"
    unpacked_data
  rescue => e
    puts "NATS: Error while processing message: #{e.message}"
  end
end

#publish_message(subject, message) ⇒ Object

Publish a message to a subject using MessagePack



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# File 'lib/nats_messaging/nats_service.rb', line 29

def publish_message(subject, message)
  packed_message = message.to_msgpack # Serializar a MessagePack

  if @js
    begin
      ack = @js.publish(subject, packed_message)
      puts "NATS: Message sent to #{subject}: #{message}, ACK: #{ack.inspect}"
    rescue NATS::JetStream::Error::NotFound
      @nats.publish(subject, packed_message)
      puts "NATS: Stream not found, falling back to regular NATS publish"
    rescue => e
      puts "NATS: Unexpected error: #{e.message}"
    end
  else
    begin
      @nats.publish(subject, packed_message)
      puts "NATS: Message sent to #{subject}: #{message}, ACK: #{ack.inspect}"
    rescue => e
      puts "NATS: Unexpected error: #{e.message}"
    end
  end
end

#send_request(subject, message) ⇒ Object

Send a request to a subject and wait for response using MessagePack



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# File 'lib/nats_messaging/nats_service.rb', line 82

def send_request(subject, message)
  puts "NATS: Sending request to #{subject} with message: #{message}"
  begin
    packed_message = message.to_msgpack # Serializar el mensaje
    response = @nats.request(subject, packed_message, timeout: 5) # Timeout of 5 seconds
    unpacked_response = MessagePack.unpack(response.data) # Deserializar respuesta
    puts "NATS: Received reply: #{unpacked_response}"
    yield(subject, unpacked_response) if block_given?
    unpacked_response
  rescue NATS::IO::Timeout
    puts "NATS: Request timed out for subject: #{subject}"
    nil
  rescue => e
    puts "NATS: Unexpected error: #{e.message}"
    nil
  end
end

#subscribe_to_subject(subject, durable_name = "durable_name") ⇒ Object

Subscribe to a subject using MessagePack



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# File 'lib/nats_messaging/nats_service.rb', line 53

def subscribe_to_subject(subject, durable_name = "durable_name")
  puts "NATS: Subscribing to #{subject}"
  if @js
    @subscriptions[subject] = @js.subscribe(subject, durable: durable_name) do |msg|
                    unpacked_data = process_received_message(msg, subject)
                    yield(msg.subject, unpacked_data) if block_given?
                    unpacked_data
                   end
  else
    @subscriptions[subject] = @nats.subscribe(subject) do |msg|
                    unpacked_data = process_received_message(msg, subject)
                    yield(msg.subject, unpacked_data) if block_given?
                    unpacked_data
                   end
  end
end