Class: Cod::Service

Inherits:
Object
  • Object
show all
Defined in:
lib/cod/service.rb

Overview

Cod::Service abstracts the pattern where you send a request to a central location (with possibly multiple workers handling requests) and receive an answer. It solves problems related to timeouts, getting your answer and not any kind of answer, etc…

Synopsis: 

# On the server end: 
service = Cod.service(central_location)
service.one { |request| :answer }

# On the client end: 
service = Cod.client(central_location, answer_here)

# asynchronous, no answer
service.notify [:a, :request]   # => nil
# has an answer: 
service.call [:a, :request]   # => :answer

Depending on the setup of the channels, this class can be used to implement intra- and interprocess communication, very close to RPC. There are two ways to build on this:

  • Using method_missing, implement real RPC on top. This is usually rather simple (since Cod does a lot of work), see github.com/kschiess/zack for an example of this.

  • Using the ‘case’ gem, implement servers in an (erlang) actor like fashion.

Direct Known Subclasses

Beanstalk::Service

Defined Under Namespace

Classes: Client

Instance Method Summary collapse

Constructor Details

#initialize(channel) ⇒ Service

Returns a new instance of Service.



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# File 'lib/cod/service.rb', line 32

def initialize(channel)
  @channel = channel
end

Instance Method Details

#one ⇒ Object

Waits until a request arrives on the service channel. Then reads that request and hands it to the block given. The block return value will be returned to the service client.

Use Cod::Client to perform the service call. This will keep track of messages sent and answers received and a couple of other things.



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# File 'lib/cod/service.rb', line 44

def one
  rq, answer_chan = @channel.get
  res = yield(rq)
  answer_chan.put res if answer_chan
end