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 = server_channel.service
service.one { |request| :answer }

# On the client end: 
service = answer_channel.client(server_channel)

# 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| ... } ⇒ 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.

Yields:

  • (Object) —

    request made by the client. The return value of the block will be returned to the client.



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# File 'lib/cod/service.rb', line 46

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