Class: ZmqJsonRpc::Client

Inherits:
Object
  • Object
show all
Defined in:
lib/simple_json_rpc/client.rb

Overview

You shall instanciate this class with a connect string which follows the zeroMQ conventions: api.zeromq.org/2-1:zmq-connect After connecting you can call any method on this class and it will be sent to the server. If something goes wrong ZmqJsonRpc::ClientError is thrown. timeout is measured in milliseconds.

NOTE The client does not keep the connection alive. For each request, a new connection is esablished and torn down after the response. This could become a performance issue.

Instance Method Summary collapse

Constructor Details

#initialize(connect = "tcp://127.0.0.1:49200", timeout = 10000, logger = nil) ⇒ Client

Returns a new instance of Client.


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# File 'lib/simple_json_rpc/client.rb', line 17

def initialize(connect="tcp://127.0.0.1:49200", timeout=10000, logger=nil)
  @connect = connect
  @timeout = timeout
  @logger = logger
end

Dynamic Method Handling

This class handles dynamic methods through the method_missing method

#method_missing(meth, *args, &block) ⇒ Object


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# File 'lib/simple_json_rpc/client.rb', line 62

def method_missing(meth, *args, &block)
  self.send_rpc(meth, args)
end

Instance Method Details

#send_rpc(method, params = []) ⇒ Object


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# File 'lib/simple_json_rpc/client.rb', line 23

def send_rpc(method, params=[])
  begin
    # connect socket
    @context = ZMQ::Context.new(1)
    @socket = @context.socket(ZMQ::REQ)
    @socket.connect(@connect)
    @socket.setsockopt(ZMQ::SNDTIMEO, @timeout)
    @socket.setsockopt(ZMQ::RCVTIMEO, @timeout)

    # build and send request
    req_id = SecureRandom.uuid
    request = {
      id: req_id,
      jsonrpc: "2.0",
      method: method.to_s,
      params: params
    }        
    @logger.debug "zmqjsonrpc client sends request: #{request.inspect})" unless @logger.nil?
    rc = @socket.send_string(request.to_json) # this will always succeed, even if the server is not reachable.

    # interpret response
    response = ''
    rc = @socket.recv_string(response)
    raise "Could talk to the server (server unreachable? time out?)" if rc < 0
    @logger.debug "zmqjsonrpc client got response: #{response})" unless @logger.nil?
    resjson = JSON.parse(response)
    # check response
    raise "Response's id did not match the sent id" if resjson["id"] != req_id
    raise "Response's version number is not supported (#{resjson["jsonrpc"]})" if resjson["jsonrpc"].strip != "2.0"
    raise "Server returned error (#{resjson["error"]["code"] || "?"}): #{resjson["error"]["message"]}\n#{resjson["error"]["data"]}" if resjson["error"]
    
    return resjson["result"]
  rescue => e
    raise ClientError, e.message
  ensure
    @socket.close rescue ''
  end
end