Merge pull request #91 from devin-c/dynamic_discovery

Dynamic discovery for zmq server and client

README.md

@@ -303,8 +303,7 @@ any other filter calls which would run afterwards, as well as canceling
 invocation of the service method. Note: You must actually return false,
 not just a "falsey" value such as nil.
 
-__After Filters__ – There is no request shortcutting since the after
-filter runs after the request. Duh.
+__After Filters__ – No request shortcutting.
 
 #### Filter options
 
@@ -415,6 +414,44 @@ Many different options can be passed to the `.client` call above
 (such as `:timeout => 600`). See the `lib/protobuf/rpc/client.rb`
 and `lib/protobuf/rpc/service.rb` files for more documentation.
 
+### Dynamic Discovery (ZMQ Only)
+It is possible to setup the RPC server and client in a way that
+allows servers to be dynamically discovered by the client.
+
+#### In the client
+```ruby
+ServiceDirectory.start do |config|
+  config.port = 53000
+end
+
+# If your server also runs this code, it will default to the
+# given port when sending beacons and have its own service
+# directory. You can prevent this code from running on the
+# server if needed:
+unless defined? ::Protobuf::CLI
+  ServiceDirectory.start do |config|
+    config.port = 53000
+  end
+end
+```
+
+#### Starting the server
+```
+$ rpc_server --broadcast-beacons --beacon-port 53000 ...
+```
+
+The client will listen on the specified port for beacons broadcast
+by servers. Each beacon includes a list of services provided by the
+broadcasting server. The client randomly selects a server for the
+desired service each time a request is made.
+
+__CAUTION:__ When running multiple environments on a single network,
+e.g., qa and staging, be sure that each environment is setup with
+a unique beacon port; otherwise, clients in one environment _will_
+make requests to servers in the other environment.
+
+Check out {Protobuf::ServiceDirectory} for more details.
+
 ## 3. RPC Interop
 
 The main reason I wrote this gem was to provide a ruby implementation

lib/protobuf.rb

@@ -15,7 +15,7 @@ module Protobuf
   # Default is Socket as it has no external dependencies.
   DEFAULT_CONNECTOR = :socket
 
-	module_function
+  module_function
 
   # Client Host
   #
@@ -53,14 +53,14 @@ def self.connector_type=(type)
   # the Garbage Collector when handling an rpc request.
   # Once the request is completed, the GC is enabled again.
   # This optomization provides a huge boost in speed to rpc requests.
-	def self.gc_pause_server_request?
-		return @_gc_pause_server_request unless @_gc_pause_server_request.nil?
-		gc_pause_server_request = false
-	end
+  def self.gc_pause_server_request?
+    return @_gc_pause_server_request unless @_gc_pause_server_request.nil?
+    gc_pause_server_request = false
+  end
 
-	def self.gc_pause_server_request=(value)
-		@_gc_pause_server_request = !!value
-	end
+  def self.gc_pause_server_request=(value)
+    @_gc_pause_server_request = !!value
+  end
 
   # Print Deprecation Warnings
   #
@@ -72,14 +72,14 @@ def self.gc_pause_server_request=(value)
   # ENV['PB_IGNORE_DEPRECATIONS'] to a non-empty value.
   #
   # The rpc_server option will override the ENV setting.
-	def self.print_deprecation_warnings?
-		return @_print_deprecation_warnings unless @_print_deprecation_warnings.nil?
-		print_deprecation_warnings = ENV.key?('PB_IGNORE_DEPRECATIONS') ? false : true
-	end
-
-	def self.print_deprecation_warnings=(value)
-		@_print_deprecation_warnings = !!value
-	end
+  def self.print_deprecation_warnings?
+    return @_print_deprecation_warnings unless @_print_deprecation_warnings.nil?
+    print_deprecation_warnings = ENV.key?('PB_IGNORE_DEPRECATIONS') ? false : true
+  end
+
+  def self.print_deprecation_warnings=(value)
+    @_print_deprecation_warnings = !!value
+  end
 
 end