Simple Queue Service

Gemfile

@@ -3,6 +3,11 @@ source "http://rubygems.org"
 # Specify your gem's dependencies in em-aws.gemspec
 gemspec
 
-# 2012-02-06:
-# Use latest Webmock until the hash_including functionality is released
-gem "webmock", git: 'https://github.com/bblimke/webmock.git'
+group :development do
+  # 2012-02-06:
+  # Use latest Webmock until the hash_including functionality is released
+  gem "webmock", git: 'https://github.com/bblimke/webmock.git'
+  gem "guard-rspec"
+  gem "growl"
+end
+

Guardfile

@@ -0,0 +1,10 @@
+# A sample Guardfile
+# More info at https://github.com/guard/guard#readme
+
+guard 'rspec', version: 2, cli: '-c -f doc' do
+  watch(%r{^spec/.+_spec\.rb$})
+  watch(%r{^lib/(.+)\.rb$})     { |m| "spec/#{m[1]}_spec.rb" }
+  watch('spec/spec_helper.rb')  { "spec" }
+  watch(%r{^spec/support/(.+)\.rb$})                  { "spec" }
+end
+

README.markdown

@@ -83,19 +83,38 @@ All request blocks are passed a **Response** object.  If the query succeeded (i.
 
 If the query failed (usually with a status in the 400s), the `errback` blocks are called.  The response is a subclass of **FailureResponse** and contains the error `:code` and `:message` returned by Amazon.  Attempting to reference other attributes raises an exception with the same information. 
 
-## Miscellany ##
+## General Notes ##
+
+The following behavior is true for all AWS services:
 
 * **EM::AWS** uses HTTP POST by default for all Query Protocol calls. It is possible to override this by passing `method: :get` on service object initialization, but this will limit the amount of data that can be passed.
 * SSL is enabled by default. You can disable it globally with `EM::AWS.ssl = false` or locally by passing `ssl: false` on service object initialization.
 * XML response values that include lists of `<member>` elements will be flattened into arrays.
 * XML response values that include `<key>` and `<value>` pairs will be flattened into Ruby hashes.
-* Some services (e.g. SQS) allow you to set multiple attributes in a single call.  Passing a hash as the value of a query parameter will automatically expand to the appropriate `Attribute.1.Name`, `Attribute.1.Value`, etc. parameters.
-* Do not taunt Happy Fun Ball.
 * Network errors and Amazon HTTP 500 errors are automatically retried; the number of attempts can be set with the `EM::AWS.retries` attribute. (The default is 10.) 
 * The retry delay follows a Fibonacci sequence: the first two retries are 1 second apart, then 2 seconds, then 3, then 5, etc.  A full cycle of 10 retries thus takes 143 seconds. If the error is not resolved by that time, it will be returned as a **FailureResponse**.
 * If any query receives a `Throttling` response from Amazon, it will also be retried, and subsequent calls to the same service will be subject to a 1 second delay.  The delay will expire if two minutes pass without a throttling error.
 
+## SQS ##
+
+The Simple Queue Service behaves differently from most other Amazon services, in that most calls must be made to a _queue URL_ rather than a root path.  This must be supplied on initialization of the **EM::AWS::SQS** object.  If you already know the URL of the queue you want to work with, you can simply pass it with the `:url` parameter:
+
+    queue = EM::AWS::SQS.new url: 'https://sqs.us-east-1.amazonaws.com/1234567890/My-Interesting-Queue'
+
+If you know a queue's name but not its URL, you can use the `.get` class method to call 'GetQueueUrl' and create the proper SQS object:
+
+    queue = EM::AWS::SQS.get 'My-Interesting-Queue'
+
+You can also create a queue that doesn't exist yet using the `.create` class method, passing any optional attributes as a hash:
+
+    queue = EM::AWS::SQS.create 'My-Interesting-Queue', 
+        visibility_timeout: 120,
+        maximum_message_size: 8192
+
+(If a queue with that name already exists, the `.create` class method has the same net effect as `.get`, except that Amazon will return an error if you pass any attributes that are different from the ones already set.)
 
 
+      
+
 
 

Rakefile

@@ -1 +1,46 @@
 require "bundler/gem_tasks"
+$:.unshift File.join(File.dirname(__FILE__), 'lib')
+require 'em-aws'
+
+
+namespace :clean do
+  EM::AWS.aws_access_key_id = ENV['AWS_ACCESS_KEY_ID']
+  EM::AWS.aws_secret_access_key = ENV['AWS_SECRET_ACCESS_KEY']
+
+  desc "Deletes any leftover SQS queues (EM-AWS-Test-Queue-*)"
+  task :queues do
+    EM.run do
+      q = EM::Queue.new
+      sqs = EM::AWS::SQS.new
+      puts "Retrieving test queues..."
+      list = sqs.list_queues(queue_name_prefix: 'EM-AWS-Test-Queue') 
+      list.callback {|r| q.push *Array(r[:queue_url])}
+      list.errback do |r|
+        puts "ERROR: #{r.error}"
+        EM.stop
+      end
+
+      EM.add_periodic_timer(0.1) do 
+        q.pop do |url|
+          puts "Deleting #{url}..."
+          queue = EM::AWS::SQS.new url: url
+          del = queue.delete_queue 
+          del.callback {|r| puts "  --Deleted #{url}"}
+          del.errback do |r| 
+            puts "  **ERROR: #{r.error} on #{url}"
+            q.push url
+          end
+        end
+      end
+
+      EM.add_periodic_timer(5) do
+        if q.empty?
+          puts "All queues deleted."
+          EM.stop
+        end
+      end
+
+    end
+  end
+
+end

lib/em-aws/query.rb

@@ -19,7 +19,7 @@ module Query
       def initialize(options = {})
         super
         @method = options.delete(:method) || :post
-        @signer = SignatureV2.new(aws_access_key_id, aws_secret_access_key, method, endpoint) if aws_access_key_id && aws_secret_access_key
+        @signer = SignatureV2.new(aws_access_key_id, aws_secret_access_key, method, url) if aws_access_key_id && aws_secret_access_key
       end
 
       def call(action, params = {}, &block)

lib/em-aws/query/response_parser.rb

@@ -68,7 +68,11 @@ def collapse_stack(value)
             @stack.last[value[:key]] = value[:value]
           when Symbol
             if @stack.last.is_a?(Hash)
-              @stack.last[element] = value
+              if @stack.last.has_key?(element)
+                @stack.last[element] = Array(@stack.last[element]) << value
+              else
+                @stack.last[element] = value
+              end
             else 
               raise "I don't know how to add #{element} to #{@stack}"
             end

lib/em-aws/query/signature_v2.rb

@@ -10,11 +10,11 @@ module Query
       class SignatureV2
         attr_reader :access_key, :secret_key, :method, :host, :path
 
-        def initialize(access_key, secret_key, method, endpoint)
+        def initialize(access_key, secret_key, method, url)
           @access_key = access_key
           @secret_key = secret_key
           @method = method
-          if endpoint =~ %r!^(https?://)?([^/]+)(/[^?]*)!
+          if url =~ %r!^(https?://)?([^/]+)(/[^?]*)!
             @host, @path = $2, $3
           end
         end

lib/em-aws/service.rb

@@ -17,6 +17,7 @@ class Service
                   :aws_secret_access_key,
                   :region,
                   :ssl,
+                  :path,
                   :options
 
       def initialize(options = {})
@@ -29,25 +30,25 @@ def initialize(options = {})
         else
           @ssl = EventMachine::AWS.ssl
         end
-        @endpoint = options.delete(:endpoint)
+        @url = options.delete(:url)
         @options = options
       end
 
       def service
         self.class.name[/.*::(?<class>.+)/, :class].downcase
       end
 
-      def endpoint
-        @endpoint ||= "#{ssl ? 'https' : 'http'}://#{service}.#{region}.amazonaws.com/"
+      def url
+        @url ||= "#{ssl ? 'https' : 'http'}://#{service}.#{region}.amazonaws.com/#{path}"
       end
 
-      protected
+      private
 
       def send_request(request, &block)
         if request.method == :get
-          http_request = EventMachine::HttpRequest.new(endpoint).get query: request.params
+          http_request = EventMachine::HttpRequest.new(self.url).get query: request.params
         else
-          http_request = EventMachine::HttpRequest.new(endpoint).send request.method, body: request.params
+          http_request = EventMachine::HttpRequest.new(self.url).send request.method, body: request.params
         end
 
         http_request.errback do |raw_response|

lib/em-aws/sqs.rb

@@ -2,8 +2,41 @@
 
 module EventMachine
   module AWS
+
+    # NOTE: If you want to work with an individual queue, be sure to specify either the 
+    # :url parameter for the queue URL or the :queue_name.
     class SQS < Service
       include Query
+
+      API_VERSION='2011-10-01'
+
+      def queue_name
+        url[/https?:\/\/.*?\/(.+)/,1]      
+      end
+
+      # Retrieves an SQS object by queue name. Returns nil if the queue can't be found.
+      def self.get(name)
+        url, retriever = nil, self.new
+        retriever.get_queue_url(queue_name: name) {|r| url = r.queue_url}
+        if url
+          self.new url: url
+        else
+          nil
+        end
+      end
+
+      # Creates a queue by name and returns an SQS object pointing to it.  This operation
+      # is idempotent (i.e. will return the same object) if the queue name already exists,
+      # so long as no attributes are different.
+      def self.create(name)
+        url, creator = nil, self.new
+        creator.create_queue(queue_name: name) {|r| url = r.queue_url}
+        if url
+          self.new url: url
+        else
+          nil
+        end
+      end
     end
   end
 end

spec/em-aws/query/query_result_spec.rb

@@ -26,6 +26,10 @@
     subject.topics.first.should == {topic_arn: 'arn:aws:sns:us-east-1:429167422711:EM-AWS-Test-Topic'}
   end
 
+  it "treats multiple elements with the same name as an array" do
+    subject.plural_thing.should == [17, 'hello', 9.2]
+  end
+
   it "handles key/value entry pairs" do
     subject[:attributes].should have(3).keys
     subject.attributes['Foo'].should == 'Bar'

spec/em-aws/sqs_spec.rb

@@ -1,30 +1,53 @@
 require_relative '../spec_helper'
 
-describe EventMachine::AWS::SQS, :live do
-  subject {EM::AWS::SQS.new}
+describe EventMachine::AWS::SQS do
 
   before(:all) do
-    queue_name = "EM-AWS-Test-Queue-#{Time.now.to_i}"
-    create_response = subject.create_queue(queue_name: queue_name)
-    create_response.should be_success
-    @queue = create_response.queue_url
+    @queue_name = "EM-AWS-Test-Queue-#{Time.now.to_i}"
   end
-
-  it_behaves_like "an AWS Query"
 
-  it "can create a queue" do
-    @topic.should =~ /^arn:aws:sns:.*#{@test_topic}$/
-  end
+  it_behaves_like "an AWS Query"
 
-  it "can retrieve a list of queues" do
-    response = subject.list_queues
-    response.queues.should include({queue_url: @topic})
+  it "derives the queue name from the URL" do
+    this = EM::AWS::SQS::new url: 'http://dummy.amazonaws.com/fake-queue-name'
+    this.queue_name.should == 'fake-queue-name'
   end
-
-  after(:all) do
-    delete_response = subject.delete_queue(topic_arn: @topic)
-    delete_response.should be_success
+
+  context "operations", :live do
+    before(:all) do
+      @queue = EM::AWS::SQS.create @queue_name
+      sleep 60
+    end
+
+    subject { @queue }
+
+    it "points to the proper queue" do
+      subject.url.should =~ /http.*\/#{@queue_name}$/
+    end
+
+    it "can retrieve a list of queues" do
+      response = subject.list_queues
+      response.queue_url.should include(subject.url)
+    end
+
+    it "can get the queue by name" do
+      queue = EM::AWS::SQS.get @queue_name
+      queue.url.should == subject.url
+    end
+
+    it "can set attributes on the queue" do
+      subject.set_queue_attributes attribute: {maximum_message_size: 1024}
+      sleep 10
+      response = subject.get_queue_attributes attribute_name: [:maximum_message_size]
+      response.attribute[:maximum_message_size].should == 1024
+    end
+
+
+    after(:all) do
+      sleep 10
+      delete_response = subject.delete_queue
+      delete_response.should be_success
+    end
   end
-
 
 end

spec/support/dummy_http_response.rb

@@ -19,6 +19,9 @@ def response
         <TopicArn>arn:aws:sns:us-east-1:429167422711:bigthink_alarms</TopicArn>
       </member>
     </Topics>
+    <PluralThing>17</PluralThing>
+    <PluralThing>hello</PluralThing>
+    <PluralThing>9.2</PluralThing>
     <Attributes>
       <entry>
         <key>Foo</key>