Class: OpenWFE::Extras::SqsListener

Inherits:
Service
  • Object
show all
Includes:
MonitorMixin, Rufus::Schedulable, WorkItemListener
Defined in:
lib/openwfe/extras/listeners/sqslisteners.rb

Overview

Polls an Amazon SQS queue for workitems

Workitems can be instances of InFlowWorkItem or LaunchItem.

require 'openwfe/extras/listeners/sqslisteners'

ql = OpenWFE::SqsListener("workqueue1", engine.application_context)

engine.add_workitem_listener(ql, "2m30s")
    #
    # thus, the engine will poll our "workqueue1" SQS queue
    # every 2 minutes and 30 seconds

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(queue_name, application_context) ⇒ SqsListener

Returns a new instance of SqsListener.



79
80
81
82
83
84
85
86
87
88
 
# File 'lib/openwfe/extras/listeners/sqslisteners.rb', line 79

def initialize (queue_name, application_context)

    @queue_name = queue_name.to_s

    service_name = "#{self.class}::#{@queue_name}"

    super service_name, application_context

    linfo { "new() queue is '#{@queue_name}'" }
end

Instance Attribute Details

#queue_name ⇒ Object (readonly)

The name of the Amazon SQS whom this listener cares for



77
78
79
 
# File 'lib/openwfe/extras/listeners/sqslisteners.rb', line 77

def queue_name
  @queue_name
end

Instance Method Details

#decode_object(message) ⇒ Object

Extracts a workitem from the message’s body.

By default, this listeners assumes the workitem is stored in its “hash form” (not directly as a Ruby InFlowWorkItem instance).

LaunchItem instances (as hash as well) are also accepted.



135
136
137
138
139
140
141
 
# File 'lib/openwfe/extras/listeners/sqslisteners.rb', line 135

def decode_object (message)

    o = Base64.decode64 message.message_body
    o = YAML.load o
    o = OpenWFE::workitem_from_h o
    o
end

#trigger(params) ⇒ Object

polls the SQS for incoming messages



93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
 
# File 'lib/openwfe/extras/listeners/sqslisteners.rb', line 93

def trigger (params)
    synchronize do

        ldebug { "trigger()" }

        qs = Rufus::SQS::QueueService.new

        qs.create_queue @queue_name
            # just to be sure it is there

        while true

            l = qs.get_messages(
                @queue_name, :timeout => 0, :count => 255)

            break if l.length < 1

            l.each do |msg|

                o = decode_object msg

                handle_item o

                msg.delete

                ldebug do 
                    "trigger() " +
                    "handled successfully msg #{msg.message_id}" 
                end
            end
        end
    end
end