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#--
# Licensed to the Apache Software Foundation (ASF) under one
# or more contributor license agreements. See the NOTICE file
# distributed with this work for additional information
# regarding copyright ownership. The ASF licenses this file
# to you under the Apache License, Version 2.0 (the
# "License"); you may not use this file except in compliance
# with the License. You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing,
# software distributed under the License is distributed on an
# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
# KIND, either express or implied. See the License for the
# specific language governing permissions and limitations
# under the License.
#++
module Qpid
module Messaging
# +Receiver+ is the entity through which messages are received.
#
# An instance of +Receiver+ can only be created using an active (i.e., not
# previously closed) Session. See Qpid::Messaging::Session.create_receiver
# for more details.
#
# ==== Example
#
# # create a connection and a session
# conn = Qpid::Messaging::Connection.new :url => "mybroker:5762"
# conn.open
# session = conn.create_session
#
# # create a receiver that listens on the "updates" topic of "alerts"
# receiver = session.create_receiver "alerts/updates"
#
# # wait for an incoming message and process it
# incoming = receiver.get Qpid::Messaging::Duration::FOREVER
# process(incoming)
#
class Receiver
def initialize(session, receiver_impl) # :nodoc:
@session = session
@receiver_impl = receiver_impl
end
def receiver_impl # :nodoc:
@receiver_impl
end
# Retrieves a message from the local queue, or waits for up to
# the duration specified for one to become available.
#
# If no message is received within the specified time then a
# MessagingException is raised.
#
# ==== Options
#
# * duration - the timeout to wait
#
# ==== Examples
#
# # retrieves a message, also handles exceptions raised on no messages
# begin
# # checks for a message, returning immediately
# msg = recv.get Qpid::Messaging::Duration::IMMEDIATE
# puts "Received this message: #{message.content}"
# rescue
# puts "No messages available.
# end
#
def get(duration = Qpid::Messaging::Duration::FOREVER)
message_impl = @receiver_impl.get duration.duration_impl
create_message_wrapper message_impl unless message_impl.nil?
end
# Retrieves a message from the receiver's subscription, or waits
# for up to the duration specified for one to become available.
#
# If no message is fetched within the specified time then a
# MessagingException is raised.
#
# ==== Options
#
# * duration - the timeout to wait (def. Duration::FOREVER)
#
# ==== Examples
#
# # retrieves a message, also handles exceptions raised on no messages
# begin
# # checks for a message, times out after one second
# msg = recv.fetch Qpid::Messaging::Duration::SECOND
# puts "Fetched this message: #{message.content}"
# rescue
# puts "No messages available.
# end
#
def fetch(duration = Qpid::Messaging::Duration::FOREVER)
message_impl = @receiver_impl.fetch duration.duration_impl
create_message_wrapper message_impl unless message_impl.nil?
end
# Sets the capacity.
#
# The capacity of a +Receiver+ is the number of Messages that can be
# pre-fetched from the broker and held locally. If capacity is 0 then
# messages will never be pre-fetched and all messages must instead be
# retrieved using #fetch.
#
# ==== Options
#
# * capacity - the capacity
#
# ==== Examples
#
# # create a receiver and give it a capacity of 50
# recv = session.create_receiver "alerts/minor"
# recv.capacity = 50
#
def capacity=(capacity); @receiver_impl.setCapacity capacity; end
# Returns the capacity.
def capacity; @receiver_impl.getCapacity; end
# Returns the number of messages locally held.
#
# The available is always 0 <= available <= capacity.
#
# If the #capacity is set to 0 then available will always be 0.
#
# ==== Examples
#
# # output the number of messages waiting while processing
# loop do
# puts "There are #{recv.available} messages pending..."
# # wait forever (the default) for the next message
# msg = recv.get
# # process the message
# dispatch_message msg
# end
#
def available; @receiver_impl.getAvailable; end
# Returns the number of messages that have been received and acknowledged
# but whose acknowledgements have not been confirmed by the sender.
def unsettled; @receiver_impl.getUnsettled; end
# Closes this +Receiver+.
#
# This does not affect the owning Session or Connection.
def close; @receiver_impl.close; end
# Returns whether the +Receiver+ is closed.
def closed?; @receiver_impl.isClosed; end
# Returns the name of this +Receiver+.
def name; @receiver_impl.getName; end
# Returns the owning Session for this +Receiver+.
def session; @session; end
private
def create_message_wrapper message_impl # :nodoc:
Qpid::Messaging::Message.new(:impl => message_impl)
end
end
end
end
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