Class: Gcloud::Pubsub::Project

Inherits:
Object
  • Object
show all
Defined in:
lib/gcloud/pubsub/project.rb

Overview

# Project

Represents the project that pubsub messages are pushed to and pulled from. Topic is a named resource to which messages are sent by publishers. Subscription is a named resource representing the stream of messages from a single, specific topic, to be delivered to the subscribing application. Message is a combination of data and attributes that a publisher sends to a topic and is eventually delivered to subscribers.

See Gcloud#pubsub

Examples:

require "gcloud"

gcloud = Gcloud.new
pubsub = gcloud.pubsub

topic = pubsub.topic "my-topic"
topic.publish "task completed"

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(project, credentials) ⇒ Project 



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# File 'lib/gcloud/pubsub/project.rb', line 52

def initialize project, credentials
  project = project.to_s # Always cast to a string
  fail ArgumentError, "project is missing" if project.empty?
  @service = Service.new project, credentials
end

Instance Attribute Details

#service ⇒ Object 



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# File 'lib/gcloud/pubsub/project.rb', line 48

def service
  @service
end

Class Method Details

.default_project ⇒ Object 



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# File 'lib/gcloud/pubsub/project.rb', line 75

def self.default_project
  ENV["PUBSUB_PROJECT"] ||
    ENV["GCLOUD_PROJECT"] ||
    ENV["GOOGLE_CLOUD_PROJECT"] ||
    Gcloud::GCE.project_id
end

Instance Method Details

#create_topic(topic_name) ⇒ Gcloud::Pubsub::Topic Also known as: new_topic

Creates a new topic.

Examples:

require "gcloud"

gcloud = Gcloud.new
pubsub = gcloud.pubsub
topic = pubsub.create_topic "my-topic"


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# File 'lib/gcloud/pubsub/project.rb', line 169

def create_topic topic_name
  ensure_service!
  grpc = service.create_topic topic_name
  Topic.from_grpc grpc, service
rescue GRPC::BadStatus => e
  raise Error.from_error(e)
end

#project ⇒ Object

The Pub/Sub project connected to.

Examples:

require "gcloud"

gcloud = Gcloud.new "my-todo-project",
                    "/path/to/keyfile.json"
pubsub = gcloud.pubsub

pubsub.project #=> "my-todo-project"


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# File 'lib/gcloud/pubsub/project.rb', line 69

def project
  service.project
end

#publish(topic_name, data = nil, attributes = {}) {|batch| ... } ⇒ Message+

Publishes one or more messages to the given topic. The topic will be created if the topic does previously not exist and the autocreate option is provided.

A note about auto-creating the topic: Any message published to a topic without a subscription will be lost.

Examples:

require "gcloud"

gcloud = Gcloud.new
pubsub = gcloud.pubsub

msg = pubsub.publish "my-topic", "new-message"

Additionally, a message can be published with attributes:

require "gcloud"

gcloud = Gcloud.new
pubsub = gcloud.pubsub

msg = pubsub.publish "my-topic", "new-message", foo: :bar,
                                                this: :that

Multiple messages can be sent at the same time using a block:

require "gcloud"

gcloud = Gcloud.new
pubsub = gcloud.pubsub

msgs = pubsub.publish "my-topic" do |batch|
  batch.publish "new-message-1", foo: :bar
  batch.publish "new-message-2", foo: :baz
  batch.publish "new-message-3", foo: :bif
end

With autocreate:

require "gcloud"

gcloud = Gcloud.new
pubsub = gcloud.pubsub

msg = pubsub.publish "new-topic", "new-message", autocreate: true

Options Hash (attributes):

  • :autocreate (Boolean) —

    Flag to control whether the provided topic will be created if it does not exist.

Yields:

  • (batch) —

    a block for publishing multiple messages in one request

Yield Parameters:



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# File 'lib/gcloud/pubsub/project.rb', line 286

def publish topic_name, data = nil, attributes = {}
  # Fix parameters
  if data.is_a?(::Hash) && attributes.empty?
    attributes = data
    data = nil
  end
  # extract autocreate option
  autocreate = attributes.delete :autocreate
  ensure_service!
  batch = Topic::Batch.new data, attributes
  yield batch if block_given?
  return nil if batch.messages.count.zero?
  publish_batch_messages topic_name, batch, autocreate
end

#subscribe(topic_name, subscription_name, deadline: nil, endpoint: nil, autocreate: nil) ⇒ Gcloud::Pubsub::Subscription Also known as: create_subscription, new_subscription

Creates a new Subscription object for the provided topic. The topic will be created if the topic does previously not exist and the autocreate option is provided.

Examples:

require "gcloud"

gcloud = Gcloud.new
pubsub = gcloud.pubsub

sub = pubsub.subscribe "my-topic", "my-topic-sub"
puts sub.name # => "my-topic-sub"

The name is optional, and will be generated if not given.

require "gcloud"

gcloud = Gcloud.new
pubsub = gcloud.pubsub

sub = pubsub.subscribe "my-topic"
puts sub.name # => "generated-sub-name"

Wait 2 minutes for acknowledgement and push all to an endpoint:

require "gcloud"

gcloud = Gcloud.new
pubsub = gcloud.pubsub

sub = pubsub.subscribe "my-topic", "my-topic-sub",
                       deadline: 120,
                       endpoint: "https://example.com/push"

With autocreate:

require "gcloud"

gcloud = Gcloud.new
pubsub = gcloud.pubsub

sub = pubsub.subscribe "new-topic", "new-topic-sub", autocreate: true


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# File 'lib/gcloud/pubsub/project.rb', line 358

def subscribe topic_name, subscription_name, deadline: nil, endpoint: nil,
              autocreate: nil
  ensure_service!
  options = { deadline: deadline, endpoint: endpoint }
  grpc = service.create_subscription topic_name,
                                     subscription_name, options
  Subscription.from_grpc grpc, service
rescue GRPC::BadStatus => e
  if autocreate && e.code == 5
    create_topic topic_name
    return subscribe(topic_name, subscription_name,
                     deadline: deadline, endpoint: endpoint,
                     autocreate: false)
  end
  raise Error.from_error(e)
end

#subscription(subscription_name, project: nil, skip_lookup: nil) ⇒ Gcloud::Pubsub::Subscription? Also known as: get_subscription, find_subscription

Retrieves subscription by name.

Examples:

require "gcloud"

gcloud = Gcloud.new
pubsub = gcloud.pubsub

subscription = pubsub.subscription "my-sub"
puts subscription.name

Skip the lookup against the service with skip_lookup:

require "gcloud"

gcloud = Gcloud.new
pubsub = gcloud.pubsub

# No API call is made to retrieve the subscription information.
subscription = pubsub.subscription "my-sub", skip_lookup: true
puts subscription.name


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# File 'lib/gcloud/pubsub/project.rb', line 411

def subscription subscription_name, project: nil, skip_lookup: nil
  ensure_service!
  options = { project: project }
  if skip_lookup
    return Subscription.new_lazy subscription_name, service, options
  end
  grpc = service.get_subscription subscription_name
  Subscription.from_grpc grpc, service
rescue GRPC::BadStatus => e
  return nil if e.code == 5
  raise Error.from_error(e)
end

#subscriptions(prefix: nil, token: nil, max: nil) ⇒ Array<Gcloud::Pubsub::Subscription> Also known as: find_subscriptions, list_subscriptions

Retrieves a list of subscriptions for the given project.

Examples:

require "gcloud"

gcloud = Gcloud.new
pubsub = gcloud.pubsub

subscriptions = pubsub.subscriptions
subscriptions.each do |subscription|
  puts subscription.name
end

With pagination: (See Subscription::List#token)

require "gcloud"

gcloud = Gcloud.new
pubsub = gcloud.pubsub

all_subs = []
tmp_subs = pubsub.subscriptions
while tmp_subs.any? do
  tmp_subs.each do |subscription|
    all_subs << subscription
  end
  # break loop if no more subscriptions available
  break if tmp_subs.token.nil?
  # get the next group of subscriptions
  tmp_subs = pubsub.subscriptions token: tmp_subs.token
end


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# File 'lib/gcloud/pubsub/project.rb', line 467

def subscriptions prefix: nil, token: nil, max: nil
  ensure_service!
  options = { prefix: prefix, token: token, max: max }
  grpc = service.list_subscriptions options
  Subscription::List.from_grpc grpc, service
rescue GRPC::BadStatus => e
  raise Error.from_error(e)
end

#topic(topic_name, autocreate: nil, project: nil, skip_lookup: nil) ⇒ Gcloud::Pubsub::Topic? Also known as: get_topic, find_topic

Retrieves topic by name.

The topic will be created if the topic does not exist and the autocreate option is set to true.

Examples:

require "gcloud"

gcloud = Gcloud.new
pubsub = gcloud.pubsub
topic = pubsub.topic "existing-topic"

By default nil will be returned if the topic does not exist.

require "gcloud"

gcloud = Gcloud.new
pubsub = gcloud.pubsub
topic = pubsub.topic "non-existing-topic" #=> nil

With the autocreate option set to true.

require "gcloud"

gcloud = Gcloud.new
pubsub = gcloud.pubsub
topic = pubsub.topic "non-existing-topic", autocreate: true

Create a topic in a different project with the project flag.

require "gcloud"

gcloud = Gcloud.new
pubsub = gcloud.pubsub
topic = pubsub.topic "another-topic", project: "another-project"

Skip the lookup against the service with skip_lookup:

require "gcloud"

gcloud = Gcloud.new
pubsub = gcloud.pubsub
topic = pubsub.topic "another-topic", skip_lookup: true


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# File 'lib/gcloud/pubsub/project.rb', line 139

def topic topic_name, autocreate: nil, project: nil, skip_lookup: nil
  ensure_service!
  options = { project: project }
  return Topic.new_lazy(topic_name, service, options) if skip_lookup
  grpc = service.get_topic topic_name
  Topic.from_grpc grpc, service
rescue GRPC::BadStatus => e
  if e.code == 5
    return create_topic(topic_name) if autocreate
    return nil
  end
  raise Error.from_error(e)
end

#topics(token: nil, max: nil) ⇒ Array<Gcloud::Pubsub::Topic> Also known as: find_topics, list_topics

Retrieves a list of topics for the given project.

Examples:

require "gcloud"

gcloud = Gcloud.new
pubsub = gcloud.pubsub

topics = pubsub.topics
topics.each do |topic|
  puts topic.name
end

With pagination: (See Topic::List#token)

require "gcloud"

gcloud = Gcloud.new
pubsub = gcloud.pubsub

all_topics = []
tmp_topics = pubsub.topics
while tmp_topics.any? do
  tmp_topics.each do |topic|
    all_topics << topic
  end
  # break loop if no more topics available
  break if tmp_topics.token.nil?
  # get the next group of topics
  tmp_topics = pubsub.topics token: tmp_topics.token
end


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# File 'lib/gcloud/pubsub/project.rb', line 218

def topics token: nil, max: nil
  ensure_service!
  options = { token: token, max: max }
  grpc = service.list_topics options
  Topic::List.from_grpc grpc, service
rescue GRPC::BadStatus => e
  raise Error.from_error(e)
end