Class: XQueue

Inherits:
Object
  • Object
show all
Defined in:
lib/xqueue_ruby/xqueue_ruby.rb

Defined Under Namespace

Classes: AuthenticationError, IOError, NoSuchQueueError, UpdateFailedError, XQueueError

Constant Summary collapse

XQUEUE_DEFAULT_BASE_URI =

The base URI of the production Xqueue server.

'https://xqueue.edx.org'

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(django_name, django_pass, user_name, user_pass, queue_name) ⇒ XQueue

Creates a new instance and attempts to authenticate to the queue server.

  • django_name, django_pass: first set of auth credentials (see

above)

  • user_name, user_pass: second set of auth credentials (see

above)

  • queue_name: logical name of the queue



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# File 'lib/xqueue_ruby/xqueue_ruby.rb', line 75

def initialize(django_name, django_pass, user_name, user_pass, queue_name)
  @queue_name = queue_name
  @base_uri = XQueue.base_uri
  @django_auth = {'username' => django_name, 'password' => django_pass}
  @session = Mechanize.new
  @session.add_auth(@base_uri, user_name, user_pass)
  @valid_queues = nil
  @error = nil
  @authenticated = nil
end

Instance Attribute Details

#base_uri ⇒ Object (readonly)

The base URI used for this queue; won’t change for this queue even if you later change the value of XQueue.base_uri



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# File 'lib/xqueue_ruby/xqueue_ruby.rb', line 46

def base_uri
  @base_uri
end

#error ⇒ Object (readonly)

Error message, if any, associated with last unsuccessful operation



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# File 'lib/xqueue_ruby/xqueue_ruby.rb', line 38

def error
  @error
end

#queue_name ⇒ Object (readonly)

Queue from which to pull, established in constructor. You need a new XQueue object if you want to use a different queue.



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# File 'lib/xqueue_ruby/xqueue_ruby.rb', line 42

def queue_name
  @queue_name
end

Class Method Details

.base_uri ⇒ Object

The base URI used when new queue instances are created



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# File 'lib/xqueue_ruby/xqueue_ruby.rb', line 49

def self.base_uri
  @@base_uri ||= URI(XQUEUE_DEFAULT_BASE_URI)
end

.base_uri=(uri) ⇒ Object 



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# File 'lib/xqueue_ruby/xqueue_ruby.rb', line 52

def self.base_uri=(uri)
  @@base_uri = URI(uri)
end

Instance Method Details

#authenticate ⇒ Object

Authenticates to the server. You can call this explicitly, but it is called automatically if necessary on the first request in a new session.



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# File 'lib/xqueue_ruby/xqueue_ruby.rb', line 89

def authenticate
  response = request :post, '/xqueue/login/', @django_auth
  if response['return_code'] == 0
    @authenticated = true
  else

    raise(AuthenticationError, "Authentication failure: #{response['content']}")
  end
end

#authenticated? ⇒ Boolean

Returns true if the session has been properly authenticated to server, that is, after a successful call to authenticate or to any of the request methods that may have called authenticate automatically.

Returns:

  • (Boolean) 


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# File 'lib/xqueue_ruby/xqueue_ruby.rb', line 102

def authenticated? ; @authenticated ; end

#get_submission ⇒ Object

Retrieve a submission from this queue. Returns nil if queue is empty, otherwise a new XQueue::Submission instance.



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# File 'lib/xqueue_ruby/xqueue_ruby.rb', line 129

def get_submission
  authenticate unless authenticated?
  if queue_length > 0
    begin
      json_response = request(:get, '/xqueue/get_submission/',  {:queue_name => @queue_name}) 
      XQueueSubmission.parse_JSON(self, json_response)
    rescue StandardError => e  # TODO: do something more interesting with the error.
      raise e
    end
  else
    nil
  end
end

#list_queues ⇒ Object 



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# File 'lib/xqueue_ruby/xqueue_ruby.rb', line 118

def list_queues
  authenticate unless authenticated?
  if @valid_queues.nil?
    old, @queue_name = @queue_name, 'I_AM_NOT_A_QUEUE'
    begin queue_length rescue nil end
  end
  @valid_queues
end

#put_result(header, score, correct = true, message = '') ⇒ Object

Record a result of grading something. It may be easier to use XQueue::Submission#post_back, which marshals the information needed here automatically.

  • header: secret header key (from ‘xqueue_header’ slot in the

‘content’ object of the original retrieved submission)

  • score: integer number of points (not scaled)

  • correct: true (default) means show green checkmark, else red ‘x’

  • message: (optional) plain text feedback; will be coerced to UTF-8



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# File 'lib/xqueue_ruby/xqueue_ruby.rb', line 152

def put_result(header, score, correct=true, message='')
  payload = JSON.generate({
      :xqueue_header => header,
      :xqueue_body => {
        :correct   => (!!correct).to_s.capitalize,
        :score     => score,
        :message   => message.encode('UTF-8',
          :invalid => :replace, :undef => :replace, :replace => '?'),
      }
    })
  response = request :post, '/xqueue/put_result', payload
  if response['return_code'] != 0
    raise UpdateFailedError, response['content']
  end
end

#queue_length ⇒ Object

Returns length of the queue as an integer >= 0.



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# File 'lib/xqueue_ruby/xqueue_ruby.rb', line 105

def queue_length
  authenticate unless authenticated?
  response = request(:get, '/xqueue/get_queuelen/', {:queue_name => @queue_name})
  if response['return_code'] == 0 # success
    response['content'].to_i
  elsif response['return_code'] == 1 && response['content'] =~ /^Valid queue names are: (.*)/i
    @valid_queues = $1.split(/,\s+/)
    raise NoSuchQueueError, "No such queue: valid queues are #{$1}"
  else
    raise IOError, response['content']
  end
end