Class: Amazon

Inherits:
Service show all
Includes:
ActionView::Helpers::SanitizeHelper, MetadataHelper, UmlautHttp
Defined in:
app/service_adaptors/amazon.rb

Overview

AWS API account is required. NOTE: You may want to the API Terms of Service

  and make sure you feel comfortable with them. 

More about registering for and finding your AWS access key and secret key
can be found here:

docs.amazonwebservices.com/AWSECommerceService/latest/DG/AWSCredentials.html docs.amazonwebservices.com/AWSECommerceService/latest/DG/ViewingCredentials.html

NOTE: Discovery of :search_inside and :excerpts links requires screen-scraping

     an Amazon back-end endpoint.  If you are uncomfortable with this mode of
     access, disable those service types, or do not use this adapter. 

 services.yml params:
 api_key:    required. AWS "access key". 
 secret_key:  required unless make_aws_call==false. AWS "secret access key". 
 associate_tag: required unless make_aws_call==false. Now required by Amazon API. 
                sign up for an associates_id at: https://affiliate-program.amazon.com/
                it's the same thing as your 'associate id'. 
 service_types: Optional. Array of strings of service type values to be
                loaded, to over-ride defaults.
 make_aws_call:  default true.   If false, then either uses an ASIN stored
                   in referent from previous service, or tries assuming
                   that an ISBN, if present, is the ASIN. 
                   of services ran an amazon service adaptor
                   Can be used to split amazon into
                   two waves, since highlighted_link and cover_image
                   calls require _another_ HTTP request to amazon
                   and screen scrape. Or can be used if you don't
                   have access to Amazon API. 

See example of two-wave amazon in config/umlaut_distribution/services.yml-dist.

Constant Summary

Constants inherited from Service

Service::LinkOutFilterTask, Service::StandardTask

Instance Attribute Summary collapse

Attributes inherited from Service

#group, #name, #priority, #request, #service_id, #status, #task

Instance Method Summary collapse

Methods included from UmlautHttp

#http_fetch, #proxy_like_headers

Methods included from MetadataHelper

#get_doi, #get_epage, #get_gpo_item_nums, #get_identifier, #get_isbn, #get_issn, #get_lccn, #get_month, #get_oclcnum, #get_pmid, #get_search_creator, #get_search_terms, #get_search_title, #get_spage, #get_sudoc, #get_top_level_creator, #get_year, #normalize_lccn, #normalize_title, #raw_search_title, title_is_serial?

Methods included from MarcHelper

#add_856_links, #edition_statement, #get_title, #get_years, #gmd_values, #service_type_for_856, #should_skip_856_link?, #strip_gmd

Methods inherited from Service

#credits, #display_name, #handle_wrapper, #link_out_filter, #preempted_by, required_config_params, #translate

Constructor Details

#initialize(config) ⇒ Amazon

Returns a new instance of Amazon


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# File 'app/service_adaptors/amazon.rb', line 51

def initialize(config)
  # defaults
  @url = 'http://webservices.amazon.com/onca/xml'     
  @reader_base_url = 'http://www.amazon.com/gp/reader/'
  @display_name = "Amazon.com"
  @display_text = "Amazon's page"
  @service_types = ["abstract", "highlighted_link", "cover_image", "search_inside", "referent_enhance", "excerpts"]
  @make_aws_call = true
  @http_timeout = 5
  
  @credits = {
    "Amazon" => "http://www.amazon.com/"
  }
  
  super(config)

  # Need the secret_key after 15 aug 09.
  unless (@secret_key || ! @make_aws_call)
    if ( Time.now < Time.gm(2009, 8, 15))
      Rails.logger.warn("Amazon service will require a secret_key after 15 August 2009 to make Amazon API calls.")
    else
      raise Exception.new("Amazon API now requires a secret_key. The Amazon service can only be used with make_aws_call=false unless you have an Amazon secret key configured.")
    end
  end

  # Only a few service types can get by without an aws call
  if (! @make_aws_call &&
        @service_types.find {|type|  ! ["search_inside", "highlighted_link", "excerpts"].include?(type)} )
      raise Exception.new("You can only set make_aws_call == false on the definition of an Amazon service adaptor when the adaptor is also set to generate no service responses other than highlighted_link, search_inside, and excerpts")
  end
end

Instance Attribute Details

#urlObject (readonly)

Returns the value of attribute url


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# File 'app/service_adaptors/amazon.rb', line 49

def url
  @url
end

Instance Method Details

#add_asin_service_responses(request, asin, item_url) ⇒ Object


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# File 'app/service_adaptors/amazon.rb', line 303

def add_asin_service_responses(request, asin, item_url)
  # we want to highlight Amazon to link to 'search in this book', etc.
  if asin
    # Search or Look inside the book offered? We only know by trying and
    # then screen-scraping.
    search_inside = false
    look_inside = false

    # Check for search_inside or look_inside if we're configured
    # to supply "excerpts" or search_inside, that's what we
    # need it for.
    if ( @service_types.include?("excerpts") ||
         @service_types.include?("search_inside"))
      
      
      # Checking an Amazon JSON url endpoint which can tell us whether
      # we have search-inside or look-inside
      client      = HTTPClient.new()
      client.transparent_gzip_decompression = true
      client.connect_timeout  = 3
      client.send_timeout     = 3
      client.receive_timeout  = 3

      service_url = "http://www.amazon.com/gp/search-inside/service-data"
      form_vars   = {"method" => "getBookData", "asin" => asin}
      headers     = proxy_like_headers(request).merge("Accept" => "application/json, text/javascript, */*; q=0.01")

      response    = client.post service_url, form_vars, headers
      hash        = JSON.parse(response.body)

      if hash["searchable"].to_s == "true"
        search_inside= true          
      end

      if hash["litbPages"].kind_of?(Array) && hash["litbPages"].length > 0
        look_inside = true
      end        
    end

    reader_url = @reader_base_url + asin

    if ( @service_types.include?("search_inside") && search_inside )
      request.add_service_response( 
        :service => self,
        :display_text=>@display_name,
        :display_text_i18n => "display_name",
        :url=> reader_url,
        :service_type_value => :search_inside
       )   
    end

    # Link to look inside if we have it, otherwise ordinary amazon detail
    # page. 

    if (@service_types.include?("excerpts") &&
        ( search_inside || look_inside ))
      
                       
       request.add_service_response(
          :service=>self,
          :url => reader_url, 
          :asin=>asin,
          :display_text => @display_name,
          :display_text_i18n => "display_name",
          :service_type_value => 'excerpts')
       
    elsif ( @service_types.include?("highlighted_link"))
        # Just link to Amazon page if we can. If we did the AWS request
        # before, afraid we didn't store the item url, just the
        # asin, reconstruct a valid one, even if not the one given to us
        # by AWS. 
        amazon_page = item_url || ("http://www.amazon.com/o/ASIN/" + asin)
        
                       
        request.add_service_response(
          :service=>self,
          :url => amazon_page, 
          :asin=>asin,
          :display_text => @display_text,
          :display_text_i18n => "display_text",
          :service_type_value => 'highlighted_link')
    end
    
  end

end

#add_aws_service_responses(request, aws_response) ⇒ Object


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# File 'app/service_adaptors/amazon.rb', line 182

def add_aws_service_responses(request, aws_response)
  return_hash = Hash.new
      
  aws = Nokogiri::XML(aws_response.body)
  # extract and collect info from the xml    
  
  # if we get an error from Amazon, return now. 
  err = (aws.at("ItemLookupResponse/Items/Request/Errors/Error"))
  err = (aws.at("ItemLookupErrorResponse")) if err.blank?
  
  unless (err.blank?)
    if ((err.at('Code').text == 'AWS.InvalidParameterValue') ||
        (err.at('Code').text == 'AWS.ECommerceService.ItemNotAccessible'))
      # Indicates an ISBN that Amazon doesn't know about, or that
      # was mal-formed. We can't tell the difference, so either
      # way let's silently ignore. 
      return
    else
      raise Exception.new("Error from Amazon web service: " + err.to_s)
    end
  end

  asin = (aws.at("ItemLookupResponse/Items/Item/ASIN")).inner_text

  # Store the asin in the referent as non-metadata private data, so
  # a future background service can use it. Store as a urn identifier.
  request.referent.add_identifier("urn:asin:#{asin}") unless asin.blank?

  return_hash[:asin] = asin
  
  if ( @service_types.include?("cover_image") )
    # collect cover art urls
    ["small","medium","large"].each do | size |
      if (img = aws.at("ItemLookupResponse/Items/Item/"+size.capitalize+"Image/URL"))
        request.add_service_response(
          :service=>self, 
          :display_text => 'Cover Image',
          :key=>size, 
          :url => img.inner_text, 
          :asin => asin, 
          :size => size,
          :service_type_value => :cover_image)          
      end
    end
    
  end

  item_url = (aws.at("ItemLookupResponse/Items/Item/DetailPageURL")).inner_text
  # Store to return to caller
  return_hash[:item_url] = item_url

  
  # get description
  if (  @service_types.include?("abstract") &&
       desc =
       (aws.at("ItemLookupResponse/Items/Item/EditorialReviews/EditorialReview/Content")))
    
    desc_text =  desc.inner_text

    unless ( desc_text.blank? )
      request.add_service_response(
        :service=>self, 
        :display_text => "Description from Amazon.com",
        :display_text_i18n => "description", 
        :url => item_url, 
        :key=>'abstract', 
        :value_string=>asin, 
        :content=> sanitize(desc_text) ,
        :content_html_safe => true,
        :service_type_value => 'abstract')
    end
  end
  

  if ( @service_types.include?("similar_item"))
    # Get Amazon's 'similar products' to help recommend other useful items
    (aws.search("ItemLookupResponse/Items/Item/SimilarProducts/SimilarProduct")).each do |similar|
      request.add_service_response(
        :service=>self,
        :key=>'book', 
        :value_string=>(similar.at("ASIN")).inner_text, 
        :value_alt_string=>(similar.at("Title")).inner_text,
        :service_type_value => 'similar_item')
    end

 end

  if ( @service_types.include?("referent_enhance"))
    item_attributes = aws.at("ItemLookupResponse/Items/Item/ItemAttributes")
    
    request.referent.enhance_referent('format', 'book', false) unless request.referent.format == 'book'
     = request.referent.
    unless (['btitle'] || ['title'])
      if title = (item_attributes.at("Title"))
        request.referent.enhance_referent('btitle', normalize_aws_title(title.inner_text))
      end

    end

    # Don't overwrite aulast with our full au
    unless (['au'] || ['aulast'])
      if author = (item_attributes.at("Author"))
        request.referent.enhance_referent('au', author.inner_text)
      end
    end

    unless ['pub']
      if pub = (item_attributes.at("Publisher"))
        request.referent.enhance_referent('pub', pub.inner_text)
      end
    end      
    unless ['tpages']
      if tpages = (item_attributes.at("NumberOfPages"))
        request.referent.enhance_referent('tpages', tpages.inner_text)
      end
    end
  end

  return return_hash
end

#handle(request) ⇒ Object


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# File 'app/service_adaptors/amazon.rb', line 94

def handle(request)
  
  isbn = request.referent.['isbn']
  isbn = isbn.gsub(/[^0-9X]/,'') if isbn
  
  # does it look like a good ISBN?
  return request.dispatched(self, true) if isbn.blank? || ! [10,13].include?(isbn.length)

  # Make sure it's REALLY a good ISBN, and 
  # Convert 13 to 10 if neccesary, cause we're using it as an ASIN.     
  # An ISBN-13 is never an ASIN.    
  isbn = ISBN.ten( isbn )
  
  
  begin

    selected_aws_vals = {}
    if ( @make_aws_call )

      aws_response = make_aws_request( isbn )
      
      return request.dispatched(self, true) if aws_response.blank?

      # Add service responses based on AWS response
      selected_aws_vals = 
        self.add_aws_service_responses(request, aws_response)
    end

    if ( selected_aws_vals == nil)
      # no aws found.
      return request.dispatched(self, true)
    end
    
    # Add service responses based on ASIN--may be run in a
    # later service wave. Look up asin in db if we don't have
    # it from current service exec. 
    asin = selected_aws_vals[:asin] || 
        get_identifier(:urn, "asin", request.referent)
        
    self.add_asin_service_responses(request, asin, selected_aws_vals[:item_url])
    
  rescue TimeoutError
    # Try again later if we timeout; temporary error condition. 
    return request.dispatched(self, DispatchedService::FailedTemporary)    
  rescue Exception => e
    # Unexpected error, fatal error condition. 
    return request.dispatched(self, DispatchedService::FailedFatal, e)
  end
  
  return request.dispatched(self, true)
end

#make_aws_request(isbn) ⇒ Object


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# File 'app/service_adaptors/amazon.rb', line 146

def make_aws_request(isbn)
  # We're assuming the ISBN is the ASIN Amazon ID. Not neccesarily valid
  # assumption, but works enough of the time and there's no easy
  # alternative.

            

  query_params = {
    "Service"=>"AWSECommerceService",
    "AWSAccessKeyId"=>@api_key,
    "AssociateTag"=>@associate_tag,
    "Operation"=>"ItemLookup",
    "ResponseGroup"=>"Large",
    "ItemId"=>isbn }
  
  # has to be signed
  query = nil

  if ( @secret_key )
    aws = AwsProductSign.new(:access_key => @api_key, 
                             :secret_key => @secret_key )
    query = aws.query_with_signature( query_params )
  else
    query = query_params.collect {|key, value| CGI.escape(key) + '=' + CGI.escape(value)}.join("&")
  end
    
  uri = URI.parse(self.url+'?'+query)
  # send the request
  http = Net::HTTP.new(uri.host, 80)  
  http.open_timeout = @http_timeout
  http.read_timeout = @http_timeout
  http_response = http.send_request('GET', uri.path + '?' + uri.query)    
  
  return http_response
end

#normalize_aws_title(title) ⇒ Object

amazon is in the habit of including things in parens at the end of the title that aren't really part of the title. The parens are really an edition and/or series statement. We have nowhere good to store that.


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# File 'app/service_adaptors/amazon.rb', line 407

def normalize_aws_title(title)
  title.sub(/\([^)]*\)\s*$/, '')
end

#response_url(service_response, submitted_params) ⇒ Object

Catch url_for call for search_inside, because we're going to redirect


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# File 'app/service_adaptors/amazon.rb', line 391

def response_url(service_response, )
  if ( ! (service_response.service_type_value.name == "search_inside" ))
    return super(service_response, )
  else
    # search inside!
    base = service_response[:url]
    query = CGI.escape(["query"] || "")
    url = base + "/ref=sib_dp_srch_pop?v=search-inside&keywords=#{query}&go=Go%21"
    return url
  end
end

#service_types_generatedObject


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# File 'app/service_adaptors/amazon.rb', line 84

def service_types_generated
  types = Array.new

  @service_types.each do |type|
    types.push( ServiceTypeValue[type])
  end
  
  return types
end