Class: Worldcat

Inherits:
Service show all
Includes:
MetadataHelper, UmlautHttp
Defined in:
app/service_adaptors/worldcat.rb

Constant Summary

Constants inherited from Service

Service::LinkOutFilterTask, Service::StandardTask

Instance Attribute Summary

Attributes inherited from Service

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

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, #response_url, #translate

Constructor Details

#initialize(config) ⇒ Worldcat

Returns a new instance of Worldcat.



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# File 'app/service_adaptors/worldcat.rb', line 14

def initialize(config)
  # defaults
  @suppress_precheck = false # it seems unneccesary to pre-check worldcat, it's mostly ALWAYS a positive hit. And pre-checking against worldcat is running into Worldcat's rate limiting defenses. If neccesary, you can turn this off. Really, we should be using the Worldcat API anyway. 
  @base_url = 'http://www.worldcat.org/'
  @display_text = 'Find in other libraries'
  @display_text_i18n = 'display_text'
  @display_name = 'OCLC WorldCat.org'
  
  @credits = {
    "OCLC WorldCat.org" => "http://www.worldcat.org/"
  }
  
  super(config)
end

Instance Method Details

#handle(request) ⇒ Object 



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# File 'app/service_adaptors/worldcat.rb', line 33

def handle(request)
  isbn = get_identifier(:urn, "isbn", request.referent)
  issn = get_identifier(:urn, "issn", request.referent)
  oclcnum = get_identifier(:info, "oclcnum", request.referent)
  
  
  isxn_key = nil
  isxn_value = nil
  if (! oclcnum.blank?)
    isxn_key = 'oclc'
    isxn_value = oclcnum    
  elsif (! issn.blank?)
    isxn_key = 'issn'
    #isxn_value = ref_metadata['issn'] + '+dt:ser'
    isxn_value = issn
  elsif (! isbn.blank?)
    isxn_key = 'isbn'
    isxn_value = isbn
  else
    # We have no useful identifiers
    return request.dispatched(self, true)
  end

  # Do some cleanup of the value. Sometimes spaces or other
  # weird chars get in there, why not strip out everything that
  # isn't a number or X?
  isxn_value = isxn_value.gsub( /[^\dX]/, '')
  # and URL escape just to be safe, although really shouldn't be neccesary
  isxn_value = URI.escape( isxn_value )
  
  # We do a pre-emptive lookup to worldcat to try and see if worldcat
  # has a hit or not, before adding the link.
  isxn_key = URI.escape( isxn_key )
  uri_str = @base_url+isxn_key+'/'+isxn_value
  uri_str +=  "&loc=#{URI.escape(@search_zip_code.to_s)}" if @search_zip_code

  
  begin
    worldcat_uri = URI.parse(uri_str)
  rescue Exception => e
    Rails.logger.error("Bad worldcat uri string constructed?")
    Rails.logger.error(e)
    return request.dispatched(self, DispatchedService::FailedFatal)
  end

  unless ( @suppress_precheck )
  
    http = Net::HTTP.new worldcat_uri.host
    http.open_timeout = 7
    http.read_timeout = 7

    
    begin
      # Fake being a proxy to send info on actual end-user client to worldcat,
      # to lessen chance of worldcat traffic limiters. 
      headers = proxy_like_headers( request, worldcat_uri.host )
      wc_response = http.get(worldcat_uri.path, headers)
    rescue  Timeout::Error => exception
      return request.dispatched(self, DispatchedService::FailedTemporary, exception)
    end

    # Bad response code?
    unless wc_response.code == "200"
      # Could be temporary, could be fatal. Let's say temporary. 
      return request.dispatched(self, DispatchedService::FailedTemporary, Exception.new("oclc returned error http status code: #{wc_response.code}"))
    end

    # Sadly, worldcat returns a 200 even if there are no matches.
    # We need to screen-scrape to discover if there are matches.
    if (wc_response.body =~ /The page you tried was not found\./)
      # Not found in worldcat, we won't add a link.
      return request.dispatched(self, true)
    end
  end
  
  request.add_service_response(
    :service=>self, 
    :url=>worldcat_uri.to_s,
    :display_text=>@display_text,
    :display_text_i18n => @display_text_i18n,
    :service_type_value => :highlighted_link
    )
  
  return request.dispatched(self, true)
end

#service_types_generated ⇒ Object 



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# File 'app/service_adaptors/worldcat.rb', line 29

def service_types_generated
  return [ServiceTypeValue['highlighted_link']]
end