Class: BentoSearch::XerxesEngine

Inherits:
Object
  • Object
show all
Extended by:
HTTPClientPatch::IncludeClient
Includes:
SearchEngine
Defined in:
app/search_engines/bento_search/xerxes_engine.rb

Overview

a **very limited and hacky** bento search engine for the Xerxes Metalib front-end. Probably not suitable for real production use, just a demo, and used for testing. Does not support pagination, or fielded searching. will do a new Metalib search every time you call it, which will be slow.

Machine running this code needs to have IP-address authorization to search xerxes.

jrochkind is using it for his article search provider comparison testing instrument.

Constant Summary

Constants included from SearchEngine

SearchEngine::DefaultPerPage

Class Method Summary collapse

Instance Method Summary collapse

Methods included from HTTPClientPatch::IncludeClient

include_http_client

Methods included from SearchEngine

#fill_in_search_metadata_for, #initialize, #normalized_search_arguments, #public_settable_search_args, #search

Methods included from SearchEngine::Capabilities

#max_per_page, #search_field_definitions, #search_keys, #semantic_search_keys, #semantic_search_map, #sort_definitions, #sort_keys

Class Method Details

.required_configuration ⇒ Object

also optional configuration

xerxes_context

will send as ‘context’ query param to xerxes, for analytics



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# File 'app/search_engines/bento_search/xerxes_engine.rb', line 29

def self.required_configuration
  ["base_url", "databases"]
end

Instance Method Details

#search_implementation(arguments) ⇒ Object 



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# File 'app/search_engines/bento_search/xerxes_engine.rb', line 33

def search_implementation(arguments)
  
  # We're gonna have to do a search 'screen scrape' style, then refresh it
  # until it's ready, and then request format=xerxes when it's ready
  # to get XML. A bit hacky. 
  
  request_url = xerxes_search_url(arguments)
  
  
  response = http_client.head request_url
  
  # It's supposed to be a redirect
  unless HTTP::Status.redirect?(response.status) && response.headers["Location"]
    r = Results.new
    r.error ||= {}
    r.error["status"] = response.status
    r.error["message"] = "Xerxes did not return expected 302 redirect"
    
    return r
  end
  
  # Okay, now fetch the redirect, have to change it to an absolute
  # URI cause Xerxes semi-illegally returns a relative one.
  refreshes = 0
  results_url = nil
  status_url = (URI.parse(request_url) + response.headers["Location"]).to_s
  while ( refreshes < 5 )
    # cause of VCR, can't request the exact same URL twice
    # with different results. Add `try` on the end. 
    response = http_client.get( status_url + "&try=#{refreshes}")
      
    # Okay, have to follow the meta-refresh
    html = Nokogiri::HTML( response.body )
    
    if HTTP::Status.redirect? response.status
      # Okay, redirect means we're done with status and
      # we've got actual results url
      results_url = URI.parse(request_url) + response.headers["Location"]
      break
    end        
    
    if ( refresh = html.css("meta[http-equiv='refresh']")  )
      wait = configuration.lookup!("refresh_wait", (refresh.attribute("content").value.to_i if refresh.attribute("content")))  
      # wait how long Xerxes asked before refreshing.
      refreshes += 1
      sleep wait
    end
  end
      
  results = Results.new
  
  # any errors?
  if results_url.nil? && refreshes >= 5
    results.error ||= {}
    results.error["message"] = "#{refreshes} refreshes exceeded maximum"
    return results
  end
  
  # Okay, fetch it as format xerxes
  
  xml = Nokogiri::XML( http_client.get(results_url.to_s + "&amp;format=xerxes").body ) 
  
  results = Results.new
  
  xml.xpath("//results/records/record").each do |record|
    item = ResultItem.new
    results << item
    
    item.title = node_text record.at_xpath("xerxes_record/title")
    
    xerxes_fmt_str = node_text(record.at_xpath("xerxes_record/format")).downcase
    
    item.format = if xerxes_fmt_str.include?("article")
      "Article"
    elsif xerxes_fmt_str.include?("Book")
      "Book"
    else
      nil
    end
            
    item.link           = node_text record.at_xpath("xerxes_record/links/link[@type='original_record']/url")
    
    item.year           = node_text record.at_xpath("xerxes_record/year")
    item.volume         = node_text record.at_xpath("xerxes_record/volume")
    item.issue          = node_text record.at_xpath("xerxes_record/issue")
    item.start_page     = node_text record.at_xpath("xerxes_record/start_page")
    item.end_page       = node_text record.at_xpath("xerxes_record/end_page")                        
    
    item.abstract = node_text(record.at_xpath("xerxes_record/abstract") || record.at_xpath("xerxes_record/summary"))
    
    item.openurl_kev_co = node_text record.at_xpath("openurl_kev_co")
    
    # have to get journal title out of openurl, sorry        
    if item.openurl_kev_co
      openurl = OpenURL::ContextObject.new_from_kev(   item.openurl_kev_co )
      if openurl && openurl.referent && openurl.referent.format == "journal"
        item.journal_title = openurl.referent.jtitle
      end
    end          
    item.issn           = node_text record.at_xpath("xerxes_record/standard_numbers/issn")    
    
    # authors
    record.xpath("xerxes_record/authors/author").each do |author|
      next unless author.at_xpath("aulast") # don't even have a lastname, we can do nothing
      
      item.authors << Author.new(:first => node_text(author.at_xpath("aufirst")),
        :middle => node_text(author.at_xpath("auinit")),
        :last => node_text(author.at_xpath("aulast"))
        )
    end
    
    
  end
  return results     
end