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+require 'date'
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+require 'cgi'
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+module Agents
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+ class PublicTransportAgent < Agent
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+ cannot_receive_events!
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+ description <<-MD
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+ The Public Transport Agent monitors if any bus is expected to arrive at a particular stop in 5 minutes or less.
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+ You must specify 5 things for it too work correctly. Your state, city, route, stop and destination. All these things
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+ should be in the language that nextbus understands. For details check out http://www.nextbus.com/predictor/stopSelector.jsp?a=sf-muni and http://www.apihub.com/nextbus/api/nextbus-api/docs/reference.
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+
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+ Specify the following user settings:
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+ - stops (array)
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+ - agency (string)
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+ - alert_window_in_minutes (integer)
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+
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+
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+
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+ This Agent generates Events based on NextBus GPS transit predictions. First, select an agency by visiting http://www.nextbus.com/predictor/agencySelector.jsp and finding your transit system. Once you find it, copy the part of the URL after `?a=`. For example, for the San Francisco MUNI system, you would end up on http://www.nextbus.com/predictor/stopSelector.jsp?a=sf-muni and copy "sf-muni". Put that into this Agent's agency setting.
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+
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+ Next, find the stop tags that you care about. To find the tags for the sf-muni system, for the N route, visit this URL:
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+ http://webservices.nextbus.com/service/publicXMLFeed?command=routeConfig&a=sf-muni&r=N
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+
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+ The tags are listed as tag="1234". Copy that number and add the route before it, separated by a pipe (|) symbol. Once you have one or more tags from that page, add them to this Agent's stop list. E.g,
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+
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+ agency: "sf-muni"
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+ stops: ["N|5221", "N|5215"]
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+
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+ This Agent will generate predictions by requesting a URL similar to the following:
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+
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+ http://webservices.nextbus.com/service/publicXMLFeed?command=predictionsForMultiStops&a=sf-muni&stops=N|5221&stops=N|5215
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+
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+ Finally, set the arrival window that you're interested in. E.g., 5 minutes. Events will be created by the agent anytime a new train or bus comes into that time window.
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+
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+ alert_window_in_minutes: 5
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+
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+
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+having the agent's default check period be every minute, and creating an Event in #check whenever a new tripTag (supplied by the predictionsForMultiStops API) shows up within alert_window_in_minutes from the stop. Do not create events for the same tripTag more than once per stop. I'd do this by keeping a list of [stop tag, tripTag, timestamp] tuples in memory and checking to make sure one doesn't already exist before making a new Event. This memory should get cleaned up when timestamp is older than an hour (or something) so that it doesn't fill up all of the Agent's memory.
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+
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+The NextBusAgent doesn't need to receive Events.
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+
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+It needs to fetch XML from one URL, store a list of timestamps in memory, and make Events.
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+
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+
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+ MD
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+
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+
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+ default_schedule "every_2m"
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+
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+ event_description <<-MD
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+ Events look like this:
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+ { "routeTitle":"N-Judah",
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+ "stopTag":"5215",
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+ "prediction":
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+ {"epochTime":"1389622846689",
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+ "seconds":"3454","minutes":"57","isDeparture":"false",
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+ "affectedByLayover":"true","dirTag":"N__OB4KJU","vehicle":"1489",
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+ "block":"9709","tripTag":"5840086"
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+ }
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+ }
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+ MD
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+ def session
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+ @session ||= Patron::Session.new
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+ @session.connect_timeout = 10
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+ @session.timeout = 60
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+ @session.headers['Accept-Language'] = 'en-us,en;q=0.5'
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+ @session.headers['User-Agent'] = "Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10_6_4; en-US) AppleWebKit/534.12 (KHTML, like Gecko) Chrome/9.0.584.0 Safari/534.12"
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+ @session
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+ end
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+ def check_me
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+ binding.pry
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+ end
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+ def check_url
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+
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+ stop_query = URI.encode(options["stops"].collect{|a| "&stops=#{a}"}.join)
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+
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+ u = "http://webservices.nextbus.com/service/publicXMLFeed?command=predictionsForMultiStops&a=#{options["agency"]}#{stop_query}"
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+ log "Fetching #{u}"
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+ u
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+ end
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+ def stops
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+ options["stops"].collect{|a| a.split("|").last}
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+ end
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+ def check
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+ puts "*************************\n\n\n\nI get called!!!\n\n\n\n**************************************"
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+ page = session.get(check_url)
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+ page = Nokogiri::XML page.body
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+ predictions = page.css("//prediction")
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+ puts "predictions #{predictions.to_xml}"
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+ puts "minutes #{predictions.collect{|a| a["minutes"]}.join(",")}"
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+ predictions.each do |pr|
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+ parent = pr.parent.parent
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+ vals = {routeTitle: parent["routeTitle"], stopTag: parent["stopTag"]}
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+ if pr["minutes"] && pr["minutes"].to_i < 60
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+ vals = vals.merge Hash.from_xml(pr.to_xml)
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+ if not_already_in_memory?(vals)
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+ create_event(:payload => vals)
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+ add_to_memory(vals)
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+ else
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+ end
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+ end
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+ end
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+ end
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+ def add_to_memory(vals)
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+ self.memory["existing_routes"] ||= []
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+ self.memory["existing_routes"] << {stopTag: vals["stopTag"], tripTag: vals["prediction"]["tripTag"], epochTime: vals["prediction"]["epochTime"], currentTime: Time.now}
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+ end
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+ def not_already_in_memory?(vals)
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+ m = self.memory["existing_routes"]
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+ m.select{|h| h[:stopTag] == vals["stopTag"] &&
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+ h[:tripTag] == vals["prediction"]["tripTag"] &&
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+ h[:epochTime] == vals["prediction"]["epochTime"]
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+ }.count == 0
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+ end
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+ def default_options
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+ {
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+ agency: "sf-muni",
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+ stops: ["N|5221", "N|5215"],
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+ alert_window_in_minutes: 5
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+ }
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+ end
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+
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+ def validate_options
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+ errors.add(:base, 'agency is required') unless options['agency'].present?
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+ errors.add(:base, 'alert_window_in_minutes is required') unless options['alert_window_in_minutes'].present?
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+ errors.add(:base, 'stops are required') unless options['stops'].present?
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+ end
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+ def working?
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+ event_created_within?(2) && !recent_error_logs?
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+ end
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+ end
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+end
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Umar M. Sheikh