Getting keywords out of a search

SomeBolt.scala

import com.example.util.Codec
import com.example.storm.bolts.IntervalBolt
import com.github.theon.uri.Uri.parseUri

class SomeBolt (serializer:Serializer, ticksBeforeFlush: Int, bufferLimit: Int)
  extends IntervalBolt(ticksBeforeFlush) with Codec{
  
  def bufferOffInterval(input: Tuple) = ???
  def onInterval() = ???
  override def declareOutputFields(declarer:OutputFieldsDeclarer) = ???

  def extractKeywords(category: String, url: String) : List[String] = {
    val query_key = if (url.contains("http://search.yahoo.com/")) "p" else "q"
    if (category == "search")
      parseUri(url).query.params.getOrElse(query_key, List()).flatMap(x => x.decodeUrl.split(" "))
    else List()
  }
}