Finding the top n ranked topics using Redis

The topology will compute a rolling ranking of the most popular words in the past 5 minutes. The word counts are stored in individual windows of 60 seconds in length. It consists of the following components:

• Twitter stream spout (twitterstream.py): This reads tweets from the Twitter sample stream. This spout is unchanged from Chapter 4, Example Topology – Twitter.
• Splitter bolt (splitsentence.py): This receives tweets and splits them into words. This is also identical to the one in Chapter 4, Example Topology – Twitter.
• Rolling word count bolt (rollingcount.py): This receives words and counts the occurrences. The Redis keys look like twitter_word_count:<start time of current window in seconds>, and the values are stored in a hash using the following simple format:

  {
      "word1": 5,
      "word2", 3,
  }

  This bolt uses the Redis expireat command to discard old data after 5 minutes. These lines of code perform the...