Chapter 1, Getting Acquainted with Storm, provides detailed information about Storm's use cases, different installation modes, and configuration in Storm.

Chapter 2, The Storm Anatomy, tells you about Storm-specific terminologies, processes, fault tolerance in Storm, tuning parallelism in Storm, and guaranteed tuple processing, with detailed explanations about each of these.

Chapter 3, Introducing Petrel, introduces a framework called Petrel for building Storm topologies in Python. This chapter walks through the installation of Petrel and includes a simple example.

Chapter 4, Example Topology – Twitter, provides an in-depth example of a topology that computes statistics on Twitter data in real time. The example introduces the use of tick tuples, which are useful for topologies that need to compute statistics or do other things on a schedule. In this chapter, you also see how topologies can access configuration data.

Chapter 5, Persistence Using Redis and MongoDB, updates the sample Twitter topology for the use of Redis, a popular key-value store. It shows you how to simplify the complex Python calculation logic with built-in Redis operations. The chapter concludes with an example of storing Twitter data in MongoDB, a popular NoSQL database, and using its aggregation capabilities to generate reports.

Chapter 6, Petrel in Practice, teaches practical skills that will make developers more productive using Storm. You learn how to use Petrel to create automated tests for your spout and bolt components that run outside of Storm. You also see how to use a graphical debugger to debug a topology running inside Storm.

Appendix, Managing Storm Using Supervisord, is a practical demonstration of monitoring and control of Storm using a supervisor over the cluster.

You will need a computer with Python 2.7, Java 7 JDK, and Apache Storm 0.9.3. Ubuntu is recommended but not required.

This book is for beginners as well as advanced Python developers who want to use Storm to process big data in real time. While familiarity with the Java runtime environment is helpful for installing and configuring Storm, all the code examples in this book are in Python.

In this book, you will find a number of styles of text that distinguish between different kinds of information. Here are some examples of these styles, and an explanation of their meaning.

Code words in text, database table names, folder names, filenames, file extensions, pathnames, dummy URLs, user input, and Twitter handles are shown as follows: "Storm configurations can be done using storm.yaml, which is present in the conf folder".

A block of code is set as follows:

import nltk.corpus

from petrel import storm
from petrel.emitter import BasicBolt

class SplitSentenceBolt(BasicBolt):
    def __init__(self):
        super(SplitSentenceBolt, self).__init__(script=__file__)
        self.stop = set(nltk.corpus.stopwords.words('english'))
        self.stop.update(['http', 'https', 'rt'])

When we wish to draw your attention to a particular part of a code block, the relevant lines or items are set in bold:

import logging
from collections import defaultdict

from petrel import storm
from petrel.emitter import BasicBolt

Any command-line input or output is written as follows:

tail -f petrel24748_totalrankings.log

New terms and important words are shown in bold. Words that you see on the screen, in menus or dialog boxes for example, appear in the text like this: "Finally, click on Create your Twitter application".

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