Over the last few years, the boom that the World has experienced with the Internet breakthrough has pushed almost every programming language or platform to welcome the rise of web development toolkits, libraries, and frameworks.
The Python programming language has grown a rather large list of these environments though apart from a few of them such as Zope and Twisted most have a fairly small community. It is in this context that CherryPy came into existence when Rémi Delon, its creator, decided that he needed a tool that would work as he wanted for his own personal projects. He then released CherryPy under a free software license so that anyone could use, distribute, and contribute to the project.
CherryPy is a Python library implementing the HTTP protocol, which is at the very core of the Web, using common Python idioms. On top of that CherryPy offers its own view and concepts on how to help a developer to build web applications while being minimally intrusive through its own simple and straightforward API.
This book will guide you through the CherryPy library with the aim of giving you the key to make the best of it in your own web applications.
The first four chapters are dedicated to CherryPy, providing information ranging from its history to an in-depth presentation of its key features. The rest of the book will then take you into the development of a photoblog application. Each chapter tries to provide enough background to allow you to ponder the why and how of each decision made. Indeed writing software applications is not a precise science and compromises need to be undertaken for the better, however, the truth is that writing software usually does not go quite as planned. I have written this book with the hope that in the end you would have learnt much more than using a Python library.
Chapter 1 presents the story behind CherryPy and a high-level overview of the project.
Chapter 2 guides you through the installation and deployment of CherryPy via common strategies like using distutils, setuptools, or subversion.
Chapter 3 gives an overview of the main and the most common aspects of CherryPy, which will give you an understanding of what the library can do.
Chapter 4 goes into an in-depth review of the main aspects of the library such as its support for the HTTP protocol or the WSGI interface. It also extensively discusses the tool feature of the CherryPy API.
Chapter 5 introduces the application, which will be the unifying theme for the rest of the book. The chapter reviews the basic entities that the application will manipulate before moving onto explaining how we will map them into a relational database. This will allow us to explain the concept of ORM and perform a quick comparison between SQLAlchemy, SQLObject, and Dejavu.
Chapter 6 presents the idea behind web services by reviewing REST and the Atom Publishing Protocol.
Chapter 7 describes how to use a templating engine such as Kid to generate web pages dynamically. The chapter also introduces Mochikit a JavaScript toolkit to perform client-side development.
Chapter 8 extends chapter 7 by diving into the world of Ajax, which has reminded web developers that they can create extremely powerful applications by simply using the browser capabilities, the JavaScript language, and the HTTP protocol.
Chapter 9 makes a strong point that any application should be reasonably well tested and introduces some testing strategies like unit testing, functional testing, and load testing.
Chapter 10 ends the book by reviewing some methods to deploy a CherryPy application under a common web-server front end like Apache and lighttpd. The chapter also explains how to enable SSL from your CherryPy application.
Throughout this book we will assume that you have the following packages installed and available.
Python 2.4 or above
CherryPy 3.0
You need to have a basic knowledge of the Python language.
The book is principally geared towards web developers who wish to learn how the Python programming language can fit their requirements. Although the CherryPy toolkit is at the core of the book, many common libraries are introduced in order to open the book to a larger audience.
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.
There are three styles for code. Code words in text are shown as follows: "A newer and more common way of deploying a package is to use the easy_install command to install eggs."
A block of code will be set as follows:
body
{
background-color: #663;
color: #fff;
}
p
{
text-align: center;
}Any command-line input and output is written as follows:
python ez_setup.py
New terms and important words are introduced in a bold-type font. Words that you see on the screen, in menus or dialog boxes for example, appear in our text like this: "The next step is to run those tests by clicking the All button."
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