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The PEAR Installer Manifesto

Chapter 2. Mastering PHP Software Management with the PEAR Installer

In this chapter, we learn how to turn PHP software into distributable PEAR packages. In September 2005, version 1.4.0 of the PEAR installer was released. This release was a milestone, marking the transformation of PEAR from a niche-market tool for installing small libraries distributed by pear.php.net to a full-fledged application installation tool. For the first time, it is possible to distribute large-scale applications, and even complete web-based database-intensive applications can be installed and configured in one step.

The PEAR installer now can be used to install traditional web-based applications like phpMyAdmin and non-PEAR libraries like the popular Smarty template engine (both happen to be installable through the http://pearified.com PEAR channel). Two of the primary design goals of the PEAR installer are to:

Make it possible to distribute application development across multiple development teams (i.e. stop re...

File/Directory Attributes: name, role, and baseinstalldir

The<file> and<dir> tags have a number of options available to them. Both tags require a name attribute, defining the name of the element as located on disk. Unlike an operating system, package.xml does not allow empty directories. All<dir> tags must contain at least one<file> tag. As described in the previous section, there are two ways to describe the location of a file in package.xml, either with a complete relative path separated by the UNIX path separator /:

<file role="php" name="foo/test.php"/>

Or, alternately as:

<dir name="foo">
<file role="php" name="test.php"/>
</dir>

All files must have a role attribute. This attribute tells the installer how to handle a file. The default list of allowed file roles is:

Role	Description
Default File Roles
php	PHP script files, like "PEAR.php"
data	Data files used by the script (read-only)
doc	Documentation files
test	Test scripts...

Key benefits

Learn how to effectively organize your application development from the creator of the latest versions of the PEAR Installer, version 1.4.0 onwards

Bring the power of versioning and rollbacks to your live website

Embed the PEAR Installer in your web applications to manage plug-ins from a remote server

Description

PEAR stands for PHP Extension and Application Repository, and its primary purpose is to support code re-use. PEAR provides both an advanced installer and a code repository at http://pear.php.net. PEAR code is organized into discrete re-usable components called packages. A package consists of a group of files and a descriptor file called package.xml that contains metadata about the package's contents, such as the package version, any special dependencies, and textual information such as the package description and authors. The software that transforms a package from an inert grouping of files into a dynamic software package is called the PEAR Installer and is itself a PEAR package. In other words, the PEAR Installer can be used to upgrade itself. It truly is a very powerful application. In short, the PEAR Installer is one of the most effective tools for managing a high-quality software library, high-quality applications, or high-quality websites. This book will show you a new way of organizing your PHP development, by leveraging the full power of the PEAR Installer. In a sense, the PEAR Installer is a step above a software design pattern, a meta-development pattern that can be used to systematically organize all of your PHP development. You will learn how to organize your code into packages using the package.xml format. You will learn about the revolutionary new PEAR Channel concept, and how to safely and reliably depend on external PHP libraries from sources such as pear.php.net and other PEAR channels. You will learn about the PEAR_PackageFileManager package, and how to customize individual installations of your PHP code through file roles, file tasks, and post-installation scripts. In addition, you will learn how to use the power of PEAR to manage your web projects with the PEAR installer to bring the power of versioning and rollbacks to your live website. The synergy of the PEAR Installer and a revision control system like CVS or Subversion is also explored in depth. Next, you will learn how to set up your own PEAR Channel for distributing PHP applications, both open-source and proprietary closed-source PHP applications that can be secured using technology already built into the PEAR Installer. Finally, you will learn how to embed the PEAR Installer inside your own web application in order to manage plug-ins from a remote server. The book covers in detail designing a custom plug-in system for a fictitious blog application. The plug-in system is used to manage templates, and the PEAR Installer is used to manage the details of querying the remote server for templates, handling dependencies between versioning, and doing the actual installation process as well.

Who is this book for?

The book is not just for PHP developers who want to understand how the PEAR Installer works, and what it can do for them, but more generally for PHP developers seeking a better way to deploy their applications and manage updates. It does assume that you have a good working knowledge of PHP development, and are dealing with projects of a sufficient scale and complexity to warrant an investment in a structure process.

What you will learn

What the PEAR Installer is, and what it can do for you

Organizing your code into packages using the package.xml format

Customizing individual installations of your PHP applications through file roles, file tasks, and post-installation scripts

Using the PEAR installer to bring the power of versioning and rollbacks to your live website

Getting the PEAR Installer and source control repository working together

Setting up your own PEAR Channel for distributing your PHP applications

Embedding the PEAR Installer inside your own web application to manage plug-ins from a remote server

What do you get with Print?

Instant access to your digital copy whilst your Print order is Shipped

Paperback book shipped to your preferred address

Redeem a companion digital copy on all Print orders

Access this title in our online reader with advanced features

DRM FREE - Read whenever, wherever and however you want

Brett Bieber Dec 14, 2006

I recently finished a book on the PEAR installer written by Greg Beaver. The book itself is an excellent read for anyone who develops installable PHP libraries or applications, and one I would highly recommend for anyone interested in building small to large PHP web applications.Throughout the book, Greg demonstrates the complex features of the PEAR installer and package description file (package.xml) to guide you through understanding methods of distributing, installing, and maintaining PHP (and other) projects. The book is filled with real world examples and working applications from the guy who (seriously) 'wrote the book' on the PEAR installer.To anyone who is building distributed PHP applications or reusable libraries, this book is a must have for understanding release deployment strategies and how they are managed with powerful ease. The author knows his stuff, and has used every one of the examples within real word applications. The book has everything from "Hello World" installable applications to a full blown source code repository and distribution system through PEAR channels.With the book you will have all of the necessary information to build and maintain your complex PHP applications and easily distribute them across many servers, clients, or the open source community.If you're at the point in your application development where the unzip-and-go distribution method has reached its limit (typically the first bug after the first zip), the time has come to start building installable PEAR packages and to take advantage of all the capabilities the PEAR installer offers.Despite maintaining my own PEAR channel server (...........) for over a year now, I still found plenty of information to continue the ease with which the PEAR installer offers. So even if you are an experienced PEAR developer, the book is still a good read and shelf reference.I highly recommend the book, check it out.

Amazon Verified review

Travis Swicegood Jun 11, 2007

"Isn't PEAR just a bunch of packages you can install?" That's the question you'll receive most of the time if you ask a PHP developer if his software can be installed through the PEAR Installer. There's been a lot of work happening in PEAR that's culminated most recently in the PEAR elections and the announcement of Pyrus - PEAR 2. A major force behind all of these changes, including work on the PEAR Installer, is Greg Beaver. With this book, he can claim "he wrote the book on PEAR". Not that anyone could have disagreed with him before getting this book published. :-)This past weekend I read through the PEAR Installer Manifesto. For anyone who's not familiar the PEAR installer and how it can be used in projects outside of PEAR, I would point them to this book. It's only six chapters long, but it walks through the ways to use the PEAR Installer to enhance your projects - large or small, open or closed source, free or pay. This book covers the basics of what the PEAR Installer is, how to use it to distribute your own packages, and explains how to deploy a website using the installer. The book closes out with the two chapters that make this book a must read to someone already familiar with the PEAR Installer, but not familiar with what it is capable of: a chapter on PEAR channels and one on embedding the PEAR installer.A PEAR channel isn't a difficult thing to setup; there are blog posts aplenty on the topic. This chapter fill in the gaps in those posts answering the "why" to how things are done. I've setup my own channel before, but I hadn't investigated the internals to figure out exactly how everything ticked. Chapter 5 - Releasing to the World: PEAR Channels, fills in the gaps and gives you a thorough understanding of what makes a channel tick.Chapter 6 - Embedding the PEAR Installer: Designing a Custom Plug-In System, discusses several methods of handling plug-in systems then demonstrates how to create one using the PEAR Installer as a base. This chapter really starts to show exactly how powerful the installer can be once you start to re-purpose it, making it more than the command line tool we all use to download and install code. Thinking of the possibilities this introduced, I actually got giddy. Yes, I know... I'm a geek.This is a four star rating, so there were a few things that weren't exactly what I had hoped for. I hoped this would serve as a full reference to the installer. While this book takes you a lot of great jumping off points, it doesn't have the thoroughness I wanted. There are areas where the complexity of the code you're calling isn't covered in depth and you're left with a "this is all you'll need to know for this task" type comment. It took a visit to Greg's PEAR channel to fully understand how to package a custom file role. The book demonstrated the required PHP for the role and showed the custom XML, but didn't explicitly state that they were to be packaged together or how they were to be packaged. An appendix offering an in-depth overview of the code related to the installer would be a great addition to this book. With the recent news of Pyrus, that might be outdated before it could be ready though.I would have liked to have seen a more in-depth comparison to competing methods of building/packaging software. Instead, the only alternative that is discussed at any length is "unzip and go". It would have been interesting to see the comparison of the PEAR Installer to a traditional build system - such as PHP's phing or Java's Ant - and to explore using the installer inside a phing/Ant environment and how they could compliment each other. For example, using phing to handle the build process, while using PEAR channels and the installer to handle distribution and installation.This book is definitely worth the read for anyone interested in the PEAR Installer and understanding what it is capable of. The absence of a full reference to the installer code and no mention of viable alternatives to handle packaging are the only things that kept me from rating this book at 5 stars.

PJS5 Aug 11, 2010

I bought this book because I found PEAR rather confusing. The first time I read it I was bewildered so I thought I must have missed something and read it again but found myself none the wiser. I was hoping it would clarify things, teach me how to create my own PEAR packages and how to use PEAR to deploy apps etc. Instead the book seems to just talk about how great and simple PEAR is. It prefers to talk about PEAR in a general sense, offering no real guidance on how to actually use it for anything. The instruction that is present is very basic and already prominent on the PEAR website. A complete waste of time.

The PEAR Installer Manifesto: The PEAR Installer maintainer shows you the power of this code management and deployment system to revolutionize your PHP application development

What do you get with Print?

The PEAR Installer Manifesto

Chapter 2. Mastering PHP Software Management with the PEAR Installer

Distributing Libraries and Applications

Using Versioning and Dependencies to Help Track and Eliminate Bugs

Versioning

Distribution and Upgrades for the End User

An Overview of package.xml Structure

Tags Shared between package.xml 1.0 and 2.0

Package Metadata

New Tags in package.xml

File/Directory Attributes: name, role, and baseinstalldir

Summary

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