In a supersaturated market, it is difficult to make an impression with a PHP book these days. The books of real value are those that focus on ways to apply the language to real world problems. These books delve into the depths of a particular application domain, showing PHP code and outlining design principles along the way. They are useful to current and prospective PHP programmers alike because they can introduce both not to PHP itself, but to an existing class of problems and how PHP can be applied to solve them. PHP Web 2.0 Mashup Projects is one of these books.
Most technology-related books on the shelves are several inches thick and an inherently daunting chore to sift through. Luckily, this book is not one of those. Do not let the size fool you, though; it is positively packed with useful information. It hits the high points of each topic it covers, giving you enough in the way of code samples and step-by-step explanations to get started, as well as resources to help you get better acquainted with topics that might be of particular interest to you.
The book is divided into six chapters, each of which covers a set of particular protocols, data formats, and APIs for acquiring and processing data in order to create a particular mashup application. These projects include:
A search engine to find products on Amazon by their Universal Product Code
A search engine to combine results from MSN and Yahoo!
A video jukebox that pulls songs from Last.fm and videos from YouTube
A traffic incident reporting application that sends SMS alerts
An illustrated tube station line map using Google Maps and Flickr for related photos
The book's structure and layout make it easy to follow, whether you prefer to read it linearly or jump around to specific sections. It is an excellent reference that I can see myself returning to time and time again.
One of the strengths of the book is that it has a very wide base of coverage. It starts by introducing basics in interacting with web services and extracting the desired data from their responses using core PHP libraries. The REST, XML-RPC, and SOAP protocols and the WSDL standard are all covered in enough depth to get you started, so you can work with a web service regardless of the protocol or protocols it offers. The author does an excellent job of selecting example web services and data standards from large and well-known to small and obscure. For real world APIs, you will find the likes of Amazon, YouTube, Google, and Flickr, as well as sources that might not be household names, such as the Internet UPC Database. Data standards include general formats like XML, RDF, and JSON and more specialized formats like RSS and XSPF.
Another strength is that the book encourages good principles from the start. It advocates object-oriented design principles for code reuse and a DRY philosophy. It suggests using third-party libraries such as those in PEAR in order to avoid unnecessary reinvention of the wheel, but still shows you how to roll your own if and when it becomes necessary. The books also covers usability, particularly in the last chapter when it discusses AJAX and race conditions, and pays special attention to application security, an area of increasing concern in web applications. Unlike some books, this one includes tips for development outside its own showcased projects to alleviate you from having to spend your own time troubleshooting common issues or digging for solutions to "gotcha" situations.
And last but certainly not least, the book demonstrates that sometimes you have to be resourceful in locating and acquiring your data, particularly in Chapter 5 where one of my own areas of interest, web scraping, is covered. The topic is explained in plain language and supplemented with examples walking you through exactly how it can be used to acquire data for your own mashups. Web scraping is not a frequently broached topic and I applaud the author for making a point to include it. I believe it is a genuinely useful methodology that can help in data acquisition when no other options are available.
I cannot give the book an entirely glowing review, though. There are some errata present, both in content and code samples. Most are small, but some are enough to throw off a reader not already familiar with the material being covered. I've submitted some of these via the publisher's web site already, though I have yet to receive any related communications or see them show up on the web site at the time that I write this review. These issues are able to be corrected, though, and the quality of the book's content outshines them.
Overall, PHP Web 2.0 Mashup Projects is an excellent example of creativity in finding new ways to aggregate data sets in useful combinations. It is a testament to the possibilities of the internet when access to data is opened up and freedom to use that data enables developers to create exciting and inspiring new solutions. Mashups show the internet's potential increasing in leaps and bounds and this book can get you on your way to contributing to their future development.