Beginning Google Maps Applications with PHP and Ajax

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Beginning Google Maps Applications with PHP and Ajax

Just as PHP and other Web scripting languages have made it possible to create dynamic Web pages, online mapping services are making it possible to create dynamic maps that can be customized by a website owner, or made customizable by a site visitor. In the case of Google Maps, this is done using the built-in application programming interface (API), which is described in a new book, Beginning Google Maps Applications with PHP and Ajax: From Novice to Professional.

But first, a brief background: During the mid-1990s, the only generally available mapping applications were desktop programs with location data limited to major cities within the United States. Yet less than one decade later, those programs were obsolete, replaced by Web-based mapping services such as MapBlast, MapQuest, and Yahoo Maps. In early 2005, Google raised the bar, with its own Web-based mapping service that was far more attractive than the others. For countless Internet users, it was their first glimpse of the power of AJAX, a new combination of technologies that allows Web pages to be refreshed asynchronously, providing a faster user interface. But Google Maps later packed another feature, an API that allows Web developers to leverage the service's capabilities in previously unimagined ways.

The authors of Beginning Google Maps Applications with PHP and Ajax — Michael Purvis, Jeffrey Sambells, and Cameron Turner — are based in Waterloo, Ontario, Canada. The book was published on 23 August 2006, by Apress, under the ISBN 978-1590597071. The publisher maintains a Web page devoted to the title, where visitors can find an online table of contents, a sample chapter (Chapter 3, "Interacting with the User and the Server") as a PDF file, and a link for submitting errata (none of which, as of this writing, appear to have been reported — assuming there are any). In addition, the authors have a website for the book, where they offer a sample chapter (Chapter 4, "Geocoding Addresses") in PDF format, links to raw data sources, and brief entries describing a variety of related topics, including geocoding services, Google Maps Mobile (GMM), Keyhole Markup Language (KML), and building your own geocoding using Perl.

The book's material is organized into 11 chapters, grouped into three parts. The fourth and final part contains the appendices. The three primary parts can roughly be thought of as presenting the beginning, intermediate, and advanced information. Part 1, "Your First Google Maps", whets the reader's appetite by showing how to easily create some simple maps (discussed below). In addition, it contains a chapter explaining how a Google Maps mashup interacts with the user as well as the server. The final chapter in this part discusses geocoding addresses. Part 2, "Beyond the Basics", explains how to work with third-party data, how to enhance the user interface, how to optimize and scale for large data sets, and finally what possible future directions Google may take with this API. Part 3, "Advanced Map Features and Methods", presents exactly that, covering such topics as creating custom controls and info windows, adding geometric shapes to maps, and getting the most out of geocoding, including how to work with postal codes.

The authors begin Part 1 ("Your First Google Maps") by introducing Google Maps with the two most simple examples possible: Keyhole Markup Language (KML) is an XML-like formatting language that allows one to specify the names, coordinates, and descriptions of one or more locations ("placemarks") in a single file. For anyone who wishes to avoid writing the code themselves, Wayfaring is a website that allows one to create and share custom Google Maps by point and click. Even though the introduction to KML is properly brief, instead of only stating that the sample coordinates were discovered manually, the authors should mention at least one simple way to find those coordinates (such as the "Link to this page" link in Satellite view in Google Maps). Nonetheless, it was wise of the authors to use simple examples to get the reader's feet wet as quickly as possible — especially for prospective readers who might skim through the rest of the book and become intimidated by the technical diagrams, JavaScript and PHP code, MySQL queries, XML markup, and mathematical formulas.

There is much to like about this book. The explanations are straightforward, the code is readable, the examples are relevant, and the writing style is approachable. The illustrations, all of which are in black and white, are well-chosen, and not overwhelming in number. In addition to showing the expected results of the sample code, they also provide enough visual incentive to encourage the reader to give the sample code a try, and perhaps develop it further into their own mapping applications.

The book is not too lengthy, clocking in at 384 pages according to the publisher (though, oddly, reports only 350 pages, even though the last page of the appendix reads "358"). The authors resisted the increasingly common temptation to pad the book with superfluous appendices. Instead there are only two. The first explains how and where to find location data, such as addresses and latitude/longitude points. The second appendix presents the details of all of the classes, methods, properties, constants and events defined within the Google Maps API. For some reason the authors mention "objects" instead of properties and events, but I was unable to find any pre-instantiated objects mentioned in that appendix., and I am not sure such are even possible in the API.

Fortunately, the weakest section of the book, its foreword, has the least impact upon the value of the book. It fails to perform the most basic functions of a foreword, such as explaining to prospective readers why they should become actual readers, as well as what the book covers, and how the authors are qualified to provide that coverage. Instead, its author mostly discusses his personal Google Maps Mania site, and even wedges in mention of his appearance on an NPR radio show, which has little to do with the book. He also lists his first five posts to his Mania site, the first of which contains a misspelling, which should have been caught by the book's editors, or at least indicated with a "[sic]". The best part of the foreword is the first few paragraphs, which provide a brief history of Google Maps and the hacking thereof.

Like most if not all of its titles, Apress helpfully starts this book with two versions of the table of contents — the first one serving as a high-level overview, and the second providing far more detail, listing not only sections but subsections. This is a nice touch, and should be employed by all technical publishers. On the other hand, this book does not have a lay-flat binding, which is a shame, as it makes it far more difficult to read the book with both hands free for keyboarding. With the introduction of lay-flat bindings years ago, it is inconceivable to me why it has not been universally adopted, particularly by technical publishers.

Overall, Beginning Google Maps Applications with PHP and Ajax is an excellent introduction to extending the power of Google Maps on the Web, and provides enough detail to both help and entice readers to build their own Google Maps mashups.

Copyright © 2006 Michael J. Ross. All rights reserved.
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