OpenLayers 2.10 Beginner’s Guide – Erik Hazard, Packt Publishing
As with many open source projects, documentation and startup guides are freely available online, but their quality and completeness often is very variable. A paper-based guidebook is still the best way to get to grips with the complete capabilities of a complex framework like OpenLayers – but with the danger that it is likely to date quickly as the project evolves. The author is particularly brave in referring to the current version – 2.10 – in the book title, as any subsequent release (2.11 is probably just around the corner) will appear to age the book, while actually it is likely the vast majority of its content will remain relevant with the new version.
OpenLayers does have a notably steeper learning curve than (for example) the Google Maps API – although it is ultimately more powerful. A physical, complete guide like this does therefore have a definite benefit to a developer aiming to produce online mapping applications based on open source technology.
The book, slightly surprisingly, introduces some fairly weighty programmatic detail right at the beginning – in Chapter 1. For example, I wasn’t expecting a discussion of Object Orientated Programming, and defining objects, instances and classes/subclasses, so early on in the book. It could be argued that these are important concepts to learn early, o gain a good understanding of a powerful API. I do still think that these would be likely to intimidate a genuine beginner, who just wants to quickly create a map.
The vector layers – which in my opinion are the most interesting and powerful part of OpenLayers are introduced all the way back in chapter 9. Vector styling – advanced but powerful – is in the chapter after that. There are many complex method calls for vector layers, and so many of these do deserve to be introduced only late on – but introducing a subset of vector capabilities much earlier in the book would have been of benefit.
There are several typos and minor misspellings in the book, including in a couple of code examples, detracted slightly from the clarity of the book.
The OpenLayers 2.10 Beginners Guide is fantastic as a reference – it goes into great detail and is so very useful for advanced users of the OpenLayers API. But it forsakes smoothing the OpenLayers learning curve in favour of a solid ground-working of the detail – great if this is your career, not so great if you just want to download OpenLayers and create a simple map. If you are prepared to spend the time with the detail, then you will emerge an OpenLayers expert!