How would you like to have a piece of the action involving one of today's largest online marketplaces? Perhaps you have an idea for an innovative electronic storefront, but you don't want to build the back-end or try to implement the marketing campaign you need to attract the millions of users that you know you'll please.

Or maybe you're looking to integrate your enterprise with an existing e-tailer. Perhaps you have another idea altogether and just need the customers to support it. Look no further than eBay! With the eBay Software Development Kit (SDK) and lower-level web-based application programming interface (API), you can craft applications that tap eBay's vast product, server, and customer resources. Your application can be hosted on a web server, on your customers' desktop workstations, or on the latest mobile gadgets such as a personal digital assistant or smart phone.

eBay Application Development shows you how to do just that. After reading this book, you'll understand what the eBay interfaces provide through both their SDK and their API; how you can partner with eBay to design, develop, certify, and deploy your application; and, most important, the technical nuts-and-bolts behind actually writing applications that use both the SDK and API.

In reading it, I got a good understanding of what I could and couldn't do with eBay, and a better start than I would have with the eBay documentation alone.

I was not at all happy with the author's use of C# psudo-code rather than showing actual code. Did he have some super-secret app that he didn't want to share? I downloaded the code from the web site, but there were many examples that did not work.

Your choices with this book are C# and Pearl. There's not a line of VB.NET. Also, the web site only give you the sample code... nothing up there about new changes (such as Auth & Auth) that eBay has recently added.

Overall, I'm not really happy with this book. It feels like it was released to get something out there first, not best.

Rischpater points out that there are two ways to do this. The first, and chronologically it certainly was, is to write code that screen scraps eBay pages and extracts the desired data. Brittle. Because when eBay changes the layout, it breaks the scraping and you have to recode. There is also a problem for eBay. If you scrape, you end up discarding most of the page, like the HTML formatting commands. Unnecessary bandwidth usage, on both your end and eBay's. More burden on their servers.

The problem for eBay is that it cannot stop scraping. Indistinguishable from users manually requesting pages. So in part because of this, eBay offers an XML data feed and a higher level Software Development Kit (SDK). The XML feed is conceptually the simplest and also the most general, for your computer operating system and language can be anything that has an XML parser. Like linux and C++ or Java, for example. If you already know XML, this will be easy.

But the bulk of his presentation centres around using the SDK. This is a set of .NET assemblies (class libraries). So you are restricted to running your application on Microsoft Windows, because currently that is the only thing that supports .NET. But one of the virtues of .NET is that it supports a host of languages, like C, C++. C# and Perl. He strongly suggests that you consider using the SDK, and an associated library, because these are well debugged by eBay and offer functionality that has been found to be broadly useful by many developers. Whereas using the raw XML feed requires you to replicate some or most of this functionality.

Still, both are good choices, as compared to screen scraping. The book's explanations are good enough that you can tackle either.