One of the great successes online is eBay. A not-so-small cottage industry has arisen to help users buy or sell more easily. Of this, an important subset handles cases where users are companies that might want to integrate and automate their inventory needs with eBay. 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.
This book provides a decent overview of eBay development, but it stops short of providing many direct solutions to programming issues. It's more of a reference (which it does an ok job of being), full of tables of values, etc. However, that's all available in eBay's documentation. 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.
This is a good introduction to eBay's new public interface and developer program, focusing primarily on how to build applications for desktop users with their SDK. It does a good job introducing not just the interfaces and API's but also the basics of Web programming at the same time. 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.