.NET and XML: Mortal Enemies

In the past, I’ve had my issues when dealing with the compatibility between C# and XML, so much so that I’ve been inspired to write prose. At this point, I feel that it’s my duty for posterity to document the various instances where Microsoft drops the proverbial XML ball:

  1. As stated before, DTD validation of XML files (with the C# XmlReader) is broken. And when I say broken, I mean that it performs as well as a thirty-year-old VCR pulled from the ocean and then placed in a vat of hydrochloric acid. Now plug that VCR in. You’re going to get the same results.
  2. If you’re hoping to create a XSD from available XML or classes with the Visual Studio Tool (i.e., XSDT), good luck. For one, it doesn’t allow you to specify any complex rules. Also, if you’re generating a XSD schema from classes, you should know that it doesn’t work with Nullable types or any Dictionary properties, since they couldn’t budget it into their schedule.
  3. “Hey, I have a container that’s set to null. So I’ll tell C# not to mention that tag at all upon serialization, since it’s just wasted space and since I might not want that tag visible in certain cases.” It is possible…but under specific circumstances. If you plan on serializing your class as is and if you plan on not using any C# attributes on your properties, maybe. Otherwise? Nope. C# says “No soup for you!”
  4. If you want to serialize an array of strings, you get a free bonus upon serialization: all of the tags will be prefixed with a namespace (i.e., the namespace for array serialization). If you don’t want that ugly prefix, just create a wrapper container for a string array. Now do this for every literal type you can think of.
  5. Let’s say that you have a XML doc with a string that is a HTTP link. You now want to parse that XML and read that value. Of course, if that link contains a query string, all of those ampersands are already converted into instances of “&“, in order to be compatible with XML standards. “But I want my data to be read incorrectly!” Well, you’re just in luck, friend! Because when you use XmlDocument.Load() to deserialize that XML, that query string will contain “amp;” and not “&“, essentially turning the link into garbage. Huzzah!

These are only a few instances, but there’s more. (Don’t even get me started on deserializing payloads from a ASP.NET web service.) If anyone out there has their own experiences to add, I’d love to hear them.

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