Signs on the Sand

One more logger with clunky text-based log file format and appropriate plumbing (object model, writer, parser and viewer) were written by me this week. Format was defined by customer and it was non disputable unfortunately. As for me it's just ugly. Why not use XML as log format?
Pros: trivial writing/parsing, portability, readability, simplicity. Constras: everybody seems to think it's unfeasible due to XML well-formedness and hence root element end tag problem - to append records you need to seek an appropriate place hence to parse the whole XML document. That's true for XML documents, but what about XML fragment?

XML fragment is actually external general parsed entity in XML 1.0 specification terms - it's freestanding fragment of XML, which can be incorporated into an XML document by entity reference, but it's still useful on its own - one can append elements to it (and because it's not XML document, root-level well-formedness rules don't apply to it, so one can just append elements to the end of file, without necessity to parse the whole log file) and then read such log file by XmlTextReader, which [thankfully to .NET developers] supports XML fragments (see "Reading XML Fragments with the XmlTextReader").

So here is small proof-of-concept example:

Writing to log:

class Test {
  static void Main(string[] args) {
    using (FileStream fs = File.Open("log.xml", 
        FileMode.Append, FileAccess.Write, FileShare.Read)) {
        XmlTextWriter writer = new XmlTextWriter(fs, Encoding.ASCII);
        for (int i=0; i<3; i++) {
          writer.WriteElementString("item", "", 
            DateTime.Now.ToString());
          writer.WriteWhitespace("\n");
        }
        writer.Close();
    }
  }
}

First run creates log.xml:

<item>7/22/2003 11:15:42 AM</item>
<item>7/22/2003 11:15:42 AM</item>
<item>7/22/2003 11:15:42 AM</item>

Second run appends three more items:

<item>7/22/2003 11:15:42 AM</item>
<item>7/22/2003 11:15:42 AM</item>
<item>7/22/2003 11:15:42 AM</item>
<item>7/22/2003 11:16:12 AM</item>
<item>7/22/2003 11:16:12 AM</item>
<item>7/22/2003 11:16:12 AM</item>

Reading log:

class Test {
  static void Main(string[] args) {
    using (FileStream fs = File.OpenRead("log.xml")) {
      XmlParserContext context = new XmlParserContext(
        new NameTable(), null, null, XmlSpace.Default);
      XmlTextReader reader = new XmlTextReader(fs, 
        XmlNodeType.Element, context);
      while (reader.Read()) {
        if (reader.NodeType == XmlNodeType.Element) {
          Console.WriteLine("Element: {0}, Value: {1}", 
            reader.Name, reader.ReadElementString());
        }
      }
    }
  }
}

And result is:

D:\projects\Test2\bin\Debug>Test2.exe
Element: item, Value: 7/22/2003 11:15:42 AM
Element: item, Value: 7/22/2003 11:15:42 AM
Element: item, Value: 7/22/2003 11:15:42 AM
Element: item, Value: 7/22/2003 11:16:12 AM
Element: item, Value: 7/22/2003 11:16:12 AM
Element: item, Value: 7/22/2003 11:16:12 AM 

I like it. Comments?