The most performant way to validate XML against XSD

Question

I get a string variable with XML in it and have a XSD file. I have to validate the XML in the string against the XSD file and know there is more than one way (XmlDocument, XmlReader, ... ?).

After the validation I just have to store the XML, so I don't need it in an XDocument or XmlDocument.

What's the way to go if I want the fastest performance?

score 12 · Accepted Answer · answered Sep 08 '10 at 12:48

12

Others have already mentioned the XmlReader class for doing the validation, and I wont elaborate further into that.

Your question does not specify much context. Will you be doing this validation repeatedly for several xml documents, or just once? I'm reading a scenario where you are just validating a lot of xml documents (from a third party system?) and storing them for future use.

My contribution to the performance hunt would be to use a compiled XmlSchemaSet which would be thread safe, so several threads can reuse it without needing to parse the xsd document again.

var xmlSchema = XmlSchema.Read(stream, null);
var xmlSchemaSet = new XmlSchemaSet();
xmlSchemaSet.Add(xmlSchema);
xmlSchemaSet.Compile();

CachedSchemas.Add(name, xmlSchemaSet);

answered Sep 08 '10 at 12:48

sisve

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Yes, I validate and store a lot of xml document from a third party system for later use. The XSD is always the same, so your hint, compiling the schema set is much apprechiated, thanks! – Hinek Sep 10 '10 at 08:02
3

What is `CachedSchemas` in this example? – Welton v3.62 Jul 05 '11 at 22:01
1

Just a IDictionary for caching the results. – sisve Jul 06 '11 at 04:55
Why do you think XmlSchemaSet is thread safe? http://blogs.msdn.com/b/xmlteam/archive/2009/04/27/xmlschemaset-thread-safety.aspx – RichB Oct 11 '12 at 08:17
1

@RichB, that example works just as I described. Initialize a XmlSchemaSet, compile it, and then use it from several threads. But no, there is no support for what I am saying in any documentation I can find. – sisve Oct 11 '12 at 11:12
You might want to look into `XmlReaderSettings.IgnoreComments`, `IgnoreWhitespace` and `IgnoreProcessingInstructions`; My tests only apply to XML files without comments but if yours contain heavy comments, it might help (to verify) – Christian Rondeau Jun 01 '15 at 18:04

score 3 · Answer 2 · answered Sep 08 '10 at 11:09

3

I would go for the XmlReader with XmlReaderSettings because does not need to load the complete XML in memory. It will be more efficient for big XML files.

answered Sep 08 '10 at 11:09

Johann Blais

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score 2 · Answer 3 · answered Sep 08 '10 at 11:11

2

I think the fastest way is to use an XmlReader that validates the document as it is being read. This allows you to validate the document in only one pass: http://msdn.microsoft.com/en-us/library/hdf992b8.aspx

answered Sep 08 '10 at 11:11

Rune Grimstad

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score 0 · Answer 4 · edited Mar 15 '16 at 07:02

Use an XmlReader configured to perform validation, with the source being a TextReader.

You can manually specify the XSD the XmlReader is to use if you don't want to rely on declarations in the input document (with XmlReaderSettings.Schemas property)

A start (just assumes XSD-instance declarations in the input document) would be:

var settings = new XmlReaderSettings {
   ConformanceLevel = ConformanceLevel.Document,
   ValidationType = ValidationType.Schema,
   ValidationFlags = XmlSchemaValidationFlags.ProcessSchemaLocation |
                     XmlSchemaValidationFlags.ProcessInlineSchema,
};

int warnings = 0;
int errors = 0;
settings.ValidationEventHandler += (obj, ea) => {
   if (args.Severity == XmlSeverityType.Warning) {
      ++warnings;
   } else {
      ++errors;
   }
};

XmlReader xvr = XmlReader.Create(new StringReader(inputDocInString), settings);

try {
   while (xvr.Read()) {
      // do nothing
   }

   if (0 != errors) {
      Console.WriteLine("\nFailed to load XML, {0} error(s) and {1} warning(s).", errors, warnings);
   } else if (0 != warnings) {
      Console.WriteLine("\nLoaded XML with {0} warning(s).", warnings);
   } else {
      System.Console.WriteLine("Loaded XML OK");
   }

   Console.WriteLine("\nSchemas loaded durring validation:");
   ListSchemas(xvr.Schemas, 1);

} catch (System.Xml.Schema.XmlSchemaException e) {
   System.Console.Error.WriteLine("Failed to read XML: {0}", e.Message);
} catch (System.Xml.XmlException e) {
   System.Console.Error.WriteLine("XML Error: {0}", e.Message);
} catch (System.IO.IOException e) {
   System.Console.Error.WriteLine("IO error: {0}", e.Message);
}

The most performant way to validate XML against XSD

4 Answers4