Question

Ok, I am fairly new to working with xml, xpath etc.

I am in the midst of writing a windows service that will pick up information from a queue. It will process this information and part of the processing of this information is using xpath on a xmldocument that I am creating than loading.

Code Snippet. :

XmlDocument _xmlDocument = new XmlDocument();
_xmlDocument.Load(svgFile);
_xmlNamespaceManager = new XmlNamespaceManager(_xmlDocument.NameTable);
_xmlNamespaceManager.AddNamespace("svg", "http://www.w3.org/2000/svg");

After the above snippet I am then doing some xpath functionality, I need to use this as there are some pre-written functions that will save me a large amount of time.

Here is the real issue, when I am using the AddNamespace above it is going out to that uri and taking up way too much time doing so (validating etc). My thought was if I could just download the DTD and create a local file that it would save that time that is being wasted going out to the web. Unfortunately, without AddNamespace xpath will not work.

I have researched this out on the web and haven’t been able to find a solution for this. The xml is created internally so I am not worried too much about having the most current schema from the web at this moment. I am more worried about generating the data from the service in a timely manner. Maybe I am completely wrong and this isn’t possible, but programmatically speaking I don’t see how this hasn’t been done before.

Answer 1

I ended up having to create my own xmlresolver class and then downloading the dtd and a bunch of mod files associated with it locally. Then rather than doing an xmldocument.load, you perform something like the below. :

            XmlReaderSettings settings = new XmlReaderSettings();
            settings.ValidationType = ValidationType.DTD;
            settings.ProhibitDtd = false;
            settings.XmlResolver = new MyCoolResolver();
            binDirectory = binDirectory + "/content";
            string myFileLocation = binDirectory + "/MyFile.svg";

            using (XmlReader reader = XmlReader.Create(myFileLocation , settings))
            {
                try
                {
                    while (reader.Read())
                    {
                        _xmlDocument.Load(reader);
                    }
                }
                catch (XmlException e)
                {
                    Console.WriteLine(e.Message);
                }
            }

Then your class is just something like this for your myXmlResolver class.

namespace ReallyCoolProject
{
    public class MyCoolResolver : XmlUrlResolver
    {
         public override object GetEntity(Uri absoluteUri, string role, Type ofObjectToReturn)
         {
            string binDirectory =               Path.GetDirectoryName(System.Reflection.Assembly.GetEntryAssembly().Location);
            binDirectory = binDirectory + "/mods";

            if (absoluteUri.OriginalString.Contains("-//W3C//DTD SVG 1.1//EN"))
            {
                return File.Open(binDirectory + "/svg11.dtd", FileMode.Open);
            }

            if (absoluteUri.OriginalString.Contains("-//W3C//ENTITIES SVG 1.1 Document Model//EN"))
            {
                return File.Open(binDirectory + "/svg11-model.mod", FileMode.Open);
        }

        //.....many many more mod files than this

     }
    }
}

**Personal note can’t take all the credit as I took bits and pieces from a bunch of examples on the web.