Scott Hanselman

Not quite enumerating (iterating) enums

March 19, '06 Comments [9] Posted in ASP.NET | Internationalization | XML
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Warning/Disclaimer: This post is very likely useless and random, providing neither prescriptive guidance nor valuable suggestion. These are the ramblings of an idiot with possibly low blood sugar. There are at LEAST a dozen ways to write this silly thing. This is a largely academic post, as the end result doesn't affect the product fundamentally and the code in question only runs at startup so questions of perf is meaningless. End of speech.

Given:

I've got this giant XSD (XML Schema) with a pile of enumerations that represent languages. No, I don't own the XSD, it's a small part of a giant specification. I don't want to modify the schema.

I generated a giant C# from file from this giant schema via XSD.exe. I don't want to modify the generated code. (Random aside, when I generate code, I like to name the files *.g.cs to make it clear.)

The enum looks like this (there's 454 of them, FYI)...

public enum LanguageEnum {

 

    AAR,

    ABK,

    ACE,

    ACH,

    //snip.... 

    ZUL,

    ZUN,

}

These are the ISO 639.1 3-letter Language Codes. These are going to be in an XML Document that will be HTTP POST'ed to a URI endpoint. I want to 'convert' them to a System.Globalization.CultureInfo via a mapping mechanism and set the CultureInfo on the current thread.

The names of the enums are important, not any implied underlying value. (They don't map to ints, etc)

The constructor for System.Globalization.CultureInfo takes a string like en-us (the ISO 639-1 Alpha 2, not these Alpha 3 codes. Restated, they want "en" or "en-us" not "ENG." However, this info IS inside of CultureInfo.ThreeLetterISOLanguageName.

I'd like clean mapping, but don't feel like writing it manually.

I wrote it this way first in a fit about 90 seconds long. Note the weird try catch. Note also that this works (i.e. achieves the goal).

(Aside,I write a lot of methods like this that lazy-initialize against a hashtable of schmutz, so this is a common pattern for me.)

private static volatile Hashtable iso639toCultureInfo = null;

private static object hashtableLock = new object();

 

public void SetThreadCulture(LanguageEnum foolanguage)

{

    //Get a hashtable that maps the ISO639 three letter name to Windows Cultures

    if(iso639toCultureInfo == null)

    {

        lock(hashtableLock)

        {

            if (iso639toCultureInfo == null)

            {

                iso639toCultureInfo = new Hashtable();

                foreach (CultureInfo ci in CultureInfo.GetCultures(CultureTypes.NeutralCultures))

                {

                    string potentialFooLanguage = ci.ThreeLetterISOLanguageName;

                    try

                    {

                        //May throw an exception because FOO doesn't support this language

                        LanguageEnum lang = (LanguageEnum)Enum.Parse(typeof(LanguageEnum),potentialFooLanguage,true);

                        //May ALSO throw an exception because we already added it

                        iso639toCultureInfo.Add(lang.ToString(),ci);

                    }

                    catch (Exception)

                    {

                        ;

                    }

                }

            }

        }

    }

 

    CultureInfo fooCulture = iso639toCultureInfo[foolanguage.ToString()] as CultureInfo;

    if(fooCulture != null)

    {

        System.Threading.Thread.CurrentThread.CurrentCulture =
           System.Threading.Thread.CurrentThread.CurrentUICulture = 
              fooCulture;

    }

}

All the Unit Tests passed, blah blah, then I had a change of heart and did this about 30 seconds later:

    private static volatile Hashtable iso639toCultureInfo = null;

    private static object hashtableLock = new object();

 

    public void SetThreadCulture(LanguageEnum foolanguage)

    {

        //Get a hashtable that maps the ISO639 three letter name to Windows Cultures

        if(iso639toCultureInfo == null)

        {

            lock(hashtableLock)

            {

                if (iso639toCultureInfo == null)

                {

                    iso639toCultureInfo = new Hashtable();

                    StringCollection languages = new StringCollection();

                    languages.AddRange(Enum.GetNames(typeof(LanguageEnum)));

 

                    foreach (CultureInfo ci in CultureInfo.GetCultures(CultureTypes.NeutralCultures))

                    {

                        string potentialFooLanguage = ci.ThreeLetterISOLanguageName.ToUpper();

                        if(languages.Contains(potentialFooLanguage))

                        {

                            iso639toCultureInfo.Add(potentialFooLanguage,ci);

                        }

                    }

                }

            }

        }

 

        CultureInfo fooCulture = iso639toCultureInfo[foolanguage.ToString()] as CultureInfo;

        if(fooCulture != null)

        {

            System.Threading.Thread.CurrentThread.CurrentCulture =
               System.Threading.Thread.CurrentThread.CurrentUICulture =
                  fooCulture;

        }

    }

Which way do you prefer? What would you have done?

Incidentally, of these 434 (largely obscure) languages in the enum, .NET/Windows 'supports' 50 of them as neutral cultures. Also, the enum has "FRE" for France, while the code in CultureInfo is "FRA" so I ended up changing the enum anyway. Sigh.

About Scott

Scott Hanselman is a former professor, former Chief Architect in finance, now speaker, consultant, father, diabetic, and Microsoft employee. He is a failed stand-up comic, a cornrower, and a book author.

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Microsoft Fingerprint Reader and Password Minder

March 18, '06 Comments [6] Posted in ASP.NET | XML | Tools
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FingerPrintPasswordMinderI love my Microsoft Fingerprint Reader, and I use it all the time at home. I also love Keith Brown's Password Minder, it's where I keep all my secret stuff. I also keep the pa ssword file synchronized using FolderShare.

While the software that comes with the Fingerprint Reader will also store passwords, marrying them with your fingerprint, I like the idea of keeping my passwords in the pwd.xml file - it's more mobile and sync's nicely. I use the fingerprint login for a number of sites, but I keep my financial passwords super complex and in the Password Minder.

I never realized - doh! - that the Fingerprint Reader not only managed passwords for Web Sites, but Windows Programs as well.

This makes it twice as useful as I thought it was, and that was pretty useful.

Of course, the next obvious thing was to combine the two, hence the image at right. They work great together. Might seem stupid to use one password secret store to open another, but I thought it was cool. Now maybe I'll put them all on a TrueCrypt drive...mwahahahaha

Now playing: Audrey Niffenegger - The Time Traveler's Wife, Part 1

About Scott

Scott Hanselman is a former professor, former Chief Architect in finance, now speaker, consultant, father, diabetic, and Microsoft employee. He is a failed stand-up comic, a cornrower, and a book author.

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Hanselminutes Podcast 10

March 15, '06 Comments [4] Posted in Podcast | ASP.NET | Watir | Ruby | XML | Tools
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HanselminutesMy tenth Podcast is up. This episode is about (practical) functional web testing, including Watir, FireWatir, SilkTest, WinRunner, TestComplete, Selenium and a dozen others.

We're listed in the iTunes Podcast Directory, so I encourage you to subscribe with a single click (two in Firefox) with the button below. For those of you on slower connections there are lo-fi and torrent-based versions as well.

Subscribe to my Podcast in iTunes

Our sponsors are Automated QA, PeterBlum and the .NET Dev Journal.

As I've said before this show comes to you with the audio expertise and stewardship of Carl Franklin. The name comes from Travis Illig, but the goal of the show is simple. Avoid wasting the listener's time. (and make the commute less boring)

  • Each show will include a number of links, and all those links will be posted along with the show on the site. There were 16 sites mentioned in this tenth episode, some planned, some not. We're still using Shrinkster.com on this show.
  • The basic MP3 feed is here, and the iPod friendly one is here. There's a number of other ways you can get it (streaming, straight download, etc) that are all up on the site just below the fold. I use iTunes, myself, to listen to most podcasts, but I also use FeedDemon and it's built in support.
  • Note that for now, because of bandwidth constraints, the feeds always have just the current show. If you want to get an old show (and because many Podcasting Clients aren't smart enough to not download the file more than once) you can always find them at http://www.hanselminutes.com.
  • I have, and will, also include the enclosures to this feed you're reading, so if you're already subscribed to ComputerZen and you're not interested in cluttering your life with another feed, you have the choice to get the 'cast as well.
  • If there's a topic you'd like to hear, perhaps one that is better spoken than presented on a blog, or a great tool you can't live without, contact me and I'll get it in the queue!

Enjoy. Who knows what'll happen in the next show?

Now playing: Matisyahu - Dispatch the Troops

About Scott

Scott Hanselman is a former professor, former Chief Architect in finance, now speaker, consultant, father, diabetic, and Microsoft employee. He is a failed stand-up comic, a cornrower, and a book author.

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XmlValidatingReader problems over derived XmlReaders

March 12, '06 Comments [3] Posted in Web Services | XmlSerializer | Bugs
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This whole validation ickiness deserved two posts, so I didn't mention it in the last XmlValidatingReader post.

The XML format that I'm parsing and validating isn't the savvyest of formats as it was created years ago before the XML Schema specification was complete. While it has a namespace and it's an official specification, the instance documents don't have a namespace. They are entirely "unqualified." So, basically I'm trying to validate XML documents with a namespace against a schema that expects namespaces.

Additionally, the elementFormDefault is set to "unqualified." There's a great explanation of what elementFormDefault means here.

The documents come in like this:

<FOO>
  <BAR>text</BAR>
</FOO>

Before I'd look hard at the schema I had assumed that I could load them with an XmlNamespaceUpgradeReader. This is a derivation of XmlTextReader that does nothing but lie about the Namespace of every element. I'm using System.Xml on .NET 1.1.

public class XmlNamespaceUpgradeReader : XmlTextReader

    {

        string oldNamespaceUri;

        string newNamespaceUri;

 

        public XmlNamespaceUpgradeReader( TextReader reader, string oldNamespaceUri, string newNamespaceURI ):base( reader )

        {

            this.oldNamespaceUri = oldNamespaceUri;

            this.newNamespaceUri = newNamespaceURI;

        }

 

        public override string NamespaceURI

        {

            get

            {

                // we are assuming XmlSchemaForm.Unqualified, therefore

                // we can't switch the NS here

                if ( this.NodeType != XmlNodeType.Attribute &&

                    base.NamespaceURI == oldNamespaceUri )

                {

                    return newNamespaceUri;

                }

                else

                {

                    return base.NamespaceURI;

                }

            }

        }

    }

For example, if I did this:

XmlTextReader reader = new XmlNamespaceUpgradeReader(
    File.OpenText("MyLameDocument.xml"),
    String.Empty,
    "http://thenamespaceiwant"); 


XmlDocument doc = new XmlDocument();

doc.Load(reader);

Console.WriteLine(doc.OuterXml);

I would end up with this resulting XML:

<FOO xmlns="http://thenamespaceiwant">
  <BAR xmlns="
http://thenamespaceiwant">text</BAR>
</FOO>

Seemed like this would validate. Well, not so much. The document, as you can see, is fine. It's exactly what you'd expect. But, the I remember/noticed that the document was elementFormDefault="unqualified" meaning that only the root node needs the namespace. So...

public class XmlRootNamespaceUpgradeReader : XmlTextReader

{

    string oldNamespaceUri;

    string newNamespaceUri;

 

    public XmlRootNamespaceUpgradeReader( TextReader reader, string oldNamespaceUri, string newNamespaceURI ):base( reader )

    {

        this.oldNamespaceUri = oldNamespaceUri;

        this.newNamespaceUri = newNamespaceURI;

    }

 

    public override string NamespaceURI

    {

        get

        {

            // we are assuming XmlSchemaForm.Unqualified, therefore

            // we can't switch the NS here

            if ( Depth == 0 && this.NodeType != XmlNodeType.Attribute &&

                    base.NamespaceURI == oldNamespaceUri )

            {

                return newNamespaceUri;

            }

            else

            {

            return base.NamespaceURI;

            }

        }

    }

 

    public override string Prefix

    {

        get

        {

            if(Depth == 0 && this.NodeType == XmlNodeType.Element)

            {

                return "x";

            }

            return null;

        }

    }

 

}

...which results in a document like this:

<x:FOO xmlns:x="http://thenamespaceiwant">
  <BAR
>text</BAR>
</x:FOO>

This document should now validate, and it fact it does in my test applications. When the document is loaded directly from a test file it works fine. When I run it directly through one of the extended "fake-out" XmlTextReaders, it doesn't work. It's as if my readers don't exist at all, even though their code does indeed execute.

To be clear:

Original Doc -> XmlTextReader -> XmlValidatingReader -> doesn't validate (as expected)
Original Doc -> XmlNamespaceUpgradingReader -> XmlValidatingReader -> doesn't validate (but it should!)
Original Doc -> XmlNamespaceUpgradingReader -> XmlDocument -> write to file -> read from file -> XmlValidatingReader -> doesn't validate (as expected, it's "overqualified")
Original Doc -> XmlRootNamespaceUpgradingReader -> XmlDocument -> write to file -> read from file -> XmlValidatingReader -> DOES VALIDATE (as expected)

Why don't the "fake-out" XmlTextReaders work when chained together and feeding the XmlValidatingReader directly, but they do work when there's an intermediate format?

A few things about the XmlValidatingReader in .NET 1.1 (since it's obsolete in 2.0). While its constructor takes the abstract class XmlReader, internally it insists on an XmlTextReader. This is documented, but buried IMHO. Reflector shows us:

XmlTextReader reader1 = reader as XmlTextReader;
if (reader1 == null)
{
    throw new ArgumentException(Res.GetString("Arg_ExpectingXmlTextReader"), "reader");
}

<conjecture>When a class takes an abstract base class - the one it "should" - but really requires a specific derivation/implementation internally, it's a good hint that the OO hierarchy wasn't completely thought out and/or a refactoring that was going to happen in a future version never happened.</conjecture>

Regardless, System.Xml in .NET 2.0 is much nicer and as well though-out as System.Xml 1.x was, 2.0 is considerably more thought out. However, I'm talking about 1.1.

<suspicion>I take this little design snafu as a strong hint that the XmlValidatingReader in .NET 1.1 has carnal knowledge of XmlTextReader and is probably making some assumptions about the underlying stream and doing some caching rather than taking my fake-out XmlReader's word for it.</suspicion> 

If you're on, or were on, the System.Xml team let me know what the deal is and I'll update this post.

I know that the XmlRootNamespaceUpgradingReader works because the XML is correct when it's written out to an intermediate. However, the InfoSet that the XmlValidatingReader acts on is somehow now the same.  How did we solve it? Since XmlValidatingReader needs an XmlTextReader that is more "legit," we'll give it one

Original Doc -> XmlRootNamespaceUpgradingReader -> XmlDocument -> CloneXmlReader -> XmlValidatingReader -> DOES VALIDATE

This is cheesy, but if a better way is found at least it's compartmentalized and I can fix it in one place. We quickly run through the input XmlTextReader, write the Infoset out to a MemoryStream and return a "fresh" XmlTextReader and darn it if it doesn't work just fine.

/// <summary>

/// Makes an in memory complete, fresh COPY of an XmlReader. This is needed

/// because the XmlValidatingReader takes only XmlTextReaders and isn't fooled

/// by our XmlNamespaceUpgradingReader.

/// </summary>

/// <param name="reader"></param>

/// <returns></returns>

protected XmlTextReader CloneReader(XmlTextReader reader)

{

    MemoryStream m = new MemoryStream();

    XmlTextWriter writer = new XmlTextWriter(m,Encoding.UTF8);

    while (reader.Read())

    {

        writer.WriteNode(reader,false);

    }

    writer.Flush();

    m.Seek(0,SeekOrigin.Begin);

    XmlTextReader returnedReader = new XmlTextReader(m);

    return returnedReader;

}

Madness. Many thanks to Tomas Restrepo for his help and graciousness while debugging this issue!

About Scott

Scott Hanselman is a former professor, former Chief Architect in finance, now speaker, consultant, father, diabetic, and Microsoft employee. He is a failed stand-up comic, a cornrower, and a book author.

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Loading XmlSchema files out of Assembly Resources

March 12, '06 Comments [2] Posted in XML
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I've been doing some validating of documents against an XSD lately. Validation is pretty straight forward, you take any XmlTextReader and wrap and run it through the XmlValidatingReader. The ValidationEventHandler will call you back if there's any trouble. You can poke around in the document if you like, while the validation happens, but when I'm just validating I do a while(reader.Read()) as you'll see.

I have a PILE of .XSD files - 64 of them - that represent a single specification. I load the most-leaf node to load whole spec:

XmlSchemaCollection schemas = new XmlSchemaCollection();

XmlReader reader = new XmlTextReader("TheMainSchema.xsd");

XmlSchema schema = XmlSchema.Read(reader, null);

schemas.Add(schema);

 

XmlReader readerDoc = new XmlTextReader(TheFileYouWantToValidate.xml");

XmlValidatingReader newReader = new XmlValidatingReader(readerDoc);

newReader.Schemas.Add(schemas);

newReader.ValidationEventHandler += new ValidationEventHandler(OnValidate);

 

while ( newReader.Read() );

newReader.Close();

I wanted an assembly that was self-contained and would hold all 64 of these XSD files internally as resources, and I didn't want to put them in a temp directory.

I added all the schemas to the project, right clicked "Properties" and set them all to Embedded Resources. When you request an embedded resource you need to ask for the file using the original file name as well as the namespace. Use Reflector to determine what the ultimate fully qualified resource name is if you have trouble.

It's easy to pull the main schema out of it's resource and pass the Stream into XmlSchema.Read. It's slightly less obvious how to get that schema to resolve its imports.

Schemas may reference other schemas like this:

<xsd:schema targetNamespace="foofoo"
        xmlns:xsd="
http://www.w3.org/2001/XMLSchema">
   <xsd:include schemaLocation="SomeIncludedSchemas.xsd"/>
   <xsd:include schemaLocation="SomeIncludedSchemas2.xsd"/>

In this, and most, cases schemaLocation refers to a relative file. However it could refer to a URL, or some custom scheme. Personally I find the "relative filename" style to be the most flexible. I don't like to bake too much knowledge about the outside world into my schemas. On this project, it's a (light) requirement that we use the specification schemas unchanged.

Assembly a = Assembly.GetExecutingAssembly();

Stream stream = a.GetManifestResourceStream("MyNamespace.TheMainSchema.xsd");

 

XmlSchema x = XmlSchema.Read(stream,
    new ValidationEventHandler(SchemaValidationEventHandler));

 

x.Compile(
    new ValidationEventHandler(SchemaValidationEventHandler),
    new MyCustomResolver(a));

 

schemas.Add(x);

Note the instance call to XmlSchema.Compile. The XmlSchema class will use a FileSystemResolver by default and fail to find the other 63 schemas. So, I pass in a custom resolver that will find the correct schema given the URI (the value in the schemaLocation attribute) and return it, in this example, as a stream.

private class MyCustomResolver : XmlUrlResolver

{

    private const string MYRESOURCENAMESPACE = "MyNamespace.{0}";

    private Assembly resourceAssembly = null;                               

 

    public MyCustomResolver(Assembly resourceAssembly)

    {

        if (resourceAssembly == null)
           throw new ArgumentNullException("resourceAssembly must not be null");

        this.resourceAssembly = resourceAssembly;

    }

 

    override public object GetEntity(Uri absoluteUri, string role, Type ofObjectToReturn)

    {

        if(absoluteUri.IsFile)

        {

            string file = Path.GetFileName(absoluteUri.AbsolutePath);

            Stream stream = resourceAssembly.GetManifestResourceStream(
               String.Format(MYRESOURCENAMESPACE, file));

            return stream;

        }

        return null;

    }

Here we just grab the relative filename from out of the file:/// URI that we're passed into GetEntity each time a schemaLocation needs to be resolved. Works like a charm. I wrap the whole thing in a factory method and cache the compiled XmlSchemaCollection so we don't load and compile this more than once.

There's a few ways one might want to extend this. I've seen folks build Assembly schemas like assembly:/// and embed stuff in the schemas, but eh, who has the time. This is simpler, IMHO and works for relative file locations and didn't take 10 minutes to write.

Quote of the day: I'm not a control freak, I'm a control enthusiast.

About Scott

Scott Hanselman is a former professor, former Chief Architect in finance, now speaker, consultant, father, diabetic, and Microsoft employee. He is a failed stand-up comic, a cornrower, and a book author.

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Disclaimer: The opinions expressed herein are my own personal opinions and do not represent my employer's view in any way.