Validating XML against an XSD schema

-
I have a new job. Well, I say "new" but I actually started in December 2005. Anyway, this "new" job requires me to develop compact framework apps. Seeing as Delphi doesn't support CF I am developing my application in VS2005, it's a really nice tool but I miss ECO so much!

One thing I had to do was to write an XML importer routine. This would retrieve an XML file detailing tasks due for the next seven days and then import it into the PPC's database. Because I am not responsible for generating the XML, and because it is good practise anyway, I decided to create an XSD file to validate the XML. PDA's have very little storage resources (the flash card is shared between disk and memory) so I decided to read the XML file a line at a time using the XmlReader so that the contents don't exist on the flash memory twice (disk + memory), another benefit of this approach being that I can read it directly from a ZIP file too!

In dotnet V2 the class XmlValidatingReader is obsolete, not that it would have been much good anyway considering it is not implemented in V1 of the compact framework. After some playing around I was finally able to read the XSD information from a resourced embedded into my app, and read the XML one line at a time whilst validating it against that XSD file.

Here it is:

//1 Get a stream containint the XSD
Stream xsdStream = GetType().Assembly.GetManifestResourceStream("Eden.HandheldVendor.TaskFlow.DataImport.xsd");
//2) Create an XmlTextReader that uses this stream
XmlReader xsdReader = new XmlTextReader(xsdStream);
//Create an XmlSchema from the embedded XSD
System.Xml.Schema.XmlSchema xsdSchema = System.Xml.Schema.XmlSchema.Read(xsdReader, null);

//4) Create some XmlReaderSettings that use this XmlSchema
XmlReaderSettings readerSettings = new XmlReaderSettings();
readerSettings.ValidationType = ValidationType.Schema;
readerSettings.Schemas.Add(xsdSchema);

//5) Set an event for validation errors
readerSettings.ValidationEventHandler +=
 new System.Xml.Schema.ValidationEventHandler(readerSettings_ValidationEventHandler);

//6) Create the xmlReader that will read the XML file using our reader settings
XmlReader xmlReader = XmlTextReader.Create(xmlStream, readerSettings);

//7) Now read the file
while (xmlReader.Read())

Comments

Post a Comment

Popular posts from this blog

Connascence

-
I’ve just finished reading What every programmer should know about object oriented design . The first couple of sections are a bit useless really, but the 3rd section is very good. I particularly liked the section on the difference types of connascence in software. There’s some basic information about it here if you fancy a brief overview of what it is about. It’s a really good book, I recommend you read it! Should only take a day if you only read the 3rd section.
Read more

Convert absolute path to relative path

-
Today I needed to convert an absolute path to a relative path based on a specified base path. E.g. c:\a\b\c -> c:\a\b\c\d\file.txt = d\file.txt c:\a\b\c -> c:\a\file.txt = ..\..\file.txt c:\a\b\c -> c:\a\x\file.txt = ..\..\x\file.txt I am surprised there is nothing in the .NET framework so I had a hunt around and converted the code from the following URL ( http://www.vergentsoftware.com/blogs/ckinsman/default.aspx?date=2006-08-07 ) into C#.... private string RelativePath(string absolutePath, string relativeTo) { string[] absoluteDirectories = absolutePath.Split('\\'); string[] relativeDirectories = relativeTo.Split('\\'); //Get the shortest of the two paths int length = absoluteDirectories.Length < relativeDirectories.Length ? absoluteDirectories.Length : relativeDirectories.Length; //Use to determine where in the loop we exited int lastCommonRoot = -1; int i
Read more

Printing bitmaps using CPCL

-
I've had no end of grief trying to print a PCX to a Zebra Printer using the CPCL printer language. Silly me, didn't notice the EG command (expanded graphics) so there was no need to convert my BMP to a PCX and then struggle with binary data. I still had a bit of grief working out how to print using the EG command because the documentation is quite frankly crap. The expected command format is EG {WidthInBytes} {HeightInPixels} {XPos} {YPos} {Data}\r\n The printer expects a 1 bit pixel matrix. So if pixel(0, 0) is set you will set "80" in the data. If pixel(0, 0) is set and pixel (7, 0) is also set you would sent "81". Basically what you need to do is to read each set of 8 horizontal pixels and then use bit operations to create a byte value 0..255, and then output this as hex 00..FF. Here's the routine :-) public void DrawBitmap(Bitmap bmp, int xPosition, int yPosition) { if (bmp == null) throw new ArgumentNullException("bmp");
Read more