Develop Reference

cXML .net XMLReader error The parameter entity replacement text must nest properly within markup declarations

Is there something I need to configure in the XmlReaderSettings to encourage .net (4.8, 6, 7) to handle some cXML without throwing the following exception:
Unhandled exception. System.Xml.Schema.XmlSchemaException: The parameter entity replacement text must nest properly within markup declarations.
Sample cXML input
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE cXML SYSTEM "http://xml.cxml.org/schemas/cXML/1.2.041/cXML.dtd">
<cXML payloadID="donkeys#example.com" timestamp="2023-02-13T01:01:01Z">
<Header>
</Header>
<Request deploymentMode="production">
</Request>
</cXML>
Sample Application
using System.Xml;
using System.Xml.Linq;
namespace Donkeys
{
internal class Program
{
static void Main()
{
XmlReaderSettings settings = new()
{
XmlResolver = new XmlUrlResolver(),
DtdProcessing = DtdProcessing.Parse,
ValidationType = ValidationType.DTD,
};
FileStream fs = File.OpenRead("test.xml"); // sample cXML from question
XmlReader reader = XmlReader.Create(fs, settings);
XDocument.Load(reader); // this blows up
}
}
}
I'm looking to use the XmlUrlResolver to cache the DTDs but without ignoring the validation I get the error above but i'm not really sure why?
So far I've tried different validation flags but they don't validate at all unless I use ValidationType.DTD which goes pop.
The actual resolver seems to work fine; if I subclass it, it is returning the DTD (as a MemoryStream) as expected.
I can add an event handler to ignore the issue but this feels lamer than I'd like.
using System.Xml;
using System.Xml.Linq;
namespace Donkeys
{
internal class Program
{
static void Main()
{
XmlReaderSettings settings = new()
{
XmlResolver = new XmlUrlResolver(),
DtdProcessing = DtdProcessing.Parse,
ValidationType = ValidationType.DTD,
IgnoreComments = true
};
settings.ValidationEventHandler += Settings_ValidationEventHandler;
FileStream fs = File.OpenRead("test.xml");
XmlReader reader = XmlReader.Create(fs, settings);
XDocument dogs = XDocument.Load(reader);
}
private static void Settings_ValidationEventHandler(object? sender, System.Xml.Schema.ValidationEventArgs e)
{
// this seems fragile
if (e.Message.ToLower() == "The parameter entity replacement text must nest properly within markup declarations.".ToLower()) // and this would be a const
return;
throw e.Exception;
}
}
}

I've spent some time over the last few days looking into this and trying to get my head around what's going on here.
As far as I can tell, the error The parameter entity replacement text must nest properly within markup declarations is being reported incorrectly. My understanding of the spec is that this message means that you have mismatched < and > elements in the replacement text of a parameter entity in a DTD.
The following example is taken from this O'Reilly book sample page and demonstrates something that genuinely should reproduce this error:
<!ENTITY % finish_it ">">
<!ENTITY % bad "won't work" %finish_it;
Indeed the .NET DTD parser reports the same error for these two lines of DTD.
This doesn't mean you can't have < and > characters in parameter entity replacement text at all: the following two lines will declare an empty element with name Z, albeit in a somewhat round-about way:
<!ENTITY % Nested "<!ELEMENT Z EMPTY>">
%Nested;
The .NET DTD parser parses this successfully.
However, the .NET DTD parser appears to be objecting to this line in the cXML DTD, which defines the Object.ANY parameter entity:
<!ENTITY % Object.ANY '|xades:QualifyingProperties|cXMLSignedInfo|Extrinsic'>
There are of course no < and > characters in the replacement text, so the error is baffling.
This is by no means a new problem. I found this unanswered Stack Overflow question which basically reports the same problem. Also, this MSDN Forum post basically has the same problem, and it was asked in 2007. So is this unclear but intentional behaviour, or a bug that has been in .NET for 15+ years? I don't know.
For those who do want to look into things further, the following is about the minimum necessary to reproduce the problem. The necessary C# code to read the XML file can be taken from the question and adapted, I don't see the need to repeat it here:
example.dtd:
<?xml version="1.0" encoding="UTF-8"?>
<!ELEMENT A EMPTY>
<!ENTITY % Rest '|A' >
<!ELEMENT example (#PCDATA %Rest;)*>
example.xml:
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE example SYSTEM "example.dtd">
<example/>
There are various ways to tweak this to get rid of the error. One way is to move the | character from the parameter entity into the ELEMENT example declaration. Replacing #PCDATA with another element (which you would also have to define) is another way.
But enough of the theory behind the problem. How can you actually move forwards with this?
I would take a local copy of the cXML DTD and adjust it to work around this error. You can download the DTD from the URL in your sample cXML input. The %Object.ANY; parameter entity is only used once in the DTD: I would replace this one occurrence with the replacement text, |xades:QualifyingProperties|cXMLSignedInfo|Extrinsic.
You then need to adjust the .NET XML parser to use your modified copy of the cXML DTD instead of fetching the the one from the given URL. You create a custom URL resolver for this, for example:
using System.Xml;
namespace Donkeys
{
internal class CXmlUrlResolver : XmlResolver
{
private static readonly Uri CXml1_2_041 = new Uri("http://xml.cxml.org/schemas/cXML/1.2.041/cXML.dtd");
private readonly XmlResolver urlResolver;
public CXmlUrlResolver()
{
this.urlResolver = new XmlUrlResolver();
}
public override object GetEntity(Uri absoluteUri, string role, Type ofObjectToReturn)
{
if (absoluteUri == CXml1_2_041)
{
// Return a Stream that reads from your custom version of the DTD,
// for example:
return File.OpenRead(#"SomeFilePathHere\cXML-1.2.401.dtd");
}
return this.urlResolver.GetEntity(absoluteUri, role, ofObjectToReturn);
}
}
}
This checks to see what URI is being requested, and if it matches the cXML URI, returns a stream that reads from your customised copy of the DTD. If some other URI is given, it passes the request to the nested XMLResolver, which then deals with it. You will of course need to use an instance of CXmlUrlResolver instead of XmlUrlResolver() when creating your XmlReaderSettings.
I don't know how many versions of cXML you will have to deal with, but if you are dealing with multiple versions, you might have to create a custom copy of the DTD for each version, and have your resolver return the correct local copy for each different URI.
A similar approach is given at this MSDN Forums post from 2008, which also deals with difficulties parsing cXML with .NET. This features a custom URL resolver created by subclassing XmlUrlResolver. Those who prefer composition over inheritance may prefer my custom URL resolver instead.

Unable to get Source Generator to do anything

I've been wrestling with Source Generators but there's a lack of tutorials and information that are hurting.
I want to generate some C# classes from a database. Using a T4 template to do this is difficult and problematic, because of issues I'm having with using SQL in T4 templates and similar.
The description of Source Generator is that "The generator can create new C# source files on the fly that are added to the user's compilation. In this way, you have code that runs during compilation. It inspects your program to produce additional source files that are compiled together with the rest of your code." which seems to match what I want.
This seems significantly more promising.
I've created a project, and put a [Generator] into it using this tutorial.
Full source:
using Microsoft.CodeAnalysis;
using Microsoft.CodeAnalysis.Text;
using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
namespace x
{
[Generator]
internal class TestGenerator : ISourceGenerator
{
public void Execute(GeneratorExecutionContext context)
{
File.Create(#"C:\temp\ITRUNS.TXT");
var sourceBuilder = new StringBuilder(#"
using System;
namespace HelloWorldGenerated
{
public static class HelloWorld
{
public static void SayHello()
{
Console.WriteLine(""Hello from generated code!"");
Console.WriteLine(""The following syntax trees existed in the compilation that created this program:"");
");
Debugger.Launch();
// using the context, get a list of syntax trees in the users compilation
var syntaxTrees = context.Compilation.SyntaxTrees;
// add the filepath of each tree to the class we're building
foreach (SyntaxTree tree in syntaxTrees)
{
sourceBuilder.AppendLine($#"Console.WriteLine(#"" - {tree.FilePath}"");");
}
// finish creating the source to inject
sourceBuilder.Append(#"
}
}
}");
// inject the created source into the users compilation
context.AddSource("helloWorldGenerator", SourceText.From(sourceBuilder.ToString(), Encoding.UTF8));
}
public void Initialize(GeneratorInitializationContext context)
{
}
}
}
I want this to run when I build the solution and create some .cs files
However, it does not run. I put some code in the execute method to create a file, and it does not create the file.
The tutorial says:
Add the source generator from a project as an analyzer and add preview to the LangVersion to the project file like this:
I don't really know what this means. Which project? I tried to download the samples as suggested, but I can't get them to build.
When I examine the code, it's quite hard to understand what they've done that is different.
And what they say in the tutorial about adding the analyzer, doesn't seem to present anywhere in the sample code!
I tried adding the project reference in the csproj that it said to add, however that didn't work - it did create an item within Analyzers but it just has a red - and says 'Ignored' on the tooltip.
I honestly don't know what else I can do to figure out how to get this to work.
I also don't know for sure if it will do what I want - autogenerate a bunch of .cs files with code in that I can use.
I'm going to give it one more go then I'll just write a console application to do it manually instead. Any ideas are welcome.

Unity to Visual Studio : Multiple assemblies with equivalent identity have been imported

I am designing an application to run on the Microsoft HoloLens using Unity for the user interaction.
The application connects to an asmx webservice to retrieve data.
I have a C# test program to test the connection and data retrieval from the webservice.
I then followed this tutorial to generate a dll based on the webservice wsdl (https://www.youtube.com/watch?v=AifcMzEbKnA)
If use the following script to generate the dll:
#echo off
if exist "Service.xml" (
del MyOwnWS.wsdl
echo Rename
rename Service.xml MyOwnWS.wsdl
echo.
)
echo WSDL
call wsdl MyOwnWS.wsdl -o:MyOwnWS.cs
echo.
echo DMCS
call dmcs /target:library MyOwnWS.cs -r:System.Web.Services,System.Data
echo.
echo Done
I added system.Data because my webservice returns DataSet data from a Database.
I dropped that dll in the Assets folder of the Unity project.
I also had to drop System.Data.dll, System.dll, and System.Web.Services.dll in it (took them from C:\Program Files\Unity Hololens 5.4.0b16-HTP\Editor\Data\Mono\lib\mono\unity folder)
When I use the Unity editor, my application connects to the webservice and retrieve the data without problems.
Next step, I followed this tutorial to make a HoloLens application from Unity (http://hololenshelpwebsite.com/Blog/EntryId/1006/HoloLens-Hello-World)
While it work for their own Hello World, when I tried to build my own project from unity I receive the following error:
error CS1703: Multiple assemblies with equivalent identity have been
imported:
'C:\Users\UserA\.nuget\packages\Microsoft.NETCore.Portable.Compatibility\1.0.0\ref\netcore50\System.dll'
and 'J:\Work\MyTestUnity\Assets\System.dll'. Remove one of the
duplicate references.Copyright (C) Microsoft Corporation. All rights
reserved.Microsoft (R) Visual C# Compiler version 1.3.1.60616
So I added a ProjectFileHook.cs file under Editor with the following content:
using System;
using System.IO;
using System.Linq;
using System.Text;
using System.Xml.Linq;
using UnityEditor;
using SyntaxTree.VisualStudio.Unity.Bridge;
using UnityEngine;
// http://forum.unity3d.com/threads/missing-c-references-to-system-data.11361/
// https://visualstudiogallery.msdn.microsoft.com/8d26236e-4a64-4d64-8486-7df95156aba9
[InitializeOnLoad]
public class ProjectFileHook
{
// necessary for XLinq to save the xml project file in utf8
class Utf8StringWriter : StringWriter
{
public override Encoding Encoding
{
get { return Encoding.UTF8; }
}
}
static void ProcessNodesWithIncludeAttribute(XDocument document, string localName, string includeValue, Action<XElement> action)
{
var nodes = document
.Descendants()
.Where(p => p.Name.LocalName == localName);
foreach (var node in nodes)
{
var xa = node.Attribute("Include");
if (xa != null && !string.IsNullOrEmpty(xa.Value) && string.Equals(xa.Value, includeValue))
{
action(node);
}
}
}
// Remove System.Data from project (not from file system so Unity can compile properly)
static void RemoveFileFromProject(XDocument document, string fileName)
{
ProcessNodesWithIncludeAttribute(document, "None", fileName, element => element.Remove());
}
// Adjust references, by using the default framework assembly instead of local file (remove the HintPath)
static void RemoveHintPathFromReference(XDocument document, string assemblyName)
{
ProcessNodesWithIncludeAttribute(document, "Reference", assemblyName, element => element.Nodes().Remove());
}
static ProjectFileHook()
{
ProjectFilesGenerator.ProjectFileGeneration += (string name, string content) =>
{
var document = XDocument.Parse(content);
RemoveFileFromProject(document, #"Assets\System.Data.dll");
RemoveHintPathFromReference(document, "System.Data");
RemoveFileFromProject(document, #"Assets\System.Web.Services.dll");
RemoveHintPathFromReference(document, "System.Web.Services");
RemoveFileFromProject(document, #"Assets\System.dll");
RemoveHintPathFromReference(document, "System");
var str = new Utf8StringWriter();
document.Save(str);
return str.ToString();
};
}
}
But it looks like this does nothing.
I am at a lost about how to fix this at the moment, and I really need experts help to figure it out.

So...
It looks like we cannot use WSDL webservice like that anymore.
Microsoft dropped the support for it in an update no so long ago.
I saw multiple articles about it, but I forgot to keep a bookmark.
So if you want look it up, you will have to go through the WUP documentation.
Instead we ended up using UnityWebRequest and Coroutines to handle the webservice communication.
We also had to update the webservice to enable Get/post calls.

Get value of version out of project.json

In a DNX application, which uses a "project.json" file, is there a way to read the value of the "version" property out of the "project.json" file?
I'm writing a library that writes something to the current HTTP response and I would like to show the version of the application in there.
Any help on how this can be done is highly appreciated.

If you set the version attribute during build (or in any other way) you can do this like that:
using System;
using System.Reflection;
[assembly:AssemblyVersionAttribute("1.2.3")]
namespace Test
{
class Program
{
public static void Main()
{
var assembly = typeof(Program).GetTypeInfo().Assembly;
var name = assembly.GetName();
Console.WriteLine($"{name.Name}: {name.Version}");
}
}
}
I did it using the new dotnet cli which is replacing dnx but it should work with dnx dnxcore50 as well.

Are you writing a Class Library or an ASP.NET application?
If a class Library, you could copy the version string to a resource file that you read in during run-time to grab the version. It's kind hard to do this sort of thing with class libraries since you don't get the beauty of a Startup and IoC.
If ASP.NET, then just add a version into your appsettings.json configuration (or a custom json file to store settings) and read it in at startup: http://docs.asp.net/en/latest/fundamentals/configuration.html

Multipe ways of doing this if you are running in a the web application, not a class library.
First way custom attributes data (should check if attribute is available):
this.GetType().Assembly.GetCustomAttributesData()
.First(x => x.AttributeType.FullName == "System.Reflection.AssemblyInformationalVersionAttribute")
.ConstructorArguments[0];
Second way
var name = this.GetType().AssemblyQualifiedName;
name = name.Substring(name.IndexOf("Version=") + 8);
var verion = name.Substring(0, name.IndexOf(", "));

Serialization problem

I have created a phonebook application and it works fine after a awhile i liked to make an upgrade for my application and i started from scratch i didn't inherit it from my old class,and i successes too ,my request
"I want to migrate my contacts from the old application to the
new one"
,so i made an adapter class for this reason in my new application with the following code
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.IO;
using System.Windows.Forms;
using System.Runtime.Serialization;
using System.Runtime.Serialization.Formatters.Binary;
namespace PhoneBook
{
class Adapter
{
PhoneRecord PhRecord; //the new application object
CTeleRecord TelRecord; //the old application object
string fileName;
public Adapter(string filename)
{
fileName = filename;
}
public void convert()
{
PhRecord = new PhoneRecord();
TelRecord = new CTeleRecord();
FileStream OpFileSt = new FileStream(fileName, FileMode.Open,FileAccess.Read);
BinaryFormatter readBin = new BinaryFormatter();
for (; ; )
{
try
{
TelRecord.ResetTheObject();
TelRecord = (CTeleRecord)readBin.Deserialize(OpFileSt);
PhRecord.SetName = TelRecord.GetName;
PhRecord.SetHomeNumber = TelRecord.GetHomeNumber;
PhRecord.SetMobileNumber = TelRecord.GetMobileNumber;
PhRecord.SetWorkNumber = TelRecord.GetWorkNumber;
PhRecord.SetSpecialNumber = TelRecord.GetSpecialNumber;
PhRecord.SetEmail = TelRecord.GetEmail;
PhRecord.SetNotes = TelRecord.GetNotes;
PhBookContainer.phBookItems.Add(PhRecord);
}
catch (IOException xxx)
{
MessageBox.Show(xxx.Message);
}
catch (ArgumentException tt)
{
MessageBox.Show(tt.Message);
}
//if end of file is reached
catch (SerializationException x)
{
MessageBox.Show(x.Message + x.Source);
break;
}
}
OpFileSt.Close();
PhBookContainer.Save(#"d:\MyPhBook.pbf");
}
}
}
the problem is when i try to read the file ctreated by my old application i receive serialization exception with this message
"Unalel to find assembly 'PhoneBook,Version=1.0.0.0,Culture=neutral,PublicK eyToken=null"
and the source of exception is mscorlib.
when i read the same file with my old application (Which is the origin of the file) i have no problem and i don't know what to do to make my adapter class work.

When the class is serialised, it includes the assembly information of the class.
It does this so the deserializer knows what type of class to create with the serialised data.
The problem is that while the two classes may seem to be identical, they are not because they are in different assemblies.
The recommended way to do this is to always put serializable classes in a class library. Then in your situation V2.0 of your application can reference the V1.0 assembly, and then you can deserialize the objects.
If your V1.0 classes aren't in a class library (e.g. they're embedded in an executable), you can build your V2.0 classes in a class library, and add functionality to your V1.0 app to transform classes to V2.0 classes.
Post any questions you might have as comments.
Hope this helps.

BinaryFormatter is not very tolerant to assembly changes. I long ago reached the conclusion that it is OK (just about) for transport, but not good for any kind of storage - it is just too brittle.
In short, I would use another serializer - but contract-based, not type-based (so any type with the same cnotract can share the data):
in many cases XmlSerializer will do; it has some limitations (public types and members), but it works generally
with .NET 3.0, DataContractSerializer is useful
or if you want something outside of the code libs, protobuf-net is very fast and efficient
Of those, only DataContractSerializer will currently support "graph" mode (rather than trees).
If you have existing data that you're fighting, I would be sorely tempted to use the old code (or something very close to it) to re-write the data in a contract-based form. Although you say you've only just created it, so maybe this isn't a problem.

As previously stated the file contains the fully qualified assembly name of your class, which has changed in your new project. If you your assembly, class name and namespaces match, you can set the Assembly format to simple on the formatter:
BinaryFormatter.AssemblyFormat = FormatterAssemblyStyle.Simple;
This use LoadWithPartialName when the formatter tries to load this type. See MSDN for more info.
You could also write a serialization binder to resolve the differences.