SQL Server Q&A

Symptoms
When you use a common language runtime (CLR) object in Microsoft SQL Server 2005, you may receive an error message that is similar to the following:

Msg 6522, Level 16, State 2, Line 1
A .NET Framework error occurred during execution of user defined routine or aggregate ‘ObjectName’:
System.InvalidOperationException: Cannot load dynamically generated serialization assembly. In some hosting environments assembly load functionality is restricted, consider using pre-generated serializer. Please see inner exception for more information. —> System.IO.FileLoadException: LoadFrom(), LoadFile(), Load(byte[]) and LoadModule() have been disabled by the host.
System.IO.FileLoadException:
at System.Reflection.Assembly.nLoadImage(Byte[] rawAssembly, Byte[] rawSymbolStore, Evidence evidence, StackCrawlMark& stackMark, Boolean fIntrospection)
at System.Reflection.Assembly.Load(Byte[] rawAssembly, Byte[] rawSymbolStore, Evidence securityEvidence)
at Microsoft.CSharp.CSharpCodeGenerator.FromFileBatch(CompilerParameters options, String[] fileNames)
at Microsoft.CSharp.CSharpCodeGenerator.FromSourceBatch(CompilerParameters options, String[] sources)
at Microsoft.CSharp.CSharpCodeGenerator.System.CodeDom.Compiler.ICodeCompiler.CompileAssemblyFromSourceBatch(CompilerParameters options, String[] sources)
at System.CodeDom.Compiler.CodeDomProvider.CompileAssemblyFromSource(CompilerParameters options, String[] s
System.InvalidOperationException:
at System.Xml.Serialization.Compiler.Compile(Assembly parent, String ns, CompilerParameters parameters, Evidence evidence)
at System.Xml.Serialization.TempAssembly.GenerateAssembly(XmlMapping[] xmlMappings, Type[] types, String defaultNamespace, Evidence evidence, CompilerParameters parameters, Assembly assembly, Hashtable assemblies)
at System.Xml.Serialization.TempAssembly..ctor(XmlMapping[] xmlMappings, Type[] types, String defaultNamespace, String location, Evidence evidence)
at System.Xml.Serialization.XmlSerializer.GenerateTempAssembly(XmlMapping xmlMapping, Type type, String defaultNamespace)
at System.Xml.Serialization.XmlSerializer..ctor(Type type, String defaultNamespace)
at System.Xml.Serialization.XmlSe…For example, you may receive the error message when you use a CLR object that calls a Web service or performs conversion from user-defined types to XML inside SQL Server.
Resolution
This issue occurs when a CLR object is converted to the XML data type. When this conversion occurs, the Windows Communication Foundation (formerly code-named “Indigo”) tries to do the following: Generate a new XML serialization assembly.Save the assembly to disk.Load the assembly into the current application domain. However, SQL Server does not allow for this kind of disk access in the SQL CLR for security reasons. Therefore, you receive the error message that is mentioned in the “Symptoms” section. Several scenarios may cause the CLR object to be converted to the XML data type.
For more information about the Windows Communication Foundation, visit the following Microsoft Developer Network (MSDN) Web site:
http://msdn2.microsoft.com/en-us/library/ms735119.aspx(http://msdn2.microsoft.com/en-us/library/ms735119.aspx)You may receive the error message that is mentioned in the “Symptoms” section in the following scenarios: The CLR code that implements CLR objects explicitly uses the XmlSerializer class. These CLR objects may include stored procedures, functions, user-defined types, aggregates, and triggers.You use a Web service in the CLR code.You send or receive CLR objects to or from SQL Server by using direct HTTP/SOAP access to SQL Server. The CLR object converts a user-defined type to the XML data type.

Symptoms
When you validate your XML document by using the XmlValidatingReader class with respect to an external document type definition (DTD), and the DTD has an error, the stream that is opened by XmlValidatingReader to load the DTD is not closed. Therefore, when you try to open the DTD with write permissions, you receive the following error message:

An unhandled exception of type ‘System.IO.IOException’ occurred in mscorlib.dll
Additional information: The process cannot access the file “DTDFileName” because it is being used by another process.
Resolution
When you use XmlValidatingReader to validate an XML document with respect to DTD, the .NET Framework internally opens a stream to read the DTD. When the error occurs while validating the XML document, the stream that is used to read the DTD is not closed, and you receive the error message that is listed in the “Symptoms” section.