ASP.NET Errors

API Q&A
1

We decided to try to make a part of our integration utilizing the ASP.NET library for XML-RPC, but we seem to be running into errors. When I attempt to duplicate the sample project I am getting the following error when the code makes the api call.

<Error>
<Message>An error has occurred.</Message>
<ExceptionMessage>The 'ObjectContent`1' type failed to serialize the response body for content type 'application/xml; charset=utf-8'.</ExceptionMessage>
<ExceptionType>System.InvalidOperationException</ExceptionType>
<StackTrace/>
<InnerException>
<Message>An error has occurred.</Message>
<ExceptionMessage>Type 'CookComputing.XmlRpc.XmlRpcFaultException' with data contract name 'XmlRpcFaultException:http://schemas.datacontract.org/2004/07/CookComputing.XmlRpc' is not expected. Consider using a DataContractResolver if you are using DataContractSerializer or add any types not known statically to the list of known types - for example, by using the KnownTypeAttribute attribute or by adding them to the list of known types passed to the serializer.</ExceptionMessage>
<ExceptionType>System.Runtime.Serialization.SerializationException</ExceptionType>
<StackTrace> at System.Runtime.Serialization.XmlObjectSerializerWriteContext.SerializeAndVerifyType(DataContract dataContract, XmlWriterDelegator xmlWriter, Object obj, Boolean verifyKnownType, RuntimeTypeHandle declaredTypeHandle, Type declaredType) at System.Runtime.Serialization.XmlObjectSerializerWriteContext.SerializeWithXsiTypeAtTopLevel(DataContract dataContract, XmlWriterDelegator xmlWriter, Object obj, RuntimeTypeHandle originalDeclaredTypeHandle, Type graphType) at System.Runtime.Serialization.DataContractSerializer.InternalWriteObjectContent(XmlWriterDelegator writer, Object graph, DataContractResolver dataContractResolver) at System.Runtime.Serialization.DataContractSerializer.InternalWriteObject(XmlWriterDelegator writer, Object graph, DataContractResolver dataContractResolver) at System.Runtime.Serialization.XmlObjectSerializer.WriteObjectHandleExceptions(XmlWriterDelegator writer, Object graph, DataContractResolver dataContractResolver) at System.Runtime.Serialization.DataContractSerializer.WriteObject(XmlWriter writer, Object graph) at System.Net.Http.Formatting.XmlMediaTypeFormatter.WriteToStream(Type type, Object value, Stream writeStream, HttpContent content) at System.Net.Http.Formatting.XmlMediaTypeFormatter.WriteToStreamAsync(Type type, Object value, Stream writeStream, HttpContent content, TransportContext transportContext, CancellationToken cancellationToken) --- End of stack trace from previous location where exception was thrown --- at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw() at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) at System.Web.Http.Tracing.ITraceWriterExtensions.<TraceBeginEndAsyncCore>d__24.MoveNext() --- End of stack trace from previous location where exception was thrown --- at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw() at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) at System.Web.Http.WebHost.HttpControllerHandler.<WriteBufferedResponseContentAsync>d__1b.MoveNext()</StackTrace>
</InnerException>
</Error>

I do not understand how to fix this data contract resolver issue.

2

Good morning Alex,

We don’t have any in-house experience with CookComputing’s XmlRpc library (and we’re a Java shop, not .NET so I can be of limited help), but I would assume from the exception that it is trying to deserialize a string to a long or some other invalid conversion.

I would step through the debugger and isolate the payload that it’s trying to parse, and look for anything that may be causing serialization issues. If there isn’t anything there, then it’s probably a configuration issue with the library.