Deserialization issue when consuming ASMX Web Service from Xamarin Android .NET6 App

[adolfo1981]

Android application type

Android for .NET (net6.0-android)

Affected platform version

VS 2022 Version 17.3.0 Preview 5.0 (64 bit)

Description

I'm upgrading an existing Xamarin Traditional (Android) application into .NET 6 but I'm running into deserialization problems. Our Android app integrates with a .NET Framework 4.8 ASMX Web Service on the backend. This has been working fine for years but doesn't work after we move to .NET 6.

I was able to create a repro project on my GitHub: https://github.com/adolfo1981/Net6AndroidWebServiceTest

Here are the details from deserialization error.
Exception:
The formatter threw an exception while trying to deserialize the message: There was an error while trying to deserialize parameter http://tempuri.org/:HelloWorldResponse. The InnerException message was 'There was an error deserializing the object of type ServiceReference1.HelloWorldResponseBody. Unexpected end of file. Following elements are not closed: HelloWorldResult, HelloWorldResponse, Body, Envelope. Line 1, position 298.'. Please see InnerException for more details.

StackTrace:

at System.Runtime.Serialization.XmlObjectSerializer.ReadObjectHandleExceptions(XmlReaderDelegator reader, Boolean verifyObjectName, DataContractResolver dataContractResolver)
   at System.Runtime.Serialization.XmlObjectSerializer.ReadObjectHandleExceptions(XmlReaderDelegator reader, Boolean verifyObjectName)
   at System.Runtime.Serialization.DataContractSerializer.ReadObject(XmlDictionaryReader reader, Boolean verifyObjectName)
   at System.ServiceModel.Dispatcher.DataContractSerializerOperationFormatter.PartInfo.ReadObject(XmlDictionaryReader reader, XmlObjectSerializer serializer) in /_/src/System.Private.ServiceModel/src/System/ServiceModel/Dispatcher/DataContractSerializerOperationFormatter.cs:line 657
   at System.ServiceModel.Dispatcher.DataContractSerializerOperationFormatter.PartInfo.ReadObject(XmlDictionaryReader reader) in /_/src/System.Private.ServiceModel/src/System/ServiceModel/Dispatcher/DataContractSerializerOperationFormatter.cs:line 652
   at System.ServiceModel.Dispatcher.DataContractSerializerOperationFormatter.DeserializeParameterPart(XmlDictionaryReader reader, PartInfo part, Boolean isRequest) in /_/src/System.Private.ServiceModel/src/System/ServiceModel/Dispatcher/DataContractSerializerOperationFormatter.cs:line 521

My GitHub repro repo consists of the following projects:

• HelloAndroid (NET6 - .net6.0-android Target Framework Moniker)
• WebServiceServer (.NET Framework 4.8)
• WebServiceClient (.NET 6) --> referenced by HelloAndroid project to consume ASMX Web Services

Steps to Reproduce

1. Create a Xamarin Android (NET 6) project similar to @jamesmontemagno https://github.com/jamesmontemagno/net6-mobile-samples/tree/main/HelloAndroid
2. Create a .NET Framework 4.8 WebServiceServer application following instructions like this: https://www.c-sharpcorner.com/article/how-to-create-a-web-service-project-in-net-using-visual-studio/
3. Create a .NET 6 (Class Library) WebServiceClient and add a Connected Service -> Web Service pointing to a wsdl or deployed asmx file
4. From Main Activity create an instance of the generated soap client and call HelloWorldAsync method:

var soapClient = new WebServiceSoapClient(WebServiceSoapClient.EndpointConfiguration.WebServiceSoap);
//Async test
var helloResponse = await soapClient.HelloWorldAsync();

Expected Result: Get string response from HelloWorldAsync() method
Actual Result: I get the deserialization issue mentioned above

Repro Project: https://github.com/adolfo1981/Net6AndroidWebServiceTest

IMPORTANT:

The repro project points to my local IP (Bottom of Reference.cs file) and needs to be changed to IP of the user running the code. I could not use localhost because I was getting connectivity issues and only worked when setting my local IP.

Things that I've tried:

• Generating the Web Service Client with 'Reuse referenced assemblies' enabled and disabled and that had no effect. Kept getting deserialization issue
• Tried changing the HelloAndroid.csproj TargetFramework from .net6,0-android to .net6.0-android31.0 and nothing changed even after deleting /bin and /obj folders in this project

Did you find any workaround?

No workaround has been found

Relevant log output

No response

[adolfo1981]

Any update? This is holding a big mobile app migration. We need to move to net6 to support some required Google maps SDK upgrades. Hope someone can provide some help.

[adolfo1981]

I added a ClientTestConsole .NET6 project that references my WebServiceClient and successfully calls my HelloWorldsAsync method receiving a valid response to prove that Web Service client consumption works outside of the Android environment.

[adolfo1981]

msbuild.zip
I uploaded the msbuild.binlog generated through this command in case it helps:
dotnet build HelloAndroid.csproj /bl:msbuild.binlog

[adolfo1981]

I was able to capture request and responses when running Android Emulator (failed call with deserialization error) and when running Console app (Successful call). I did not find significant differences on soap requests and responses. (See attached):
Request and Response Fiddler Captures.zip

The biggest difference I saw was on the Emulator Request which sent a Connection: Keep-Alive header and User-Agent as you can see below:

This makes me think that the problem is with some possible Assembly mismatch or conflict trying to deserialize the message when running from Xamarin Android app.

[waelwederni4]

Any update Here ?