I've created a Xamarin.Forms project with a netstandard2.0 targeting library instead of a shared or PCL library. So far this compiles and works. I'm using an up2date version of Visual Studio 2017 Community.
I also have created a WCF service that gonna be hosted on windows itself (not IIS). I've configured my app.config to provide a Metadata Exchange Endpoint:
<?xml version="1.0"?>
<configuration>
<startup>
<supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.0"/>
</startup>
<system.serviceModel>
<services>
<service behaviorConfiguration="MM.Server.ServiceServerBehavior" name="MM.Server.ServiceServer">
<endpoint address="net.tcp://localhost:8730/MMServer/" binding="netTcpBinding" bindingConfiguration="NetTcpBinding_IServiceServer" bindingName="NetTcpBinding_IServiceServer_EndPoint" contract="MM.Contracts.IServiceServer">
<identity>
<dns value="localhost"/>
</identity>
</endpoint>
<endpoint address="http://localhost:8731/MMServer/mex" binding="mexHttpBinding" contract="IMetadataExchange"/>
<host>
<baseAddresses>
<add baseAddress="net.tcp://localhost:8730/MMServer/"/>
</baseAddresses>
</host>
</service>
</services>
<behaviors>
<serviceBehaviors>
<behavior name="MM.Server.ServiceServerBehavior">
<serviceMetadata httpGetEnabled="true" httpGetUrl="http://localhost:8731/MMServer/mex" />
<serviceDebug includeExceptionDetailInFaults="true"/>
</behavior>
</serviceBehaviors>
</behaviors>
<bindings>
<netTcpBinding>
<binding name="NetTcpBinding_IServiceServer" closeTimeout="00:01:00" openTimeout="00:01:00" receiveTimeout="00:10:00" sendTimeout="00:01:00" transactionFlow="false" transferMode="Buffered" transactionProtocol="OleTransactions" hostNameComparisonMode="StrongWildcard" listenBacklog="10" maxBufferPoolSize="2147483647" maxBufferSize="2147483647" maxConnections="10" maxReceivedMessageSize="2147483647">
<readerQuotas maxDepth="32" maxStringContentLength="2147483647" maxArrayLength="2147483647" maxBytesPerRead="2147483647" maxNameTableCharCount="16384"/>
<reliableSession ordered="true" inactivityTimeout="01:00:00" enabled="false"/>
<security mode="None"><!-- TODO: Add more security later -->
<transport clientCredentialType="None" protectionLevel="None"/>
</security>
</binding>
</netTcpBinding>
</bindings>
</system.serviceModel>
</configuration>
This is a very simple configuration and I don't care about security for now. The service runs, successfully.
Now I cannot simply add a service reference to my Xamarin.Forms project, since netstandard does not provide System.ServiceModel.
I've found out that I can use the SLsvcUtil.exe from the Silverlight SDK to generate the client proxy for my WCF service that is compatible to Xamarin.Forms targeting netstandard instead, however I cannot get it running.
No matter how I try to use the SLsvcUtil.exe while my WCF service is running, I always get the error:
Error: An error occurred in the tool.
Error: Object reference not set to an instance of an object.
Here is my batch that I used to execute SLsvcUtil.exe:
set "namespace=*,MM.Services"
set "mexPath=http://localhost:8731/MM/mex"
set "svcutil=C:\Program Files (x86)\Microsoft SDKs\Silverlight\v5.0\Tools\SLsvcUtil.exe"
set "outputDir=C:\vsproj\Xamarin\MM\MM.App"
"%svcutil%" %mexPath% /directory:"%outputDir%" /namespace:"%namespace%"
pause
http://localhost:8731/MM/mex returns the full WSDL, successfully.
How can I get a working generated client proxy for my Xamarin.Forms app that is targeting netstandard2.0? I'm open for any alternative that leads to the same desired result.
Take a look at the official Microsoft WCF client for .NET Core. I think this should work also with Xamarin since it is designed for .NET Core.