70-513 Question #310: Real Exam Question with Answer & Explanation

A Windows Communication Foundation (WCF) solution uses the following contract to share a message across its clients (Line numbers are included for reference only) 01 <ServiceContract0> 02 PuElic Interface ITeamMessageService 04 <OperationContractO> 05 Function GetMessage() As String 07 <OperationContract0> 08 Sub PutMessage(Byval message As String) O9 End Interface The code for the serAce class is as follows. 10 Public Class TeamMessageService0 11 Implements lTearmt4essageService 13 Dim key As Guid = Guid.NewGuid() 14 Dim message As String = "Today's Message' 16 PuUic Function GetMessage0As String - 17 lmpements lTearm*AessageServiceGetMessage 19 Retun String. Fommat("Message:{0) Key:{ 1}", message, key) 20 End Function 22 PubIic Sub PutMessage(ByV message As Stnng) - 23 lmpements lTearrlessageService PutMessage 25 Me message = message 26 End Sub 28 End Class The service is self-hosted The hosting code rs as follows 29 Dim host As ServiceHost = New ServiceHost(GetType(TearrwiessageSeMce))? 30 Dim binding As Basic HttpBindngt New BasicHttpBindiig(BasicHttpSecurityMode. None) 31 host.AddServiceEndpoint( "MyAppication lTearrtAessageService", binding Thttp /Ilac aihost. 1 2345) 32 host Open() You need to ensure that all clients calling GetMessage will retrieve the same string, even if the message is upd(ed by clients calling PutMessage what should you do?