70-513 Question #147: 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 <ServiceContract()> 02 Public Interface ITeamMessageService 04 <OperationContract()> 05 Function GetMessage() As String 07 <OperationContract()> 08 Sub PutMessage(ByVal message As String) 09 End Interface The code for the service class is as follows. 10 Public Class TeamMessageService 11 Implements ITeamMessageService 13 Dim key As Guid = Guid.NewGuid() 14 Dim message As String = "Today s Message" 16 Public Function GetMessage() As String _ 17 Implements ITeamMessageService.GetMessage 19 Return String.Format("Message:{0}. Key:{1}", message, key) 20 End Function 22 Public Sub PutMessage(ByVal message As String) _ 23 Implements ITeamMessageService.PutMessage 25 Me.message = message 26 End Sub 28 End Class The service is self-hosted. The hosting code is as follows. 29 Dim host As ServiceHost = New ServiceHost(GetType(TeamMessageService)) 30 Dim binding As BasicHttpBinding = New BasicHttpBinding(BasicHttpSecurityMode.None) 31 host.AddServiceEndpoint( "MyApplication.ITeamMessageService", binding, 32 host.Open() You need to ensure that all clients calling GetMessage will retrieve the updated string if the message is updated by any client calling PutMessage. What should you do?