WCF Fundamentals Quiz

Channel listeners are responsible for creating channels and receiving messages from the network or lower layers in the WCF channel stack. They wait for incoming connections and create appropriate channel objects.

NetNamedPipeBinding is designed for local machine communication using named pipes and does not support TransportWithMessageCredential security mode. The other listed bindings (BasicHttp, WSHttp, WSFederationHttp) all support this credential type.

DataContractSerializer is the default serializer used by WCF to translate .NET objects into XML. XmlSerializer is an alternative that must be explicitly opted into, while DataContractFormatter is not a standard standalone serializer class.

Enabling sessions in WCF requires both: (1) marking the service contract with SessionMode.Required, and (2) setting InstanceContextMode to PerSession in the ServiceBehavior. Option A shows the contract requirement, Option B shows the service behavior - both are necessary.

To ensure a net.tcp WCF service starts and runs continuously from boot, hosting in a managed Windows Service is the standard practice. While IIS 7.0 with WAS supports net.tcp, it starts services on-demand rather than starting them automatically at server boot unless specifically configured (like alwaysRunning, but the simple choice here is hosting in a Windows Service). Hosting in WPF is incorrect for headless background execution.

WCF REST services are created by adding WebGet (for HTTP GET) or WebInvoke (for other HTTP methods) attributes to operation contracts. Both approaches are valid for creating RESTful services.

WSFederationHttpBinding with Message security is the correct choice for STS-based token authentication when SSL/TLS is not available. This binding is specifically designed for federated security scenarios where a Security Token Service issues tokens. TransportWithMessageCredential requires SSL transport security, which the scenario explicitly states clients cannot use.

Delegation is required when the WCF service needs to access remote resources on behalf of the client (multi-hop scenario). Impersonation only allows accessing local resources on the service machine. Identification allows the service to identify the client but cannot impersonate at all.

TransportWithMessageCredential mode combines SSL transport security with message credentials. The message sub-element must specify clientCredentialType (like UserName) for proper configuration. Option D uses 'MessageWithTransportCredential' which is not a valid security mode name.

In Windows Communication Foundation (WCF), the wsDualHttpBinding is designed specifically to support dual-way communication, which inherently requires and supports reliable sessions by default. BasicHttpBinding does not support reliable messaging by default, and netTcpBinding supports reliable sessions but requires explicit configuration or different defaults depending on context.

wsDualHttpBinding does not support streaming because it uses HTTP for both request and response channels, and HTTP is inherently message-based (no streaming). TCP and named pipe protocols (netTcpBinding, netNamedPipeBinding) support streaming. basicHttpBinding can support streaming with appropriate transferMode settings.

WCF provides four contract types: ServiceContract (defines service interface), OperationContract (marks service operations), DataContract (marks serializable types), and MessageContract (customizes message structure). There is no ExceptionContract - exceptions are handled using FaultException and FaultContract attributes.

WcfTestClient.exe is the official WCF service testing tool provided with Visual Studio. It allows testing service operations without writing client code. The other options are fictitious tool names that do not exist in the .NET Framework.

The System.ServiceModel namespace contains the core classes, interfaces, and structures required to build and consume WCF service clients and hosts. Namespaces like System.Web, System.Data, and System.Service do not contain these WCF-specific constructs.

IDispatchMessageInspector is the service-side interface for message inspection and logging. It provides AfterReceiveRequest (inspect incoming messages) and BeforeSendReply (inspect outgoing responses) methods. IClientMessageInspector is the client-side equivalent.

wsHttpBinding supports multiple security modes including Transport, Message, and TransportWithMessageCredential. Message security can use Windows credentials or issued tokens (from an STS). The question correctly identifies issued token authentication as a supported option. Transport security with Windows is also supported, but Message with issued tokens is the best answer listed.

In WCF 4.0, default protocol mapping assigns basicHttpBinding to the http scheme, wsHttpBinding to the secure http scheme, and webHttpBinding to rest. The other options are incorrect because they represent non-default configurations or distinct bindings.

The Ad-Hoc discovery model uses multicast announcement messages where services announce their presence on the network. Interested clients listen for these announcements. This is contrasted with managed discovery which uses a centralized discovery proxy. WS-Discovery protocol supports this ad-hoc multicast model.

WebFaultException is the specific exception type for WCF RESTful services (WebHttpBinding). It allows returning HTTP status codes along with fault information. FaultException is for SOAP services. RESTException and WebHttpFaultException do not exist in WCF.

Team Foundation Server (TFS) ships with two process templates by default: MSF for Agile Software Development and MSF for CMMI Process Improvement. These templates define work item types, workflows, and process guidance. Additional templates can be created or imported, but only two are available out-of-the-box.