WCF and Flex Web Technologies Quiz

In Windows Communication Foundation (WCF), the ConcurrencyMode enumeration specifies whether a service class supports single-threaded, multi-threaded, or reentrant operations. The valid values are Single, Reentrant, and Multiple. Because all three options represent valid members of the enumeration, 'All' is the correct choice.

The TransferMode property in WCF can be set to Buffered, Streamed, StreamedRequest, or StreamedResponse. Buffered mode transfers entire messages, while Streamed modes enable streaming in one or both directions. The All option correctly encompasses all these values.

In WCF, only Message, Stream, and types implementing IXMLSerializable can be used as parameters for streaming operations. These types support streaming because they can be read and written sequentially without buffering the entire message.

WCF supports multiple session types including Reliable sessions (guaranteed message delivery), Secure sessions (encrypted communication), and Transport sessions (connection-oriented messaging). The All option correctly encompasses all available session types.

NetTcpBinding is the WCF binding that supports port sharing through the TCP port sharing service. This allows multiple WCF services to share the same TCP port, which is useful for hosting multiple services on the same endpoint.

System.Transactions is the .NET namespace used for handling transactions in WCF. It provides classes like TransactionScope for managing distributed transactions across multiple resources and services.

Streaming in WCF is supported by NetNamedPipeBinding (for same-machine communication), NetTcpBinding (for cross-machine TCP communication), and BasicHttpBinding (for HTTP-based streaming). These bindings can transfer large messages as streams instead of buffering the entire message.

InstanceContextMode enumeration in WCF includes three values: Single (one instance for all clients), PerSession (one instance per client session), and PerCall (new instance per method call). The All option correctly encompasses all these available modes.

WCF transports implement three categories of quotas: memory allocation limits prevent excessive buffer consumption, timeout quotas control operation duration, and collection size limits restrict the number of items in data structures. Together these protect services from resource exhaustion attacks.

WS-AtomicTransaction (WS-AT) is an interoperable protocol standard defined in the WS-* specifications that enables distributed transaction coordination across different platforms and vendors. It allows WCF services to participate in transactions with non-WCF systems.

Service Trace Viewer (SvcTraceViewer.exe) supports multiple trace formats including Windows Event Tracing (.etl) files, Crimson tracing files, and WCF's own .svcLog format. This flexibility allows developers to view traces from various sources in a single tool.

The PortSharingEnabled property, when set to true on a binding's base address, enables multiple WCF services to share the same TCP port using the Net.TCP Port Sharing Service. This conserves network resources and allows more services on limited ports.

The ReceiveTimeout property controls session lifetime in WCF - if no message is received within this timeout period, the session is considered closed and the channel faults. Unlike SendTimeout (outgoing) or OpenTimeout (connection establishment), this specifically governs incoming message tolerance.

WCF transports implement three categories of quotas: memory allocation limits prevent excessive buffer consumption, timeout quotas control operation duration, and collection size limits restrict the number of items in data structures. Together these protect services from resource exhaustion attacks.

In Apache Flex/ActionScript container layouts, VBox automatically arranges its child components in a vertical column. HBox arranges them horizontally, Canvas uses absolute positioning, and ViewStack manages stacked views showing one at a time.

In Adobe Flex, the [Bindable] metadata tag is used to mark a variable or property as eligible for data binding. When a property is marked as bindable, it can be used as the source or destination in data binding expressions, and changes to the property will automatically update bound destinations.

The 'static' keyword in many programming languages (including PHP, which this appears to be from) allows a method or property to be accessed without instantiating the class. A 'static function' can be called directly using ClassName::methodName() without creating an object. Options A and B alone are incorrect syntax - it must be 'static function' together.

When the mx:HTTPService class in Adobe Flex returns complex data (like XML or JSON), the default resultFormat is 'object'. This means the response is automatically parsed and converted into an ActionScript object structure. Other formats like 'xml', 'e4x', or 'text' must be explicitly specified if needed.

The allowMultipleSelections property enables users to select multiple items from a List control, typically using Ctrl-click for non-contiguous selection or Shift-click for ranges. selectedIndices returns the indices of selected items, while selectedItem returns a single selection.