Windows Communication Foundation (WCF) is a platform for distributed system development and SOA. Large-scale production systems are typically deployed in redundant environments with multiple Web servers, application servers, and database servers. System administrators typically configure appliance or software load balancers to handle distribution of load among each tier-and this requires WCF architects and developers to be aware of the potential implications of their service configurations. This session focuses on the affects of transport and application sessions; overhead related to channel creation and the benefits of shared proxies and multithreading; the implications of shared proxies on load balancing; and appropriate deployment configurations to support this distributed scenario. We also discuss the impact of the forthcoming Microsoft .NET Framework 4 release and the Windows Application Server ("Dublin") on these scenarios to help you plan for future migration.