This article looks at a line of business application built using .NET 2.0, Windows Communication Foundation, and Visual Studio 2005 that automatically chooses the most suitable connection based on the state of the user’s network connection, providing reliability via message queuing on top of it.
Since network connectivity cannot always be guaranteed, what happens when the network goes down or a network connection is simply unavailable? How can you provide your users with the best connected experience regardless of the state of the network?
I’ll start off with an overview and step-by-step configuration of a WCF service that exposes multiple bindings and wrap up with a pattern for adding logic to a Windows Forms test harness client that detects available network options and chooses the appropriate WCF binding at run time. Where the network is down or otherwise unavailable, I will provide the user with a reliable, “always on” computing experience using Queued Calls via Microsoft Message Queuing (MSMQ). As you will learn, MSMQ integrates seamlessly with WCF services. When network state is online, I will explore appropriate uses for TCP and HTTP depending on the geographical location of the user.
In addition to queued calls, WCF provides a number of powerful reliability features that are supported out of the box including WS-Reliable Messaging for managing message delivery even across multiple hops, and WS-Atomic Transactions for implementing distributed transactions. In this article, I will focus specifically on Queued Services, which are implemented seamlessly in WCF using Microsoft Message Queue (MSMQ). I will discuss these additional reliability features in future articles.
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