//sharing a channel cache between two workflow applications in a single app-domain.
sharedChannelCache = new SendMessageChannelCache(new ChannelCacheSettings { MaxItemsInCache = 5 }, new ChannelCacheSettings { MaxItemsInCache = 5 });

WorkflowApplication workflowApp1 = new WorkflowApplication(workflow);
workflowApp1.Completed = new Action<WorkflowApplicationCompletedEventArgs>(OnCompleted);
workflowApp1.Extensions.Add(sharedChannelCache);

WorkflowApplication workflowApp2 = new WorkflowApplication(workflow);
workflowApp2.Completed = new Action<WorkflowApplicationCompletedEventArgs>(OnCompleted);
workflowApp2.Extensions.Add(sharedChannelCache);

//disabling the channel cache so that channels are closed after being used.
SendMessageChannelCache disabledChannelCache = new SendMessageChannelCache(new ChannelCacheSettings { MaxItemsInCache = 0 }, new ChannelCacheSettings { MaxItemsInCache = 0 });

WorkflowApplication workflowApp3 = new WorkflowApplication(workflow);
workflowApp3.Completed = new Action<WorkflowApplicationCompletedEventArgs>(OnCompleted);
workflowApp3.Extensions.Add(disabledChannelCache);