This chapter covered quite a few topics related to workflow hosting and communication between a host and a workflow instance. The WorkflowRuntime class is responsible for creating new workflow instances and managing runtime services. Runtime services are classes that perform specialized work related to runtime management, such as workflow persistence and threading behavior. The workflow runtime also exposes several events that enable you to monitor for relevant activities related to the workflow runtime itself as well as workflow instances.
Communication is an important part of the workflow infrastructure. You can use parameters to pass data to workflows upon their creation and receive data upon workflow completion. This chapter also introduced local communication services. Local communication services enable a workflow host and a workflow instance to communicate with each other using a communication contact defined as a .NET interface and its subsequent implementation as a class.