The PenComm API enables desktop applications to interact with smartpens that are attached to the desktop computer. 

The PenComm API has two main components:

• PenComm Client Library: This library provides classes and structures that help applications communicate with smartpens. When an application uses these classes, the library sends requests to the PenComm Service for processing. The PenComm Service processes the requests and sends back results directly to the desktop application. The PenComm Client Library communicates with the PenComm Service using Inner Process Communication (IPC). A desktop application can communicate with one or more smartpens by simply making calls into the PenComm Library. 

• PenComm Service: This system service centralizes smartpen communications and maintains a machine-wide smartpen state to ensure properly overlapped communications and efficient data transfers. The PenComm Service processes requests received from desktop applications and sends back the results. The PenComm Service handles concurrent communcation between a single desktop application and multiple smartpens, and between multiple applications and multiple smartpens.