EmStar Devices

Devices, Devices, Devices!!!

EmStar applications are a

A paragraph or two explaining that each component in emstar is a separate process, and the communicate through device files in /dev

The device libraries all follow the same event based programing pattern: the main() of a process declares the callbacks for the device or client in struct that is specific to that device, calls a function which creates a device, then enters the event loop. As data is read or written to the deivce, or as timers fire, the callbacks fire. For some devices like the command device, there are a few callbacks that provide very simple semantics. For other devices such as the packet device, there are more complex

Timers and events

Timers and Events are used for ....

Status Device and Client

Facts about the Status Device and Client. How to use the status client. Advanved status device usages with multiple clients.

Command Device

The Command Device is a subset of the status device.

Query Device and Client

The Query Device and Client provide a query and response interface for the device and client side.

Packet Device and Client

The Packet Device and Client are ideal for reliably communicating between processes. Unlike a Status Device there is a queue on data written to the device by clients and a queue on data being output to the clients. This allows the data to be processed asynchronously by the device and allows the clients to get all the updates (unlike the state updates of the status device).

Sensor Device and Client

The Sensor Device and Client provide a sensor interface both streaming and non streaming.

Logring Device

A nice easy way to provide a Log Device.