The Kevoree Book

Component

Description

A component is a piece of code which can tack data in input and produces data in ouput.

Examples

  • Ticker : Emit a random value every N seconds.
  • ConsolePrinter : Print everything it receive.
  • ArduinoController : Can be used as a proxy to an arduino device.

Interface

A component interact with the rest of a kevoree system through its interface. It is composed of different elements, usually described by annotated field and method (at least in our existing implementations in java, javascript/typescript and C#).

Input

A field annotated with input will receive data from any channel connected to it.

Output

A field annotated with output offer the ability to send data through channels connected to it.

Start

The method annotated with Start will be called when an instance of the component need to be started.

Stop

The method annotated with Stop will be called when an instance of the component need to be stopped.

Update

The method annotated with Update will be called when an instance of the component need to be updated.

Param

A field annotated with Param will be instantiated with a value provided by the model.

KevoreeInject

A few interfaces to the external system are provided to the components by injection of interfaces instances. The core will match every KevoreeInject annotated field and will look for a instance of its interface.

The provided interfaces are :

  • Logger : Offers a way to log messages. For more detail read the Logger page
  • Context : Provider accessors to the node node, the instance path and the instance name.
  • ModelService : Offers operators on the node's model. For example you can use it to publish a new model, which will be adapted by the core.

Naming rules reminder

As defined in the generalities part, every component must follow this name rule : kevoree-${platform}-comp-${componentName} (e.g kevoree-js-comp-ticker, kevoree-dotnet-comp-consoleprinter, kevoree-java-comp-arduino-controller).