See also: Skills in the Xentara user manual

The Skill Class

A Xentara skill is represented by a global object of a skill class derived from xentara::skill::Skill::Class. You can derive xentara::skill::Skill::Class yourself, but it is easiest to use the template class xentara::skill::Skill::ConcreteClass, which implements all of the required callbacks using template parameters.

The skill class object must have static storage duration, i.e. it must be a static member variable or a global variable. Usually, it is most convenient to make the skill class object a static member of the actual skill object class (see below).

Note: Many plugin frameworks require the use some sort of preprocessor macro to publish the plugin functionality. Xentara does not require such a macro. Instead, the skill class objects automatically register themselves when they are constructed.

The skill class object does not contain any functionality. Instead, it provides the following meta information about the skill to Xentara:

The skill's name. This is used to construct the type decriptor of skill elements in the Xentara model file.
The skill's unique UUID.
The types of elements the skill provides.

The skill class object must also provide a callback to create the skill object itself, which contains the actual functionality.

The plugin framework provides a template class xentara::skill::Skill::ConcreteClass, which takes all of the required information as template parameters and implements all the callbacks for you.

The Skill Object

The actual functionality of a skill is encapsulated is a custom class derived from xentara::skill::Skill. The skill should contain all the global functionality of the skill that is not directly tied to a specific element type.

The skill provides a callback to create top-level elements. A top-level element is an element that is not a child of another skill element, but that either have no parent element, or reside within an element group See Creating Skill Element Objects on how skill elements are created.

Element Classes

See also: Skill Elements in the Xentara user manual

Each type of element (bus, device, data point, service, client etc.) supported by the skill is represented by a global object of a custom element class type derived from xentara::skill::Element::Class. You can derive xentara::skill::Element::Class yourself, but it is easiest to use the template class xentara::skill::Element::ConcreteClass, which implements all of the required callbacks using template parameters.

The element class object must have static storage duration, i.e. it must be a static member variable or a global variable. The element class should contain a static member function instance() that returns a the element class object, so that it can be used together with xentara::skill::Skill::ConcreteClass. If you use xentara::skill::Element::ConcreteClass instead of writing your own class, the global instance is created automatically. Otherwise, it is usually most convenient to make the element class object a static member variable of your custom class.

The element class object itself does not contain any functionality. Instead, it provides the following meta information about the element type to Xentara:

The element class's name. This is used to construct the type decriptor used in the Xentara model file to identify the element type.
The element class's unique UUID.
The configuration attributes published by the elements of this class.

The actual elements themselves are created by the skill object, or by the parent element.

The plugin framework provides a template class xentara::skill::Element::ConcreteClass, which takes all of the required information as template parameters and implements all the callbacks for you. This class also implements the instance() method required to use the class together with xentara::skill::Skill::ConcreteClass.

Elements

See also: Skill Elements in the Xentara user manual

The actual functionality of an element is provided by a custom class derived from xentara::skill::Element. This class should contain all element specific functionality.

A element will usually publish configuration and status attributes. See Publishing Attributes on how to publish attributes in general, and Publishing Config Parameters as Xentara Attributes on how to publish configuration attributes.

A element may also publish one or more events. See Publishing Events on how to publish events.

An element may also publish one or more tasks that can be scheuled in an execution pipeline. See Publishing Tasks on how to publish tasks.