Component Guide 2: Containers
Containers are components that hold one or more instances of a Capsule for use within a host (or parent) Capsule. The elements of a Container are called members or elements. Containers interface with the components in their parent through Connector Pins, which are represented as horizontal lines on the left and right side of the container body. (Left and right sides correspond to input and output pins, respectively.) Every Connector Pin is given a label, and they correspond roughly to the DataInputs and DataOutputs (i.e., the Interface) of the constituent Capsule type(s), although some Containers add pins. Pin connection uses a common dialog format for all Containers and is shown below.
Pins are addressed using dot notation. If Container X has Pin Y, then X.Y is a reference for the Pin.
Each container type extends and enriches the environment of its elements by assigning new functionalities that are only valid within the context of the container. These new functionalities are realized by a set of primitive operators (primops) provided by the Container. (We refer to such primops as service providers.) The data structure of the container together with the service providers comprise an abstract data type that effects a specific topological environment.
Every aggregator has a means for uniquely identifying its members. We'll refer to this as its Aggregator Id.