Generating parts and ports

Introduction

Objecteering C++ Developer provides a system used to generate C++ code for part and ports. Parts and ports are UML 2.0 features designed to represent limited connexions in component architecture, as well as their integration through the connection of predefined plugs.

Figure 61-b. Modeling parts and ports

Modeling a class with connection ports

Some classes can publish or require certain information, declared by an interface. In the example proviced in Figure 61-b above, the "Camera" class publishes an "iVision" interface as a provided interface. Thus, the camera publishes all this information to this channel. The "Arm" class publishes an "iControl" interface to obtain the information necessary for its use by a normalized channel.

To create a generatable port on a class, simply create a port, name it and then specify required or provided interfaces, represented by lollipops. A single port can simultaneously have provided and required interfaces, as in the "Brain" example shown in Figure 61-c below.

Note: Don’t forget to specify interfaces to type the plug by double-clicking on the lollipop.

Figure 61-c. The "Provided interface edition" window

Using generated code in a class with ports

Internally, every port is a class, which is automatically generated and does not appear in the model. The name of this class is normalized through the concatenation of the class name, the port name and the "Port" keyword.

Class	Port	C++ name of the port
Brain	Cmd	BrainCmdPort
Camera	Vis	CameraVisPort
Arm	Ctrl	ArmCtrlPort

Every operation on the connection point must therefore be carried out using this port. This generated class is the access point to interfaces.

The port class provides access to provided and required interfaces. To retrieve the interface, an accessor is automatically created from "get", the "Required" or "Provided" keyword and the type of the interface. For example, the "CameraVisPort" class contains an accessor named "getProvidedIVision ()". Using these accessors, the class does not know the linked element. This system provides important separation of issues.

For example, if the brain takes the information from the vision device through the "Command" port, and in order to call the "move" command via the same port, a method must contains the following code:

Void Brain::move () {

// Retrieving the command port

BrainCmdPort *cmdPort = getCmdPort ();

// getting the required plug

IVision vision = cmdPort->getRequiredIVision ();

Data d = vision.getData ();

// getting the provided plug

ICommand command = cmdPort->getProvidedIControl ();

Command.move (d);

}

Creating an internal structure for part/port integration

In a part/port model, a class will instanciate all classes for component assembly within its internal structure, and you, as the user, need simply connect them. However, these elements must be coherent with the static model. For this reason, Objecteering C++ Developer contains a wizard to help you to create this model.

To create an internal structure model, create an integration class. In the internal structure, simply create parts and set their type to instanciated classes. Next, launch the "Complete internal structure model" command. This command will complete the model by creating attributes in the class to refer to instances, by adding ports and provided/required interfaces relative to the static model of these classes, and by keeping the model consistent.

Once all these elements are instanciated, you should simply connect the elements in order to initialize the parts. When the class containing an internal structure is generated, this will automatically lead to generation of the instanciation and connection code. This means that you can concentrate on business code instead of integration code, which is totally generated.

Figure 61-d. Running the "Complete internal structure model" command

Note: The "Complete internal structure model" command can also update the internal structure model. If you change the static model of a class containing ports, for example by adding a new lollipop, the launch of this command will update those internal structures which use it.