Customize the component

A general overview of writing and invoking Business Logic Tier (BLT) components will help you not only understand how they are invoked, but also customize them to perform your desired business logic.

The following diagram shows how the BLT components are invoked:

The client uses the BLTClientFactory.NET class to create the component through the BLT infrastructure. The infrastructure controls invocation on remote hosts and process isolation. The infrastructure runs in a separate process from the client. The client and component may or may not be on separate computers. The client chooses where to instantiate the component – locally or remotely. The client and component are always on computers within the same domain.

The component is hosted in a special BLTHost process. This process is provided by the AVEVA Enterprise SCADA Infrastructure, and loads the component Dynamic Link Library (DLL) when the component is invoked.

The infrastructure calls the interface code, which is in the <name>Component object that is derived from the BLTComponent class. This class uses the IBLT interface to retrieve parameters from the client. The parameters are stored in the <name>Processor object, which derives from the BLTProcessor class.