Echelon LNS Manual de usuario descargar pdf (Pagina 293)

LNS Programmer's Guide

279

downloaded from Echelon’s website at http://www.echelon.com/

. You should consult this

manual before developing an LNS component application.

LNS Plug-In API

Director applications call plug-ins using the LNS Plug-In API. This ActiveX-based API

defines an automation object that provides a standard interface between a director

application and a plug-in. Director applications can launch plug-ins and communicate

with them using the methods and properties of the automation object. A set of ActiveX

exceptions is defined for passing back error information from the plug-in to the director.

Registering Plug-Ins

LNS plug-ins and device controls must be registered in the Windows Registry. Each plug-

in also registers one or more commands in an LNS database so that director applications

can find the plug-ins.

A special class of plug-in commands is provided which can register new plug-ins. This

allows plug-in registration to be fully automated. The installation program for a plug-in

only has to create a single entry in the Windows Registry for the plug-in. The plug-in

then performs the tasks required to register all of its commands within the LNS

database, and carries out any other initialization steps that it requires. This allows

registration to be bootstrapped, so that the first step can occur either before or after the

LNS Server has been installed.

Registering a Plug-In in the LNS Database

Plug-in commands are registered in an LNS database using ComponentApp objects.

Each ComponentApp object represents a single command that is handled by the plug-in.

A single plug-in can handle many commands. ComponentApp objects are contained

within the ComponentApps collections. The following objects within the LNS Object

Hierarchy have ComponentApps collections:

• ObjectServer

• System

• DeviceTemplate

• LonMarkObject

Registering a Plug-In in the Windows Registry

In accordance with Microsoft’s registration requirements for COM components, all plug-

ins must be registered in the Windows Registry. This includes generating a unique GUID

(Globally Unique Identifier) for each component, registering the GUID and OLE name in

the Windows Registry, and registering the type library information. Different

development tools provide varying amounts of support for the COM registration tasks.

The Visual Basic runtime generates GUIDs and type libraries automatically when a

Visual Basic OLE server is run. Visual C++ and MFC provide classes and macros to

assist the developer with these tasks.

1 2 ... 288 289 290 291 292 293 294 295 296 297 298 ... 367 368

Sin comentarios

Echelon LNS Manual de usuario Pagina 293