Echelon LNS Plug-in - Manual (Page 12)

Introduction
An LNS plug-in is an out-of-process automation server that implements the COM-based LNS Plug-in
API so that it may be instantiated and controlled by an LNS plug-in director application. Plug-ins
provide a standard way to extend and customize the functionality of LNS applications. For example,
plug-ins allow device manufacturers to provide customized software that simplifies the configuration,
monitoring, or control of their devices (plug-ins that are specific to a particular type of device are
sometimes referred to as device plug-ins). Plug-ins can also add new functionality to LNS applications
such as alarming, logging, and trending. The LNS Plug-in API is further described in Chapter 3, How
Plug-ins Work with Directors.
An LNS plug-in director application (herein referred to as a director) is a complex, general-purpose
network manager that is extensible in its functionality, because it can call LNS plug-ins. For example
Echelon’s LonMaker Integration Tool is an LNS plug-in director application that can call LNS
plug-ins to extend its functionality—typically to perform manufacturer-specific device configuration.
When a plug-in is installed on a computer, the setup program installs a number of items for the plug-in
to the computer’s registry. This enables directors to determine which plug-ins a user has installed on
their computer and call the plug-ins at appropriate times. Directors can make access to plug-ins
completely transparent to the end-user. This means that the user cannot tell when a task is built-in to
the director and when it is being provided by a plug-in called by the director.
Plug-ins provide many benefits to network integrators, who are the end-users of tools. Plug-ins make
tools easier to use and make network integrators more productive. They reduce the cost of training
network integrators on the use of tools. They also reduce the time and cost of installing, configuring,
and maintaining systems.
Tool and device manufacturers also benefit from plug-ins. For tool manufacturers, plug-ins make tools
extensible and thus more valuable. Network integrators can incrementally add features—from the
tool’s manufacturer or from other plug-in vendors—to adapt the tool to their needs. A tool that
supports plug-ins is a tool that will become easier to use, more productive, and more powerful over
time.
For device manufacturers, plug-ins allow them to make their devices easy to install, configure, and
maintain—without the cost of having to develop an entire, customized tool. Devices that come with
plug-ins have a competitive edge: they are cheaper to install and service, and they are easier to use.
The LNS Plug-in Framework Developer’s Kit allows plug-ins to function in the .NET environment and
interoperate with COM-based directors. It includes the .NET components needed for interfacing with
the COM-based LNS API in the .NET environment. It provides a set of example software and
framework assemblies that let you efficiently develop plug-ins with the latest .NET programming tools
and re-distribute your plug-ins. It provides the plug-in API and COM interaction so that you do not
need to provide it in your .NET application.
Overview of Plug-ins
A plug-in is a type of LNS application that implements the COM-based LNS Plug-in API. The Plug-in
API consists of the LNS Plug-in Commands (see Appendix A, Standard Plug-in Commands), the LNS
Plug-in Properties (see Appendix B, Standard Plug-in Properties), and LNS Plug-in Exceptions (see
Appendix D, Standard Plug-in Exceptions). A plug-in is defined by the actions that it can perform (for
example, by the set of commands that it provides and by the class of objects that each command
operates on). For example, a plug-in might implement two actions, a test command of AppDevice
class objects and a test command of Router class objects.
Types of Plug-ins
There are two types of plug-ins: device plug-ins and system plug-ins.
Device plug-ins apply to a single device or a single functional block within a device. For example, you
could create a device plug-in for a device developed with the NodeBuilder tool that allows users to set