Echelon LNS - Manual (Page 294)

LNS Programmer's Guide 280
Registering Plug-In Commands in the Windows Registry
Registration commands for plug-ins must also be registered in the Windows Registry.
Registration commands are plug-in commands automatically invoked by a director
application to register the plug-in application’s commands within an LNS network
database. Registration commands may also perform other initialization tasks required by
a plug-in, such as creating a device template, importing an external interface file for the
device template, and registering device controls with the device template. This is
described in more detail in the LNS Plug-in Programmer's Guide, which can be
downloaded from Echelon’s website at
http://www.echelon.com/ .
Accessing Extension Data
LNS client applications may require data that is not available in the LNS database, so
the applications can maintain their own databases. If they do, they must create their own
scheme for sharing the data between multiple instances of themselves on a network, and
must develop a mechanism for associating the data with data items in the LNS database.
LNS provides Extension objects to make maintaining application specific data within
the LNS database simpler. The data stored in the Extension objects can be associated
with objects within the LNS database, and LNS automatically provides a mechanism for
accessing the data from multiple clients on a network. The following LNS objects include
an Extensions collection that can be used for maintaining application specific data:
AppDevice, Channel, DeviceTemplate, LonMarkObject, Network,
NetworkServiceDevice, ObjectServer, Router, Subnet, Subsystem and
System.
Implementing an LNS Director Application
An LNS director application is an application that can manage and invoke LNS plug-in
applications, as described previously in this chapter. Typical LNS director applications
are generic network management or monitoring tools that use plug-in software to
delegate device-specific tasks such as device configuration. See the LNS Plug-In
Programmer’s Guide for more information about the LNS plug-in interface and API, and
about creating LNS plug-in applications. You may also find the example director
application included with LNS Turbo Edition useful when reviewing this section. For
more information on the example director application in this document, see Appendix C,
LNS Turbo Edition Example Application Suite.
This section discusses special considerations you will need to make when creating an
LNS director application. An LNS director application must be able to perform the
following tasks:
• Recognize newly installed or updated plug-in software, and manage the
completion of the plug-in registration process.
• For any applicable operation, determine the applicable plug-in software and
launch that application.
• Optionally support advanced plug-in management operations, such as
temporarily disabling a plug-in, deregistering plug-ins, etc.