Echelon LonBridg Server - Manual (Page 34)

28 LonBridge API
can act on the change (for example, update a GUI window) without waiting
for the response from the remote L ON W ORKS device.
The <is_pending> message is usually followed by the <is> message.
The attributes for the <is_pending> message vary depending on the device
and the original output message for which this message is the response. The
reported attributes include a fixed set of attributes that identify the device,
followed by the attributes defined within the <device> element in the
devices.xml file. The fixed and variable attributes are defined in
Instances
Directory on page 16.
<lon>
The <lon> element defines the LonBridge XML message, and is the top-most
element for the message.
The <lon> element is required, and only one <lon> element is allowed per
message.
LonBridge Commands for Output Messages
A LonBridge application sends LonBridge output messages to the LonBridge
Server to manage and communicate with devices within the L ON W ORKS network.
The LonBridge XML for output messages includes the following XML elements:
<discover>
The <discover> message instructs the LonBridge Server to perform device
discovery.
<get>
The <get> message retrieves an object and its attributes with optional
matching criteria. If no object or criteria is specified, the LonBridge Server
returns all objects and their attributes. If an object or criteria is specified
but, no objects match the criteria, the LonBridge Server returns an empty
message (that is, <lon></lon>).
Table 5 lists the attributes for the <get> message.
Table 5. Attributes for the <get> Message
Attribute Description Required?
select Specifies a comma-separated list of
returnable attribute names. If omitted, all
attributes are returned.
Optional
where Specifies an expression that must evaluate
to TRUE for the attribute to be returned.
Required if
select is
specified
<lon>
The <lon> element defines the LonBridge XML message, and is the top-most
element for the message.