System information

i.LON SmartServer 2.0 Programmer’s Reference
3-7
3.4.4 Read Functions
You can use the Read function to read the value, status, or priority of a data point on the Data Server
(Dp_Cfg), read the entries in an alarm log or data log, and read the events scheduled in a Scheduler or
Calendar. To use the Read function, you need to provide the <UCPTname> of the item to be read.
This could be a data point, or an Alarm Notifier, Data Logger, Scheduler, or Calendar functional block.
The Read function returns a list of <Item> elements of a Dp_Data type for each data point referenced
by the input you supplied to the function.
3.4.5 Write Functions
You can use the Write function to update the value, priority, or status of a data point on the Data Server
or to update an entry in an Alarm Log. To use the Write function, you need to provide an <Item>
element of a Dp_Data type that includes the <UCPTname> of the item to be updated, which could be a
data point or an Alarm Notifier functional block. When using the Write function, you can use the
output supplied by the corresponding Read function as the basis for your input.
3.4.6 Delete Functions
Use the Delete functions to delete items from an application. For example, you can use the Delete
function to delete an Alarm Generator functional block or to delete a data point on Data Logger. To
delete an item, you must provide an <Item> element of a specific xsi:type (corresponding to the item’s
driver) that includes the <UCPTname> of the item to be deleted.
3.5 Performance Issues
The SmartServer contains 64 MB of RAM, which allows for complicated application configurations
and extensive network use. However, even with this amount of memory, it is still possible for very
high levels of network traffic to the SmartServer, especially using the SOAP interface, to eventually
exhaust its memory. This could result in delays in network access of the SmartServer, performance
problems for the SmartServer applications, or in the worst case even a reboot of the SmartServer.
If your SmartServer exhibits some of these symptoms, you should consider reducing the level of
network traffic to it. The following numbers are guidelines that apply to the use of the SmartServer’s
SOAP interface. While they are not absolute limits or guarantees of performance, they may be helpful
to follow when attempting to manage the SmartServer’s network traffic load or troubleshoot a
performance problem.
As a result, you should follow these guidelines when programming SOAP applications:
• Limit the number of data points referenced in a single Get or Read message to no more than 100.
• Limit the number of alarm log records read in a single message to no more than 100. For more
information on reading alarm log records, see
Chapter 7.
• Limit the number of data log records read in a single message to no more than 150. For more
information on reading data log records, see
Chapter 5.
• If the combined XML file sizes for a given application exceed 100 KB, do not try to read all the
configuration data for that application in a single Get message. This could potentially happen with
the Scheduler application if all of its functional blocks were used, or possibly with the Alarm
Notifier application.
• Do not send a request message larger than 100 KB. Some possible examples of this might be
using a single Set message to define more than 100 data points or write to 40 Alarm Notifiers.
• Limit the number of simultaneous SOAP clients to no more than the number of Web tasks
specified in the WebParams.dat file on the SmartServer, which is eight. Also note that you
should not open more than two or three Web browsers for a given SmartServer.