Obtaining Property Information

Most callback methods need to obtain information about resource and resource type properties of the data service. The API provides the scha_resource_get() function for this purpose.

Two kinds of resource properties, system-defined properties and extension properties, are available. System-defined properties are predefined whereas you define extension properties in the RTR file.

When you use scha_resource_get() to obtain the value of a system-defined property, you specify the name of the property with the -O parameter. The command returns only the value of the property. For example, in the sample data service, the Monitor_start method needs to locate the probe program so it can launch it. The probe program resides in the base directory for the data service, which is pointed to by the RT_BASEDIR property, so the Monitor_start method retrieves the value of RT_BASEDIR, and places it in the RT_BASEDIR variable, as follows.

RT_BASEDIR=`scha_resource_get -O RT_BASEDIR -R $RESOURCE_NAME -G \
$RESOURCEGROUP_NAME`

For extension properties, you must specify with the -O parameter that it is an extension property and supply the name of the property as the last parameter. For extension properties, the command returns both the type and value of the property. For example, in the sample data service, the probe program retrieves the type and value of the probe_timeout extension property, and then uses awk to put the value only in the PROBE_TIMEOUT shell variable, as follows.

probe_timeout_info=`scha_resource_get -O Extension -R $RESOURCE_NAME \
-G $RESOURCEGROUP_NAME Probe_timeout` 
PROBE_TIMEOUT=`echo $probe_timeout_info | awk '{print $2}'`