Component instrumentation sends unsolicited messages, to the Service Layer to signal some particular situation. The messages are known as events. When the messages reach a management application, they are known as indications. The indication ID identifies indications. The IDs start at the number 1. Events are often a sign of a catastrophic occurrence or other activity that the system should know about immediately. The event identification is specific to a given component and appears as an unsolicited "get." You specify event structures as groups in the component's MIF file.
In DMI, all commands are specified by using data blocks. Component instrumentation uses the function call DmiIndicate() to send the indication block and any following blocks to the Service Layer for processing. The C language prototype call is as follows:
unsigned long DmiIndicate(PTR command)where command is the complete command block. The system returns a 32-bit status value to indicate success or failure.
The Service Layer immediately returns control to the component instrumentation while it processes the indication. The component instrumentation is free to issue additional indications, but it cannot reuse the original indication block buffer until the Service Layer processing is complete. Simultaneous indications from a component instrumentation must use different indication blocks. When the Service Layer has completed processing the indication, it calls the function pResponseFunc() identified in the original indication block. At that point, the component instrumentation can reuse the block.