Availability Guide for Application Design

Instrumenting an Application for Availability
Availability Guide for Application Design—525637-004
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The DSM Subsystem Environment
The following paragraphs give a brief overview of how you can help to increase the
availability of your application using SPI programming to generate event messages. A
set of standard event messages provided by HP is adequate for most applications. You
also have the option of building event messages from scratch. For full details about
using SPI procedures or EMS procedures to build event messages, refer to the EMS
Manual.
When to Use SPI Programming for Event Generation
You can use SPI programing techniques to generate event messages for any
application or subsystem that delivers messages to EMS. In many cases, however, it is
easier to use EMS FastStart to build messages than it is to use SPI or EMS
procedures.
If your application causes events with more than one subject, has events that include
error lists or foreign tokens, or uses multiple occurrences of a specific token in the
same event, then you must generate event messages yourself, using EMS or SPI
procedures. To build your own event messages, you can use standard event
messages which provide standard information for a given event type or you can create
event messages from scratch.
How SPI Works
In order to generate event messages from your application using EMS or SPI
procedures, you must:
•
Use a data definition language (DDL) file to define all the tokens you will use in
your application.
•
Build event messages and send them to an EMS collector process
Standard Event Messages
Building event messages using SPI procedures can be complex and error prone. To
reduce the complexity and likelihood of error, HP provides standard error messages
that cover the most likely situations reported by event messages. These standard
event messages provide message buffers for the following types of events:
•
An object has become available.
•
An object has become unavailable.
•
An object has experienced some other state change.
•
Operator attention is needed.
•
Operator attention is finished.
•
A transient fault has occurred.
•
A usage threshold has been passed.
EMS procedures are available to build EMS message buffers for these standard
events, including most of the tokens you are likely to need. If you need additional
tokens, you can use the same SPI procedures you would use for nonstandard event
messages to add tokens to the standard event messages.