Oracle 5.0, Справочное руководство

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Connector/Net Programming
1924
the MySQL Enterprise Monitor server to monitor. The parameter
postInterval
is how often to post
the data to MySQL Enterprise Monitor, in seconds.
20.2.5.14.2. Building Custom Listeners
To build custom listeners that work with the MySQL Connector/Net Trace Source, it is necessary to
understand the key methods used, and the event data formats used.
The main method involved in passing trace messages is the
TraceSource.TraceEvent
method.
This has the prototype:
public void TraceEvent(
TraceEventType eventType,
int id,
string format,
params Object[] args
)
This trace source method will process the list of attached listeners and call the listener's
TraceListener.TraceEvent
method. The prototype for the
TraceListener.TraceEvent
method is as follows:
public virtual void TraceEvent(
TraceEventCache eventCache,
string source,
TraceEventType eventType,
int id,
string format,
params Object[] args
)
The first three parameters are used in the standard as defined by Microsoft . The last three parameters
contain MySQL-specific trace information. Each of these parameters is now discussed in more detail.
int id
This is a MySQL-specific identifier. It identifies the MySQL event type that has occurred, resulting in a
trace message being generated. This value is defined by the
MySqlTraceEventType
public enum
contained in the MySQL Connector/Net code:
public enum MySqlTraceEventType : int
{
ConnectionOpened = 1,
ConnectionClosed,
QueryOpened,
ResultOpened,
ResultClosed,
QueryClosed,
StatementPrepared,
StatementExecuted,
StatementClosed,
NonQuery,
UsageAdvisorWarning,
Warning,
Error
}
The MySQL event type also determines the contents passed using the parameter
params Object[]
args
. The nature of the
args
parameters are described in further detail in the following material.
string format
This is the format string that contains zero or more format items, which correspond to objects in the
args array. This would be used by a listener such as
ConsoleTraceListener
to write a message to
the output device.