SQL Trace Architecture
In SQL Trace, events are gathered if they are instances of event classes listed in the trace definition. These events can be filtered out of the trace or queued for their destination. The destination can be a file or SQL Server Management Objects (SMO), which can use the trace information in applications that manage SQL Server. The following diagram shows how SQL Trace gathers events during a tracing.
The Event Sources can be any source that produces the trace event, such as Transact-SQL batches or SQL Server events, such as deadlocks. For more information about events, see SQL Server Event Class Reference. After an event occurs, if the event class has been included in a trace definition, the event information is gathered by the trace. If filters have been defined for the event class in the trace definition, the filters are applied and the trace event information is passed to a queue. From the queue, the trace information is either written to a file or can be used by SMO in applications, such as SQL Server Profiler.