contents/understanding-lttng/core-concepts/domain.md

   1 ---
   2 id: domain
   3 ---
   4
   5 A tracing _domain_ is the official term the LTTng project uses to
   6 designate a tracer category.
   7
   8 There are currently three known domains:
   9
  10   * Linux kernel
  11   * user space
  12   * Java Util Logging (JUL)
  13
  14 Different tracers expose common features in their own interfaces, but,
  15 from a user's perspective, you still need to target a specific type of
  16 tracer to perform some actions. For example, since both kernel and user
  17 space tracers support named tracepoints (probes manually inserted in
  18 source code), you need to specify which one is concerned when enabling
  19 an event because both domains could have existing events with the same
  20 name.
  21
  22 Some features are not available in all domains. Filtering enabled
  23 events using custom expressions, for example, is currently not
  24 supported in the kernel domain, but support could be added in the
  25 future.