BABELTRACE2-SOURCE()                                    BABELTRACE2-SOURCE()

NAME         top

       babeltrace2-source.ctf.lttng-live - Babeltrace 2's LTTng live source
       component class

DESCRIPTION         top

       A Babeltrace 2 source.ctf.lttng-live message iterator connects to a
       local or remote LTTng (see <>) relay daemon,
       receives the streams of a specific tracing session, and emits
       corresponding messages.

           CTF streams over
           LTTng live (TCP)
             |   +--------------------+
             |   | src.ctf.lttng-live |
             '-->|                    |
                 |                out @--> Sorted messages of one
                 +--------------------+    or more streams

       More information about LTTng live is available in the LTTng
       Documentation (see <>).

       See babeltrace2-intro(7) to learn more about the Babeltrace 2 project
       and its core concepts.

       A source.ctf.lttng-live component has a single output port: its
       message iterator muxes (sorts) the messages from the various CTF data
       streams internally.

       A source.ctf.lttng-live message iterator handles the messages of one,
       and only one LTTng tracing session. A single LTTng tracing session
       can contain one or more traces, depending on the active tracing
       domains and the configured user space buffering scheme.

       The component connects to an LTTng relay daemon using the inputs
       parameter. This is an array of exactly one string which is the URL of
       the LTTng relay daemon to connect to.

       By default, if the remote tracing session name does not exist, the
       message iterator returns "try again later". This default mode makes
       the message iterator never end: even if the remote tracing session is
       destroyed, the message iterator keeps on waiting for a tracing
       session with the same name to exist. You can change this behaviour
       with the session-not-found-action initialization parameter.

           As of this version, you can only create one message iterator per
           source.ctf.lttng-live component. This is because the LTTng live
           protocol accepts at most one client per tracing session per LTTng
           relay daemon.


       inputs=URL [array of one string]
           Use URL to connect to the LTTng relay daemon.

           URL is an array of exactly one string of which the format is:


               LTTng relay daemon’s host name or IP address.

               LTTng relay daemon’s listening port.

               If not specified, the component uses the default port (5344).

               Target’s host name or IP address.

               Name of the LTTng tracing session from which to receive data.

       session-not-found-action=(continue | fail | end) [optional string]
           When the message iterator does not find the specified remote
           tracing session (SESSION part of the inputs parameter), do one

           continue (default)
               Keep on trying, returning "try again later" to the downstream
               user until the tracing session exists.

               With this action, the message iterator never ends, as the
               LTTng live protocol cannot currently indicate that a tracing
               session will never exist.



PORTS         top

           | src.ctf.lttng-live |
           |                    |
           |                out @

           Single output port.

QUERY OBJECTS         top
       See to learn more about
       this query object.

       For a string input which honors the LTTng live URL format (see the
       inputs parameter), the result object is 0.75.

       You can query the sessions object to get a list of available LTTng
       tracing sessions for a given LTTng relay daemon URL.


       url=URL [string]
           Use URL to connect to the LTTng relay daemon.

           The format of URL is:


               LTTng relay daemon’s host name or IP address.

               LTTng relay daemon’s listening port.

               If not specified, the query operation uses the default port

       Result object (array of maps, one element for each available tracing

       client-count [unsigned integer]
           Current number of LTTng live clients connected to the relay
           daemon to receive data from this tracing session.

       session-name [string]
           Tracing session’s name.

       stream-count [unsigned integer]
           Current number of CTF streams in this tracing sessions, including
           the metadata streams.

       target-hostname [string]
           Hostname of the tracing session.

           This is not necessarily the relay daemon’s hostname.

       timer-us [unsigned integer]
           Tracing session’s configured live timer’s period (µs) (see

       url [string]
           URL to use as the first element of the inputs parameter to
           connect to the same LTTng relay daemon and receive data from this
           tracing session.

BUGS         top

       If you encounter any issue or usability problem, please report it on
       the Babeltrace bug tracker (see

RESOURCES         top

       The Babeltrace project shares some communication channels with the
       LTTng project (see <>).

       ·   Babeltrace website (see <>)

       ·   Mailing list (see <>) for support and

       ·   IRC channel (see <irc://>): #lttng on

       ·   Bug tracker (see <>)

       ·   Git repository (see <>)

       ·   GitHub project (see <>)

       ·   Continuous integration (see

       ·   Code review (see <>)

AUTHORS         top

       The Babeltrace 2 project is the result of hard work by many regular
       developers and occasional contributors.

       The current project maintainer is Jérémie Galarneau

COPYRIGHT         top

       This component class is part of the Babeltrace 2 project.

       Babeltrace is distributed under the MIT license (see

SEE ALSO         top

       babeltrace2-intro(7), babeltrace2-plugin-ctf(7), lttng-relayd(8),

COLOPHON         top

       This page is part of the babeltrace (trace read and write libraries
       and a trace converter) project.  Information about the project can be
       found at ⟨⟩.  If you have a bug
       report for this manual page, send it to
       This page was obtained from the project's upstream Git repository
       ⟨git://⟩ on 2020-02-08.  (At that
       time, the date of the most recent commit that was found in the repos‐
       itory was 2020-02-03.)  If you discover any rendering problems in
       this HTML version of the page, or you believe there is a better or
       more up-to-date source for the page, or you have corrections or
       improvements to the information in this COLOPHON (which is not part
       of the original manual page), send a mail to


Pages that refer to this page: babeltrace2(1)babeltrace2-convert(1)babeltrace2-plugin-ctf(7)