babeltrace-source.ctf.lttng-live(7)
===================================
:manpagetype: component class
:revdate: 5 October 2017


NAME
----
babeltrace-source.ctf.lttng-live - Babeltrace's LTTng live source
component class


DESCRIPTION
-----------
The Babeltrace compcls:source.ctf.lttng-live source component class,
provided by the man:babeltrace-plugin-ctf(7) plugin, once instantiated,
connects to a local or remote http://lttng.org/[LTTng] relay daemon and
emits the received notifications on its output ports. More information
about LTTng live is available in the
http://lttng.org/docs/#doc-lttng-live[LTTng Documentation].

A compcls:source.ctf.lttng-live component handles the notifications 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 param:url
parameter.

For each trace, the component creates one output port per effective data
stream. The name of a data stream output port is `stream-` followed by
its unique LTTng live ID within the tracing session.

The component names each trace `[HOSTNAME/]SESSION/PATH`, with:

`HOSTNAME`::
    Value of the trace's `hostname` environment constant. If this
    environment constant does not exist, or if its value is not a
    string, then this part is omitted.

`SESSION`::
    Tracing session name.

`PATH`::
    Other path elements up to the trace directory containing the
    `metadata` file from the LTTng relay daemon's point of view.
    For example:
+
----
kernel
----
+
----
ust/uid/1000/64-bit
----

For example:

----
myhost/auto-20150909-223909/ust/uid/1000/64-bit
----

A compcls:source.ctf.lttng-live never blocks: it asks the downstream
component to try again later instead.


INITIALIZATION PARAMETERS
-------------------------
param:url='URL' (string, mandatory)::
    The URL to use to connect to the LTTng relay daemon. The format
    of 'URL' is:
+
--
[verse]
net[4]://__RDHOST__[:__RDPORT__]/host/__TGTHOST__/__SESSION__

'RDHOST'::
    LTTng relay daemon's host name or IP address.

'RDPORT'::
    LTTng relay daemon's listening port. If not specified, the default
    port, 5344, is used.

'TGTHOST'::
    Target's host name or IP address.

'SESSION'::
    Name of the LTTng tracing session from which to receive data.
--


PORTS
-----
Output
~~~~~~
When you create the component, its only output port is `no-stream`. This
port exists as long as there is no data stream output port. The port
only asks the downstream component to try again later.

For each received LTTng trace, the component creates one output port for
each effective data stream. The name of a data stream output port is
`stream-ID`, where `ID` is a unique LTTng live ID within the tracing
session.


QUERY OBJECTS
-------------
`sessions`
~~~~~~~~~~
You can query the `sessions` object to get a list of available LTTng
live tracing sessions for a given LTTng relay daemon URL.

Parameters:

`url` (string, mandatory)::
    The URL to use to connect to the LTTng relay daemon. The format
    of 'URL' is:
+
--
[verse]
net[4]://__RDHOST__[:__RDPORT__]

'RDHOST'::
    LTTng relay daemon's host name or IP address.

'RDPORT'::
    LTTng relay daemon's listening port. If not specified, the default
    port, 5344, is used.
--

Returned object (array of maps, one element for each tracing session):

`url` (string)::
    URL to use as the param:url parameter to connect to the same LTTng
    relay daemon and receive data from this tracing session.

`target-hostname` (string)::
    Hostname of the tracing session. This is not necessarily the
    relay daemon's hostname.

`session-name` (string)::
    Tracing session's name.

`timer-us` (integer)::
    Tracing session's configured live timer (µs)
    (see man:lttng-create(1)).

`stream-count` (integer)::
    Current number of streams in this tracing sessions, including the
    metadata streams.

`client-count` (integer)::
    Current number of LTTng live clients connected to the relay daemon
    to receive data from this tracing session.


LIMITATIONS
-----------
A compcls:source.ctf.lttng-live component only accepts a connection
to one of its output port if all its output ports are connected to the
input ports of the same downstream component.


ENVIRONMENT VARIABLES
---------------------
include::common-ctf-plugin-env.txt[]


Component class
~~~~~~~~~~~~~~~
include::common-common-compat-env.txt[]

`BABELTRACE_SRC_CTF_LTTNG_LIVE_LOG_LEVEL`::
    Component class's log level. The available values are the
    same as for the manopt:babeltrace(1):--log-level option of
    man:babeltrace(1).


include::common-footer.txt[]


SEE ALSO
--------
man:babeltrace-plugin-ctf(7),
man:babeltrace-intro(7),
man:lttng-relayd(8),
man:lttng-create(1)