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BABELTRACE2-QUERY-(7) Babeltrace 2 manual BABELTRACE2-QUERY-(7) - Babeltrace 2's support info query object

The Babeltrace 2 query object indicates, for a given source component class, whether or not its instance can handle a given input, and if so, what’s the confidence of this support.

Said input can be a simple string, an existing file path, or an existing directory path. Components which expect some form of URI can handle a string input, while components which expect an existing file or directory can handle a file/directory path input.

When the source component class’s query method replies that its component can handle a given input, it can also specify the name of a group in which to put that input. All the inputs of a given group, for a given component class, should be passed when instantiating the component class as its inputs initialization parameter (array of strings).

The babeltrace2-convert(1) command queries this object from specific source component classes to find the most appropriate for a given non-option argument.

input=INPUT [string]
Check input INPUT.

Depending on the type parameter, this is a simple string, a file path, or a directory path.

type=(string | file | directory) [string]

Input type, one of:


input parameter is a simple string.


input parameter is a file path.


input parameter is a directory path.

It is expected that the query method does not recurse into this directory: the result object indicates whether or not the component class supports this specific directory (input).

The result object can be one of:

•A simple real value which is the weight, between 0 and 1, of the support by the component class for the given input.

A weight of 0 means the input is unsupported while a weight of 1 means it’s fully supported. Any value in between shows how confident the component class is about the support of the given input.

•A map with a weight and an optional group name.

When it’s a map, the expected entries are:

group=GROUP-NAME [optional string]

Put the given input into a group named GROUP-NAME for this component class.

If this entry is missing, then the given input gets its own, unique group.

weight=WEIGHT [real]

Weight, between 0 and 1, of the support by the component class for the given input.

The semantics are the same as when the result object is a simple real value.

Example 1. String input.

input: net://relayd177/host/node23/active
type: string

Example 2. File path input.

input: /home/user/traces/2019-08-26/
type: file

Example 3. Simple weight (unique group).


Example 4. Weight and specific group.

group: 63a4b7e5-37f0-4254-a048-a0cff9e5b761
weight: 0.75

Example 5. Weight within a map (unique group).

weight: 0.6

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

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

•Babeltrace website (see <>)

•Mailing list (see <>) for support and development:

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

•Bug tracker (see <>)

•Git repository (see <>)

•GitHub project (see <>)

•Continuous integration (see <>)

•Code review (see <>)

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

The current project maintainer is Jérémie Galarneau <>.

This query object is part of the Babeltrace 2 project.

Babeltrace is distributed under the MIT license (see <>).

babeltrace2-intro(7), babeltrace2-query(1), babeltrace2-convert(1)
14 September 2019 Babeltrace 2.0.3