= babeltrace2-query-babeltrace.support-info(7)
:manpagetype: query object
:revdate: 14 September 2019


== NAME

babeltrace2-query-babeltrace.support-info - Babeltrace 2's support info
query object


== DESCRIPTION

The `babeltrace.support-info` 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 nlparam:inputs initialization parameter (array of strings).

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


== PARAMETERS

param:input='INPUT' vtype:[string]::
    Check input 'INPUT'.
+
Depending on the param:type parameter, this is a simple string, a file
path, or a directory path.

param:type=(`string` | `file` | `directory`) vtype:[string]::
    Input type, one of:
+
--
`string`::
    param:input parameter is a simple string.

`file`::
    param:input parameter is a file path.

`directory`::
    param: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 (param:input).
--


== RESULT OBJECT

The result object can be one of:

* [[simple-real]]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:

qres:group='GROUP-NAME' vtype:[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.

qres:weight='WEIGHT' vtype:[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,simple real value>>.


== EXAMPLES

=== Query parameters

.String input.
====
[source,yaml]
----
input: net://relayd177/host/node23/active
type: string
----
====

.File path input.
====
[source,yaml]
----
input: /home/user/traces/2019-08-26/quad.tr
type: file
----
====

=== Result object

.Simple weight (unique group).
====
[source,yaml]
----
0.5
----
====

.Weight and specific group.
====
[source,yaml]
----
group: 63a4b7e5-37f0-4254-a048-a0cff9e5b761
weight: 0.75
----
====

.Weight within a map (unique group).
====
[source,yaml]
----
weight: 0.6
----
====


include::common-footer.txt[]


== SEE ALSO

man:babeltrace2-intro(7),
man:babeltrace2-query(1),
man:babeltrace2-convert(1)
