4.3.1. Filter

Filter is a command that adds filters to restrict the spied information based on user-defined criteria.

4.3.1.1. Key-words

These are the key-words recognize as this command: filter filters f F.

4.3.1.2. Categories

Defines a category filter used to restrict the spied information. Each category can include one or more filter strings, and information is printed if it matches any of the strings within the category.

The current categories supported by the filter command are:

  • partitions

  • topic

4.3.1.3. Arguments

Filter command supports from 0 to 4 arguments:

4.3.1.3.1. No argument

When no arguments are given to this command, the information shown is a list with all the list of filters added during runtime.

The information shown is divided into lists, one for each category added at runtime. For each list, the added filters are displayed.

The output format is as follows: Output Format.

4.3.1.3.2. 1 argument: <clear/remove>

  • clear: This argument clear all the list of categories added to the filters.

  • remove: This argument delete all the list of categories added to the filters.

4.3.1.3.3. 2 argument: <clear/remove> <partitions/topic>

  • clear: This argument clear the list partitions/topic added to the filters.

  • remove: This argument delete the list partitions/topic from the filters.

4.3.1.3.4. 3 argument: <add/remove> <partitions/topic> <filter_str/topic_name>

  • add partitions/topic: This argument add filter_str to partitions filter list.

  • remove partitions: This argument delete filter_str from partitions filter list.

  • remove topic: This argument delete the filter of the topic topic_name.

4.3.1.3.5. 4 argument: <set> topic <topic_name> <filter_str>

  • set: This argument set filter_str to topic topic_name filter list.

4.3.1.4. Output Format

The filters information is retrieved with the following format:

Filter lists (1)

  category_1 (2):
    - filter_str_1
    - filter_str_2

  category_2 (2):
    - filter_str_1

4.3.1.5. Example

Let’s assume we have a DDS network where a ShapesDemo applications is running with the following two DataWriters:

  • Circle (partition A) [key_topic_value: color = RED]

  • Square (partitions B and C) [key_topic_value: color = BLUE]

This would be the expected output for the following commands:

  • filter add partitions A:

Nothing, the filter “A” is added to the category “partitions”.

  • filters:

--------
Filters:
--------

  Topic:

  Partitions:
    - A

  • topics vv:

- name: Circle
type: ShapeType
datawriters:
  - 01.0f.72.e4.86.f3.9b.a0.00.00.00.00|0.0.6.2 [A]
rate: 12.5391 Hz
dynamic_type_discovered: true

  • filter add partitions B:

Nothing, the filter “B” is added to the category “partitions”.

  • filters:

--------
Filters:
--------

  Topic:

  Partitions:
    - A
    - B

  • topics vv:

- name: Circle
  type: ShapeType
  datawriters:
    - 01.0f.72.e4.86.f3.9b.a0.00.00.00.00|0.0.6.2 [A]
  rate: 12.5391 Hz
  dynamic_type_discovered: true
- name: Square
  type: ShapeType
  datawriters:
    - 01.0f.72.e4.86.f3.9b.a0.00.00.00.00|0.0.7.2 [B|C]
  rate: 12.5391 Hz
  dynamic_type_discovered: true

  • f set topic Circle "color = 'BLUE'"

Nothing, the filter “color = ‘BLUE’” is added to the topic filter in the topic_name “Circle”.

  • f set topic Square "color = 'BLUE'"

Nothing, the filter “color = ‘BLUE’” is added to the topic filter in the topic_name “Square”.

  • filters

--------
Filters:
--------

  Topic:
    Circle: "color = 'BLUE'"
    Square: "color = 'BLUE'"

  Partitions:
    - A
    - B

  • echo all

Prints only the information of the topic Square, (the topic Circle is filtered because the key value “color” is “RED”)

---

topic: Square [ShapeType]
writer: 01.0f.9f.6d.b8.ca.6e.52.00.00.00.00|0.0.3.2
partitions: ""
timestamp: 2026/01/16 12:03:14
data:
---
{
    "color": "BLUE",
    "shapesize": 30,
    "x": 81,
    "y": 35
}
---

topic: Square [ShapeType]
writer: 01.0f.9f.6d.b8.ca.6e.52.00.00.00.00|0.0.3.2
partitions: ""
timestamp: 2026/01/16 12:03:14
data:
---
{
    "color": "BLUE",
    "shapesize": 30,
    "x": 87,
    "y": 37
}
---

  • filter remove partitions B:

Nothing, the filter “B” is removed from the category “partitions”.

  • topics vv:

- name: Circle
type: ShapeType
datawriters:
  - 01.0f.72.e4.86.f3.9b.a0.00.00.00.00|0.0.6.2 [A]
rate: 12.5391 Hz
dynamic_type_discovered: true

  • filters:

Filter lists (1)

partitions (1):
  - A

  • filter clear:

  • filters:

--------
Filters:
--------

  Topic:

  Partitions: