4.1.2. Writers

Writers is a command that retrieves information of the DataWriters currently active in the network.

4.1.2.1. Key-words

These are the key-words recognize as this command: writer writers datawriter datawriters publication publications w W.

4.1.2.2. Arguments

Writers command support 0 or 1 argument:

4.1.2.2.1. No argument

When no arguments are given to this command, the information shown is a list with every DataWriter currently active in the network, giving their :term:<Guid>, the name of their respective DomainParticipants, and the topic name and topic data type name. The output format is as follows: Simple Writer info.

4.1.2.2.2. Verbose

This argument queries for more complete information about each of the DataWriters in the network. It adds information about the QoS. The output got is a list of DataWriters with verbose information. Check the verbose section in order to know which key-words are available for this argument.

4.1.2.2.3. Guid

This argument requires a string with Guid format. This command queries the database for a single DataWriter and retrieves its verbose information. This Guid must exist inside the DDS network.

Note

If you are using eProsima Fast DDS Spy as one-shot application, you will need to put GUID in quotes.

4.1.2.3. Output Format

The writer information is retrieved in 2 formats depending on the verbose option.

4.1.2.3.1. Simple Writer info

guid: <guid>
name: <participant name>
topic: <topic name> [<topic data type name>]

4.1.2.3.2. Verbose Writer info

name: <writer name>
guid: <guid>
topic:
    - <topic name>
    - <topic data type name>
qos:
    - durability: <volatile | transient-local>
    - reliability: <reliable | best-effort>

4.1.2.4. Example

Let’s assume we have a DDS network where 2 ShapesDemo applications are running.

This would be the expected output for the command writers:

- guid: 01.0f.44.59.21.58.14.d2.00.00.00.00|0.0.1.2
  participant: Fast DDS ShapesDemo Participant
  topic: Triangle [ShapeType]
- guid: 01.0f.44.59.da.57.de.ec.00.00.00.00|0.0.6.2
  participant: Fast DDS ShapesDemo Participant
  topic: Circle [ShapeType]
- ...

This would be the expected output for the command writers verbose:

- guid: 01.0f.44.59.21.58.14.d2.00.00.00.00|0.0.1.2
  participant: Fast DDS ShapesDemo Participant
  topic:
    name: Triangle
    type: ShapeType
  qos:
    durability: volatile
    reliability: best-effort
- guid: 01.0f.44.59.da.57.de.ec.00.00.00.00|0.0.6.2
  participant: Fast DDS ShapesDemo Participant
  topic:
    name: Circle
    type: ShapeType
  qos:
    durability: transient-local
    reliability: reliable
- ...

This would be the expected output for the command writers 01.0f.44.59.da.57.de.ec.00.00.00.00|0.0.6.2:

guid: 01.0f.44.59.da.57.de.ec.00.00.00.00|0.0.6.2
participant: Fast DDS ShapesDemo Participant
topic:
  name: Circle
  type: ShapeType
qos:
  durability: transient-local
  reliability: reliable