4.1.3. Readers

Readers is a command that retrieves information of the DataReaders currently active in the network.

4.1.3.1. Key-words

These are the key-words recognize as this command: reader readers datareader datareaders subscription subscriptions r R.

4.1.3.2. Arguments

Readers command support 0 or 1 argument:

4.1.3.2.1. No argument

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

4.1.3.2.2. Verbose

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

4.1.3.2.3. Guid

This argument requires a string with Guid format. This command queries the database for a single DataReader 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.

4.1.3.3. Output Format

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

4.1.3.3.1. Simple Reader info

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

4.1.3.3.2. Verbose Reader info

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

4.1.3.4. Example

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

This would be the expected output for the command readers:

- 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 readers 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 readers 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