This part will show how to deploy a system using eProsima Micro XRCE-DDS in a real environment.
An example of this can be found in
Previous tutorials are based on all in one examples, that is, examples that create entities, publish or subscribe and then delete the resources. One possible real purpose of this consists in differentiating the logic of creating entities and the actions of publishing and subscribing. It can be done by creating two differents Clients. One in charge of configuring the entities in the Agent, and run possibly once, only for creating the entities at configuration time. And other/s that logs in the same session as the configured Client (sharing the entities) and only publishes or subscribes data.
This way allows creating Clients in a real scenario only with the purpose of sending and receiving data. Related to it, the concept of profile allows building the Client library only with the chosen behavior (only publish or only subscribe, for example). See eProsima Micro XRCE-DDS Client for more information about this.
Next diagram shows an example about how to configure the environment using a configurator client.
The environment contains two Agents (is perfectly possible to use only one Agent too), and two Clients, one for publishing and another for subscribing.
In this state a configurator client is connected to the Agent A with the client key that will be used by the future publisher client (0xAABBCCDD). Once a session is logged in, the configurator client creates all the necessary entities for the publisher client. This implies the creation of participant, topic, publisher, and datawriter entities. These entities have a representation as DDS entities, and can be reached now from the DDS world. That implies that a possible subscriber DDS entity could already be listening topics if it matches with a publisher DDS entity through the DDS world.
Then, the publisher client is connected to the Agent A. This Client logs in session with its Client key (0xAABBCCDD). At that moment, it can use all entities created related to this client key. Because all entities that it used were successfully created by the configurator client, the publisher client can immediately publish to DDS.
Again, the configurator client connects and logs in, this time to Agent B, now with the subscriber’s key (0x11223344). In this case, the entities that the configurator client creates are a participant, a topic, a subscriber, and a datareader. The entities created by the configuraton client will be available until the session is deleted.
Once the subscriber is configured, the subscriber client logs in the Agent B. As all their entities have been created previously, so it only needs to configure the read after login. Once the data request message has been sent, the subscriber will receive the topics from the publisher through the DDS world.