fastdds:qos profile

fastdds中的domain participant、topic、publisher、subscriber、data writer、data reader均可以设置qos。qos几乎是dds配置的代名词了，所有的配置都在qos中。

设置qos，可以在代码中指定，也可以通过xml格式的配置文件来指定。如下是HistoryQosPolicy的配置方式：

代码：

// This example uses a DataWriter, but it can also be applied to DataReader and Topic entities

DataWriterQos writer_qos;

// The HistoryQosPolicy is constructed with kind = KEEP_LAST and depth = 1 by default

// It is possible to adjust the depth and keep the kind as KEEP_LAST

writer_qos.history().depth = 20;

// Or you can also change the kind to KEEP_ALL (depth will not be used).

writer_qos.history().kind = KEEP_ALL_HISTORY_QOS;

// Use modified QoS in the creation of the corresponding entity

writer_ = publisher_->create_datawriter(topic_, writer_qos);

xml:

<topic>

<historyQos>

<kind>KEEP_LAST</kind> 

<depth>20</depth> 

</historyQos>

</topic>

1participant qos

(1)create_participant

需要传入qos

①如果传入的直接是PARTICIPANT_QOS_DEFAULT，那么如果xml文件中有qos profile设置了is_default_profile为true，则使用xml中的qos；否则使用PARTICIPANT_QOS_DEFAULT。

②如下代码所示，通过PARTICIPANT_QOS_DEFAULT构造了pqos，pqos不做任何修改，内容和PARTICIPANT_QOS_DEFAULT是完全一样的，那么即使xml中有qos profile设置了is_default_profile为true，也不会使用xml中的配置，而是使用pqos的配置。

cpp 复制代码

    DomainParticipantQos pqos = PARTICIPANT_QOS_DEFAULT;
    pqos.name("static_edp_delivery_pub_participant");
    auto factory = DomainParticipantFactory::get_instance();
    if (RETCODE_OK != factory->check_xml_static_discovery(xml_file_name))
    {
        throw std::runtime_error("Error parsing publisher xml file");
    }
    participant_ = factory->create_participant(config.domain, pqos, nullptr, StatusMask::none());

（2）create_participant_with_default_profile

如果xml中有profile配置了is_default_profile为true，则使用xml配置；否则，使用PARTICIPANT_QOS_DEFAULT。

（3）create_participant_with_profile

指定profile名，如果xml不存在该profile，则创建失败。

2topic、subscriber、publisher

创建topic、subscriber、publisher，也有两个创建api：create_xxx，create_xxx_with_profile。

topic、subscriber、publisher均是域参与者的资源，在DomainParticipant中创建。

data writer和data reader也有类似的两个创建的api，data writer属于publisher的资源，data reader属于subscriber的资源。

cpp 复制代码

    /**
     * Create a Publisher in this Participant.
     *
     * @param qos QoS of the Publisher.
     * @param listener Pointer to the listener (default: nullptr)
     * @param mask StatusMask that holds statuses the listener responds to (default: all)
     * @return Pointer to the created Publisher.
     */
    FASTDDS_EXPORTED_API Publisher* create_publisher(
            const PublisherQos& qos,
            PublisherListener* listener = nullptr,
            const StatusMask& mask = StatusMask::all());

    /**
     * Create a Publisher in this Participant.
     *
     * @param profile_name Publisher profile name.
     * @param listener Pointer to the listener (default: nullptr)
     * @param mask StatusMask that holds statuses the listener responds to (default: all)
     * @return Pointer to the created Publisher.
     */
    FASTDDS_EXPORTED_API Publisher* create_publisher_with_profile(
            const std::string& profile_name,
            PublisherListener* listener = nullptr,
            const StatusMask& mask = StatusMask::all());

    /**
     * Create a Subscriber in this Participant.
     *
     * @param qos QoS of the Subscriber.
     * @param listener Pointer to the listener (default: nullptr)
     * @param mask StatusMask that holds statuses the listener responds to (default: all)
     * @return Pointer to the created Subscriber.
     */
    FASTDDS_EXPORTED_API Subscriber* create_subscriber(
            const SubscriberQos& qos,
            SubscriberListener* listener = nullptr,
            const StatusMask& mask = StatusMask::all());

    /**
     * Create a Subscriber in this Participant.
     *
     * @param profile_name Subscriber profile name.
     * @param listener Pointer to the listener (default: nullptr)
     * @param mask StatusMask that holds statuses the listener responds to (default: all)
     * @return Pointer to the created Subscriber.
     */
    FASTDDS_EXPORTED_API Subscriber* create_subscriber_with_profile(
            const std::string& profile_name,
            SubscriberListener* listener = nullptr,
            const StatusMask& mask = StatusMask::all());

    /**
     * Create a Topic in this Participant.
     *
     * @param topic_name Name of the Topic.
     * @param type_name Data type of the Topic.
     * @param qos QoS of the Topic.
     * @param listener Pointer to the listener (default: nullptr)
     * @param mask StatusMask that holds statuses the listener responds to (default: all)
     * @return Pointer to the created Topic.
     */
    FASTDDS_EXPORTED_API Topic* create_topic(
            const std::string& topic_name,
            const std::string& type_name,
            const TopicQos& qos,
            TopicListener* listener = nullptr,
            const StatusMask& mask = StatusMask::all());

    /**
     * Create a Topic in this Participant.
     *
     * @param topic_name Name of the Topic.
     * @param type_name Data type of the Topic.
     * @param profile_name Topic profile name.
     * @param listener Pointer to the listener (default: nullptr)
     * @param mask StatusMask that holds statuses the listener responds to (default: all)
     * @return Pointer to the created Topic.
     */
    FASTDDS_EXPORTED_API Topic* create_topic_with_profile(
            const std::string& topic_name,
            const std::string& type_name,
            const std::string& profile_name,
            TopicListener* listener = nullptr,
            const StatusMask& mask = StatusMask::all());

3判断profile是否存在

在实际开发中，首先判断某个profile是否存在，如果存在则使用该profile，如果不存在，则使用默认qos，可以通过如下api来判断。

get_participant_qos_from_profile(name,qos)

get_publisher_qos_from_profile(name, qos)

get_subscriber_qos_from_profile(name, qos)

get_datawriter_qos_from_profile(name, qos)

get_datareader_qos_from_profile(name, qos)

get_topic_qos_from_profile(name, qos)