15.3.2.2. 创建实体并加载静态发现 XML 文件

在创建实体时，本地的写入器/读取器属性必须与通过远程实体加载的静态发现 XML 文件中定义的属性匹配。

发布者 (PUBLISHER)

C++代码示例

// Participant configuration
DomainParticipantQos participant_qos;
participant_qos.name("HelloWorldPublisher");
participant_qos.wire_protocol().builtin.discovery_config.use_SIMPLE_EndpointDiscoveryProtocol = false;
participant_qos.wire_protocol().builtin.discovery_config.use_STATIC_EndpointDiscoveryProtocol = true;
participant_qos.wire_protocol().builtin.discovery_config.static_edp_xml_config("HelloWorldSubscriber.xml");

// DataWriter configuration
DataWriterQos writer_qos;
writer_qos.endpoint().user_defined_id = 1;
writer_qos.endpoint().entity_id = 2;

// Create the DomainParticipant
DomainParticipant* participant =
        DomainParticipantFactory::get_instance()->create_participant(0, participant_qos);
if (nullptr == participant)
{
    // Error handling
    return;
}

// Create the Publisher
Publisher* publisher =
        participant->create_publisher(PUBLISHER_QOS_DEFAULT);
if (nullptr == publisher)
{
    // Error handling
    return;
}

// Create the Topic with the appropriate name and data type
std::string topic_name = "HelloWorldTopic";
std::string data_type = "HelloWorld";
Topic* topic =
        participant->create_topic(topic_name, data_type, TOPIC_QOS_DEFAULT);
if (nullptr == topic)
{
    // Error handling
    return;
}

// Create the DataWriter
DataWriter* writer =
        publisher->create_datawriter(topic, DATAWRITER_QOS_DEFAULT);
if (nullptr == writer)
{
    // Error handling
    return;
}

XML配置文件

<?xml version="1.0" encoding="UTF-8" ?>
<profiles xmlns="http://www.eprosima.com">
    <participant profile_name="participant_profile_static_pub">
        <rtps>
            <name>HelloWorldPublisher</name>
            <builtin>
                <discovery_config>
                    <EDP>STATIC</EDP>
                    <static_edp_xml_config>file://HelloWorldSubscriber.xml</static_edp_xml_config>
                </discovery_config>
            </builtin>
        </rtps>
    </participant>

    <data_writer profile_name="uc_publisher_xml_conf_static_discovery">
        <userDefinedID>1</userDefinedID>
        <entityID>2</entityID>
    </data_writer>
</profiles>

订阅者 (SUBSCRIBER)

C++代码示例

// Participant configuration
DomainParticipantQos participant_qos;
participant_qos.name("HelloWorldSubscriber");
participant_qos.wire_protocol().builtin.discovery_config.use_SIMPLE_EndpointDiscoveryProtocol = false;
participant_qos.wire_protocol().builtin.discovery_config.use_STATIC_EndpointDiscoveryProtocol = true;
participant_qos.wire_protocol().builtin.discovery_config.static_edp_xml_config("HelloWorldPublisher.xml");

// DataWriter configuration
DataWriterQos writer_qos;
writer_qos.endpoint().user_defined_id = 3;
writer_qos.endpoint().entity_id = 4;

// Create the DomainParticipant
DomainParticipant* participant =
        DomainParticipantFactory::get_instance()->create_participant(0, participant_qos);
if (nullptr == participant)
{
    // Error handling
    return;
}

// Create the Subscriber
Subscriber* subscriber =
        participant->create_subscriber(SUBSCRIBER_QOS_DEFAULT);
if (nullptr == subscriber)
{
    // Error handling
    return;
}

// Create the Topic with the appropriate name and data type
std::string topic_name = "HelloWorldTopic";
std::string data_type = "HelloWorld";
Topic* topic =
        participant->create_topic(topic_name, data_type, TOPIC_QOS_DEFAULT);
if (nullptr == topic)
{
    // Error handling
    return;
}

// Create the DataReader
DataReader* reader =
        subscriber->create_datareader(topic, DATAREADER_QOS_DEFAULT);
if (nullptr == reader)
{
    // Error handling
    return;
}

XML配置文件

<?xml version="1.0" encoding="UTF-8" ?>
<profiles xmlns="http://www.eprosima.com">
    <participant profile_name="participant_profile_static_sub">
        <rtps>
            <name>HelloWorldSubscriber</name>
            <builtin>
                <discovery_config>
                    <static_edp_xml_config>file://HelloWorldPublisher.xml</static_edp_xml_config>
                </discovery_config>
            </builtin>
        </rtps>
    </participant>

    <data_reader profile_name="uc_subscriber_xml_conf_static_discovery">
        <userDefinedID>3</userDefinedID>
        <entityID>4</entityID>
    </data_reader>
</profiles>

总结

在这段代码中，创建了一个发布者和一个订阅者，每个参与者都根据静态发现机制（使用指定的 XML 配置文件）进行配置。发布者和订阅者通过匹配的 ID 和名称建立连接，允许数据在它们之间进行交换。


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