A method for implementing topic priority in airborne networks

Abstract

This invention discloses a data distribution method for implementing topic priority in an airborne network. The method categorizes topic data in the airborne network according to attribute characteristics, determines the priority of each category, and establishes an information channel between any nodes for each priority level. The method configures the priority of each topic, and during the discovery of topic endpoints in the data distribution service, topics are matched, and information channels of corresponding priorities are selected according to the topic's priority attributes to establish routing relationships between topics. When performing topic distribution, the data is distributed to the corresponding topic subscribers according to the established topic routing relationships. This invention utilizes information channel priority attributes to enable topics of different priorities to establish message channels or virtual link routes with different priority attributes, thereby providing differentiated data distribution services based on topic priority settings.

Description

Technical Field

[0001] This invention relates to the field of data transmission technology, and more specifically to a data distribution method for implementing topic priority in an airborne network. Background Technology

[0002] Data Distribution Service (DDS) is a distributed data transmission middleware technology with rich QoS policy support. It can meet the requirements of publish / subscribe mode for information interaction, as well as real-time and dynamic flexibility in an IP network and data-centric architecture. It effectively realizes loose coupling between related systems, enabling application systems to adapt to dynamic scalability, interoperability and portability in distributed and heterogeneous environments.

[0003] For airborne avionics systems, real-time deterministic airborne data exchange networks, such as FC-AE (Fibre Channel Avionics Environment) and AFDX (Avionics Full Duplex Switched Ethernet), are currently widely used. Their statically deterministic information channel configuration improves the real-time nature and determinism of information exchange and enables differentiated services on information channels with different attributes. However, this also reduces the system's scalability and the flexibility of information exchange. Adapting data distribution services to airborne networks allows them to retain traditional advantages while meeting the data communication and interoperability requirements of Distributed Integrated Modular Avionics Systems (DIMA), thereby enhancing the system's scalability and the flexibility of information exchange to some extent.

[0004] However, the DDS specification does not define how DDS middleware should handle topic data with different priorities, making it generally difficult or impossible to differentiate between high-priority and low-priority data. The corresponding transport priority QoS policy (DDS_TransportPriorityQosPolicy) is optional, only allowing different priorities to be specified for data sent by DDS_DataWriter. For the TCP / IP transport protocol stack, the priority set in the transport priority policy is used to set the TOS (Type of Service) bit in the IPv4 header used by DDS_DataWriter to send topic data; its effectiveness depends on the execution platform and network switching equipment. For commonly used airborne network protocols, the general approach to data distribution services is to configure fixed message channels or virtual links between nodes (i.e., information channels metatrafficMulticastLocator and metatrafficUnicastLocator for discovery communication, and defaultUnicastLocator for user communication; where metatrafficMulticastLocator is used for domain participant discovery, and metatrafficUnicastLocator is used for topic endpoint discovery, and metatrafficUnicastLocator and defaultUnicastLocator share the same information channel), respectively to implement dynamic discovery routing for topic endpoints and data routing for user topic endpoints. Fixed message channels or virtual links have fixed priority attributes and cannot provide differentiated deterministic and real-time distribution services for topic data with different priority attributes.

[0005] See Figure 1 The general method for implementing data distribution services in the airborne network shown pre-configures two fixed information channels between any nodes: the metatrafficMulticastLocator (ICH_MTM) for domain participant discovery, the metatrafficUnicastLocator (ICH_MTU) for topic endpoint discovery, and the defaultUnicastLocator (ICH_DU) for user topic data transmission. ICH_MTU and ICH_DU share the same information channel. Since all user topic data between two defined nodes shares the same information channel routing relationship, it is impossible to achieve topic-based data distribution according to priority. Summary of the Invention

[0006] Given that traditional data distribution methods in airborne networks cannot provide differentiated deterministic and real-time services for topic data with different priority attributes, the purpose of this invention is to provide a data distribution method for topic priority in airborne networks, which retains the functionality of data distribution services in airborne networks while solving the problem of differentiated services for topic data with different priorities.

[0007] The objective of this invention is achieved through the following technical solution:

[0008] A method for implementing topic-priority data distribution in an airborne network includes the following steps:

[0009] Step 1: Classify the subject data of the airborne network according to attribute characteristics, determine the priority of each category of subject, and establish an information channel between any nodes for each priority.

[0010] Step 2: Configure the priority of each topic. During the discovery of topic endpoints in the data distribution service, topics are matched and information channels with corresponding priorities are selected according to the topic's priority attributes to establish routing relationships between topics.

[0011] Step 3: When performing topic distribution, the topic is distributed to the corresponding topic subscribers according to the established topic routing relationship.

[0012] Preferably, in step two, matching topics and selecting information channels with corresponding priorities according to the topic's priority attributes to establish routing relationships between topics includes the following steps:

[0013] Local nodes periodically publish data for the built-in topic "DCPSParticipant" to all external nodes through the information channel routing of the built-in topic "DCPSParticipant". The "DCPSParticipant" contains the information channels used by the node to publish the built-in topics "DCPSSubscription" and "DCPSPublication" as well as the information channels for user topics of different priorities.

[0014] Upon receiving the built-in topic "DCPSParticipant" data published periodically by a new external node, a receiving thread is created for the information channel to publish the built-in topics "DCPSSubscription" and "DCPSPublication" data to the new external node by parsing the built-in topic "DCPSParticipant" data. After obtaining the relevant information of the topics published and subscribed by the external node users, a compatibility check is performed on the topic type, priority type, and QoS policy with the local user subscribed and published topics.

[0015] For external node users publishing topics that match, the GUID of the topic's DDS_DataWriter is added to the subscription matching relationship database. Based on the priority of the user's topic, the corresponding information channel of the external node is selected and added, along with the GUID of the topic's DDS_DataWriter, to the subscription routing relationship database of the topic's corresponding local DDS_DataReader. The information channel is then added to the thread receiving data from the external node. For external node users subscribing to topics that match, the GUID of the topic's DDS_DataReader is added to the publishing matching relationship database. Based on the priority of the topic, the corresponding information channel of the local node is selected and added, along with the GUID of the topic's DDS_DataReader, to the publishing routing relationship database of the topic's corresponding local DDS_DataWriter.

[0016] Preferably, in step three, when distributing topic data, the DDS_DataWriter first queries the publication matching relationship database of the topic to obtain the GUID of the corresponding matching DDS_DataReader; then, it queries the routing relationship of the DDS_DataReader in the publication routing relationship database of the DDS_DataWriter to obtain its receiving information channel, and publishes the DDS data frame containing the topic data through the information channel.

[0017] Preferably, in step three, the subscriber's subscription process is as follows: The DDS topic data receiving thread restricts the reception of topic data from the information channels involved in the subscription routing table. By judging the conformity of the topic data and parsing the GUID of the topic publisher DDS_DataWriter in the data frame, it queries the subscription matching relationship library and routing relationship library of the corresponding DDS_DataReader for the local subscription topic. Finally, it passes the effective payload of the topic data to the corresponding DDS_DataReader and then provides it to the user through notification or passive query.

[0018] The beneficial effects of this invention are as follows:

[0019] In airborne networks, by utilizing the priority attributes of message channels or virtual links, different priority topics can be routed through message channels or virtual links with different priority attributes, thereby enabling differentiated data distribution services based on topic priority settings. Attached Figure Description

[0020] Figure 1 A schematic diagram illustrating a general method for allocating information channels for data distribution services.

[0021] Figure 2 A schematic diagram illustrating the information channel allocation method for implementing topic priority data distribution services.

[0022] Figure 3 A flowchart illustrating the process of topic discovery and route matching.

[0023] Figure 4 A flowchart illustrating the process of distributing topic data.

[0024] Figure 5 A flowchart illustrating the process of subscribing to topic data. Detailed Implementation

[0025] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments.

[0026] This embodiment illustrates a data distribution method for implementing topic priority in an airborne network, which mainly includes the following steps:

[0027] Step 1: Classify the subject data of the airborne network according to attribute characteristics, determine the priority of each category of subjects, and then proceed as follows: Figure 2 As shown, an information channel is established between any nodes for each priority level (for simplicity, this embodiment uniformly defines message transmission channel and virtual link as information channel, represented by the letters ICH).

[0028] As an example, topic data includes DDS's built-in topics "DCPSParticipant", "DCPSSubscription", and "DCPSPublication", as well as user topics, and is divided into the following four types:

[0029] 1) Emergency topic data;

[0030] 2) Event topic data;

[0031] 3) Periodic theme data;

[0032] 4) Data block topic data;

[0033] The corresponding information channel ICH and priority are assigned as follows:

[0034] 1) Emergency information channel, with a priority level of 0;

[0035] 2) Event information channel, with a priority level of 1;

[0036] 3) Periodic information channel, with a priority level of 2;

[0037] 4) Data block information channel, with a corresponding priority level of 3;

[0038] 0 has the highest priority, and the larger the number, the lower the priority.

[0039] Step 2: Configure the priority of each topic through the transmission priority QoS policy. During the data distribution service topic endpoint discovery process, the topics are matched and the information channels with the corresponding priorities are selected according to the topic priority attributes to establish the routing relationship between topics.

[0040] The built-in topic “DCPSParticipant” corresponds to periodic data with a priority of 2 and an information channel identifier of ICH_MTM_S(2), used for domain participant discovery. The built-in topics “DCPSSubscription” and “DCPSPublication” correspond to event data with a priority of 1 and an information channel identifier of ICH_MTU_SD(1), used for topic endpoint discovery. The data types of user topics are classified according to type, and the user can choose the corresponding priority. During topic discovery and route matching, the user selects the corresponding level of information channel to distribute data. The information channel identifiers are ICH_DU_SD(0), ICH_DU_SD(1), ICH_DU_SD(2), and ICH_DU_SD(3), used for user topic data distribution. The letter “S” indicates the source node number, and the letter “D” indicates the destination node number. The built-in topics “DCPSSubscription” and “DCPSPublication” share the same information channel with the event type user topics with a priority of 1, identified as ICH_MTU / DU_SD(1).

[0041] See Figure 3 The described topic data discovery and matching route establishment process includes the following steps:

[0042] The local and external node publishing channels discovered by domain participants adopt a pre-configured multicast channel method. Local node A periodically publishes data of the built-in topic "DCPSParticipant" to all external nodes through the information channel route ICH_MTM_A(2) of the built-in topic "DCPSParticipant". The "DCPSParticipant" data contains the information channel ICH_MTU used by the node to publish the built-in topics "DCPSSubscription" and "DCPSPublication" data and the information channel ICH_DU of user topics with different priorities.

[0043] After receiving the topic "DCPSParticipant" data published by the new external node X period through the information channel ICH_MTM_X(2), the receiving thread of the information channel ICH_MTU_XA(1) for the new external node to publish the built-in topic "DCPSSubscription" and "DCPSPublication" data is created by parsing the built-in topic "DCPSParticipant" data. After obtaining the relevant information of the external node's published topic and subscribed topic, the compatibility check of topic type, priority type and QoS policy with the local subscribed topic and published topic is performed. For a matching external node publishing a topic, the GUID of the topic DDS_DataWriter is added to the subscription matching relationship database. Based on the priority n of the user topic, the corresponding ICH_DU_XA(n) information channel of the external node is selected and added to the subscription routing relationship database of the topic's local DDS_DataReader along with the GUID of the topic DDS_DataWriter. The ICH_DU_XA(n) information channel is also added to the thread receiving data from the external node. For a matching external node subscribing to a topic, the GUID of the topic DDS_DataReader is added to the publishing matching relationship database. Based on the priority n of the topic, the corresponding ICH_DU_AX(n) information channel of the local node is selected and added to the publishing routing relationship database of the topic's local DDS_DataWriter along with the GUID of the topic DDS_DataReader.

[0044] Step 3: When performing topic distribution, the topic is distributed to the corresponding topic subscribers according to the established topic routing relationship.

[0045] Figure 4 The process of topic data distribution is described. Users execute the data distribution process for a topic through the topic's DDS_DataWriter. The DDS_DataWriter first queries the topic's publishing matching database to obtain the GUID of the corresponding matching DDS_DataReader; then, it queries the DDS_DataReader's routing relationship in the DDS_DataWriter's publishing routing database to obtain its receiving information channel ICH_DU_AX(n), and publishes the DDS data frame containing the topic's data through this information channel.

[0046] Figure 5The process of subscribing to topic data is described. The DDS topic data receiving thread limits the data received to the information channels involved in the routing table. By judging the data conformity and parsing the GUID of the topic publisher DDS_DataWriter in the data frame, it queries the subscription matching relation library and subscription routing relation library of the corresponding DDS_DataReader for the subscribed topic. Finally, it passes the effective payload of the topic data to the corresponding DDS_DataReader and then provides it to the user through notification or passive query.

[0047] It is understood that those skilled in the art can make equivalent substitutions or modifications to the technical solution and inventive concept of the present invention, and all such substitutions or modifications should fall within the protection scope of the appended claims.

Claims

1. A data distribution method for implementing topic priority in an airborne network, characterized in that... Includes the following steps: Step 1: Classify the subject data of the airborne network according to attribute characteristics, determine the priority of each category of subject, and establish an information channel between any nodes for each priority. Step 2: Configure the priority of each topic. During the data distribution service topic endpoint discovery process, topics are matched and information channels with corresponding priorities are selected according to the topic's priority attributes to establish routing relationships between topics. This includes the following steps: Local nodes periodically publish data on the built-in topic "DCPSParticipant" to all external nodes through the information channel of the built-in topic "DCPSParticipant"; "DCPSParticipant" contains the information channels used by the node to publish data on the built-in topics "DCPSSubscription" and "DCPSPublication" and the information channels of user topics with different priorities; Upon receiving the new external node's periodically published built-in topic "DCPSParticipant", the system parses the built-in topic "DCPSParticipant" data and creates a receiving thread for the information channel that publishes the built-in topics "DCPSSubscription" and "DCPSPublication" data for the new external node. After obtaining the relevant information of the external node's published and subscribed topics, the system performs compatibility checks on topic type, priority type, and QoS policy with the local subscribed and published topics. For external nodes that publish topics that match, the GUID of the topic's DDS_DataWriter is added to the subscription matching relationship database. Based on the user topic's priority, the corresponding information channel for the external node is selected and added, along with the GUID of the topic's DDS_DataWriter, to the subscription routing relationship database of the topic's corresponding local DDS_DataReader. The information channel is then added to the thread receiving data from the external node. For external nodes that subscribe to topics that match, the GUID of the topic's DDS_DataReader is added to the publish matching relationship database. Based on the topic's priority, the corresponding information channel for the local node is selected and added, along with the GUID of the topic's DDS_DataReader, to the publish routing relationship database of the topic's corresponding local DDS_DataWriter. Step 3: When performing topic distribution, the topic is distributed to the corresponding topic subscribers according to the established topic routing relationship.

2. The data distribution method for implementing topic priority in an airborne network according to claim 1, characterized in that... In step three, when distributing topic data, DDS_DataWriter first queries the topic's publishing matching relationship database to obtain the GUID of the corresponding matching DDS_DataReader; then, it queries the DDS_DataReader's routing relationship in the DDS_DataWriter's publishing routing relationship database to obtain its receiving information channel, and publishes the DDS data frame containing the topic data through this information channel.

3. The data distribution method for implementing topic priority in an airborne network according to claim 1, characterized in that... In step three, the subscription process for subscribers is as follows: The DDS topic data receiving thread restricts the reception of topic data from the information channels involved in the subscription routing table. By judging the conformity of the topic data and parsing the GUID of the topic publisher DDS_DataWriter in the data frame, it queries the subscription matching relationship database and subscription routing relationship database of the corresponding DDS_DataReader for the subscribed topic locally. Finally, it passes the effective payload of the topic data to the corresponding DDS_DataReader and then provides it to the user through notification or passive query.

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