A TTE network system design method based on distributed data distribution (DDS)

Abstract

The application discloses a TTE network system design method based on a distributed data distribution DDS, and belongs to the field of network communication.The TTE network system comprises a distributed network DDS middleware, a TTE switching device based on an RTlinux real-time operating system, a TTE terminal system device, and a system backbone network formed by the TTE network.The network mainly comprises one switching node and three terminal device nodes with three redundancies, and the nodes are connected in a star mode.For the TTE switching device, the DDS is used to take charge of the data interaction interface of the service layer, and the service flow application layer only needs to be configured with a publishing / subscription requirement mode, so that the diversified requirement of the TTE network service layer data is met.The application reduces the diversified scheduling requirement of the real-time distribution of the service layer data flow on the basis of meeting the TTE hard real-time, and combines the soft real-time scheduling of the DDS middleware, so as to construct a distributed network architecture which is data-centered, extensible, independent of platform and position, and combines the soft and hard real-time scheduling, and realizes high performance, strong real-time and high reliability.

Description

Technical Field

[0001] This invention relates to the field of network communication technology, and in particular to a TTE network system design method based on Distributed Data Distribution (DDS). Background Technology

[0002] In the history of aviation and aerospace development, architectures have evolved from discrete to integrated to comprehensive. Currently, we are in the stage of advanced comprehensive architecture, where weapons / equipment integrate and transmit highly integrated information from sensing, control, video, diagnostics, and maintenance to achieve rapid transmission, sensing, decision-making, and feedback. This ensures smooth information exchange and collaborative combat capabilities between various pieces of equipment, meeting the needs of future distributed, information-based collaborative operations. Currently popular equipment buses include ARINC429, 1553B, AFDX, 1394B, and FC, but these all have limitations and are often specialized, failing to meet the requirements of advanced, integrated intelligent equipment. Therefore, a new type of Time-Triggered Ethernet (TTE) bus with high-precision time synchronization and the ability to integrate multiple mixed services has emerged. It combines the flexibility and openness of traditional Ethernet with high-precision clock synchronization, deterministic transmission, fault tolerance, and redundancy mechanisms. This maintains good Ethernet interconnectivity while supporting the integrated transmission of multiple mixed services, meeting the needs of next-generation weaponry's integrated and intelligent upgrades / replacements.

[0003] DDS middleware is a lightweight middleware technology that provides real-time information delivery. Currently, information distribution middleware products are widely used in spacecraft, space payload software communication systems, ship control, and military network systems in developed countries.

[0004] The purpose of the DDS specification is to build a "global data bus" into which all nodes in the system can connect. Data publishing / subscription between nodes is accomplished through the DDS standard interface, effectively reducing the coupling between various system components. The DCPS (Data-Centric Publish / Subscribe Model) layer provides the infrastructure for data publishing and is the core of the DDS specification. DDS constructs a scalable, platform-independent distributed network with DCPS capabilities. Summary of the Invention

[0005] The purpose of this invention is to provide a design method for a TTE network system based on Distributed Data Distribution System (DDS) to solve the problems in the background art.

[0006] To address the aforementioned technical problems, this invention provides a TTE network system design method based on Distributed Data Distribution System (DDS). The TTE network system includes a distributed network DDS middleware, an RTlinux real-time operating system, a time-triggered Ethernet switching device, time-triggered Ethernet end-system devices, and a TTE network as the system backbone. The method comprises the following steps:

[0007] Step A: Build a TTE network hardware architecture based on Distributed Data Distribution (DDS). The network hardware architecture mainly consists of three switches and six end systems with triple-redundant optical ports.

[0008] Step B: Port the DDS middleware on the RTlinux real-time operating system to complete the initialization of the DDS communication driver under the TTE network architecture, the registration function for publishing topics, the definition of the TTE network data format to be published, the implementation of the publishing topic function, the registration of the subscription topic processing function and the implementation of the specific processing function.

[0009] Step C: Implement the distributed data distribution service function of the DDS middleware. Combining the characteristics of the TTE network architecture, connect both topic publishers and topic subscribers to the DCPS information database. The DCPS information database obtains their topic information, address naming identifiers, and MAC addresses, and implements the function of retrieving and identifying topic information of topic publishers and subscribers. Finally, it sends the MAC address and TTE service flow data network identifier of the matching topic subscriber to the message publisher and caches the identifiers according to the rules. Alternatively, when the message publisher receives a topic message from a message subscriber, the message subscriber extracts the TTE data packet memory pool naming rule identifier by parsing the packet header, then filters the data packet according to the rule identifier. If it is determined that the message subscriber needs the data, it is stored in the corresponding cache space for further processing.

[0010] Step D: Based on step C, the RTlinux-based real-time operating system with distributed data distribution (DDS) functionality is ported to the TTE terminal system's business CPU, and multi-service data transmission in multi-message mode is completed.

[0011] In one implementation, in step A, the nodes in the network hardware structure are connected in a star topology. To ensure the accuracy of the system time triggering, the system needs to have a time synchronization function and a time synchronization retransmission function.

[0012] In one implementation, in step B, Distributed Data Distribution (DDS) is used for the interaction of service layer data streams in the backbone network. DDS can completely isolate the operating system and network protocol stack. Applications directly use the distributed network DDS middleware to send and receive messages. During service layer data interaction, for time-triggered Ethernet switching devices, the service layer data interaction interface is taken over by DDS. The service flow application layer only needs to configure the publish / subscribe demand method, which largely meets the diverse data needs of the TTE network service layer.

[0013] In one implementation, in step C, the number of topic publishers and topic subscribers can be increased or decreased as needed, and multiple topic subscribers can subscribe to the same topic simultaneously. The protocol used is the TTE network transmission protocol. If a topic subscriber needs to resynchronize the overall network time for some reason, the distributed network DDS middleware will cache this message until the time synchronization is completed and the time synchronization accuracy is met. Only then will the topic subscriber reconnect to the system and send the message.

[0014] In one implementation, step D, multi-service data transmission and reception in multi-message mode, includes:

[0015] Message subscribers need to call relevant functions of the RTlinux real-time operating system to complete system initialization, network configuration parameter initialization, topic subscription / publishing configuration, and send queue and receive queue configuration, and complete the configuration and initialization of data sending and receiving. The entire system hardware network interface uses optical ports as the transmission medium.

[0016] The underlying data in the system is ultimately sent and received through the TTE switch. The TTE switch has the main functions of multi-message to multi-service interaction and TTE data exchange scheduling.

[0017] The message publisher allocates address space based on the DDS message naming identifier and stores it in the TTE memory scheduling pool. Then, by adding TTE-related transmission protocols, the TTE switch is used to forward the data. The message receiver then parses and processes the data based on the message naming identifier.

[0018] In the TTE network system design method based on Distributed Data Distribution System (DDS) provided in this invention, the service layer data interaction interface is taken over by DDS, and the service flow application layer only needs to configure the publish / subscribe demand mode, which largely meets the diverse data needs of the TTE network service layer. This invention is a method that, based on the hard real-time requirements of time-triggered Ethernet networks, combines the soft real-time scheduling of DDS middleware, greatly reducing the diverse scheduling requirements for real-time distribution of service layer data flows. It can construct a data-centric, scalable, platform- and location-independent distributed network architecture that combines hard and soft real-time scheduling, meeting the requirements of high performance, strong real-time performance, and high reliability. Attached Figure Description

[0019] Figure 1 This is a diagram of the TTE network topology;

[0020] Figure 2 It is a DDS publish / subscribe model;

[0021] Figure 3 This is a flowchart of the DDS publisher process;

[0022] Figure 4 This is a flowchart of the DDS receiver process;

[0023] Figure 5 This is a diagram illustrating the principle of multi-message data transmission.

[0024] Figure 6 This is an overall block diagram of data transmission. Detailed Implementation

[0025] The following detailed description, in conjunction with the accompanying drawings and specific embodiments, provides a further detailed explanation of the TTE network system design method based on Distributed Data Distribution (DDS) proposed in this invention. The advantages and features of this invention will become clearer from the following description. It should be noted that the accompanying drawings are all in a very simplified form and use non-precise proportions, and are only used to facilitate and clarify the illustration of the embodiments of this invention.

[0026] Figure 1 This is a schematic diagram of the TTE network topology. The network is mainly divided into three switches (switch A, switch B, and switch C) and six end systems (end systems 1-6) with triple redundant optical ports. The nodes are connected in a star topology. To ensure the accuracy of the system's time triggering, the system needs to have time synchronization function and time synchronization retransmission function.

[0027] Figure 2The DDS publish / subscribe model is built upon the PS model, creating a data-centric publish / subscribe model. It primarily consists of domains, QoS policies (Quality of Service), domain participants, topics, publishers, and subscribers. Domains represent logically isolated networks, ensuring complete isolation between multiple applications across different DDS domains. Domain participants are introduced to implement the functionality of DDS domains. Topics serve as the identifier and fundamental means of distinguishing data types for data interaction between publishers and subscribers. Publishers are DCPS objects responsible for actually sending data; their main function is to transmit published data to every subscriber associated with the specified domain. Subscribers are DCPS objects responsible for actually receiving data; their main function is to transmit data received from publishers within the specified domain to all associated data readers.

[0028] Figure 3 This is a flowchart for the DDS publisher. The publisher mainly completes the initialization of the DDS communication driver under the TTE network architecture, the registration function of the publishing topic, the definition of the data format to be published in the TTE network, the implementation of the publishing topic function, the registration of the subscription topic processing function and the implementation of the specific processing function (i.e., implementing the functions of the subscribed topic).

[0029] Figure 4 The flowchart for the DDS receiver shows that when the message publisher receives a topic message from the message subscriber, the message subscriber parses the packet header, extracts the TTE packet memory pool naming rule identifier, and then filters the packet according to the rule identifier. If it is determined that the message subscriber needs the data, it is stored in the corresponding cache space for further processing.

[0030] Figure 5 The diagram illustrates the principle of multi-message data transmission. When a message subscriber in the end system device needs to publish a topic message, it first uses DCPS to obtain the relevant topic information rules, and then caches the information according to the rule identifier. If there are multiple different message subscribers in the end system device at the same time, the subscriber to which the data packet belongs is first distinguished, and then the data is read into the corresponding subscriber's TTE memory pool according to the header identifier of the data packet.

[0031] Figure 6The overall data transmission diagram is presented, divided into three layers from top to bottom according to the software architecture. The Distributed Data Distribution Service (DDS) middleware is implemented using the C language. The RTLinux operating system requires an improved network socket interface (Click_Socket) and a portable operating system interface (Posix) for DDS to run. DDS adapts to the network and operating system layers based on Click_Socket and Posix, completing the adaptation of DDS in the RTLinux operating system environment. Then, the DDS middleware is combined with the TTE real-time network scheduling module using the AXI bus interface, thus completing the design of a new real-time hardware and software integrated Ethernet architecture.

[0032] The above description is merely a description of preferred embodiments of the present invention and is not intended to limit the scope of the present invention in any way. Any changes or modifications made by those skilled in the art based on the above disclosure shall fall within the protection scope of the claims.

Claims

1. A design method for a TTE network system based on Distributed Data Distribution System (DDS), characterized in that, The TTE network system includes a distributed network DDS middleware, an RTlinux-based real-time operating system, time-triggered Ethernet switching devices, time-triggered Ethernet end-system devices, and a TTE network backbone network, comprising the following steps: Step A: Build a TTE network hardware architecture based on Distributed Data Distribution (DDS). The network hardware architecture mainly consists of three switches and six end systems with triple-redundant optical ports. Step B: Port the DDS middleware on the RTlinux real-time operating system to complete the initialization of the DDS communication driver under the TTE network architecture, the registration function for publishing topics, the definition of the TTE network data format to be published, the implementation of the publishing topic function, the registration of the subscription topic processing function and the implementation of the specific processing function. Step C: Implement the distributed data distribution service function of DDS middleware. Combining the characteristics of TTE network architecture, complete the connection of topic publishers and topic subscribers to DCPS information database. DCPS information database obtains their topic information, address naming identifier and MAC address, and implements the function of retrieving and identifying topic information of topic publishers and topic subscribers. Finally, send the MAC address of the matching topic subscriber and the TTE business flow data network identifier to the message publisher, and cache the identifier according to the rule identifier. Alternatively, when a message publisher receives a topic message from a message subscriber, the message subscriber parses the packet header, extracts the TTE packet memory pool naming rule identifier, and then filters the packet according to the rule identifier. If it is determined that the message subscriber needs the data, it is stored in the corresponding cache space for further processing. Step D: Based on step C, the RTlinux real-time operating system with distributed data distribution (DDS) function is ported to the TTE terminal system's business CPU, and multi-service data transmission in multi-message mode is completed.

2. The TTE network system design method based on Distributed Data Distribution (DDS) as described in claim 1, characterized in that, In step A, the nodes in the network hardware structure are connected in a star topology. To ensure the accuracy of the system time triggering, the system needs to have time synchronization function and time synchronization retransmission function.

3. The TTE network system design method based on Distributed Data Distribution (DDS) as described in claim 2, characterized in that, In step B, Distributed Data Distribution (DDS) is used for the interaction of service layer data streams in the backbone network. DDS can completely isolate the operating system and network protocol stack. Applications directly use the distributed network DDS middleware to send and receive messages. During service layer data interaction, for time-triggered Ethernet switching devices, the service layer data interaction interface is taken over by DDS. The service flow application layer only needs to configure the publish / subscribe demand method, which largely meets the diverse data needs of the TTE network service layer.

4. The TTE network system design method based on Distributed Data Distribution (DDS) as described in claim 1, characterized in that, In step C, the number of topic publishers and topic subscribers can be increased or decreased as needed, and multiple topic subscribers can subscribe to the same topic simultaneously. The protocol used is the TTE network transmission protocol. If a topic subscriber needs to resynchronize the overall network time for some reason, the distributed network DDS middleware will cache this message until the time synchronization is completed and the time synchronization accuracy is met. Only then will the topic subscriber reconnect to the system and send the message.

5. The TTE network system design method based on Distributed Data Distribution (DDS) as described in claim 4, characterized in that, In step D, the multi-service data transmission and reception in the multi-message mode includes: Message subscribers need to call relevant functions of the RTlinux real-time operating system to complete system initialization, network configuration parameter initialization, topic subscription / publishing configuration, and send queue and receive queue configuration, and complete the configuration and initialization of data sending and receiving. The entire system hardware network interface uses optical ports as the transmission medium. The underlying data in the system is ultimately sent and received through the TTE switch. The TTE switch has the main functions of multi-message to multi-service interaction and TTE data exchange scheduling. The message publisher allocates address space based on the DDS message naming identifier and stores it in the TTE memory scheduling pool. Then, by adding TTE-related transmission protocols, the TTE switch is used to forward the data. The message receiver then parses and processes the data based on the message naming identifier.

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