dds相关介绍，使用

The OMG DDS standard is optimized for high performance, highly-scalable Industrial Internet of Things (IoT) and large-scale Consumer IoT application environments which require real-time data communication exchange. It is already well-proven in mission-critical systems in industries ranging from smart transportation to healthcare to smart energy.

OMG DDS标准针对需要实时数据通信的高性能、高可扩展的工业级物联网和大规模消费级物联网应用环境进行了优化。 DDS已在智能交通、医疗保健、智能能源等行业的关键任务系统中得到了充分证验证。

DDS is the foundation of other industry standards including OpenFMB, Adaptive AUTOSAR, MD PnP, GVA, NGVA, and ROS2.

DDS是其他行业标准的基础，包括OpenFMB，自适应AUTOSAR，MD PnP，GVA，NGVA和ROS2。

Based on the use of DDS in thousands of applications, we can predict the need for DDS in new projects. If you answer “yes” to any of the following questions, DDS is likely the best connectivity framework technology for your project.

基于在数千个应用程序中使用DDS，我们可以预测新项目中对DDS的需求。 如果您对以下任何一个问题回答是肯定的，则DDS可能是适合您项目的最佳连接框架技术之一。

• Do you have latency, network bandwidth/throughput, or scaling issues because you measure latency in ms or less, or you have more than 10 different applications, or you have more than a thousand data items to share?
  您是否存在通信延迟、网络带宽/吞吐量或扩展问题，比如您需要以毫秒为单位或更短的时间来衡量延迟，比如有超过10个不同的应用程序，或者比如需要要共享超过一千种数据项？
• If your system goes offline for 5 minutes (or even 5 ms), is it a serious problem? Or, do you struggle to configure, startup, or failover to backup servers?
  如果系统离线5分钟（甚至5毫秒）是否将导致严重的问题？ 您在配置、启动或故障转移到备份服务器方面是否面临困难？
• Are you building a system that will take more than a year to write, last more than three years, and is expected go through multiple versions or integrate with legacy applications?
  您是否正在构建一个系统，该系统将花费一年多的时间编写，持续三年以上，并且有望通过多个版本或与旧版应用程序集成？

These questions help identify your critical performance, reliability, and integration needs. If you answer yes to any of these questions, you should evaluate DDS as a solution, since it offers many additional benefits.

这些问题有助于确定您的关键性能、可靠性和集成需求。如果您对这些问题中的任何一个回答是“是”，那么您应该将DDS作为一个解决方案进行评估，因为它提供了许多额外的好处。

The OMG DDS middleware standard helps users reliably and securely harness ever-increasing amounts of device- generated data while processing the data in real-time, and acting on events as quickly as they occur. As a result, it enables smarter decisions, new services, additional revenue streams, and reduced costs. The OMG DDS middleware standard can also simplify the development, deployment, and management of IoT applications, speeding time-to-market. It provides:

OMG DDS中间件标准可帮助用户可靠、安全地利用不断增长的设备生成的数据，同时实时处理数据，并在事件发生时尽快采取响应。因此，它可以实现更明智的决策、新的服务、更多收入来源并降低成本。OMG DDS中间件标准还可以简化IoT应用程序的开发，部署和管理，从而缩短产品上市时间。 它提供：

• Ease of Integration: The data-centric approach used by DDS allows the definition of common and extensible data models for seamless Information Technology (IT) / Operational Technology (OT) interoperability. Its loose and anonymous data-sharing abstraction completely hides connectivity and topology details from applications.
  易于集成：DDS使用以数据为中心的方法，可以定义通用和可扩展的数据模型，以实现无缝的信息技术（IT）/操作技术（Operational Technology , OT）互操作性。它松散的匿名数据共享抽象完全隐藏了应用程序的连接和拓扑细节。
• Performance Efficiency and Scalability: DDS implementations can achieve point-to-point latencies that are as low as 30 µsec. and throughput of several million messages per second. It uses a very efficient wire protocol, content- and time-based filtering. When properly architected, DDS-based systems can achieve near-linear scalability.
  性能效率和可扩展性：DDS实现可实现低至30微秒的点到点延迟，以及每秒几百万条消息的吞吐量。它使用非常有效的有网络议，基于内容和时间的过滤机制等。经过适当的架构设计，基于DDS的系统可以实现近乎线性的可伸缩性。
• Advanced Security: The OMG DDS Security Specification defines a comprehensive Security Model and Service Plugin Interface (SPI) architecture for compliant DDS implementations. DDS provides standardized authentication, encryption, access control and logging capabilities to enable secure data connectivity end-to-end in an IoT system.
  高级安全性：OMG DDS安全规范为兼容DDS实现定义了一个全面的安全模型和服务插件接口（SPI）架构。DDS提供标准化的身份验证、数据加密、访问控制和日志记录功能，以实现物联网系统中端到端的安全数据连接。
• Open Standard: The OMG DDS middleware specification is a mature, proven standard open to participation by both vendors and users. It enables end-to-end vendor interoperability and eases IoT system development and integration through fully open, future-proof APIs with no vendor lock -n.
  开放标准：OMG DDS中间件规范是一个成熟、经验证的标准，对供应商和用户开放。它支持端到端的跨供应商产品的互操作性，并通过完全开放、面向未来的API（无供应商绑定）简化物联网系统开发和集成。
• QoS-Enabled: A rich set of QoS policies allows DDS to control of all aspects of data distribution, such as timeliness, traffic prioritization, reliability and resource usage.
  支持QoS：丰富的QoS策略集使DDS可以控制数据分发的各个方面，如及时性（timeliness）、流量优先级（traffic prioritization）、可靠性（reliability）和资源使用情况（resource usage）等。
• Scalable Discovery: For large-scale dynamic systems, DDS offers automatic discovery that provides plug-and-play functionality to simplify system integration and orchestration.
  可扩展的发现机制：对于大型动态系统，DDS提供了自动发现功能，该功能提供即插即用特性以简化系统集成和业务流程。
• Applicability: DDS can transparently address peer-to-peer, device-to-device, device-to-cloud, and cloud-to-cloud communication. Implementations are available for embedded, mobile, web, enterprise and cloud applications.
  适用性：DDS可以透明地处理点对点、设备对设备、设备对云以及云对云通信，支持嵌入式、移动、web、企业和云应用程序。

• Programming language-, operating system-, transport- and hardware-independence
  编程语言、操作系统、网络传输和硬件无关性
• Configurable redundancy for extremely reliable operation
  可配置冗余，以实现极其可靠的操作
• Multicast support for scalable data delivery
  多播支持可扩展数据传输
• Standard-wire protocol for seamless multi-vendor application interoperability
  标准网络协议，可实现无缝的跨供应商应用程序的互操作性
• Data selection and filtering to ensure efficient use of network and CPU resources
  数据选择和过滤功能，以确保有效利用网络和CPU资源
• Extensible data-type evolution for practical long-term architecture lifecycle
  可扩展的数据类型演进，可面向长生命周期的实用架构
• Proven operation for mission-critical system building
  在关键任务系统（mission-critical system）中得到实际验证
• A future-proof international standard to eliminate proprietary stovepipes
  消除“烟囱式”软件孤岛的面向未来的国际标准

Applications designed for the Consumer Internet of Things (IoT) and the Industrial IoT must be able to efficiently scale and securely share data. However, there are qualitative differences in system requirements for these two types of IoT applications:

面向消费级物联网（IoT）和工业级物联网设计的应用程序，必须能够有效地扩展、安全地共享数据。然而，这两种类型的物联网应用的系统需求存在质的差异：

Qualitative Comparison of system requirements for Consumer and Industrial IoT applications.Source: Cutter Journal December 2014【消费级和工业级物联网应用系统需求的定性比较。资料来源：Cutter Journal 2014年12月】

The Consumer and Industrial IoT share many of the same requirements. However, each requirement has a very different relative importance. For example, Industrial IoT applications must deal with high individual data rates. Single sources, such as an aircraft engine, produce high volumes of data. Consumer IoT applications don’t usually deal with high individual data rates. However, all IoT applications must deal with high aggregated volumes of data.

消费级和工业物联网具有许多相同的要求。 但是，每个要求具有相对不同的相对重要性。 例如，工业物联网应用必须处理高数据率的单类数据（high individual data rates）。 单一来源（例如飞机发动机）会产生大量数据。 消费级物联网应用通常不处理高数据率的单类数据（high individual data rates）。 但是，所有物联网应用程序都必须处理大量聚合数据（high aggregated volumes of data）。

Several specialized messaging/data-sharing protocols are often considered for IoT applications, including:

物联网应用通常考虑几种专门的消息/数据共享协议，包括：

• Message Queue Telemetry Transport (MQTT), a broker-reliant publish/subscribe messaging protocol designed to be used with TCP/IP
  消息队列遥测传输（MQTT），一种依赖于代理的发布/订阅消息协议，设计用于TCP/IP
• Advanced Message Queuing Protocol (AMQP), which defines an efficient, binary, peer-to-peer protocol for transporting messages between two network processes (usually a client and a broker)
  高级消息队列协议（AMQP），它定义了在两个网络进程（通常是客户端和代理）之间传输消息的有效的二进制对等协议
• Constrained Application Protocol (CoAP) is a software protocol that was designed to support the connectivity of simple low power electronic devices (e.g. wireless sensors) with Internet based systems
  受限应用协议（CoAP）是一种软件协议，旨在支持简单的低功耗电子设备（如无线传感器）与基于互联网的系统之间的连接

The following table provides a comparison of the technologies listed above. A number of these IoT protocols were designed for simplicity and as such can support only a very limited set of use cases. DDS on the other hand is a feature-rich standard that transparently handles much of an IoT system’s data connectivity complexity, therefore, easing developer efforts.

下表提供了上述技术的比较。 这些物联网协议中有许多是为了简化而设计的，因此只能支持非常有限的一组用例。 另一方面，DDS是一个功能丰富的标准，可以透明地处理物联网系统的许多数据连接复杂性，因此减轻了开发人员的工作量。

Many real systems include devices, servers, mobile nodes, and more. They have diverse communication needs, but it’s better – and easier – to use a single communication paradigm when possible. System designers should determine which of the protocols meets the primary challenge of their intended applications. Then, if possible, extend that primary choice to all aspects of the system.

许多真实的系统包括各种各样的设备、服务器、移动节点等等。 他们有各种各样的通信需求，但在可能的情况下尽量使用单一的通信协议会更好，也更容易。 系统设计者应确定哪种协议满足其预期的主要应用场景。然后，将该主要协议扩展应用到系统的其他设备和软件中。

For example, inter-device data use is a different use case from device data collection. Requirements for turning on your light switch (best with CoAP) are much different than the requirements for managing the generation of that power (best with DDS), monitoring the transmission lines (best with MQTT), or communicating power usage within the data center (best with AMQP).

例如，设备间数据使用与设备数据收集是不同的用例场景。打开灯开关（最好使用CoAP）的要求与管理该电源的生成（最好使用DDS）、监视传输线（最好使用MQTT）或在数据中心内通信电源使用（最好使用AMQP）的需求大不相同。

Overall, DDS is the most versatile of these protocols. It can manage tiny devices, connect large, high-performance sensor networks and close time-critical control loops. It can also serve and receive data from the cloud.

总的来说，DDS是这些协议中最通用的。它可以管理微型设备，连接大型高性能传感器网络，并对时间要求严格的控制回路。它还可以应用于云端服务，并从云端接收数据。

DDS communication is peer-to-peer. Elimination of message brokers and servers simplifies deployment, minimizes latency, maximizes scalability, increases reliability, and reduces cost and complexity. Using DDS does require building a data model and understanding data-centric principles. It is ideal for IoT applications that require a lasting, reliable, high-performance architecture.

DDS通信是点到点对等的。消除消息代理和服务器简化了部署，最小化了通信延迟，最大化了可扩展性，提高了可靠性，并降低了成本和复杂性。使用DDS确实需要构建一个数据模型并理解以数据为中心的原理。DDS非常适合需要持久、可靠、高性能体系结构的物联网应用。