Data Distribution Service

The Data Distribution Service ( DDS ) is a standard which has been specified by the Object Management Group.

Overview

It provides a middleware for data-centric communication in highly dynamic distributed systems dar. It is based on a publisher-subscriber concept that supports deterministic resource management.

The specification is divided into two areas:

  • Data -Centric Publish-Subscribe ( DCPS ) describes the basic concepts of data distribution
  • Data Local Reconstruction Layer ( DLRL ) provides an abstraction layer for applications based on DCPS available

Concepts

The DDS specification contains the following core concepts:

  • A topic is an application-specific data type ( for example in IDL defined ), which specifies what type of information at a DDS package.
  • A domain is used for the logical structure and contains a lot of topics.
  • A publisher is a participant in the DDS system, the data (Topics ) provides.
  • A Subscriber is a participant in the DDS system, the receiver for specific data (Topics ) is.

By using Quality -of- service parameters to define its requirements on the quality of data transmission declaratively a Subscriber. He can also create filters, only to receive, for example, data in a given range of topics.

Depending on the implementation, find the components (Publisher and Subscriber ) itself (eg RTI) or by means of a central server (for example, the Interface Repository TAO). The process of the mutual locating is called Discovery. The Discovery without a central server is realized, for example, via multicast.

Implementations

There are several implementations on the market ( not exhaustive):

  • OpenDDS
  • DDS for TAO
  • RTI Data Distribution Service (formerly NDDS, commercial implementation of the DDS standards )
  • BEE DDS

Various implementations are partly compatible with each other when the control wire protocol such as the RTI and PrismTech implementation.

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