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.