DDS™ - The Proven Data Connectivity Standard for IoT™ Nov. 2016 | Page 5

QoS

DATA QoS
READER

DATA
WRITER
DATA
WRITER
DATA
WRITER
DATA
WRITER

QoS
QoS

TOPIC A

QoS

QoS
DATA
READER
QoS
DATA
READER

QoS

TOPIC C
QoS

QoS

QoS

DDS DOMAIN

QoS

DATA
WRITER

TOPIC B

FILTERS

TOPIC D

FILTERS

DATA QoS
READER

QoS
DATA
READER
QoS
DATA
READER

DDS provides QoS-controlled data-sharing. Applications communicate by publishing and subscribing to Topics identified by
their Topic name. Subscriptions can specify time and content filters and get only a subset of the data being published on the
Topic. Different DDS Domains are completely independent from each other. There is no data-sharing across DDS domains.

GLOBAL DATA SPACE
DDS conceptually sees a local store of data called the “global data space.” To the application, the global data
space looks like native memory accessed via an API. You write to what looks like your local storage. In reality,
DDS sends messages to update the appropriate stores on remote nodes. You read from what looks like a
local store.

Source
WPT1
WPT2
WPTN

Speed

Power

Phase

37.4
10.7
50.2

122.0
74.0
150.07

-12.20
-12.23
-11.98

Inside a DDS domain the unit of information sharing is data-objects within Topics. The topic is identified by its name and the
data-object by some ‘Key” attributes. This is similar to how key attributes are used to identify records in a Database. This figure is
conceptual. DDS communicates peer-to-peer and does not require the data to be brokered by a server or cloud.

5

WHAT IS DDS?

The essence of data centricity is that DDS knows what data it stores and controls how to share that data.
Programmers using traditional message-centric middleware must write code that sends messages. Programmers using data-centric middleware write code that specifies how and when to share data and then directly
share data values. Rather than managing all this complexity in the application code, DDS directly implements
controlled, managed, secure data sharing for you.