7/31/2003 - RTI announced the Data Distribution Service for Real-Time Systems (DDS) specification is now an adopted OMG (Object management Group) specification. The OMG architecture board voted to adopt DDS at the Paris Technical Meeting held last month. The DDS specification provides a publish-subscribe communications model critical to many real-time systems. Applications like communication, command and control systems, distributed simulators, distributed control systems, medical equipment, avionics and industrial automation need to distribute data in real-time. This standard will directly benefit these distributed real-time applications.
The DDS Standard
The publish-subscribe communications model is already popular for data distribution in real-time applications. There are some commercial and many in-house implementations in use today. However, to-date, there have been no general-purpose data-distribution standards.
"The OMG Middleware, and Related Services Platform Task Force (MARS PTF) produced the DDS specification to address the need for a data-centric publish-subscribe standard, " states Char Wales, co-chair of the MARS PTF at OMG. "CORBA covers the client-server communication requirements for distributed real-time systems and DDS covers the data-distribution requirements. The DDS specification will be a significant addition to OMG's real-time networking standards."
The OMG developed the CORBA standard years ago. It has become widely used in distributed systems. However, CORBA's client-server communications model is not well suited for real-time applications that need to distribute data. Applications like shipboard control systems, telemetry and command systems, optical switch control plane communications, and innumerable others need real-time data distribution. DDS fills this prevalent need and completes the real-time networking standards picture.
Client-Server and Publish-Subscribe Data Distribution
CORBA - the OMG's Common Object Request Broker Architecture - provides a client-server communications model for distributed systems. Client-server communications is characterized by an organization where certain applications - servers - offer services that other applications - clients - access. Communications is initiated by the client that must bind to the server and invoke operations to change or access information. Client-server, and CORBA in particular, is a popular model in enterprise applications where clients access databases and other centralized resources on the servers. However, it is not well suited for distributing data in real-time applications.
Publish-subscribe Data Distribution is an ideal communications mechanism for moving data. "The publish-subscribe communications model excels at efficiently distributing data between applications," states Gerardo-Pardo Castellote, RTI chief technology officer and co-author of the DDS specification. "Establishing communications is simple. Publishers register data they will be producing with the middleware and subscribers register the data they are interested in receiving. Then the publisher just sends, or publishes, the data. This model is robust, efficient and data-centric. Publish-subscribe is exactly what most real-time systems need."
RTI (Real-Time Innovations, www.rti.com)is a leading provider of software tools, middleware, and professional services for distributed real-time systems and embedded applications. RTI's NDDS middleware provides robust, efficient, publish-subscribe communications for distributed, real-time system builders. The NDDS tools simplify the development and deployment of NDDS-based applications. And for over 10 years, the RTI's ScopeTools product line has have been helping embedded system developers produce higher quality, more reliable solutions.
RTI, StethoScope, Real-Time Innovations, ScopeTools, NDDS, WaveWorks and Constellation are registered trademarks or trademarks of Real-Time Innovations, Inc.
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