RTI releases Real-Time Publish-Subscribe specification

Sunnyvale, Calif.-Real-Time Innovations (RTI) has announced availability of an open, publish-subscribe protocol.

By Gary Mintchell, senior editor November 28, 2001

Sunnyvale, Calif.- Real-Time Innovations (RTI) has announced availability of an open, publish-subscribe protocol. The Real-Time Publish-Subscribe (RTPS) Wire Protocol Specification was released in November by the Interface for Distributed Automation (IDA) Group, together with the IDA Communication, Runtime Model and Device Description Specification, at the SPS/IPC/Drives show (Nürnberg, Germany).

Continuing its commitment to open standards, RTI also announced its intention to respond to the Request for Proposal (RFP) issued by the Object Management Group (OMG) for a data distribution service for real-time applications. The two initiatives will give software developers and system-builders the ability to create real-time, data-oriented applications that can be leveraged across multiple network transports.

The RTPS protocol specification is made available by RTI to software developers through the IDA Group, a consortium of vendors organized to produce an open standard for vertical and horizontal integration of industrial automation systems based on distributed intelligence. IDA Group members will be able to develop their own implementations of the protocol.

The RTPS protocol provides publish-subscribe services over the industry-standard UDP provided with Internet Protocol (IP) stacks. Publish-subscribe simplifies application design because it eliminates network programming. For example, an application simply specifies that it wants to receive data on a specific ‘topic’ or that it wants to publish data on a topic. The underlying middleware takes care of the entire message addressing and data distribution chores regardless of the number and location of the publishers or subscribers. The RTPS protocol extends the basic publish-subscribe model so that programmers can set message deadlines, set up automatic hot-swap for redundant publishers, control data flow rates, and use multicast to make optimal use of available network bandwidth. The protocol has a modular message design that allows nodes running different versions of the protocol and products from different vendors to communicate.

‘The CORBA distributed object model and services, that have been so successful for office automation, impose too much overhead for most control systems and are missing essential services for determinism and fault-tolerance,’ states Dr. Gerardo Pardo-Castellote, RTI’s chief technology officer. ‘The OMG Real-Time Special Interest Group (RT SIG) produced the Data Distribution Service for Real-Time Systems RFP to define a set of transport- and platform-independent interfaces and methods. These services will provide a data-centric publish-subscribe model that eliminates the network programming for one-to-many communications. This model will offer special help to developers, who want to update or synchronize groups of variables in complex data structures. Coding will be much simpler, and network load will be dramatically reduced over the current methods.’

The full RFP is available on the OMG web site at: https://www.omg.org/techprocess/meetings/schedule/Data_Distribution_Service_RFP.html . RTI also plans to publish the RTPS specification in December 2001 as an IETF Informational Request for Comment (RFC).