July CoreDX DDS Connection

July CoreDX DDS Connection 2025

Welcome to the Twin Oaks Computing, Inc Newsletter!

Our monthly newsletter brings you news and information about Twin Oaks Computing and our CoreDX DDS middleware. Be sure to "like", "follow" and "friend" us on our Social Networking sites for fun facts, free giveaways, and stories about Communications Middleware, Technology, and Twin Oaks Computing.

Come Visit Twin Oaks Computing at GVSETS in Novi, MI

August 11-14, 2025

The NDIA Michigan Chapter presents the 17th Annual Ground Vehicle Systems Engineering & Technology Symposium (GVSETS) & Modernization Update this August in Novi, Michigan. GVSETS provides the opportunity for the Ground Systems community to network and share technical research and innovations while discussing capability gaps and modernization needs.

CoreDX DDS is a MIL-STD 3071 (TMS) and GVA/NGVA compliant DDS solution. CoreDX DDS is used by the Army to develop the next generation tactical microgrid requirements and test tools, by vendors developing MIL-STD 3071 compliant microgrid components, and in GVA and NGVA compliant vehicle systems.

Visit Twin Oaks Computing at Booth #232 to discuss our CoreDX DDS product line and TMS or GCA/NGVA solutions.

CoreDX DDS Tips & Tricks

Welcome to this month's edition of CoreDX DDS Tips & Tricks, where our engineers provide quick bits of information to help our customers.

What you need to know about History QoS kinds: KEEP_LAST and KEEP_ALL

The History QoS policy is one of the most commonly configured DDS QoS policies. And, it's one of the most commonly misunderstood QoS policies. Here's what you need to know:

Each and every DataReader and DataWriter has their own data cache. The DataWriter cache holds samples written by the application that are being held for delivery to current or future DataReaders. The DataReader cache holds samples received from peer DataWriters that are being held for data processing.

If a DataReader or DataWriter cache is configured to hold a defined maximum number of samples and/or instances (via History.depth or Resource Limits QoS policies), it is possible the data cache may become full. The History.kind setting configures the CoreDX DDS behavior when another sample needs to be added to an already full data cache.

With KEEP_ALL, the new sample will NOT be added to a full cache. Rather, the operation will fail (on the DataWriter), or the sample will be rejected (on a DataReader). [With a Reliable Reliability configuration, the DataReader will NACK that sample and may receive it later].

With KEEP_LAST, CoreDX DDS will remove an existing (old) sample from the cache and insert a new sample. No errors are generated.

For more information on the History QoS policy and its effect on DataReader and DataWriter caches, check out the published CoreDX DDS Sample and Instance whitepaper.

CoreDX DDS Tips & Tricks are intended to be useful for engineers using CoreDX DDS. If you have any questions, please contact us.

Try the full-featured CoreDX DDS product free for 30 days

Check out the newest DDS standardized features and get your hands on the leading small footprint Data Distribution Service implementation to see what it can do for you.

CoreDX DDS v5 continues to focus on resources and performance while incorporating new features and enhancements. Our evaluation copies include the full DDS API and standardized wire protocol, including:

• All language bindings for the DDS API's (C,C++, Cxx, C#, Java, Python, JavaScript)
• Full X-Types support including IDL, XML, and Dynamic type representations
• Remote Procedure Call over DDS (RPC over DDS)
• XML Application Definition
• DDS Security (upon request)

With these enhanced features, CoreDX DDS is the perfect middleware solution to meet the challenges of today's Industrial Internet of Things (IIoT) systems. Learn more here.

The evaluation is available here for direct download for the most common platforms, including Linux, MacOS, and Windows. Download your free 30 day trial of CoreDX DDS here.

Upcoming Events

August 12-14, 2025: GVSETS, Novi, MI, USA

August 25, 2025: U.S. Air Force - FACE and SOSA Consortial Technical Interchange Meeting and Expo, Novi, Location TBD

September 15-19, 2025: OMG Technical Meeting, Leeds, UK

December 1-5, 2025: I/ITSEC, Orlando, FL, USA

December 8-12, 2025: OMG Technical Meeting, San Francisco, CA, USA