What is Eclipse iceoryx?🔗
The technology behind Eclipse iceoryx originated in the automotive domain. With the introduction of video-based driver assistance, the amount of data to be exchanged between different threads of execution increased to GBytes/sec. The resources on these embedded systems were constrained and a solution was needed to use precious runtime for functional computations, not for shifting around bytes in memory.
The simple answer was to avoid copying of messages inside the middleware that manages the data communication between the different software nodes. This can be done by using shared memory that can be accessed by the producers and consumers of messages. On its own, this is not a new innovation as the approach has been used since the 1970s. However, iceoryx takes the approach further, ending up in an inter-process-communication technology with a publish/subscribe and request/response architecture that is fast, flexible and dependable.
With the iceoryx API, a publisher can write the message directly into a chunk of memory that was previously requested from the middleware. When the message is delivered, subscribers receive reference counted pointers to these memory chunks, which are stored in queues with configurable capacities. The same principle applies to clients and servers. With this iceoryx achieves what we refer to as true zero-copy — an end-to-end approach from producers to consumers without creating a single copy.
Avoiding the copies on API level is crucial when GBytes of sensor data have to be processed per second on robotics and autonomous driving systems. Therefore the iceoryx team contributed to the standardization of true zero-copy capable APIs in ROS 2 and AUTOSAR Adaptive.
On modern processors iceoryx has a latency of less than 1 µs for transferring a message. And the best message is that this latency is constant as size doesn't matter. Want to give it a try? Then have a look at our iceperf example after having made the first steps.
iceoryx already supports Linux, QNX and MacOS as operating systems as well as C and C++ as user APIs. Windows and Rust are the next ones on the list. The typed C++ API is the most comfortable when you want to directly use the iceoryx API on the user side. The untyped C++ API and the C API provide a data agnostic interface that is often preferred when integrating iceoryx as shared memory backbone into a bigger framework.
The APIs support polling access and event-driven interactions with the WaitSet and Listener. Applications can be started and stopped flexibly as there is a service discovery behind the scenes that dynamically connects matching communication entities.
That iceoryx has the right set of features can be seen from the already existing integrations in middleware and frameworks such as Eclipse Cyclone DDS, eCAL from Continental, RTA-VRTE from ETAS and Apex.Middleware from Apex.AI.
The predecessor of iceoryx is running in millions of vehicles worldwide. All iceoryx maintainers hail from the safety critical automotive domain. Hence, they know the necessary requirements and have these in mind for the design and implementation of features. The usage of heap, exceptions and any undefined behavior are to be avoided to increase the predictability. Instead a custom memory allocation is being used, based on static memory pools. Additionally, the handling of return values and error cases was inspired by upcoming C++ features and other languages like Rust (details can be found here).
As different processes are operating on shared data structures, avoiding deadlocks is becoming all the more important. iceoryx uses lock-free data structures like the multi-producer multi-consumer (MPMC) queue that was written portably thanks to modern C++.
The tools available for automotive-compliant software development are always one or two releases behind the latest C++ standard. This fact, combined with our already mentioned constraints, led to a bunch of STL like C++ classes that have the goal to combine modern C++ with the reliability needed for the domains iceoryx is used in. They can be found in the iceoryx hoofs which are introduced here.