C++ Actor Framework VS rotor

CAF

I'd like to mention the native actor model implementation CAF, the C++ Actor Framework, and share some experiences. (Disclaimer: I've been developing on CAF in the past and have a good relationship with the creator.) CAF (1) provides native actors without an VM layer, (2) type-safe interfaces so that the compiler yells at you when a receiver cannot handle a message, and (3) transparent copy-on-write messaging so that you can still push stuff through pipelines and induce only copies only when a ref count is greater than one.

In our telemetry engine VAST, we've been using CAF successfully for several years for building a distributed system that always has a saturated write path. CAF provides a credit-based streaming abstraction as well, so that you can have backpressure across a chain of actors, making burst-induced OOM issues a blast from the past. You also get all the other benefits of actors, like linking and monitoring, to achieve well-defined failure semantics: either be up and running or collectively fail, but still allowing for local recovery—except for segfaults, this is where "native" has a disadvantage over VM-based actor models.

With CAF's network transparent runtime, a message ender doesn't need to know where receiver lives; the runtime either passes the message as COW pointer to the receiver or serializes it transparently. Other actor model runtimes support that as well, but I'm mentioning it because our experience showed that this is great value: we can can slice and dice our actors based on the deployment target, e.g., execute the application in one single process (e.g., for a beefy box) or wrap actors into single OS processes (e.g., when deploying on container auto-scalers).

The deep integration with the C++ type system allowed us to define very stable RPC-like interfaces. We're currently designing a pub/sub layer as alternate access path, because users are interested in tapping into streaming feeds selectively. This is not easy, because request-response and pub/sub are two ends of a spectrum, but it turns out we can support nicely with CAF.

Resources:

- CAF: https://github.com/actor-framework/actor-framework

- VAST: https://tenzir.github.io/vast/docs/understand-vast/actor-mod... (sorry for the incompleteness, we're in migration mode from the old docs, but this page is summarizing the benefits of CAF for us best)

- Good general actor model background: http://dist-prog-book.com/chapter/3/message-passing.html#why...

VAST is a flight recorder and security content execution engine. On the one hand, there exists a continuous stream of high-volume data sources (such as network telemetry as NetFlow, Zeek, Suricata, and endpoint telemetry). On the other hand, VAST processes needle-in-haystack queries to provide answers to questions like "has this threat been relevant to us 8 months ago?", and supports threat hunters with an interactive query capability to explore the data. From an engineering perspective, we focus especially on the separation of read and write path, concurrent message passing in an actor model runtime (CAF), and leveraging open standards, like Apache Arrow, to establish a high-bandwidth data plane for sharing data with downstream tooling. A flexible plugin API enables additional security-specific use cases on top, such as realtime matching of threat intelligence or mining of asset data for passive inventorization.

Technologies: Apache Arrow, Flatbuffers, C++ Actor Framework, Linux, Docker, Kubernetes

If your architecture fits into inter-process messaging, i.e. spawn threads which do similar or different tasks and inform each other via messages, try to use actor framework, i.e. rotor (disclaimer: I'm the author). If there is a need to expand messaging even more, i.e. across the network, you can try to use caf, which provides that facility out of the box.

What you achieved, is handlers decoupling, i.e. when one handler knows nothing about other handler, which leads to good application testability. However, with standard promise/future bases messaging, if performance matters (and it usually does, otherwise why use C++?), i doubt that your implementation overwhelms the performance of specialized actor libraries, like sobjectizer ("batteries included" actors toolbox) or rotor (DIY-like actor constructor set; disclaimer: I'm the author of it).

I have been reading the documents from Boost.fibre and Boost.Signals2 which I could use, maybe ASIO for async. I also checked ZeroMQ (this seems to be more or less "only" for networking), Copper and Rotor. If this were just a simple MCU project I would just take the FreeRTOS and would have everything I need. Now I'm just lost how to structure my code / how to realize my main loop.

I would like to present my project rotor, which is event loop friendly C++ actor micro framework with Erlang-like microframework with supervising capabilities.

rotor actor library (I'm the author) was designed to solve similar problem, which I named "actor intrusiveness", when almost every piece of code should be written in form of actor, and, the working threads, which spin actors, are out of your control.

PS. I'm the author of rotor framework )

May be actor frameworks like caf, sobjectizer or rotor is something, that you are looking for.