eCAL VS Cap'n Proto

New version (5.94) of the high performance interprocess / interhost communication framework eCAL is available. eCAL supports different transport layer like shared memory for interprocess and udp multicast for interhost communication. It does not force the user to use a specific serialization format but supports some of the standards like google protobuf, capnproto or flatbuffers. The API is wrapped to C, C++, Python, C#, Rust and Go (the last two I never tested ;-)). Here you can find all the documentation. Check out the great applications for monitoring, record and replay. eCAL is Apache 2 licensed, repository hosted here. Have fun :-)

I you just need a fast publish / subscribe framework for windows you can give eCAL a try. The setup is done in less a minute and their is no dependency hell. Just to mention it as alternative. Documentation here

I would concider using eCAL since it blasts everything out of the water in terms of performance and comes with some handy tooling for inspection of messages in-travel.

Source on GitHub: https://github.com/continental/ecal

Check out eCal.

This really makes me want to try https://github.com/continental/ecal with https://github.com/google/flatbuffers to see how they compare. I also know that gpc for cpp at least stops functioning by about 4 MB of request size. Which I find stupid. What if I want to send uncompressed bitmaps!

Congratulations. Well done. eCAL will update as soon as possible to the new release. The new custom header and the n:m pub/sub support are really welcome new features.

Here is their counter callback example: https://github.com/continental/ecal/blob/master/samples/cpp/counter/counter_rec_cb/src/counter_rec_cb.cpp

Yeah I pretty much only use my own alternate container implementations (from KJ[0]), which avoid these footguns, but the result is everyone complains our project is written in Kenton-Language rather than C++ and there's no Stack Overflow for it and we can't hire engineers who know how to write it... oops.

[0] https://github.com/capnproto/capnproto/blob/v2/kjdoc/tour.md

- may massively reduce the latency involved.

Those sharing Cap'n Proto-encoded data may have particular interest. Cap'n Proto (https://capnproto.org) is fantastic at its core task - in-place serialization with zero-copy - and we wanted to make the IPC (inter-process communication) involving capnp-serialized messages be zero-copy, end-to-end.

That said, we paid equal attention to other varieties of payload; it's not limited to capnp-encoded messages. For example there is painless (<-- I hope!) zero-copy transmission of arbitrary combinations of STL-compliant native C++ data structures.

To help determine whether Flow-IPC is relevant to you we wrote an intro blog post. It works through an example, summarizes the available features, and has some performance results. https://www.linode.com/blog/open-source/flow-ipc-introductio...

Of course there's nothing wrong with going straight to the GitHub link and getting into the README and docs.

Currently Flow-IPC is for Linux. (macOS/ARM64 and Windows support could follow soon, depending on demand/contributions.)

FWIW, my C++ toolkit library, KJ, does the same thing.[0]

But presumably you could still write a condition predicate which looks at things which aren't actually part of the mutex-wrapped structure? Or does is the Rust type system able to enforce that the callback can only consider the mutex-wrapped value and values that are constant over the lifetime of the wait? (You need the latter e.g. if you are waiting for the mutex-wrapped value to compare equal to some local variable...)

[0] https://github.com/capnproto/capnproto/blob/e6ad6f919aeb381b...

The second one is to encode data in such a way that you can read it and operate on it directly from the buffer. You write data in a layout that is the same, or easily transformed as types in memory. To do that you usually need to encode with a known schema, only Sized types to efficiently compute fields locations as offsets in the buffer, and you usually represent pointers as offset into the encode. You can look at capnproto protocol for instance https://capnproto.org/

Worked well for Cap'n Proto (the cerealization protocol)! https://capnproto.org/

With all due respect, you read completely wrong.

* The very first use case for which Cap'n Proto was designed was to be the protocol that Sandstorm.io used to talk between sandbox and supervisor -- an explicitly adversarial security scenario.

* The documentation explicitly calls out how implementations should manage resource exhaustion problems like deep recursion depth (stack overflow risk).

* The implementation has been fuzz-tested multiple ways, including as part of Google's oss-fuzz.

* When there are security bugs, I issue advisories like this:

https://github.com/capnproto/capnproto/tree/v2/security-advi...

* The primary aim of the entire project is to be a Capability-Based Security RPC protocol.

I like how they use capability-based security [0] and use Cap'n Proto protocol. This is another technology that is slow to get broad adoption, but has many things going for when compared to e.g. Protocol Buffers (Cap'n Proto is created by the primary author of Protobuf v2, Kenton Varda).

[0] https://sandstorm.io/how-it-works#capabilities

[1] https://capnproto.org

Related but not Rust-specific: FlatBuffers, Cap'n Proto.