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Shared memory path to custom path
by Murali Kishore 08 Nov '24

08 Nov '24

Hi all, Is it possible to change the shared memory segment path from /dev/shm to other directory ex. /tmp/shm_file instead of /dev/shm/shm_file. Regards, Murali Kishore

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[release] Boost 1.87.0 Beta 1 Release Candidate is available
by Marshall Clow 08 Nov '24

08 Nov '24

Available at: https://archives.boost.io/beta/1.87.0.beta1/source/ The SHA256 checksums are as follows: 26f987635320854a141a8c9c3750eb6f01edb6eb75df9454726c4a03724b2472 boost_1_87_0_b1_rc1.tar.gz 3712ead87a26ae5b8ee7dcf0c180e4c27f58e50bd32f14d77e8e04bf6a13ae51 boost_1_87_0_b1_rc1.zip e6b047e06369392241f8574a5cc1b6aa493819aa498276654477e3a08bc94167 boost_1_87_0_b1_rc1.7z deff255d96e11760f728f5f90785b138fff93f6c9a3ab24664710211a41614ad boost_1_87_0_b1_rc1.tar.bz2 As always, the release managers would appreciate it if you download the candidate of your choice and give building it a try. Please report both success and failure, and anything else that is noteworthy. -- The Release Managers

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[Release] Master branch is now closed for the beta release
by Marshall Clow 07 Nov '24

07 Nov '24

Master is closed for all changes. See the release schedule at: https://www.boost.org/development/index.html -- Release managers

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[release] Master branch closes for the 1.87.0 beta release on WEDNESDAY
by Ion Gaztañaga 05 Nov '24

05 Nov '24

Calendar is here: https://www.boost.org/development/ — The Release Managers

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Bringing Boost.Array up to date?
by Peter Dimov 05 Nov '24

05 Nov '24

I recently needed to make use of std::array in a constexpr context, and was rudely informed by the compilers that a lot of its features are only constexpr in C++17 (non-const access) or even C++20 (operator==). This makes the standard std::array not very useful in C++14 constexpr code. Ordinarily, the way we deal with such problems is to shadow the standard component in Boost.Compat and backport all features introduced in later standards. But in this specific case, we already have boost::array, and it makes no sense to introduce another one. boost::array, however, looks mostly abandoned. The thinking there was probably that it's rendered entirely obsolete by std::array, and that no further development is warranted or required. But as outlined above, this is not the case; there's still value in maintaining boost::array and keeping it up to date. I'd like to do something about that. If Array's current maintainer, Marshall, agrees, I'd like to take over the maintenance of Boost.Array and do the usual thing - port the documentation to AsciiDoc, expand the test suite, add the necessary BOOST_CONSTEXPR/BOOST_CXX14_CONSTEXPR annotations, add the features introduced by later standards such as deduction guides and to_array, deprecate/remove the nonstandard parts of boost::array that are no longer relevant in 2024, and so on. Comments?

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[release] The 1.87.0 release will close for major changes WEDNESDAY
by Ion Gaztañaga 05 Nov '24

05 Nov '24

Calendar here: https://www.boost.org/development/ Next deadline: The master branch will close for the beta next Wednesday. — The release managers

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[async-mqtt5] Formal review starts today
by Klemens Morgenstern 28 Oct '24

28 Oct '24

Hi all, the formal boost review of the async-mqtt5 library strats today, the 16th of October and will last until and including the 25th of this month. Async.MQTT5 is a professional, industrial-grade C++17 client built on Boost.Asio. This Client is designed for publishing or receiving messages from an MQTT 5.0 compatible Broker. Async.MQTT5 represents a comprehensive implementation of the MQTT 5.0 protocol standard, offering full support for publishing or receiving messages with QoS 0, 1, and 2. The library has been developed by mireo, a GPS/GIS software development company, and their CTO Ivica Siladić submitted it. The code under review is the current master, which is tagged as v1.0.2: https://github.com/mireo/async-mqtt5/releases/tag/v1.0.2 The documentation can be found here: https://spacetime.mireo.com/async-mqtt5/ Please explicitly state that you either *accept* or *reject* the inclusion of this library into boost. Also please indicate the time & effort spent on the evaluation and give the reasons for your decision. - Does this library bring real benefit to C++ developers for real world use-case? - Do you have an application for this library? - Does the API match with current best practices? - Is the documentation helpful and clear? - Did you try to use it? What problems or surprises did you encounter? - What is your evaluation of the implementation? - Do you have experience with asio? - Did you work with MQTT in the past? More information about the Boost Formal Review Process can be found at: http://www.boost.org/community/reviews.html The review is open to anyone who is prepared to put in the work of evaluating and reviewing the library. Prior experience in contributing to Boost reviews is not a requirement. Reviews can also be submitted privately to me, and I will not disclose who sent them. I might however cite passages from those reviews in my conclusion. I think I should mention that there's another mqtt library that has been proposed for boost, but has yet to find a review manager: https://github.com/redboltz/async_mqtt Some ideas of how we could review them together have been discussed on the mailing list, but this is an independent review of mireo's async-mqtt5. You don't have to consider redboltz/async_mqtt when writing your review. Thanks to Mireo & Ivica for submitting this library.

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[async-mqtt5] Review ends tomorrow
by Klemens Morgenstern 27 Oct '24

27 Oct '24

Reminder: the review period for async-mqtt5 will end tomorrow on Monday the 28th. Thanks for all the great reviews received so far!

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async-mqtt5 review
by Christian Mazakas 25 Oct '24

25 Oct '24

I'm going to vote that we REJECT async-mqtt5 from Boost. My primary reasoning is that so far almost all the review discussion I've seen is focusing solely on the Asio aspect which makes this a miss. I like Asio, and I've used it to deliver products as well. But I don't think this is the MQTT library for Boost. I think libraries like these are a mistake because they're so heavily focused on the ceremony of Asio that the actual meat and potatoes of the library is lost, which in this case is supposed to be MQTT parsing and serialization and broker management. I think there's a lot of utility in MQTT, but what I'd like to see in the future for libraries like these is a first-class interface _without_ I/O. For example, I'm not sure I saw any fuzzing of the underlying parsing code. A non-I/O based interface makes this trivial. I also have a lot of concerns here because the library uses Asio in its interfaces and it also internally uses Spirit. I haven't tried to compile anything but I can only imagine the binary size and the compilation times for a realistic project using this code. I don't have a lot of experience with MQTT as a protocol but my operating assumption is that if TLS/SSL can be made without I/O, so can anything else. I think exploring this design space will lead to a much better outcome for a library going into Boost. You can see prior art here via rustls, OpenSSL's BIO pairs, and Botan which uses a synchronous callback-based interface for handling things. By focusing on creating a pure protocol library, you give users the ability to add MQTT to their own I/O layers which has the extensibility and genericity I'd expect from a Boost library. It will also likely enable the library to be compiled which in this case would be a huge boon. For example, I have an asynchronous runtime which is dramatically faster than Asio and I'm capable of handling low-level networking coding but I can't use this library with my own. Instead, I'd have to roll my own MQTT support. In the ideal case, I'd be able to treat this library like I would Botan and I'd add MQTT support non-intrusively. All this being said, a protocol library that comes with an Asio-based impl is perfectly fine. My only qualm is when the library _only_ supports Asio as seems to be the case here. - Christian

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[async-mqtt5] Review questions
by Ruben Perez 25 Oct '24

25 Oct '24

Hi Ivica, First of all, thanks for submitting your library to Boost. I've been reading the discussion and reference and have some questions for you: 1. The limitation listed on https://spacetime.mireo.com/async-mqtt5/async_mqtt5/auto_reconnect.html about concealing configuration issues looks concerning, as it can be very frustrating for the user. As far as I know, Boost.Redis solved it by including logging as part of its API, and Boost.MySQL did it by providing an extra diagnostics output argument, populated on operation cancellation, that informs the user of potential causes to the problem. Neither of us are very happy with our solution, to be frank. But I think it's a point that might be worth solving before going into Boost. As an option, I have been looking into abusing Asio handler tracking (https://live.boost.org/doc/libs/1_86_0/doc/html/boost_asio/overview/core/ha…) to log custom events. BOOST_ASIO_HANDLER_OPERATION might be a possibility. What are your thoughts regarding this? 2. Quoting the allocators section (https://spacetime.mireo.com/async-mqtt5/async_mqtt5/asio_compliance/allocat…) "[...] associates the allocator of the first packet in the queue to the low-level Boost.Asio function async_write on the transport layer". Does this mean that the queue might use the allocator bound to the first async_publish operation that is issued? If this is the case, wouldn't it be violating the requirement that all memory allocated by an associated allocator is deallocated before the async operation completes? 3. Quoting the executors section (https://spacetime.mireo.com/async-mqtt5/async_mqtt5/asio_compliance/executo…) "The same executor must execute mqtt_client::async_run and all the subsequent async_xxx operations". This sounds like an unusual restriction. What happens if it is violated? Wouldn't it make more sense to use the executor associated with async_run for intermediate handlers, and then the async_xxx associated executor for the final one? 4. I noticed that async_mqtt5 does not implement persistent and clean sessions. I'm no MQTT expert, so I can't evaluate whether these features are relevant or not - I just know that they exist. Is there a reason why you chose to not implement them? If so, I'd suggest adding these reasons somewhere in the docs. 5. According to what I read in the docs, message payloads might contain UTF-8 encoded text or just data blobs, depending on the payload_format_indicator property passed to publish. However, std::string is always used for payloads. As I understand it, if I want to send a binary blob, I need to copy my blob to a string (probably with a reinterpret_cast in the way), and then setting payload_format_indicator. Would it make sense to expose a simpler API taking a blob (e.g. a std::vector<unsigned char>) to make this use case safer? 6. I can't find any docs (other than the examples) on how to use TLS. >From the simplest example (https://spacetime.mireo.com/async-mqtt5/async_mqtt5/hello_world_over_tls.ht…) it looks like setting up TLS requires defining some non-trivial template specializations. I'd like these to be documented. On the other hand, the specializations seem to be using only Boost.Asio types, rather than user-defined types. What would happen if two libraries separately define these hooks because they need MQTT over TLS? Wouldn't it make more sense to provide an optional header providing these functions? 7. What's the use of the TlsContext type in mqtt_client? It looks very coupled to asio::ssl::stream. 8. I've noticed that async_receive returns with an error code whenever a reconnection occurs, which forces the user to re-subscribe to topics. This contrasts with how async_publish works, where reconnection is transparent to the user. Is there a reason for this difference? Would it make sense to implement automatic resubscription on reconnection? Regards, Ruben.

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