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Vali, a C library for Varlink
- NewJazz 1y agoWhat does varlink do that grpc or capnproto don't offer? Hell, it doesn't even seem much batter than openapi...
- emersion 1y agoThe main use-case is different: gRPC and Cap'n'Proto are designed for networked servers, while D-Bus and Varlink are designed for local IPC. Varlink is a lot simpler than other alternatives.
- sam_bristow 1y agoI've only had a cursory look at Varlink, but it almost felt too simple. In particular the lack of unsigned or sized integers. This might enf up being be fine, but it gave me pause when I looked at it previously.
- wolletd 1y agoIt's JSON with some simple idea of RPC added to it. With the main idea apparently being that it is human-readable. We've been using Varlink for one project, but I've never found myself in a situation where I had any benefit from the data being JSON. You rarely read the raw data. But compared to gRPC or CapnProto, you lost compile-time type checking and now you need 10mins of testing a vending machine before you get a "key not found"-error because you missed one spot on renaming. Also, I've written varlink-cpp building on asio and nl-json at some point: https://github.com/wolletd/varlink-cpp https://github.com/wolletd/varlink-cpp. But as our varlink usage declined, it never found much usage and isn't maintained.
- emersion 1y ago"you lost compile-time type checking" makes it sound like you haven't been using code generation? Varlink has an interface definition language which makes everything type-safe.
- jauntywundrkind 1y agoVarlink exists only to be extremely simple. The Linux ecosystem was using D-Bus for basically everything. But there was some need for IPC in early boot, before any D-Bus brokers were started. Varlink was the answer, as a simple direct (vs DBus's broker mediated) IPC.
- NewJazz 1y agoSimpler is pretty subjective. A lot of people have already ingrained the complexity of grpc and/or capnproto. And more importantly, there are a lot of well maintained libraries for those protocols. At the end of the day, local or remote, it is all just pushing data over sockets, no?
- ongy 1y agoHuh, that way of doing asynchronicity is quite interesting. Though my Haskell and Rust primed brain really dislikes the way ownership of the memory allocation for the response struct works. It gets allocated by the caller (library), handed over to the function fully owned, and then gets consumed by the response function?
- andrewshadura 1y agoI'm wondering why Varlink, while incredibly similar to JSON-RPC, is designed to be incompatible with it?
- NewJazz 1y agoLinux people don't want web folks messing with their plumbing is my take lol. More realistically, adding HTTP where it is not needed adds unnecessary complexity.
- sho_hn 1y agoHere's a C++/Qt one by KDE hacker David Edmundson: https://blog.davidedmundson.co.uk/blog/introducing-qtvarlink/ https://blog.davidedmundson.co.uk/blog/introducing-qtvarlink...
- malkia 1y agojson, rpc, and that uint64_t bit integer
- burstmode 1y agoSo, there's another copy of CORBA. :-)
- guerrilla 1y agoThat's intentional. That's where this began. GNOME started out by implementing CORBA in a library called ORBit. It was eventually replaced by D-Bus which got more widespread usage across desktop environments and components. Eventually that was adopted at the OS level because of systemd and now they're replacing that with this. So, literally yes.
- blixtra 1y agoIf you want to know more about Varlink, Lennart Poettering gave a talk about it at All Systems Go! last year. https://media.ccc.de/v/all-systems-go-2024-276-varlink-now-/audio https://media.ccc.de/v/all-systems-go-2024-276-varlink-now-/...