Stream: componentize-the-world-2023

Topic: c-athon

Bailey Hayes (Sep 08 2023 at 17:12):

Zoom link incoming!

Bailey Hayes (Sep 08 2023 at 17:13):

https://cosmonic.zoom.us/j/81787322401?pwd=R2lIbmhNcWcvYVRkaGFQSDYraUwzZz09

Chris Woods (Sep 08 2023 at 17:18):

Hi Folks - We've got a table of 'C' and 'C++' folks here, we are going to walk through the creation of two C components and trying to show case the two components linked together and running.

We are setting up the Zoom call so you can follow along. Any questions, please ask here in this channel and I'll bring it up as we go along.

Chris Woods (Sep 08 2023 at 17:19):

Step 1 : Required tooling....

Bailey Hayes (Sep 08 2023 at 17:20):

Install https://github.com/bytecodealliance/wasm-tools

Bailey Hayes (Sep 08 2023 at 17:21):

Install https://github.com/Webassembly/wasi-sdk

Bailey Hayes (Sep 08 2023 at 17:21):

Install https://github.com/bytecodealliance/wit-bindgen/releases/tag/wit-bindgen-cli-0.11.0

Chris Woods (Sep 08 2023 at 17:22):

make sure you have the wasi-sdk, wasm-tools, wit bind-gen

Chris Woods (Sep 08 2023 at 17:22):

Make sure you get version 20 of the wasi-sdk ...

Chris Woods (Sep 08 2023 at 17:25):

There is no way to check what version of the wasi-sdk installed, but, if you check that you have clang version 16, that should be WASI SDK 20 .

Dan Gohman (Sep 08 2023 at 17:26):

https://github.com/Kylebrown9/wasmcon2023/

Chris Woods (Sep 08 2023 at 17:28):

We are looking at this file...
https://github.com/Kylebrown9/wasmcon2023/blob/main/wit/greeter.wit

Chris Woods (Sep 08 2023 at 17:29):

It contains a line like this - > interface %interface. The weird precentage inside of the name is a bit confusing. Interface is a keyword. Normally you wouldn't be able to use a keyword as an indentifier in your interface name, but the percentage symbol allows you to overcome this problem.

Chris Woods (Sep 08 2023 at 17:30):

Check out the c folder here -> https://github.com/Kylebrown9/wasmcon2023/tree/main/components/c

Ayako Akasaka (Sep 08 2023 at 17:33):

I am getting error .

wit-bindgen c ../../wit/greeter.wit --world proxy-greeter

Error: expected default, world or interface, found an identifier
--> ../../wit/greeter.wit:1:1
|
1 | package wasmcon2023:greet
| ^------

Ayako Akasaka (Sep 08 2023 at 17:38):

I was using old version of wit-bindgen, with latest one, no problem
wit-bindgen-cli 0.11.0 (15907098d 2023-08-30)

Shravan Narayan (Sep 08 2023 at 17:55):

c-comp-install.sh

Script to setup and install the tools so far

Notification Bot (Sep 08 2023 at 17:56):

A message was moved here from #componentize-the-world-2023 > Install sc by Shravan Narayan.

Ayako Akasaka (Sep 08 2023 at 18:01):

cargo install wasmtime-cli --features=component-model

Shravan Narayan (Sep 08 2023 at 18:10):

cargo install wasmtime-cli --features=component-model --git https://github.com/bytecodealliance/wasmtime

Shravan Narayan (Sep 08 2023 at 18:13):

Latest work-in-progress script

c-comp-install.sh

Shravan Narayan (Sep 08 2023 at 18:56):

component-endpoint.c

Greeter

Chris Woods (Sep 08 2023 at 19:12):

@Bailey Hayes - help! how do we get wasm-compose working ? :)

Shravan Narayan (Sep 08 2023 at 19:19):

C-components-WIP.zip

Here is my WIP, Run the c-comp-install.sh

Dan Gohman (Sep 08 2023 at 20:01):

In a wasmtime git checkout: wit-bindgen c crates/wasi/wit --world=wasi:cli/command

Bailey Hayes (Sep 08 2023 at 20:08):

Chris Woods said:

Bailey Hayes - help! how do we get wasm-compose working ? :)

Let's do it! Where are we building?

Bailey Hayes (Sep 08 2023 at 20:13):

I like to use https://wasmbuilder.app when I'm composing

Dan Gohman (Sep 08 2023 at 20:37):

$ wit-bindgen c crates/wasi/wit --world=wasi:cli/command
$ cat > implementation.c
#include "command.h"

bool exports_wasi_cli_run_run(void) {
return true;
}
$ clang implementation.c command.c command_component_type.o -mexec-model=reactor -o core.wasm
$ wasm-tools component new core.wasm -o component.wasm
$ cargo run --features=component-model -- --wasm-features component-model component.wasm

Dan Gohman (Sep 08 2023 at 20:49):

$ target/debug/wasmtime --wasm-features component-model component.wasm

Mats Brorsson (Sep 08 2023 at 20:56):

Here is a simple one component example not using a runner but only relying on wasmtime: https://github.com/matsbror/wasm-c-component-example.git

Christof Petig (Sep 08 2023 at 20:57):

:wave: if you, like me, are desperate to use classes with WIT from C++ (guest or host side), I created a host/guest combination matrix at https://github.com/cpetig/resource-demo/ - and I am hacking together a wit-bindgen for C++ at https://github.com/cpetig/wit-bindgen - it is far from finished, but I at least understood how to combine the existing tooling for WIT autocode generation and the easy examples in the first repo work already.
Also feel free to ask me more questions in this chat.

Christof Petig (Sep 08 2023 at 20:59):

Guest code example https://github.com/cpetig/resource-demo/blob/main/guest-cpp/main.cpp, host code example https://github.com/cpetig/resource-demo/blob/main/host-wamr/implementations.cpp

Christof Petig (Sep 08 2023 at 21:10):

(and sorry for joining late) zoom feels a bit lonely right now

Mats Brorsson (Sep 08 2023 at 21:14):

Has anyone tried wasmflow: https://wasmflow.com/docs/getting-started/native-components/

Shravan Narayan (Sep 08 2023 at 21:14):

Example of c wasm components
https://github.com/shravanrn/wasm-c-comp-example

Christof Petig (Sep 08 2023 at 21:20):

Sadly WAMR won't support real components soon, for now I work with modules containing wit information until full support is available.
Example with resouces: https://github.com/cpetig/resource-demo/blob/main/guest-c/main.c

Chris Woods (Sep 08 2023 at 21:32):

Christof Petig said:

(and sorry for joining late) zoom feels a bit lonely right now

I'm sorry about that! :( - But thank you for joining !

Chris Woods (Sep 08 2023 at 21:35):

Christof Petig said:

Sadly WAMR won't support real components soon, for now I work with modules containing wit information until full support is available.
Example with resouces: https://github.com/cpetig/resource-demo/blob/main/guest-c/main.c

Yeah, unfortunatley this is true for the WAMR tool. - I'm trying to understand the component model and get some stdout working at the moment. There is no preview2 libc implementation at the moment.

Christof Petig (Sep 08 2023 at 21:39):

@Dan Gohman what I am working on https://github.com/cpetig/wit-bindgen/blob/main/autosar/radar.wit

Christof Petig (Sep 08 2023 at 21:46):

Chris Woods said:

Yeah, unfortunatley this is true for the WAMR tool. - I'm trying to understand the component model and get some stdout working at the moment. There is no preview2 libc implementation at the moment.

I modified the preview2 adapter to link statically to libc to generate preview2 modules - which should work nicely with WAMR once I add the new interfaces.

Christof Petig (Sep 08 2023 at 21:46):

But be careful doing this, the adapter is very complex due to its memory allocation tricks.

Christof Petig (Sep 08 2023 at 21:50):

And I got a modified wasm-threads wit file which I got working with jco in the browser :ghost: , so I will have some upstreaming to do once I feel confident enough with the solution.

Chris Woods (Sep 08 2023 at 21:57):

Things we've learnt so far:

1. worlds only contain what you specify, so there is no "printf" unless you include the wasi::cli world
2. the wasi::cli world in wasmtime is the currently active version, it is what wastime implements and is slightly ahead of the not-yet stable standard.
3. the wasm-tools compose takes a yaml file, there are plans to drop the yaml file and replace it with something else, but not sure what that is at the moment.
4. wit-bindgen c produces function stubs, in a header file only, but doesn't generate the implementation *.c file. which you need to create yourself.
5. wit-bindgen c as a string type, which is intended to be UTF8, but is specified in c as a char* -> we should log an issue to change this to a uint8_t so that is is clear that this is not a typical ASCII null terminated string, strlen will not work. (create an issue on github for this)
6. wit-bindgen c generates stub functions for imported functions, these should be denoted with an "extern" keyword to indicate that they are not to be implemented in the implementation *.c file by the developer.

Mats Brorsson (Sep 09 2023 at 14:16):

I updated my repo with an example with multiple components: https://github.com/matsbror/wasm-c-component-example

It was great meeting you all yesterday and to play with components. Thanks @Dan Gohman for all the support!

Ayako Akasaka (Sep 18 2023 at 08:40):

@Christof Petig
I saw your great work(https://github.com/cpetig/resource-demo/blob/main/guest-cpp/main.cpp) and https://github.com/cpetig/wit-bindgen.git. It worked well for my project.
Are you going to push "wit-bindgen cpp-host/c-host" to main wit-bindgen? And can we contribute if it can help you to accelerate?

Christof Petig (Sep 20 2023 at 21:05):

Ayako Akasaka said:

Are you going to push "wit-bindgen cpp-host/c-host" to main wit-bindgen? And can we contribute if it can help you to accelerate?

I replied in the SIG-Guest-Languages stream (Topic: C++ language binding) but saw no further reactions. Is is possible that you can't see this reply?

Milan (Sep 20 2023 at 23:04):

I'm subscribed to SIG-Guest-Languages generally but the C++ topic was muted for me for some reason, maybe happened to others as well

Ayako Akasaka (Sep 22 2023 at 13:36):

Thank you for replying my request @Christof Petig and @Milan
Since I haven't subscribed to the "SIG-Guest-Languages" Channel, I haven't noticed. But now I can. So, let me move to there about this topic. Thanks!

Last updated: Oct 23 2024 at 20:03 UTC