Warning: this library is still under heavy active development and experimental.
It is not yet ready for general use. Current development is mostly for Windows x64
using Visual Studio 2017, but the library has also been tested on Ubuntu Linux (AMDx64)
and a Raspberry Pi (ARMv7).
NodeC is a lean and mean version of Node.js which aims to provide similar functionality as Node.js but using C directly. The main goal is improved efficiency and resource usage (in particular more predictable resource usage) but robust and asynchronous.
Previously, this would be very cumbersome as async/await style programming is very difficult in C. NodeC uses the libhandler library to provide algebraic effect handlers directly in C, making it much easier to write such code.
Preliminary NodeC API documentation is available. For a primer on algebraic effects, see the relevant section in the koka book.
Enjoy!
-- Daan.
Note: Clone the repository using --recursive as:
git clone --recursive https://github.com/koka-lang/nodec.git
Here is a mini hello world server:
#include <stdio.h>
#include <nodec.h>
const char* hello_body =
"<!DOCTYPE html>"
"<html>\n"
"<head>\n"
" <meta charset=\"utf-8\">\n"
"</head>\n"
"<body>\n"
" <h1>Hello NodeC World!</h1>\n"
"</body>\n"
"</html>\n";
static void hello_serve() {
// debug
printf("strand %i request, url: %s\n", http_req_strand_id(), http_req_url());
// do something
printf("waiting 2 secs...\n");
async_wait(2000);
// send response (adds content-type and content-length headers)
http_resp_send_body_str(HTTP_STATUS_OK,hello_body,"text/html");
}
static void hello() {
async_http_server_at( "127.0.0.1:8080", NULL, &hello_serve );
}
int main() {
async_main(hello);
return 0;
}Note how this uses async/await style programming (as with the async_wait function) to allow other
requests to be interleaved while waiting or doing other work. Similarly, we use
implicit parameters (or dynamic binding) to bind the current request and response objects
implicitly without needing to thread it around everywhere, and can thus write
http_req_url() to get the URL of the current request. Finally, exceptions are used to
automatically propagate errors and ensure robust resource finalization. All of these
control-flow features are build upon the algebraic effect handlers provided by libhandler.
For example, consider the following asynchronous function for closing a file in plain libuv:
int uv_fs_close(uv_loop_t* loop, uv_fs_t* req, uv_file file, uv_fs_cb cb);The loop parameter identifies the outer
event loop and must be explicitly passed around everywhere. We also need to pass a fresh request
object req and can then pass in the actualy file to close, file. After that we need
a top-level continuation function cb -- if there are any locals needed in that
callback, you need to explicitly allocate them and store them into the request object
to pass them to the callback. Finally, an int is returned in case an error happens.
In NodeC, using algebraic effects provided by libhandler, we can wrap that
function and have the following function signature instead:
void async_fs_close( uv_file file );Yes! much better. We only pass the essential file parameter and that is it.
The call is still asynchronous but will continue at that exact point in the
program when the file is closed (just like async/await). Furthermore, we provide
exceptions and thus there is no need to check any return value, and through
the use implicit parameters there is no need to explicitly pass around a loop parameter.
NodeC uses the libhandler, libuv, zlib, http-parser, and mbedTLS projects.
All of these are registered as submodules under the deps directory and are automatically
checked out at the right version when giving the --recursive flag to clone:
git clone --recursive https://github.com/koka-lang/nodec.git
(if you have cloned initially without --recursive you can use the git submodule update
command to fetch the submodules).
You will need:
- Microsoft Visual Studio 2017.
- Python 2.7 (for building libuv).
When you have installed those, you can run msvc-build.bat to build
the NodeC library and all its dependencies:
> .\msvc-build.bat [debug/release] [x86/x64]
By default it will build the x64 debug version.
(Unfortunately, the way libuv is built means that you can choose x86 or x64 only
once for a checkout).
Depending on your Visual Studio version you might get a build error that the build
tools have the wrong version (like 1.40). In that case you need to open the offending
solution (usually deps/zlib/contrib/vstudio/vc14/zlibvc.sln) and upgrade the solution in
Visual Studio and save it to fix this.
After it builds successfully, you can use the Microsoft Visual Studio solution at
ide\msvc\nodec.sln to play with examples in the nodec-examples project.
This has been tested on Ubuntu Linux (amd64), and on a Raspberry PI (Raspbian, ARMv7).
-
Ensure you have
automakeandlibtoolinstalled to build the libuv dependency. Usually, you can install this as:> sudo apt-get install automake libtool -
Run
make-deps.shto configure and make all dependent projects:> ./make-deps.sh -
Run
configureandmaketo build thenodeclibrary:> ./configure > make depend > makeThis will build the
libnodecx.alibrary in theout/nodecx/debug/libdirectory which includes all the dependent projects into one static library. Build a release version using:> make VARIANT=release -
Make and run the example program:
> make examples
