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bittyhttp - A Threaded Library for Building REST Services in C

bittyhttp is a new library that I've been working on that aims to make building web services in C as easy as possible. Microservices and HTTP APIs are very common these days and bittyhttp offers the ability to implement these in C without much hassle. It takes care of running the server so all the user needs to do is implement their callbacks.

When using bittyhttp, the user registers handlers to URLs with a callback function pointer. If an HTTP request is received that matches the handler URL, the callback is executed. Inside the callback, information about the HTTP request is exposed and allows the user to decide how they would like to handle the request. If no handler is found, bittyhttp defaults to acting like a standard webserver.

Check out the full project on GitHub.

Example

For instance, we can register a simple handler like this:

bhttp_add_simple_handler(server,
                            BHTTP_GET | BHTTP_POST,  // http methods
                            "/helloworld",           // pattern to match
                            helloworld_handler);     // callback function

And then implement whatever logic we need in the callback like this:

int helloworld_handler(bhttp_request *req, bhttp_response *res)
{
    /* business logic */
    bstr bs;
    bstr_init(&bs);
    bstr_append_printf(&bs, "<html><p>Hello, world! from URL: %s</p><p>%s</p><p>%s</p></html>",
                      bstr_cstring(&req->uri),
                      bstr_cstring(&req->uri_path),
                      bstr_cstring(&req->uri_query));
    bhttp_res_set_body_text(res, bstr_cstring(&bs));
    bstr_free_contents(&bs);
    
    /* add custom headers and response code */
    bhttp_res_add_header(res, "content-type", "text/html");
    res->response_code = BHTTP_200_OK;
    return 0;
}

Because bittyhttp uses a separate thread to handle each request, some care needs to be taken in the callbacks to prevent race conditions. Changing data that is not allocated inside of a callback will often require the use of mutexes or similar data structures. A database connection pool, for example, would need to be properly managed.

Use Cases

I see bittyhttp having 2 primary use cases. The first being to implement often-used API endpoints in C, for performance reasons. Perhaps authentication endpoints get hit a lot and you want to speed these up.

The second is adding HTTP support to an existing C application. Maybe you have an existing long-running application on a server somewhere and you want to expose some of its configurations via HTTP. In that case, bittyhttp would be an excellent option.

bittyhttp is GPLv3 licensed, and available on GitHub, but I would be open to relicensing it for specific cases. If you are interested in using it in your application, feel free to get in contact with me at [email protected].

squid poll

As a fun, little proof-of-concept, I created a site called squid poll. It's basically a Straw Poll clone that uses bittyhttp as its API backend. Feel free to visit the site to create your own poll, or fill out the one below:


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