docs: add README for HttpKernel project
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- Introduce HttpKernel with an overview of its purpose and features
- Provide a quick start guide and API reference for developers
- Include testing instructions, configuration options, and roadmap
- Add license information for clarity and compliance
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2025-05-08 20:15:58 +02:00
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# HttpKernel – A Type-Safe Router & Middleware Kernel for Deno
> Fluent routing • Zero-dependency core • 100 % TypeScript
HttpKernel is a small but powerful dispatching engine that turns an ordinary
`Deno.serve()` loop into a structured, middleware-driven HTTP server.
It focuses on **type safety**, **immutability**, and an **expressive builder API**
while staying framework-agnostic and dependency‑free.
---
## ✨ Key Features
* **Fluent Route Builder** – chain middleware and handlers without side effects
* **Static *and* Dynamic Matching** – use URL patterns *or* custom matcher functions
* **First-Class Generics** – strongly‑typed `ctx.params`, `ctx.query`, and `ctx.state`
* **Pluggable Error Handling** – override 404/500 (and any other status) per kernel
* **Response Decorators** – inject CORS headers, security headers, logging, … in one place
* **100 % Test Coverage** – built‑in unit tests ensure every edge case is covered
---
## 🚀 Quick Start
```ts
// Import directly from your repo or deno.land/x
import { HttpKernel } from "https://deno.land/x/httpkernel/mod.ts";
// 1) Create a kernel (optionally pass overrides)
const kernel = new HttpKernel();
// 2) Register a route with fluent chaining
kernel
.route({ method: "GET", path: "/hello/:name" })
.middleware(async (ctx, next) => {
console.log("Incoming request for", ctx.params.name);
return await next(); // continue pipeline
})
.handle(async (ctx) =>
new Response(`Hello ${ctx.params.name}!`, { status: 200 })
);
// 3) Let Deno serve the kernel
Deno.serve(kernel.handle);
```
Run it:
```bash
deno run --allow-net main.ts
# → GET http://localhost:8000/hello/Isaac
```
---
## 🧩 API Overview
| Method / Type | Purpose | Hints |
| --------------------- | ---------------------------------------------- | ------------------------------------------------------------- |
| `kernel.route(def)` | Begin defining a new route. Returns `RouteBuilder`. | `def` can be `{ method, path }` **or** `{ method, matcher }`. |
| `.middleware(fn)` | Add a middleware to the current builder. | Each call returns a *new* builder (immutability). |
| `.handle(fn)` | Finalise the route and register the handler. | Must be called exactly once per route. |
| `kernel.handle(req)` | Kernel entry point you pass to `Deno.serve()`. | Resolves to a `Response`. |
### Context Shape
```ts
interface Context<S = Record<string, unknown>> {
req: Request; // original request
params: Record<string>; // route params e.g. { id: "42" }
query: Record<string | string[]>; // parsed query string
state: S; // per‑request mutable storage
}
```
Generics let you supply your own param / query / state types for full IntelliSense.
---
## 🛠️ Configuration
```ts
new HttpKernel({
decorateResponse: (res, ctx) => {
// add CORS header globally
const headers = new Headers(res.headers);
headers.set("Access-Control-Allow-Origin", "*");
return new Response(res.body, { ...res, headers });
},
httpErrorHandlers: {
404: () => new Response("Nothing here ☹️", { status: 404 }),
500: (_ctx, err) => {
console.error(err);
return new Response("Custom 500", { status: 500 });
},
},
});
```
Everything is optional – omit what you do not override.
---
## 🧪 Testing
All logic is covered by unit tests using `std@0.204.0/testing`.
Run them with:
```bash
deno test -A
```
The CI suite checks:
* Route guards (`isStaticRouteDefinition`, `isDynamicRouteDefinition`)
* Builder immutability & middleware order
* 404 / 500 fall-backs and error propagation
* Middleware mis-use (double `next()`, wrong signatures, …)
---
## 📦 Roadmap
* 🔌 Adapter helpers for Oak / Fresh / any framework that can delegate to `kernel.handle`
* 🔍 Built‑in logger & timing middleware
* 🔒 CSRF & auth middleware presets
* 📝 OpenAPI route generator
Contributions & ideas are welcome – feel free to open an issue or PR.
---
## 📄 License
[MIT](LICENSE)