webhoster

An opt-in, stream-based, tree-processing approach to Web Hosting with NodeJS.

• Supports HTTP
• Supports HTTPS
• Supports HTTP/2

Nothing is true; everything is permitted

By default, the framework does nothing. It parses no headers. It writes no headers. It never writes to or reads from any stream. All processing is handled by middleware. All middleware is built to provide maximum throughput and do as little as possible.

install

npm install webhoster

Quick Start

** Coming soon! **

For now, take a look at /test/index.js

Core

HttpHandler.js

Class that handles the logic for handling requests and responses

• .defaultInstance - (HttpHandler) - Returns a instance of HttpHandler that can be accessed staticly.
• .middleware - (Middleware[]) - An array of middleware operations to iterate through when handling a request. It is recommended to create isolated branches (eg: /images/; /api/; /views/; etc.).
• .errorHandlers - (MiddlewareErrorHandler[]) - An array of MiddlewareErrorHandler that will handle errors and respond appropriately (eg: res.status = 500)
• .handleRequest - (function(MiddlewareFunctionParams):Promise<HttpResponse>) - handles logic for calling middleware and error handlers. Unlikely to be used directly.
• .handleHttp1Request - (function(IncomingMessage, ServerResponse):Promise<HttpResponse>) - constructs a new HttpRequest and HttpResponse based on the HTTP1 parameters and passes it to handleRequest
• .handleHttp2Stream - (function(ServerHttp2Stream, IncomingHttpHeaders, HttpResponseOptions):Promise<HttpResponse>) - constructs a new HttpRequest and HttpResponse based on the HTTP2 parameters and passes it to handleRequest

Example

  const handler = HttpHandler.defaultInstance;
  handler.middleware.push(
    new ContentDecoderMiddleware(), // Automatically decodes content
    new SendStringMiddleware(), // Auto convert strings to Buffer
    new SendJsonMiddleware(), // Auto converts objects to JSON
    new ContentEncoderMiddleware(), // Compress anything after
    new HashMiddleware(), // Hash anything after
    new ContentLengthMiddleware(), // Calculate length of anything after
    new AutoHeadersMiddleware(), // Send headers automatically
    new HeadMethodMiddleware(), // Discard body content
  );
  handler.middleware.push(
    imagesMiddleware,
    return404Middleware,
  );
  handler.errorHandlers.push(
    errorLoggerMiddleware,
    return500Middleware,
  );
  http1Server.addListener('request', handler.handleHttp1Request);
  http2Server.addListener('stream', handler.handleHttp2Stream);

HttpRequest.js

Class that provides the bare-minimum to bridge different protocols for client requests

• .read() - Promise<any> - Returns content as handled by request's content handlers. Returns .raw() if no compatible handler found.
• .stream - (Readable) - Allows for direct interaction with tail-end of the request stream pipeline. With no middleware, it emits Buffer chunks.
• .body - (ReadableStream) - Returns request's body as ReadableStream (if supported).
• .bodyUsed - (boolean) - Returns whether request's body has been read from.
• .arrayBuffer() - (Promise<ArrayBuffer>) - Returns a promise fulfilled with request's body as ArrayBuffer.
• .blob() - (Promise<Blob>) - Returns a promise fulfilled with request's body as Blob.
• .formData() - (Promise<FormData>) - Returns a promise fulfilled with request's body as FormData. Not implemented by default.
• .json() - (Promise<any>) - Returns a promise fulfilled with request's body parsed as JSON.
• .text() - (Promise<string>) - Returns a promise fulfilled with request's body as string.
• .headers - (IncomingHttpHeaders) - The response headers exactly as presented to the NodeJS Server with no modifications.
• .locals - (Object<string,any>) - Object that gets passed in every step of the middleware tree. Application-level variables should be presented here.
• .addDownstream() - (function(stream:Readable):Readable) - adds a downstream to the current pipeline. Used by preprocessor middleware for the purpose of transforming data (eg: JSON-parsing) before reaching logic middleware.

Example

async function onPostComment({ request }) {
  const content = await request.read();
  let comment;
  try {
    comment = new UserComment(content);
  } catch {
    return 400;
  }
  try {
    await insertComment(comment);
  } catch {
    return 500;
  }
  return { status: 'OK' };
}

HttpResponse.js

Class that provides the bare-minimum to bridge different protocols for client responses

• end(content:any) => HttpHandler.END - Content to be sent to the client based on the Content Handler configured. The function will call .stream.end and return HttpHandler.END.
• headers - (OutgoingHttpHeaders) - The response headers exactly as presented to the NodeJS Server with no modifications.
• content - (any) - Content that will be sent to client.
• status - (number) - The response status code
• setStatus(statusCode:number) => this - Sets .status while returning this (HttpResponse). Will throw an Error if headers have already been sent.
• code(statusCode:number) => this - Sets .status while returning this (`HttpResponse).
• async send(content:any) - Similar to end, but asynchronous. Return when the client stream ends, confirming the data was sent, or throws an error on failure. Useful for ensuring client received the data.
• stream - (Writable) - Used for interacting with the stream. With no custom middleware, it accepts a Buffer or string.
• pipeFrom(source:any) - Creates a pipeline starting with source. May insert .pipeProcessors into pipeline. Returns HttpHandler.END;
• pipelineFrom(source:any) => Promise<HttpHandler.END> - Similar to pipeFrom, but asynchronous. Return when the client stream ends, confirming the data was sent, or throws an error on failure. Useful for ensuring client received the data.
• .finalizers - Array of body processors that may read and transform .body, or simply analyze on .body.
• .canPushPath - (boolean) - true on HTTP/2 streams that support push
• .pushPath - (function(path:string):Promise) - Push a new HTTP/2 stream simulating a request for path

Example

async function onGetIndexPage(transaction) {
  if (transaction.canPushPath) {
    transaction.pushPath('/script.js').catch(() => { /* Ignore push failure */ });
    transaction.pushPath('/styles.css').catch(() => { /* Ignore push failure */ });;
  }
  transaction.response.header['content-type'] = 'text/html';
  return await getIndexPage();
}

Middleware

MiddlewareFunction

Middleware logic flows in a tree structure, allowing for continue, break, or end.

A MiddlewareFunction is a function that accepts a MiddlewareFunctionParams object structured as { res: HttpRequest, res: HttpResponse }. The function can return a instruction with the step in the tree-based logic, status code, or content body to be handled. It maybe return any of these instructions with any of the values as a literal, a Promise, or PromiseLike:

• HttpHandler.CONTINUE: Continues on the current branch to the next middleware, or moves to the next branch if there are no siblings left. alias: true|void|null|undefined
• HttpHandler.BREAK: Breaks from the current middleware branch, and continues to the next branch. alias: false
• HttpHandler.END: Terminates the entire middleware tree. alias: 0
• number: Sets status code and then ends stream. alias: res.code(statusCode).end()
• Set|Map: Add an inline middleware branch.
• Array: Explicitly passed to HttpResponse.end(). This is to support sending an Array object instead having it becoming an inline middleware branch.
• any: Any other value returned would automatically be passed to HttpResponse.end() which, in turn, uses it's own content handlers (eg: JSON; Readable), and finally terminates the middleware tree.

A MiddlewareFilter is a function that accepts a MiddlewareFunctionParams and returns a boolean or Promise<boolean> signaling whether to continue in the branch. true translates to HttpHandler.CONTINUE. false translates to HttpHandler.BREAK. There is no support for HttpHandler.END logic in a MiddlewareFilter by design.

A MiddlewareErrorHandler is an Object with a onError property. onError is like a MiddlewareFunction, but includes an err item in its parameter object. When the handler is in an error state, it will bubble upwards while searching for the next MiddlewareErrorHandler.

Middleware can be a MiddlewareFunction or MiddlewareFilter. It can also a compatible response value of either: HttpHandler.CONTINUE|true|null|void|undefined, HttpHandler.BREAK|false, HttpHandler.END|0. The response can be the value or a Promise.

To support branching, Middleware can also be a Iterable<Middleware> (eg: Set) or Map<any, Middleware>. The HttpHandler will iterate through each and flow based on the break, continue, or end instruction returned by each entry.

Included Middleware

Response Middleware

• AuthHeaders - Automatically sends response headers before writing or ending a response stream
• ContentLength - Sets Content-Length based on response stream content writes
• Hash - Sets ETag, Digest, and Content-MD5 response headers automatically
• ContentEncoder - Applies Content-Encoding to response based on Accept-Encoding request header
• SendJson - Adds response content processor that encodes objects and arrays to JSON string. Sets application/json;charset=utf-8, if content-type not set.
• SendString - Adds response content processor that encodes a string. Uses charset or uses utf-8, if not set.

Request Middleware

• ContentDecoder - Decodes Content-Encoding from request streams

Logic Middleware

• Path - Creates logic filter based on URL pathname
• Method - Creates logic filter based on request method

Other Middleware

• CORS - Handles preflight OPTION requests and sets necessary response headers for other methods

Examples:

HttpHandler.defaultInstance.middleware.push(
  new AutoHeadersMiddleware(),
  new ContentLengthMiddleware(),
  hash: (USE_HASH ? new HashMiddleware() : HttpHandler.CONTINUE),
);
HttpHandler.defaultInstance.middleware.push(
  [
    PathMiddleware.SUBPATH('/api'),
    new CORSMiddleware(),
    [MethodMiddleware.GET, myAPIGetFunctions],
    [MethodMiddleware.POST, myAPIPostFunctions],
  ],
  [
    new PathMiddleware(/^\/(index\.html?)?$/),
    indexPageMiddleware
  ],
  arrayToBePopulatedLater,
  404 // Equivalient of ({response}) => response.code(404).end()
);
HttpHandler.defaultInstance.errorHandlers.push({
  onError({error}) {
    console.error(error);
    return 500;
  },
});

Custom Middleware

async function checkToken({request, response, locals}) {
  const content = await req.read();
  try {
    const decoded = await decodeJWT(content.token);
    locals.jwt = decoded;
  } catch {
    return 401;
  }
  /**
   * Since we want the logic to continue to the next step,
   * We can either allow the function to implicitly return `undefined`
   * or explicitly use any of the following:
   *  * return undefined;
   *  * return true;
   *  * return HttpHandler.CONTINUE;
   */
}