http-transform
An extension of the Node.js Transform stream that additionally supports the HTTP header interface.
-
RequestPair: creates a pair of related streams, one writable, one readable; anything written to theclientWritableSideis readable on theserverReadableSide. -
ResponsePair: creates a pair of related streams, one writable, one readable; anything written to theserverWritableSideis readable on theclientReadableSide. -
ResponsePassThrough: creates a Duplex stream that also stores HTTP headers; anything written to it becomes readable. Headers are passed through as exactly as possible. It should typically possible to pipe a response through a ResponsePassThrough instance with no change in behavior. This is typically used to programmatically create a response that's readable the same way a Node.jsreqobject is, and can be piped to aresserver response object.
TODO
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RequestPassThrough— Request variation ofResponsePassThrough -
RequestThroughOrigin— subclass of RequestPair that applies header normalizations, as if the request is actually going through the network. -
ResponseThroughOrigin— subclass of ResponsePair that applies header normalizations, as if the response is actually going through the network.
Features
Mock a readable response object:
function makeResponse(){
const res = new ResponsePassThrough;
res.setHeader('Content-Type', 'text/plain')
res.write('Line\r\n');
return res.readableClientSide;
}Add a Content-Type to a ReadableStream:
const http = require('http');
const { createReadStream } = require('fs');
const { inherits } = require('util');
const { ResponseTransform } = require('.');
const { markdown } = require( "markdown" );
class MarkdownTransform extends ResponseTransform {
constructor() {
super();
const [ input, output ] = this.makeStreams();
output.setHeader('Content-Type', 'application/xhtml+xml');
output.write('<!DOCTYPE html>');
output.write('<html xmlns="http://www.w3.org/1999/xhtml" lang="en" dir="ltr">');
output.write(' <head>');
output.write(' <meta charset="UTF-8" />');
output.write(' <title></title>');
output.write(' <meta name="description" content="" />');
output.write(' </head>');
output.write(' <body>');
output.write(' <main id="main-content">');
input.once('readable', async function(){
var source = '';
for await(var chunk of input) source += chunk.toString();
output.write(markdown.toHTML(this.sourceContents));
output.write(' </main>');
output.write(' </body>');
output.write('</html>');
output.end();
});
}
};
const server = http.createServer(function(req, res) {
if(req.url!=='/'){
res.statusCode = 404;
res.end('404 Not Found\n');
return;
}
if(req.method!=='GET'){
res.statusCode = 501;
res.setHeader('Allow', 'GET');
res.end('501 Not Implemented\n');
return;
}
createReadStream('README.md').pipe(new MarkdownTransform).pipe(res);
});
server.listen(8080);API
ResponseTransform
A subclass of the Node.js Transform that also transforms HTTP headers and status code.
Properties/methods:
- headersReady - A promise that resolves when headers have been committed and are ready to be read
PassThrough
Accepts input and passes it to the write target(s).
This can be used to convert a typical ReadableStream into one that produces HTTP headers.
Headers
Headers is a simple container for HTTP headers. Its methods and properties are imported into ServerResponseTransform.
Properties/methods, as implemented in Node.js:
- statusCode
- statusMessage
- getHeader(name)
- setHeader(name, value)
- removeHeader(name)
- getHeaderNames()
- getHeaders()
- hasHeader(name)
- pipe(dst)
Additional methods:
- addHeader(name, value)
- pipeHeaders(dst) - copy status/message fields to
dst - pipeMessage(dst) - copy status, message fields, and pipe the stream to
dst
