http-transform
v0.0.14
Published
Transform stream that supports HTTP headers and metadata
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Readme
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
RequestPassThrough— Request variation ofResponsePassThroughRequestThroughOrigin— 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