Add cache control headers to server

bin/handlers/RenderRequestHandler.js

@@ -0,0 +1,81 @@
+const {HttpError} = require('../server/HttpError');
+const {RequestHandler} = require('../server/RequestHandler');
+const {VirtualSequenceDiagram} = require('../../lib/sequence-diagram');
+
+const NUM_MATCH = '[0-9]+(?:\\.[0-9]+)?';
+
+function beginTimer() {
+	return process.hrtime();
+}
+
+function endTimer(timer) {
+	const delay = process.hrtime(timer);
+	return delay[0] * 1e9 + delay[1];
+}
+
+function getNumeric(v, name) {
+	if(!v) {
+		return null;
+	}
+	const n = Number.parseFloat(v);
+	if(Number.isNaN(n)) {
+		throw new HttpError(400, 'Invalid value for ' + name);
+	}
+	return n;
+}
+
+function readEncoded(str, encoding) {
+	switch(encoding) {
+	case 'b64':
+		return Buffer
+			.from(decodeURIComponent(str), 'base64')
+			.toString('utf8');
+	case 'uri':
+		return str.split('/').map(decodeURIComponent).join('\n');
+	default:
+		throw new HttpError(400, 'Unknown encoding');
+	}
+}
+
+class RenderRequestHandler extends RequestHandler {
+	constructor(baseUrlPattern) {
+		super('GET', new RegExp(
+			`^${baseUrlPattern}/` +
+			`(?:(?:w(${NUM_MATCH}))?(?:h(${NUM_MATCH}))?/|z(${NUM_MATCH})/)?` +
+			'(?:(uri|b64)/)?' +
+			'(.*?)' +
+			'(?:\\.(svg))?$',
+			'i'
+		));
+		this.info = `Rendering sequence diagrams at ${baseUrlPattern}/`;
+	}
+
+	handle(req, res, {match, pickEncoding, log, writeEncoded}) {
+		this.applyCommonHeaders(req, res);
+
+		const encoding = pickEncoding();
+		const size = {
+			height: getNumeric(match[2], 'height'),
+			width: getNumeric(match[1], 'width'),
+			zoom: getNumeric(match[3], 'zoom'),
+		};
+		const code = readEncoded(match[5], (match[4] || 'uri').toLowerCase());
+		const format = (match[6] || 'svg').toLowerCase();
+
+		const timer = beginTimer();
+		const svg = VirtualSequenceDiagram.render(code, {size});
+		const delay = endTimer(timer);
+		log('RENDER (' + (delay / 1e6).toFixed(3) + 'ms)');
+
+		switch(format) {
+		case 'svg':
+			res.setHeader('Content-Type', 'image/svg+xml; charset=utf-8');
+			writeEncoded(encoding, svg);
+			break;
+		default:
+			throw new HttpError(400, 'Unsupported image format');
+		}
+	}
+}
+
+module.exports = {RenderRequestHandler};

bin/handlers/render.js

@@ -1,78 +0,0 @@
-const {HttpError} = require('../server/HttpError');
-const {RequestHandler} = require('../server/RequestHandler');
-const {VirtualSequenceDiagram} = require('../../lib/sequence-diagram');
-
-function beginTimer() {
-	return process.hrtime();
-}
-
-function endTimer(timer) {
-	const delay = process.hrtime(timer);
-	return delay[0] * 1e9 + delay[1];
-}
-
-const NUM_MATCH = '[0-9]+(?:\\.[0-9]+)?';
-const MATCH_RENDER = new RegExp(
-	'^/render/' +
-	`(?:(?:w(${NUM_MATCH}))?(?:h(${NUM_MATCH}))?/|z(${NUM_MATCH})/)?` +
-	'(?:(uri|b64)/)?' +
-	'(.*?)' +
-	'(?:\\.(svg))?$',
-	'i'
-);
-
-function getNumeric(v, name) {
-	if(!v) {
-		return null;
-	}
-	const n = Number.parseFloat(v);
-	if(Number.isNaN(n)) {
-		throw new HttpError(400, 'Invalid value for ' + name);
-	}
-	return n;
-}
-
-function readEncoded(str, encoding) {
-	switch(encoding) {
-	case 'b64':
-		return Buffer
-			.from(decodeURIComponent(str), 'base64')
-			.toString('utf8');
-	case 'uri':
-		return str.split('/').map(decodeURIComponent).join('\n');
-	default:
-		throw new HttpError(400, 'Unknown encoding');
-	}
-}
-
-function handleRender(req, res, {match, pickEncoding, log, writeEncoded}) {
-	res.setHeader('Access-Control-Allow-Origin', '*');
-
-	const encoding = pickEncoding();
-	const size = {
-		height: getNumeric(match[2], 'height'),
-		width: getNumeric(match[1], 'width'),
-		zoom: getNumeric(match[3], 'zoom'),
-	};
-	const code = readEncoded(match[5], (match[4] || 'uri').toLowerCase());
-	const format = (match[6] || 'svg').toLowerCase();
-
-	const timer = beginTimer();
-	const svg = VirtualSequenceDiagram.render(code, {size});
-	const delay = endTimer(timer);
-	log('RENDER (' + (delay / 1e6).toFixed(3) + 'ms)');
-
-	switch(format) {
-	case 'svg':
-		res.setHeader('Content-Type', 'image/svg+xml; charset=utf-8');
-		writeEncoded(encoding, svg);
-		break;
-	default:
-		throw new HttpError(400, 'Unsupported image format');
-	}
-}
-
-const render = new RequestHandler('GET', MATCH_RENDER, handleRender);
-render.info = 'Rendering sequence diagrams at /render/';
-
-module.exports = {render};

bin/server.js

@@ -2,7 +2,7 @@
 
 const {Server} = require('./server/Server');
 const {StaticRequestHandler} = require('./server/StaticRequestHandler');
-const {render} = require('./handlers/render');
+const {RenderRequestHandler} = require('./handlers/RenderRequestHandler');
 const path = require('path');
 
 const DEV = process.argv.includes('dev');
@@ -31,7 +31,11 @@ function devMapper(file, type, data) {
 	}
 }
 
+const STATIC_MAX_AGE = 10 * 60; // 10 minutes
+const RENDER_MAX_AGE = 60 * 60 * 24 * 7; // 1 week
+
 const statics = new StaticRequestHandler('')
+	.setCacheMaxAge(DEV ? 0 : STATIC_MAX_AGE)
 	.addMimeType('txt', 'text/plain; charset=utf-8')
 	.addMimeType('htm', 'text/html; charset=utf-8')
 	.addMimeType('html', 'text/html; charset=utf-8')
@@ -62,6 +66,10 @@ if(DEV) {
 	statics.setFileWatch(true);
 }
 
+const render = new RenderRequestHandler('/render')
+	.setCacheMaxAge(DEV ? 0 : RENDER_MAX_AGE)
+	.setCrossOrigin(true);
+
 new Server()
 	.addHandler(render)
 	.addHandler(statics)

bin/server/RequestHandler.js

@@ -3,7 +3,31 @@ class RequestHandler {
 		this.method = method;
 		this.matcher = matcher;
 		this.handleFn = handleFn;
-		this.info = 'Custom handler at ' + this.method + ' ' + this.matcher;
+		this.cacheMaxAge = 0;
+		this.allowAllOrigins = false;
+		this.info = `Custom handler at ${this.method} ${this.matcher}`;
+	}
+
+	setCacheMaxAge(seconds) {
+		this.cacheMaxAge = seconds;
+		return this;
+	}
+
+	setCrossOrigin(allowAll) {
+		this.allowAllOrigins = allowAll;
+		return this;
+	}
+
+	applyCommonHeaders(req, res) {
+		if(this.allowAllOrigins) {
+			res.setHeader('Access-Control-Allow-Origin', '*');
+		}
+		if(this.cacheMaxAge > 0) {
+			res.setHeader(
+				'Cache-Control',
+				`public, max-age=${this.cacheMaxAge}`
+			);
+		}
 	}
 
 	apply(req, res, info) {

bin/server/StaticRequestHandler.js

@@ -51,6 +51,7 @@ class StaticRequestHandler extends RequestHandler {
 	_handleResource(req, res, resource, {pickEncoding, log}) {
 		log('SERVE ' + resource.path);
 
+		this.applyCommonHeaders(req, res);
 		const encoding = pickEncoding(
 			PREF_ENCODINGS.filter((enc) => (resource.encodings[enc] !== null))
 		);