Embracing the Network — DIBI Conf, March 2016

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Embracing the network Patrick Hamann — DIBI, March 2016  @patrickhamann Modern techniques for building resilient front ends !

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Why?

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FT.com

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https://en.wikipedia.org/wiki/Fallacies_of_distributed_computing 1. The network is reliable. 2. Latency is zero. 3. Bandwidth is inﬁnite. 4. The network is secure. 5. Topology doesn't change. 6. There is one administrator. 7. Transport cost is zero. 8. The network is homogeneous.   The fallacies of distributed computing   PETER DEUTSCH — SUN MICROSYSTEMS, 1994

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Multiple points of failure Dmytrii Shchadei — http://www.slideshare.net/metrofun/reduce-mobile-latency " # # # $ Internal latency Firewalls, Load Balancers, Servers % Internet routing latency CDNs, ISPs, Caches, Proxies Control plane latency ~600ms on average UK 3G connection ~200ms

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Title Text

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Title Text Request Map: http://requestmap.webperf.tools/

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Baking in the assumption that everything can and will fail leads you to think diﬀerently about how you solve problems.   SAM NEWMAN — BUILDING MICROSERVICES, O’REILLY 2015 http://shop.oreilly.com/product/0636920033158.do

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1. Testing and monitoring failure 2. Designing for failure 3. Embracing failure 4. The future

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Testing for failure

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A single point of failure (SPOF) is a part of a system that, if it fails, will stop the entire system from working. SPOFs are undesirable in any system with a goal of high availability or reliability, be it a business practice, software application, or other industrial system. https://en.wikipedia.org/wiki/Single_point_of_failure

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http://uk.businessinsider.com/doubleclick-for-publishers-down-2014-11

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http://uk.businessinsider.com/doubleclick-for-publishers-down-2014-11

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http://uk.businessinsider.com/doubleclick-for-publishers-down-2014-11 http://www.stevesouders.com/blog/2010/06/01/frontend-spof/

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https://en.wikipedia.org/wiki/Fallacies_of_distributed_computing

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Facebook 2G Tuesdays - www.businessinsider.com.au/facebook-2g-tuesdays-to-slow-employee-internet-speeds-down-2015-10?op=1

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User Timing API http://www.w3.org/TR/resource-timing/ window.performance.mark(“fonts-loaded“); window.performance.mark("css-start");   performance.mark("css-end"); performance.measure("css-loading", "css-start", "css-end");

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• Test 1st and 3rd party dependencies for SPOFs • Use network shaping to simulate mobile conditions • Monitor metrics contextual to your business • Mark and measure your custom events • Alert if metrics pass their thresholds/budgets

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1. Testing and monitoring failure 2. Designing for failure 3. Embracing failure 4. The future

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Designing for failure

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Delay User perception 0 - 100ms Instant 100 - 300ms Small perceptible delay 300 - 1000ms Machine is working 1000+ ms Likely mental context switch 10,000+ ms Task is abandoned

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• Respond within a 1000ms • Avoid loading spinners • Consider using skeleton screens • Re-use familiar UI patterns within error messaging • Use human friendly copy, especially in error states • Visualise the state of the network

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1. Testing and monitoring failure 2. Designing for failure 3. Embracing failure 4. The future

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Embracing failure

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Loading fonts https://tabatkins.github.io/specs/css-font-rendering/ Chrome Opera Safari Firefox IE Timeout 3s 3s no timeout 3s 0 Fallback Yes Yes n/a Yes Yes Swap Yes Yes n/a Yes Yes

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CSS Font Rendering Controls Module https://tabatkins.github.io/specs/css-font-rendering/ @font-face { font-family: 'MyShinyFont'; src: url('http://fonts.ft.com/async.woff2'); font-display: swap; } @font-face { font-family: 'MyBlockingFont'; src: url: url('http://fonts.ft.com/blocking.woff2'); font-display: block; }

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& ServiceWorker ' ( %

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& ServiceWorker ' ( % 

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& ServiceWorker ' ( %

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Cache only self.addEventListener('install', function(event) { event.waitUntil( caches.open(cacheName).then(function(cache) { return cache.addAll([ ‘http://fonts.ft.com/fonts.css', 'http://fonts.ft.com/serif', 'http://fonts.ft.com/sans-serif' ]); }) ); }); https://jakearchibald.com/2014/offline-cookbook

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Cache only https://jakearchibald.com/2014/offline-cookbook self.addEventListener('fetch', function(event) { // If this is a request for font file if (/fonts\.ft\.com/.test(event.request)) { // If a match isn't found in the cache, the response // will look like a connection error event.respondWith(caches.match(event.request)); } });

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X Cache only & ' ( %  ( X ( ( '

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Title Text https://jakearchibald.com/2014/offline-cookbook

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Stale-while-revalidate self.addEventListener('fetch', function(event) { // Get stale from cache event.respondWith( caches.open(cacheName).then(function(cache) { return cache.match(event.request).then(function(response) { // If in cache relvalidate var network = fetch(event.request).then(function(response){ if(response.status < 400) { cache.put(event.request, response.clone()); } }); // Return stale or network if none return response || network; }); }) ); }); https://jakearchibald.com/2014/offline-cookbook

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Stale-while-revalidate & ' ( %  (

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Stale-if-error self.addEventListener('fetch', function(event) { // Always fetch response from the network event.respondWith( fetch(event.request).then(function(response) { // If we received an error response if(!response.ok) { // If we received an error response return caches.match(event.request) } else { // Response was healthy so update cached version cache.put(event.request, response.clone()); return response; } }) ); });

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Timeouts & ' ( % X * X

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Timeout race function timeout(delay) { return new Promise(function(resolve, reject) { setTimeout(function() { resolve(new Response('', { status: 408, statusText: 'Request timed out.' })); }, delay); }); } self.addEventListener('fetch', function(event) { // Attempt to fetch with timeout event.respondWith(Promise.race([timeout(2000), fetch(event.request)])); });

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Dead letter queue & ' ( % X + offline online

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• Pre-fetch and cache critical resources • Serve stale and revalidate • Serve stale if error • Always use timeouts • Queue and batch requests • Treat the network as an enhancement!

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The future

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Offline Network unavaliable

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Push notifications

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Background sync navigator.serviceWorker.ready.then(function(registration) { regitration.periodicSync.register({ tag: 'get-latet-news', // default: '' minPeriod: 12 * 60 * 60 * 1000, // default: 0 powertState: 'avoid-draining', // default: 'auto' networkState: 'avoid-cellular' // default: 'online' }).then(function(periodicsyncReg) { // success }, function() { // failure }); });

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1. Testing and monitoring failure 2. Designing for failure 3. Embracing failure 4. The future

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Thanks @patrickhamann  speakerdeck.com/patrickhamann github.com/Financial-Times ! , - Do you want to help build this stuff? Join in.