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A small overview of possible solutions for making real-time web in context of client (server is a black box)
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Real-time webIS THERE A LIFE WITHOUT SOCKET.IO AND NODE.JS?
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Who am I Eduard Trayan Software developer at EPAM Systems Zend PHP 5.3 Certified developer SensioLabs Certified Symfony Developer eduardtrayan@gmail.com
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Agenda Say some words about real-time web Do small overview about possible solutions And play game
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Real-time web
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What is the real-time web?
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Real-time web Set of technologies and practices Receiving information as soon as possible Users doesn't need to check updates http://en.wikipedia.org/wiki/Real-time_web
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Main principles – push instead of pull
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Main principles – ASAP
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Where to find a use?
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Where to find a use?
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Solutions
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Possible solutions
Proprietary solutions
Comet
Ajax polling
WebSockets
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Proprietary solutions
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Proprietary solutions
Adobe Flash
Java applet
Microsoft Silverlight
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Comet
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What is the comet?
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Comet is not a cleaner
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Comet is not a solar system body
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Comet Web application model Long-held HTTP requests Server push datahttp://en.wikipedia.org/wiki/Comet_(programming)
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CometAjax long pollingForever iframeActiveXObject htmlfileServer sent eventsXMLHTTPRequest interactive stateJSONP long polling
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Ajax long polling - algorithm
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Ajax long polling - opportunities
Cross-domain requests
Unidirectional communications between client and server
Binary or text data
Or the same opportunities as provided by XMLHTTPRequest
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Ajax long polling - disadvantagesBig delay between event and notification
Big number of requests
Big incoming traffic
Caching by browsers
Possible problems with proxy
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What solution does facebook use for chat?
1. Ajax long polling2. WebSockets3. Forever iframe4. Proprietary solutions
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Forever iframe - algorithm
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Forever iframe - opportunities
Cross-domain requests
POST requests
Unidirectional communications between client and server
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Forever iframe - disadvantagesLoad indication
Script buffering
Page buffering
Proxy buffering
Impossible to compress data
Changes in browser’s history
Hard to detect disconnections/errors
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What solution does vk.com use for chat?1. WebSockets2. JSONP long polling3. Ajax long polling4. Proprietary solutions
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ActiveXObject - algorithm
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ActiveXObject - opportunities
Cross-domain requests
POST requests
Unidirectional communications between client and server
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ActiveXObject - disadvantagesIE only
Script buffering
Page buffering
Proxy buffering
Impossible to compress data
Changes in browser’s history
Hard to detect disconnections/errors
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What solution does vseti.by use for chat?1. Forever iframe2. Proprietary solutions3. ActiveXObject htmlfile4. Ajax long polling
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SSE - algorithm
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SSE - opportunitiesMultiline messages
Cross-domain requests
Unidirectional communications between client and server
Custom events
Automatic reconnect
Error handling
Control of events
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SSE - disadvantagesDoesn’t work in IE
Doesn’t work in android browsers <4.4
Impossible to compress data
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What solution does assistent.by use?1. Forever iframe2. Proprietary solutions3. ActiveXObject htmlfile4. Ajax long polling
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XMLHTTPRequest interactive state -algorithm
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XMLHTTPRequest interactive state -opportunitiesCross-domain requests
Unidirectional communications between client and server
Binary or text data
Or the same opportunities as provided by XMLHTTPRequest
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XMLHTTPRequest interactive state -disadvantages
Doesn’t work at <IE10
Unsupported by mobile browsers
Impossible to compress data
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What solution does flowdock use for chat?1. Forever iframe2. Proprietary solutions3. WebSockets4. Ajax long polling
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JSONP long polling - algorithm
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JSONP long polling - opportunities
Cross-domain requests
Unidirectional communications between client and server
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JSONP long polling - specifics
Handling errors with callback/onload/onerror/onreadystatechange
Sending callback name in request
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JSONP long polling - disadvantagesBig delay between event and notification
Big number of requests
Big incoming traffic
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Ajax polling
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Ajax polling - algorithm
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Ajax polling - opportunities
Cross-domain requests
Unidirectional communications between client and server
Binary or text data
Or the same opportunities as provided in XMLHTTPRequest
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Ajax polling - disadvantagesBig delay between event and notification
Big number of requests
Big incoming traffic
Caching by browsers
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WebSockets
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WebSocket - algorithm
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WebSocket - opportunities
Bidirectional communications between client and server
Cross-domain requests
Binary or text data
Usage of extensions and subprotocols
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WebSocket - disadvantagesDoesn’t work at <IE10, android browsers <4.4, iOS Safary <6.0, Safary <6
Possible problems with proxy
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Useful tools
http://caniuse.com/
http://crossbrowsertesting.com/
http://www.browserstack.com/
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Questions?
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