With Service Workers, when a user calls a certain website, an interface stored on the device is brought to the screen first, rather than a page delivered by a server. Instead of downloading a series of single pages, a user connecting to a site is synchronizing an existing local data set with a master data set on the server.
Service Workers are procedural in nature, meaning developers can write scripts to carry out complex actions, such as caching material for offline use or interpreting a stream of complex instructions sent by the server for a rich Web application.
They work in asynchronous mode — in the background — and won't block any other operations on the browser. A page won't stop loading, for instance, when waiting for a large image file.
In addition to offering a buffer of content and additional local functionality, Service Workers could also improve the response times of websites, Russell said.
Today, a Web page should load within about 1,000 milliseconds to feel instantaneous to the user, Russell said. This can be a challenging time frame given the immense amount of overhead needed to contact a server and have it deliver a Web page, especially over a cellular network.
With the standard Internet TCP/IP stack running over a cellular network, anywhere from 300 to 700 milliseconds are required just to get the client and server chatting with each other.
Service Workers could speed user interactions by up to 600 milliseconds for every second of a Web transaction.
Correctly configured, Service Workers could eliminate or streamline networking operations such as DNS (Domain Name Service) Web address lookups, TCP and control plane setup, encryption handshakes and the overhead incurred by HTTP requests.
The project is one of a number of recent initiatives that Google has taken to improve the performance of the Web for users and developers. The company will typically generate new technology and then work to get it standardized so it can be used by all Web browsers.
Another project Google has underway in this regard is Web Components, which could provide a way to assemble complex Web pages using small single-function components.
Google is in the process of incorporating Service Workers into its Chrome browser by the end of the year. Firefox is also implementing Service Workers, Russell said.
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