Google Chrome
Google Chrome is a web browser released by Google
which uses the Webkit layout engine and application framework.
It was first released as a beta version for Microsoft
Windows on 2 September 2008. Google also released the entire source code of Chrome,
including itsV8 JavaScript engine, as an open source project entitled Chromium.
This move enabled third-party developers to study the source code and help port
the browser to Mac OS X and Linux.
In December 2009, Chrome was the third most widely used browser, with
4.4% of worldwide usage share of web browsers.
Features
Google Chrome aims to improve security, speed, and stability. Many of
Chrome's unique features had been previously announced by other browser
developers, but Google was the first to implement and publicly release them. For example, its most prominent graphical user interface (GUI) innovation, the merging of the address bar and search bar (the Omnibox) was first announced by Mozilla in May 2008 as a planned feature for Firefox.
Security
Chrome periodically downloads updates of two blacklists (one for phishing and one for malware), and warns users when
they attempt to visit a harmful site. This service is also made available for
use by others via a free public API called "Google Safe Browsing API".
Speed
The JavaScript virtual machine used by Chrome, the V8 JavaScript engine, has features such as dynamic code
generation, hidden class transitions and precise garbage
collection. Tests by Google in September 2008 showed that V8 was about twice as fast
as Firefox 3.0 and the WebKit nightlies.
Stability
The Gears team implemented a multi-process architecture in Chrome, similar to “Loosely Coupled Internet Explorer” (LCIE) implemented by Internet Explorer 8. By default, a separate process is
allocated to each site instance and plug-in, a procedure referred to as process isolation. This prevents tasks from interfering with
each other, increasing security and stability. An attacker successfully gaining
access to one application cannot gain access to others, and failure in one
instance results in a Sad Tab screen of death, similar to the well-known Sad Mac, except only a single tab crashes
instead of the whole application. This strategy exacts a fixed per-process cost
up front, but results in less memory bloat overall as fragmentation is confined
to each instance and no longer requires further memory allocations.
Interface
By default, the main user
interface includes back, forward, refresh, home, bookmark, go, and cancel
buttons. The home button can be configured through options to take the user to
the New Tab Page or a custom home page.
Tabs are the primary
component of Chrome's user interface and as such, have been moved to the top of
the window rather than below the controls. This subtle change contrasts with
many existing tabbed browsers which are based on windows and contain
tabs. Tabs (including their state) can be transferred seamlessly between window
containers by dragging. Each tab has its own set of controls, including
the Omnibox.
The Omnibox is the URL box at the top of each tab, which combines the functionality of both the
Address bar and search box. If you enter the URL of a site you have previously
searched from, Chrome will let you press Tab to search the site again directly from the
Omnibox. When you start typing in the Omnibox, Chrome provides suggestions for
previously visited sites (based on the URL or in-page text), popular websites
(not necessarily visited before), and popular searches. Chrome will also autocomplete the URLs of sites you visit often.
Extensions
On 9 September 2009, Google enabled extensions by default on Chrome's
Dev channel, and provided several sample extensions for testing. On 23 November
2009, Google opened Chrome's extension gallery to developer submissions,
promising a public beta launch soon. The extension gallery beta was
officially launched on 8 December 2009, containing over 300 extensions.
External links
§ Google Chrome Homepage and download site
§ Google Chrome Feature List
§ Chromium project page at Google Code
§ The Chromium blog from Google
§ Google Chrome Comic
Book
Created by Alvaro Sánchez Pérez, NIA 100275594, grouo 69
Last edition: 9:50 18/12/2009
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