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Senin, 08 September 2008

Using Peer-to-Peer Data Routing for Infrastructure-based Wireless Networks

Authors: Sethuram Balaji Kodeswaran, Olga Vladi Ratsimor, Anupam Joshi, Tim Finin, and Yelena Yesha

Book Title: First IEEE International Conference on Pervasive Computing and Communications

Date: March 18, 2003

Abstract: A mobile ad-hoc network is an autonomous system of mobile routers that are self-organizing and completely decentralized with no requirements for dedicated infrastructure support. Wireless Infrastructure in terms of base stations is often available in many popular areas offering high-speed data connectivity to a wired network. In this paper, we describe an approach where infrastructure components utilize passing by mobile nodes to route data to other devices that are out of range. In our scheme, base stations track user mobility and determine data usage patterns of users as they pass by. Based on this, base stations predict the future data needs for a passing mobile device. These base stations then collaborate (over the wired network) to identify other mobile devices with spare capacity whose routes intersect that of a needy device and use these carriers to transport the needed data. When such a carrier meets a needy device, they form ad hoc peer-to-peer communities to transfer this data. In this paper, we describe the motivation behind our approach and the different component interactions. We present the results of simulation work that we have done to validate the viability of our approach. We also describe, Numi, our framework for supporting collaborative infrastructure and ad hoc computing along with a sample application built on top of this highlighting the benefits of our proposed approach.


What's New in Firefox 3

Firefox 3 Beta 2 is a developer preview release of Mozilla's next generation Firefox browser and is being made available for testing purposes only.

These beta releases are targeted to Web developers and our testing community to gain feedback before advancing to the next stage in the release process. The final version of Firefox 3 will be released when we qualify the product as fully ready for our users. Users of the latest released version of Firefox should not expect their add-ons to work properly with this beta.

Much of the work leading up to this beta has been around developing the infrastructure to support a bunch of exciting new features. With this second beta, you'll get a taste of what's coming in Firefox 3, but there's still more to come, and much of what you'll see is still a bit rough around the edges.

Please see below for an extensive list of features and enhancements found in Firefox 3 Beta 2, as well as known issues and frequently asked questions.

As always, we appreciate your feedback either through this feedback form or by filing a bug in Bugzilla.

What's New in Firefox 3

Firefox 3 is based on the new Gecko 1.9 Web rendering platform, which has been under development for the past 28 months and includes nearly 2 million lines of code changes, fixing more than 11,000 issues. Gecko 1.9 includes some major re-architecting for performance, stability, correctness, and code simplification and sustainability. Firefox 3 has been built on top of this new platform resulting in a more secure, easier to use, more personal product with a lot under the hood to offer website and Firefox add-on developers.

[Improved in Beta 2!] Firefox 3 Beta 2 includes approximately 900 improvements over the previous beta, including fixes for stability, performance, memory usage, platform enhancements and user interface improvements. Many of these improvements were based on community feedback from the previous beta.

More Secure
  • One-click site info: Click the site favicon in the location bar to see who owns the site. Identity verification is prominently displayed and easier to understand. In later versions, Extended Validation SSL certificate information will be displayed.
  • Malware Protection: malware protection warns users when they arrive at sites which are known to install viruses, spyware, trojans or other malware. You can test it here (note: our blacklist of malware sites is not yet activated).
  • New Web Forgery Protection page: the content of pages suspected as web forgeries is no longer shown. You can test it here.
  • New SSL error pages: clearer and stricter error pages are used when Firefox encounters an invalid SSL certificate.
  • Add-ons and Plugin version check: Firefox now automatically checks add-on and plugin versions and will disable older, insecure versions.
  • Secure add-on updates: to improve add-on update security, add-ons that provide updates in an insecure manner will be disabled.
  • Anti-virus integration: Firefox will inform anti-virus software when downloading executables.
  • Vista Parental Controls: Firefox now respects the Vista system-wide parental control setting for disabling file downloads.
  • [Improved in Beta 2!] Effective top-level domain (eTLD) service better restricts cookies and other restricted content to a single domain.
  • [Improved in Beta 2!] Better protection against cross-site JSON data leaks.
Easier to Use
  • Easier password management: an information bar replaces the old password dialog so you can now save passwords after a successful login.
  • Simplified add-on installation: the add-ons whitelist has been removed making it possible to install extensions from third-party sites in fewer clicks.
  • [Improved in Beta 2!] New Download Manager: the revised download manager makes it much easier to locate downloaded files, and displays where a file came from.
  • Resumable downloading: users can now resume downloads after restarting the browser or resetting your network connection.
  • Full page zoom: from the View menu and via keyboard shortcuts, the new zooming feature lets you zoom in and out of entire pages, scaling the layout, text and images.
  • Tab scrolling and quickmenu: tabs are easier to locate with the new tab scrolling and tab quickmenu.
  • Save what you were doing: Firefox will prompt users to save tabs on exit.
  • Optimized Open in Tabs behavior: opening a folder of bookmarks in tabs now appends the new tabs rather than overwriting.
  • Location and Search bar size can now be customized with a simple resizer item.
  • Text selection improvements: multiple text selections can be made with Ctrl/Cmd; double-click drag selects in "word-by-word" mode; triple-clicking selects a paragraph.
  • Find toolbar: the Find toolbar now opens with the current selection.
  • Plugin management: users can disable individual plugins in the Add-on Manager.
  • Integration with Vista: Firefox's menus now display using Vista's native theme.
  • Integration with the Mac: Firefox now uses the OS X spellchecker and supports Growl for notifications of completed downloads and available updates.
  • [Improved in Beta 2!] Integration with Linux: Firefox's default icons, buttons, and menu styles now use the native GTK theme.
More Personal
  • Star button: quickly add bookmarks from the location bar with a single click; a second click lets you file and tag them.
  • Tags: associate keywords with your bookmarks to sort them by topic.
  • [Improved in Beta 2!] Location bar & auto-complete: type in all or part of the title, tag or address of a page to see a list of matches from your history and bookmarks; a new display makes it easier to scan through the matching results and find that page you're looking for.
  • [Improved in Beta 2!] Smart Bookmarks Folder: quickly access your recently bookmarked and tagged pages, as well as your more frequently visited pages with the new smart bookmarks folder on your bookmark toolbar.
  • [Improved in Beta 2!] Places Organizer: view, organize and search through all of your bookmarks, tags, and browsing history with multiple views and smart folders to store your frequent searches.
  • [Improved in Beta 2!] Web-based protocol handlers: web applications, such as your favorite webmail provider, can now be used instead of desktop applications for handling mailto: links from other sites. Similar support is available for other protocols (Web applications will have to first enable this by registering as handlers with Firefox).
  • Easy to use Download Actions: a new Applications preferences pane provides a better UI for configuring handlers for various file types and protocol schemes.
Improved Platform for Developers
  • New graphics and font handling: new graphics and text rendering architectures in Gecko 1.9 provides rendering improvements in CSS, SVG as well as improved display of fonts with ligatures and complex scripts.
  • Native Web page forms: HTML forms on Web pages now have a native look and feel on Mac OS X and Linux (Gnome) desktops.
  • Color management: (set gfx.color_management.enabled on in about:config and restart the browser to enable.) Firefox can now adjust images with embedded color profiles.
  • Offline support: enables web applications to provide offline functionality (website authors must add support for offline browsing to their site for this feature to be available to users).
  • A more complete overview of Firefox 3 for developers is available for website and add-on developers.
Improved Performance
  • Reliability: A user's bookmarks, history, cookies, and preferences are now stored in a transactionally secure database format which will prevent data loss even if their system crashes.
  • [Improved in Beta 2!] Speed: Major architectural changes (such as the move to Cairo and a rewrite to how reflowing a page layout works) put foundations in place for major performance tuning which have resulted in speed increases in Beta 2, and will show further gains in future Beta releases.
  • [Improved in Beta 2!] Memory usage: Over 300 individual memory leaks have been plugged, and a new XPCOM cycle collector completely eliminates many more. Developers are continuing to work on optimizing memory use (by releasing cached objects more quickly) and reducing fragmentation. Beta 2 includes over 30 more memory leak fixes, and 11 improvements to our memory footprint.

Firefox 3 Beta Release Notes

Firefox 3 Beta 2 is a developer preview release of Mozilla's next generation Firefox browser and is being made available for testing purposes only.

These beta releases are targeted to Web developers and our testing community to gain feedback before advancing to the next stage in the release process. The final version of Firefox 3 will be released when we qualify the product as fully ready for our users. Users of the latest released version of Firefox should not expect their add-ons to work properly with this beta.

Much of the work leading up to this beta has been around developing the infrastructure to support a bunch of exciting new features. With this second beta, you'll get a taste of what's coming in Firefox 3, but there's still more to come, and much of what you'll see is still a bit rough around the edges.

Please see below for an extensive list of features and enhancements found in Firefox 3 Beta 2, as well as known issues and frequently asked questions.

As always, we appreciate your feedback either through this feedback form or by filing a bug in Bugzilla.

Are the Browser Wars Back?How Mozilla's Firefox trumps Internet Explorer.

I usually don't worry about PC viruses, but last week's Scob attack snapped me awake. The clever multi-stage assault, carried out by alleged Russian spam crime lords, infiltrated corporate Web servers and then used them to infect home computers. The software that Scob (also known as Download.ject) attempted to install on its victims' machines included a keystroke logger.

In less than a day, Internet administrators sterilized the infection by shutting down the Russian server that hosted the spyware. But not before a barrage of scary reports had circled the world. "Users are being told to avoid using Internet Explorer until Microsoft patches a serious security hole," the BBC warned. (Disclosure: Microsoft owns Slate.) CNET reporter Robert Lemos zeroed in on why the attack was so scary. "This time," he wrote, "the flaws affect every user of Internet Explorer." That's about 95 percent of all Net users. No matter how well they had protected themselves against viruses, spyware, and everything else in the past, they were still vulnerable to yet another flaw in Microsoft's browser.

Scob didn't get me, but it was enough to make me ditch Explorer in favor of the much less vulnerable Firefox browser. Firefox is built and distributed free by the Mozilla Organization, a small nonprofit corporation spun off last year from the fast-fading remnants of Netscape, which was absorbed by AOL in 1999. Firefox development and testing are mostly done by about a dozen Mozilla employees, plus a few dozen others at companies like IBM, Sun, and Red Hat. I've been using it for a week now, and I've all but forgotten about Explorer.



You've probably been told to dump Internet Explorer for a Mozilla browser before, by the same propeller-head geek who wants you to delete Windows from your hard drive and install Linux. You've ignored him, and good for you. Microsoft wiped out Netscape in the Browser Wars of the late 1990s not only because the company's management pushed the bounds of business ethics, but also because its engineers built a better browser. When Netscape CEO Jim Barksdale approved the Mozilla project—an open-source browser based on Netscape's code—in 1998, it seemed like a futile act of desperation.

But six years later, the surviving members of the Mozilla insurgency are staging a comeback. The latest version of Firefox, released this Monday, has a more professional look, online help, and a tool that automatically imports your bookmarks, history, site passwords, and other settings from Explorer. Meanwhile, all-conquering Internet Explorer has been stuck in the mud for the past year, as Microsoft stopped delivering new versions. The company now rolls out only an occasional fix as part of its Windows updates. Gates and company won the browser war, so why keep fighting it?

The problem is that hackers continue to find and exploit security holes in Explorer. Many of them take advantage of Explorer's ActiveX system, which lets Web sites download and install software onto visitors' computers, sometimes without users' knowledge. ActiveX was meant to make it easy to add the latest interactive multimedia and other features to sites, but instead it's become a tool for sneaking spyware onto unsuspecting PCs. That's why the U.S. Computer Emergency Readiness Team, a partnership between the tech industry and Homeland Security, recently took the unusual step of advising people to consider switching browsers. Whether or not you do, US-CERT advises increasing your Internet Explorer security settings, per Microsoft's instructions. (Alas, the higher setting disables parts of Slate's interface.) Even if you stop using Explorer, other programs on your computer may still automatically launch it to connect to sites.

Firefox eschews ActiveX and other well-known infection paths. You can configure it to automatically download most files when you click on them, but not .exe files, which are runnable programs. I thought this was a bug before I realized Firefox was saving me from myself, since .exe files could be viruses or stealth installers.

For actual Web surfing, Firefox's interface is familiar enough to Explorer users. There's hardly anything to say about it, which is a compliment. Some interactive features designed exclusively for Internet Explorer won't appear, such as the pop-up menus on Slate's table of contents. A few sites don't display properly, but they're pretty rare. More common are those that stupidly turn non-Explorer browsers away by claiming they're "unsupported." Trusty, useful ActiveX-powered sites such as Windows Update don't load at all, but that's the idea. You can always launch Internet Explorer for those when you need to.

Firefox also adds a productivity feature that Explorer has never gotten around to: tabbed browsing. You can open several Web pages in the same window and flip through them as tabs, similar to those used in some of Windows' dialog boxes. It's tough to understand why tabbed browsing is such an improvement until you've tried it. But if you're in the habit of opening a barrage of news and blog links every morning and then reading them afterward, or clicking on several Google results from the same search, tabbed browsing is an order of magnitude more efficient and organized than popping up a whole new window for each link.

That said, be aware that getting started with Firefox isn't a one-click operation. After installing the browser, you'll need to reinstall plug-ins for some programs, as well as Sun's Java engine for any Java-powered pages. Let me save you an hour of head-scratching here: Save Sun's Java installation file to your desktop, then go back to Firefox's menus and select File -> Open File to install the downloaded .xpi file into the browser. That'll work where other methods fail without explanation.

Once you're set up, it still takes a day or two to get used to the interface and feature differences between Explorer and Firefox, as well as the fact that your favorite sites may look a little different. That's why I left it out of Slate's 20-minute anti-virus plan. But if you've got time to make the switch, the peace of mind is worth it. Mozilla also makes a free e-mail program called Thunderbird and a calendar tool called Sunbird, if you want to avoid using Outlook and Outlook Express, two other virus carriers. They're nowhere near as feature-packed as Outlook, but the e-mail client includes a spam filter that works pretty well after you train it on four or five thousand messages—in my case, one week's mail.

Will Firefox make your computer hackproof? Even Mozilla's spokespeople stress that no software can be guaranteed to be safe, and that Firefox's XPInstall system could conceivably be tricked into installing a keystroke logger instead of Sun's Java engine. But for now, there's safety in numbers—the lack of them, that is. Internet Explorer is used by 95 percent of the world. Firefox's fan base adds up to 2 or 3 percent at most. Which browser do you think the Russian hackers are busily trying to break into again?