Pages: pp. 12-15
"Assuring VoIP Quality: Not There Yet," by Art Wittmann.
Wittmann argues that service providers have yet to meet the challenge of consistent high-quality Voice-over-IP transmissions. To explain why, he describes two existing metrics used to measure voice quality: mean opinion score (MOS) and perceptual evaluation of speech quality (PESQ). MOS, the longtime standard, employs user ratings or their statistical equivalents to rate quality on a scale of one to five. A PESQ test, still relatively new, places a known sound file onto a VoIP network at point A and extracts it at point B, using computational analysis to compare the two. However, both are too labor-intensive to be ongoing practical solutions for VoIP. Wittmann also points out that neither MOS nor PESQ takes into account other quality issues such as network delays and echoes. However, he predicts major steps forward in addressing these issues over the next six to 12 months, based on the work of vendors such as Telchemy and Psytechnics.
"Google to go VoIP?" by David Greenfield.
Although the company refused to comment, Google could have plans to launch a voice-over-IP (VoIP) service; several recent developments seem to indicate that it's at least investigating the possibility. Google recently advertised for "strategic negotiator candidates with experience in ... identification, selection, and negotiation of dark fiber contracts ... as part of development of a global backbone network."
This led some analysts to theorize that Google might be looking to compete with Skype by moving into the consumer VoIP service. But unlike Skype, which uses only the Internet, Google might be investigating addressing quality and reliability in VoIP by investing in "dark," or unused, cable capacity to execute its service.
"Digital Libraries & XML-Relational Data Binding," by Rene Reitsma, Brandon Whitehead, Venkata Satya, and Gokul Suryadevara
As digital libraries become more prevalent, making them accessible electronically to a wide array of audiences is increasingly important. Developers must find ways to not only run internal searches but also let outsiders search library collections and metadata. Reitsma and colleagues are developing the US National Science Foundation-supported TeachEngineering ( www.teachengineering.com), an XML-based digital library of K–12 math and science curricula. They opted to use a separate relational XML database for searches to eliminate the lengthy task of searching the large XML collection in real time. This choice would ordinarily present difficulties — conversion into the relational model typically requires code that contains the semantics of the XML model, the relational model, or both — but the authors essentially made the XML-relational mapping rules into data used by the mapping program, instead of embedding them into the program code itself. This article describes, in detail, how they did it.
"Call Control XML and The Voice Conference Manager," by Moshe Yudkowski
One of the drawbacks of conference calls is "first-party call control," which means the call automatically ends if the person who placed it hangs up. Yudkowski outlines a method for writing an application that lets businesses grant themselves "third-party call control," much like operators who set up conference calls and then drop out without affecting the conversation. Interested developers need only a telephony server to control the phone network and an API to control the telephony server, he says. He then describes the specifics of the Voice Conference Manager (VCM) application, which initiates conference calls by combining Call Control XML (an API from the W3C) and the VoiceXML speech recognition API. Source code is available for VCM at www.ddj.com.
22 March 2005
"Beyond Wordplay," by Sebastian Rupley
Liquid Information — a project led by the inventor of the mouse, Doug Engelbart, and British researcher Frode Hegland — aims to someday allow every word on a Web page to be a link that points to multiple locations. To try it out, visit www.liquidinformation.org and click on the Demo link. According to its mission statement, Liquid Information wants to "wake people up to the possibilities of interactive text."
"IP from an Airship, "by Penny Lunt Crosman
Sanswire Networks, a subsidiary of GlobeTel, is trying to prove that it can provide wireless broadband access via a 245-foot-long unmanned airship hovering over a GPS coordinate 65,000 feet above ground. If the attempt works, plans call for offering IP communications via Wi-Fi and WiMAX to a region roughly 400 miles in diameter, potentially targeting underserved areas worldwide, including those in China and Africa. In addition to being cheaper than launching a satellite (US$4 million versus $300 million), the "stratellite" also eliminates satellite IP communication's tendency toward latency.
As of this writing, US Federal Aviation Administration concerns regarding safety shifted the first experimental flight from the company's site in San Bernardino, California, to Edwards Air Force Base, 90 miles north of Los Angeles. The launch could occur during the last two weeks of April. For more information, visit www.sanswire.com.
"Is 3G Worth the Wait? "by Andy Dornan
Last year, Verizon Wireless began offering faster third-generation (3G) cellular networks in 20 cities, and it hopes to make them available to more than half the US population by December. Its rivals, including Sprint PCS and Cingular Wireless, have plans for similar programs that bring US customers the 3G rates that have let European and Asian consumers experience download speeds of at least 2 Mbps for some time.
Dornan uses these developments to launch a discussion of many issues surrounding 3G networks from the perspectives of carriers, businesses, and consumers. For example, will carriers opt to offer outsourced IT services to enterprise customers to help convert those customers' in-house applications to cell phones, or will they offer competing applications? Exactly what kind of business-class services will the marketplace begin offering on 3G networks? How will smartphones fit into the picture? In the end, Dornan reviews various possibilities without many definitive answers. For now, however, he notes that wireless carriers seem most comfortable catering to the consumer, rather than the enterprise, market.
"Evil Twin Haunts Wi-Fi Users" by Matthew Broersma
"Evil Twin," the latest security issue for Wi-Fi users using hotspots, uses malicious servers to make users believe they're connecting to legitimate hotspots. Philip Nobles, a lecturer at Cranfield University in the United Kingdom, says anyone with the correct equipment in the vicinity of a genuine base station can create an evil twin, and he expects the practice to grow as hotspots do. The good news is that users can use basic security measures to alleviate most problems.
12 April 2005
"MIMO Means Wireless," by Craig Ellison
Ellison reviews the different multiple-input multiple-output (MIMO) technologies behind the three latest wireless-access-point client-card combinations on the market. The magazine's reviewers gave the highest score to Airgo Networks' product, which is used in the Linksys WRT54GX router. Airgo's MIMO technology uses multiple transmitters, receivers, and antennas in both the client cards and access points. The second technology, which Atheros Communications uses in its D-Link DI-624M router, uses smart-radio technology and multiple radios. Its transmitters and antennas use "beam forming" to direct output power toward the receivers, and antennas and receivers on the receiving end reverse the process, improving signal strength by as much as 5 decibels relative to isotropic (dBi). The magazine also reviewed Video 54's MIMO technology in the beta version of Netgear's RangeMax, which used seven antennas in its access-point and antenna-switching technology to send the best possible signal to users. As Ellison points out, however, these products offer stopgap solutions until the forthcoming 802.11n standard is finalized, and it's unlikely that any of them will be upgraded to meet that standard.
"Collaborative Web Surfing," by Gigi Sayfan
Cosurfer is a peer-to-peer GUI application that lets users chat and surf the Web together. It uses Internet Explorer to coordinate users' surfing — whenever one person's browser moves to a new URL, the other's is automatically updated to that same location, and the two can also exchange comments online simultaneously. Sayfan describes how to launch a new instance of IE, plug into its events, manage its navigation, and "drill down" the HTML DOM. The complete source code for Cosurfer — which includes several aspects of .NET programming — is available through www.ddj.com.
"SIP Goes Peer-to-Peer," by David Greenfield
More than one project is in the works on new P2P versions of the IETF's VoIP standard Session Initiation Protocol (SIP). Researchers at Columbia University, where SIP was created, have already developed a prototype. Assorted SIP luminaries — including Robert Sparks, CTO of Xten Networks, and Adam Roach, a distinguished engineer with Cisco Systems' Voice Technology Group — are said to be working on one, too. The new technology would give businesses the benefits of P2P protocols, lowering implementation expenses and reducing IT departments' reliance on VoIP service providers to set up an office environment.
"Exploring WS-Notification," by Marco Aiello, Manuel Zanoni, and Alessandro Zolet
Thanks, in part, to wireless connectivity standards such as the Global System for Mobile Communications (GSM), IEEE 802.11 (Wi-Fi), and IEEE 802.15.4 (ZigBee), outfitting home appliances with the ability to wirelessly connect has become simple and affordable. The authors argue that such devices still don't use the wireless infrastructure properly, however, and advocate using XML-based Web services. In particular, they outline how they used WS-Notification — which lays out a standard approach to notification using a topic-based publish-subscribe mechanism — with sensors and actuators to try to detect life-threatening situations, such as when an elderly person falls in his or her home. WS-Notification offers standard methods for building ontologies of topics for describing events, provides a way for consumers and event producers to communicate, and offers a policy for event forwarding and subscriptions. Consequently, it allows for building scalable, platform-independent systems made of autonomous nodes that exchange messages asynchronously.
"Web Services Take Hold," by Maryann Jones Thompson
Several analyst teams are predicting that interest in Web services will continue to grow in corporate IT departments. The Radicati Group predicts that the market for Web services development tools will reach US$6.2 billion by 2008. Gartner estimates that 63 percent of businesses using Web services are using them to integrate internal projects, whereas the rest are using them to join internal systems to partners or customers. A third study showed that almost 40 percent of large US businesses already use Web services and another 21 percent are either implementing or evaluating them.
"Spy Act: A License to Spy?" by Andrew Conry-Murray
Critics warn that the Securely Protect Yourself Against Cyber Trespass (SPY ACT) act, an anti-spyware bill now winding its way through the US Congress, contains loopholes large enough to let adware companies continue installing software on consumers' computers. As of this writing, the bill appears destined to allow user consent via End User License Agreements (EULAs), in which users click "Yes, I agree" to begin installations.
Although reasonable enough on its surface, the requirement could let adware firms legally hide the number and nature of the programs being downloaded by using lengthy or vague EULAs. The "SPY ACT sets out low standards for what [adware companies] have to disclose," says Ben Edelman, a spyware researcher who has given expert testimony in several spyware lawsuits.
Richard Stiennon, vice president of threat research at anti-spyware vendor Webroot Software, says the bill is valuable in that it requires adware to be "easily identifiable to the user" and says that removing it must be something that computer users can do without undue effort.
"802.1x Enables Comply or Deny for PCs," by Andrew Conry-Murray
Although the IEEE 802.1x device-authentification standard was created three years ago to serve the Ethernet LAN environment, network architects have largely chosen not to use it because of the difficulties involved in deploying it. With the advent of host policy enforcement, however, 802.1x is now garnering renewed interest among LAN architects as a way to reduce the risks associated with laptops and other potentially untrustworthy mobile devices that connect to LANs.
802.1x has become the foundation for several host policy enforcement initiatives that deny or allow network access depending on a machine's security settings. In fact, it's one of the only things the various host policy enforcement products on the market have in common because standardization efforts in the area are not yet complete. 802.1x policy enforcement — which forces a host to authenticate devices before it assigns an IP address — requires several components, including an authentication server, an authenticator, a supplicant (a software client that sits on the endpoint), and the Extensible Authentication Protocol.
"RDF: The Resource Description Framework," by Bob Ducharme
Developers can store pieces of RDF data anywhere and easily combine them into databases to query or use for reports and graphs. As a result, RDF has become part of the very foundation of the Semantic Web, and developers are finding new ways to use it because little code is needed to build applications around it.
Ducharme explains RDF's basic data structure and describes its flexibility and how software engineers are using it to manage distributed data. He also briefly describes RDF graphs and some open-source libraries that can help users write applications using RDF.
"Developments Advance Web Conferencing," by David Geer
The Web conferencing arena has become a fast-growing marketplace, with global sales increasing 70 percent between 2002 and 2004 to US$765 million. Many firms are now jumping in to see whether new innovations might send them to the front of the pack. Geer reviews the three kinds of Web conferencing options currently available. In addition to the traditional service-based concept run by a third party, some companies are offering businesses the option of owning their own conferencing servers and running the program themselves. Still others are offering hybrid solutions in which businesses buy their own on-site servers and hire carriers to manage those servers for them. The article examines the pros and cons of each option.IT Professional, www.computer.org/itpro/
"Federal Web Site Accessibility for People with Disabilities," by Eleanor T. Loiacono, Scott McCoy, and William Chin
The authors studied Web sites for US federal government agencies and their contractors and found that few make efforts to accommodate the more than 54 million Americans who are physically disabled. Yet, they also found that the sites could provide better access for the disabled without undue effort or expense. The study examined 417 sites and found very similar obstacles to accessibility, including failure to use relative sizing and positioning to accommodate users who might need to change font size (85 percent); failure to offer alternative text for all images (62 percent); and failure to offer an alternative to the mouse (42 percent).