Multimedia Matters: Breathing Easier Over XML, At Least For Now
By Peter J. Brown
During the process of preparing my accompanying feature article on rich media delivery via satellite, it was difficult at best to avoid the bright lights cast by such things as personal video recorders, interactive TV and advertising, multimedia home platform (MHP), video-on-demand, Internet protocol TV (IPTV), DVB-H-based mobile video services and even digital multimedia broadcasting (DMB).
All of these services are either rich media-driven today or will become so in the very near future. As a result, the importance of the role played by extensible markup language (XML) in the background is likely to increase, and not just because of the critical metadata dimension. To date, satellite service providers have embraced XML for a variety of reasons.
"We are trying to standardize on XML as a data exchange format for metadata and other information between our custom and off-the-shelf systems. In the long run, eliminating proprietary integrations and file formats can only lead to more efficient and timely information exchanges between Ascent Media, its clients, and business partners," says Tony Lockard, vice president, technology development at Ascent Media Network Services. "The real challenge is the evolution of standards to leverage XML on a Web services infrastructure. We see advanced authoring format (AAF), material exchange format (MXF), which is a SMPTE standard (S377M), and other wrappers as key in the evolution of interoperability of devices. For the foreseeable future, the size of these XML files or wrappers does not impact any network performance."
Among other things, XML has been an excellent way to pull in data about what is being put up on networks, according to Howard Barouxis, director of sales, Thales Broadcast & Multimedia. "This includes BTV networks, IPTV solutions that we have deployed, and EPGs that we have generated with our Jade DVB-SI generator. XML has been especially useful with less conventional program guides we have created for private networks," he says.
"Compared to the 4 GB MPEG-2 files we shift, the associated XML metadata files are tiny," says David Jamieson, head of media solutions at BT Media and Broadcast. "The biggest issue is the metadata standards that are being used to define the content of the XML files, and the digital asset management systems that need to accept and ingest the content. The most common form or metadata being used is the folded A4 sheet of paper that sits in the plastic box that holds the tape."
OK, so why was I suddenly exhibiting some satellite-driven anxiety about the potential impact of XML? Recently, there has been considerable talk of the need for a faster XML in the future. In addition, a recent article in Network World penned by James Kobielus, a senior analyst with Burton Group, an IT advisory service, entitled "Taming the XML Beast" left me feeling a bit uneasy, too. Was my anxiety grounded in reality or just some fanciful distraction stemming from the change in seasons? After all, as Dave Jamieson noted above, the amount of XML traffic is miniscule.
Jeff Schumann, my contact at Mentat, which was recently acquired by Packeteer, reassured me that everything is OK.
"XML runs over TCP, so all of the usual TCP performance problems persist. The exact performance will depend on how XML is used. If there are few requests, and, to return large blocks of data, acceleration techniques can overcome the TCP performance issues to provide essentially the same performance as over a terrestrial network. If large numbers of small blocks of data are used, without a local XML proxy, performance will be limited by the latency," says Schumann.
As far as Kobielus is concerned, while TCP performance is important, the encoding of XML in the most efficient binary scheme is even more important. Compressing XML as much as possible when transmitting it over TCP, and reducing the amount of XML data that needs to be transmitted in the first place results in what Kobielus describes as optimized XML.
"Satellite service providers need to know that the flow of XML traffic will continue to grow. It will consume a greater proportion of satellite bandwidth. But it will increasingly be encoded in efficient binaries, so, throughout the next few years, XML will not be any more bandwidth-intensive than any other binary content format," says Kobielus.
In their recently published paper entitled, "Terminal Architecture Issues for Interactive and Reactive TV Media Using MHP-Java and MPEG4," Keith Baker, senior member, IEEE; Rop Pulles; and Pavel Sasno of the Philips Digital Systems Laboratories in Eindhoven, the Netherlands, write, among other things, that:
"Creating this highly experience driven media will demand new media creation flows, and the web services industries see this as one of the major economic drivers of the coming decade. And new protocols will emerge to handle these content flows: such as TV-Anytime for PVRs (Personal Video Recorders), or RSS (Really Simple Syndication) for the news syndication industry. XML will be one of the foundation blocks for these content creation flows, communication and translation of the content for re-purposing content to different channels and terminals. Efficiency in use of XML protocols for personalization of streamed mass media is a key feature of the terminal’s capabilities."
In closing, I guess I owe some sort of an apology to readers, who with the advent of spring prefer lighter fare, but I probably deserve some credit for saying absolutely nothing whatsoever about what needs to happen in order for the IP multimedia mubsystem (IMS) agenda to go forward.
In summary, satellites and XML can live in harmony, at least for now. Rejoice and celebrate spring.
Peter Brown is Via Satellite’s Senior Multimedia & Homeland Security editor.