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Comment: Latency vs. bandwidth (Score 1) 151

by aharth (#37256538) Attached to: Google and OpenDNS Work On Global Internet Speedup
There are two factors that affect the performance of web (HTTP) lookups: latency and bandwidth. Latency depends on the distance between client and server. You won't be able to send data faster than the speed of light. Bringing the data closer to the client helps to reduce latency, especially for small lookups. Bandwidth becomes the limiting factor when you transfer (large amounts of) data over under-dimensioned pipes. In general, I'd be a much more happy person if people would use HTTP caching headers (Expires and such) more often, as then a Squid proxy can bring substantial performance gains.

Comment: Linked Data? (Score 1) 62

by aharth (#31419106) Attached to: Open Data Needs Open Source Tools
Semantic Web technologies (in particular RDF, a graph-structured data format) are ideally suited for publishing data. Also, these technologies facilitate the integration of separate pieces of information; integration is what you want to do if thousands of people start publishing structured data. Linked Data (RDF using HTTP URIs to identify things) is already used by the NYT and the UK government to publish data online.

Comment: Re:Data Search Interface (Score 1) 65

by aharth (#30840246) Attached to: Attractive Open Source Search Interfaces?
Yes, the better the data the better the system will work. However, VisiNav works quite well on relatively scruffy web data due to the integrated ranking component.
The underlying data has to be in graph-structured format (in RDF syntax); reasoning, most notably object consolidation, is supported via OWL. Once the data is indexed, users can search and browse right away. There's no configuration needed, because the ordering of data is done based on the calculated ranks. The UI can be configured via XSLT and CSS for adding a logo or changing the look and feel.
We've developed VisiNav as part of a research project, and the university owns (and manages) the IP. I guess they will make it available free of charge for educational and research organisations, but commercial applications would require a license.

Comment: Data Search Interface (Score 1) 65

by aharth (#30759202) Attached to: Attractive Open Source Search Interfaces?
Hi, there's also VisiNav which lets you assemble complex queries over data, covering keyword search and faceted browsing (as Flamenco) and a bit more (path navigation). Drag and drop UI, where people who don't know facets or path navigation can do keyword search without being distracted. -- Andreas. Disclaimer: I'm one of the developers of VisiNav.

Comment: Future Internet Symposium 2009 (Score 1) 370

by aharth (#29201845) Attached to: Who Will Fix the Internet? No One, Apparently
There's the Future Internet Symposium 2009 ( ) in Berlin next week which exactly targets the topic in the post. From the call for papers: "With over a billion users today's Internet is arguably the most successful human artifact ever created. The Internet's physical infrastructure, software, and content now play an integral part of the lives of everyone on the planet, whether they interact with it directly or not. Now nearing its fifth decade, the Internet has shown remarkable resilience and flexibility in the face of ever increasing numbers of users, data volume, and changing usage patterns, but faces growing challenges in meetings the needs of our knowledge society. Yet, Internet access moves increasingly from fixed to mobile, the trend towards mobile usage is undeniable and predictions are that by 2014 about 2 billion users will access the Internet via mobile broadband services. This adds a further layer of complexity to the already immense challenges."

Comment: Re:ah yes, semantic web via RDF is the future (Score 1) 50

by aharth (#28834533) Attached to: The Web of Data, Beyond What Google and Yahoo Show
The field has come a long way since 2001 or 2003.

The main obstacle to "this golden future" so far has been an insufficient amount of data published online. Many organisations sit on their data like hens sit on their eggs, and publishing data right requires some effort.

That's slowly changing, especially with more openness and transparency -- voluntarily or forced -- in all kinds of organisations and agencies (,, ), more people getting the idea of open data, and the establishing of simplified best practices on how to publish data on the web following the Linked Data paradigm.

It's about time that Yahoo and Google finally start to take note and add open data to their systems (which don't exploit the full power of these technologies but hey you've got to start somewhere).

Comment: Re:Linux FS for SDD drives? (Score 1) 93

by aharth (#27637517) Attached to: Creating a Low-Power Cloud With Netbook Chips

You misunderstand how that's supposed to work. You don't "free main memory" to SSD. The idea is to use SSD as a pre-buffer for RAM, so it's quicker to access than reading from disk.


But there's something wrong if the Linux kernel buffers SSD I/O in main memory and swaps code fragments to disk. At least that's what happened in my experiments.

Comment: Linux FS for SDD drives? (Score 1) 93

by aharth (#27605381) Attached to: Creating a Low-Power Cloud With Netbook Chips

I've been toying around with a Samsung 16GB SSD. Performance improvement over spinning disks in an I/O-heavy scenario was neglegible. Also, it seemed as if the Linux kernel was still using memory to buffer SSD disk I/O. Which somewhat negates the argument of using SSDs to free main memory for other stuff.

Any idea what type of OS/filesystem combination they were using?

"It ain't so much the things we don't know that get us in trouble. It's the things we know that ain't so." -- Artemus Ward aka Charles Farrar Brown