Random Bits

In the Fall 2008 IAP poster presentation contest I presented my on-going research on “Capacity proportional unstructured p2p networks”.

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This graph was generated using circo, a tool part of the graphviz package. The legend and the graph were generated separately and merged using paint. The graph represents simulation of a heterogeneous P2P network.

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A Talk given by Ian Pratt in Usenix 2008 on goals and challenges of virtualization and how they are handled in Xen. Couple of interesting snippets from the talk:-

• Live relocation - Mechanism for moving a virtual machine from one physical server to another. It performs iterative memory transfer between machines using an intermediate dirty log file for each iteration. The changes in the log file are transferred in next iteration. This would gradually reduce the size of the dirty log file to a point where it is small enough to make the switch over with negligible downtime.
• Virtualization of mobiles - To provide isolation between different types of applications running on mobile phones. For example we can have 3 VMs on a mobile phone one each for running - core radio services, vendor shipped content and user downloaded content.

Ian Pratt, a senior lecturer in University of Cambridge Computer Laboratory stresses the importance of making the university projects open source and pursuing them beyond an academic paper. He acknowledges the challenges faced in taking Xen from a research project to a production quality software as a humbling experience.

This site now provides GWebCache service at http://gwc.chandanr.net/skulls.php. It can be used to bootstrap Gnutella (Limewire, Morpheus) and Gnutella2 (Shareaza) networks. I am using the Skulls Multi-Network Web cache system for this service.

Related Info:- Gnutella Web cache scan report

The “real” CLI for windows. Unlike our favourite shells like bash where output of a command is text, PowerShell deals with .NET objects. This makes pipe’ing etc very convenient. For example we can do things like:-

• PS C:\Users\Chandan> ps | Where-Object {$_.Handles -gt 1000}

Handles NPM(K) PM(K) WS(K) VM(M) CPU(s) Id ProcessName
——- —— —– —– —– —— — ———–
2313 0 0 848 8 4 System
…

• PS C:\Users\Chandan> ps firefox | format-list

Id : 3432
Handles : 883
CPU : 369.8315707
Name : firefox

• PS C:\Users\Chandan> (ps firefox).get_Id()

3432

• PS C:\Users\Chandan> (ps firefox).ProductVersion

2.0.0.12

With the exposure of objects, Powershell scripting is somewhat similar to application-level scripting supported by protocols like DCOP. Another very interesting feature in PowerShell is the concept of PSDrives and Providers which enable use of generic methods for navigating filesytem, registry, environment etc.

• PS C:\Users\Chandan> psdrive

Name Provider Root CurrentLocation
—- ——– —- —————
C FileSystem C:\ Users\Chandan
Env Environment
HKCU Registry HKEY_CURRENT_USER
…

• PS C:\Users\Chandan> cd env:

• PS Env:\> ls

Name Value
—- —–
Path C:\Windows\System32\WindowsPowerShell\v1.0\;C:\Program Files\Microsoft Visual Studio …
TEMP C:\Users\Chandan\AppData\Local\Temp
SESSIONNAME Console
…

Links

Video: Jeffrey Snover talks about Monad/PowerShell
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Found this interesting article on Justin Frankel - the man behind Winamp, Gnutella etc. It traces the events in Justin’s life around the invention of winamp, release of gnutella and the constant suppression of his ideas in AOL.

Ever wondered what inspired the name Gnutella?

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Video describing idea behind creative commons licensing.

The above link is a MagnetURI, which was listed in MagnetMix. You need to have a p2p client like LimeWire to download and view the video. MagnetURI is a nice way to publish content from your local machine. It is kind of similar to a torrent file, but works across different p2p clients and is convenient to handle URI strings when compared to meta-files.

Wikicharts is a tool to get the most viewed pages of the month in wikipedia. No points for guessing the most viewed page of Wikipedia: the Main Page :). Wikicharts can be embedded into a wiki to get its usage statistics. Check out the wikicharts wikipedia page for details of how it works.
List of all the wikimedia tools.(takes some time to load)

A New Way to look at Networking - Van Jacobson

Zero configuration networking with Bonjour - Dr. Stuart Cheshire, Apple Computer

Scalable Internet routing table using Locator/ID Seperation protocol(LISP) - Dino Farinacci

Everything is miscellaneous - David Weinberger

Yesterday we* released the code of “AniGraph” - A visualization tool for Graph based Algorithms. This project was done a couple of years back for IEEE Indicon Student Design Contest conducted by IIT KGP branch of IEEE.

Using AniGraph one can playback the execution sequence of any Graph based Algorithm. It provides a C++ API, which can be used for recording visualisation events at key stages of the program implementing the algorithm. On executing this “AniGraph-Instrumented code”, specified events are recorded into a log file. This file can then be “played” in the AniGraph visualizer, which internally uses the “Dot” system for generating images of the graphs.

AniGraph can be used as an aid for teaching Algorithms. Since AniGraph is agnostic of the algorithm being visualized, it can be used to animate any Graph (or Tree) based algorithm.
* - Myself, Srikar and Praveena developed AniGraph during our final year in NITK, Surathkal.

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