Abstract
In this paper we discuss the design and implementation of Fellowship, a 300+ CPU, general use computing cluster based on FreeBSD. We address the design features including configuration management, network booting of nodes, and scheduling which make this cluster unique and how FreeBSD helped (and hindered) our efforts to make this design a reality.
Continue Reading…With the following procedure which make’s use of dns settings and a apache webserver it is possible to automaticly distribute the squid (or any other proxy server) proxy configuration :
Continue Reading…n an application where a user is given the ability to upload or edit a CSS file, you may want to allow them to validate it against the better known CSS validation standards. This ruby script can do just that, although it should be mentioned that it depends on curl and thus is only going to run under windows if you use something akin to CYGWIN.
Continue Reading…Using common scripting languages and their collection of Web modules, you can easily develop Web spiders.
Web spiders are software agents that traverse the Internet gathering, filtering, and potentially aggregating information for a user. Using common scripting languages and their collection of Web modules, you can easily develop Web spiders.
A spider is a program that crawls the Internet in a specific way for a specific purpose. The purpose could be to gather information or to understand the structure and validity of a Web site. Spiders are the basis for modern search engines, such as Google and AltaVista. These spiders automatically retrieve data from the Web and pass it on to other applications that index the contents of the Web site for the best set of search terms.
Similar to a spider, but with more interesting legal questions, is the Web scraper. A scraper is a type of spider that targets specific content from the Web, such as the cost of products or services. One use of the scraper is for competitive pricing, to identify the price of a given product to tailor your price or advertise it accordingly. A scraper can also aggregate data from a number of Web sources and provide that information to a user.
Continue Reading…VoIP security has been called in question recently, though there is little evidence to indicate that VoIP security is any less than conventional telephony systems.
VoIP voice data is transmitted via a packet-switched data network using IP. VoIP systems can carry a significant higher number of calls, and very much faster, than traditional PSTN networks due to compression of the voice packets, modern broadband technology and a number of other gateway developments which have reduced the previous packet delivery problems to an extent that the protocol is now a viable mainstream telephony solution to most business needs.
VoIP security should therefore be shown to be at least as effective as that of traditional telephone systems.
Continue Reading…Voice over internet protocol or VoIP is beginning to come into its own. The promise of cost savings over traditional phone lines is driving this technology into the mainstream. Leveraging your existing broadband connection to save on your monthly phone expense at first glance makes sense.
Lets take a closer look.
Continue Reading…I still remember the thrill of my father bringing home our first VCR. The features were dizzying would it really record television shows in the middle of the night when we were fast asleep Finally, just what we needed! Or did we Sadly, we only mastered the art of renting and playing movies. Confusion from unclear directions overrode our interest level in learning the finer points of our VCRs features. Dad rightly claimed that corporate design labs and family dens have different standards for what might pass as user-friendly. We used the VCR as it suited our needs while disregarding its more complex features. Some years and many technologies later user friendly is back defining, in digital terms, what is loosely referred to as Web 2.0. Web 2.0 is the latest generation Internet. Its the perfect market for users and advertisers alike: now it’s Adsense, not DoubleClick; live blogs, as opposed to static webpages.
Continue Reading…Beginners may find it difficult to relate the facts from the formal documentation on the BSD rc.d framework with the practical tasks of rc.d scripting. In this article, we consider a few typical cases of increasing complexity, show rc.d features suited for each case, and discuss how they work. Such an examination should provide reference points for further study of the design and efficient application of rc.d.
In this article Yar Tikhiy describes how to use the BSD rc.d framework.
Continue Reading…The default livebook mark refresh in Firefox is set to 30 minutes. It is possible to change this default by changing the following parameter:
browser.bookmarks.livemark_refresh_seconds
Continue Reading…Ruby provides the programmer with a set of very powerful features borrowed from the domain of functional programming, namely closures, high–order functions and first–class functions [1]. These features are implemented in Ruby by means of code blocks, Proc objects and methods (that are also objects) – concepts that are closely related and yet differ in subtle ways. In fact I found myself quite confused about this topic, having a difficulty to understand the difference between blocks, procs and methods and unsure about the best practices of using them. Additionally, having some background in Lisp and years of Perl experience, I was unsure of how the Ruby concepts map to similar idioms from other programming languages, like Lisp’s functions and Perl’s subroutines. Sifting through hundreds of newsgroup posts, I saw that I’m not the only one with this problem, and in fact quite a lot of ”Ruby Nubies” struggle with the same ideas.
Continue Reading…Whether you’ve forgotten the name of a function or the property of a cascading style sheet – handy cheat sheets deliver the information you are looking for – immediately. Most cheat sheets are available as .pdf or .png-files, so you can print them and use them every day for whatever projects you’re currently working on.
On this website you find a list of several cheatsheets including perl, ruby, xml, css, ajax, html, photoshop, mysql, ..., ...
Continue Reading…
