Low-Bandwidth Communication Tools for Science
Dissemination and management of knowledge is essential for scientific enterprise and sustainable development. For several decades, the Abdus Salam International Centre for Theoretical Physics (ICTP) in Trieste, Italy, has paid special attention to the needs of developing countries to foster, through training and research, the progress of science.
The Centre long ago realized the importance of information retrieval systems on the Internet, including the distribution of in-house preprints, yearly activities and public access catalogs.
On a technical level, Linux provides us with a cost-effective alternative for promoting distance electronic collaboration (see Resources). Based on the Linux OS, virtual laboratories and the extensive use of digital communication tools can help reduce scientific isolation, while filling the need to transfer knowledge to developing countries in the Southern Hemisphere in an unprecedented way (see Resources).
Following these principles, we have started building prototype, on-line scientific tools to further enhance electronic collaboration and to support the use of web navigation and database search by e-mail. Below, we describe two tools that Salam ICTP offers the low-bandwidth scientific community. Both packages use state-of-the-art technologies and software developed in-house, and are distributed under the GNU General Public License (GPL).
The ICTP www4mail software allows navigation and search of the entire Internet via e-mail, using any standard web browser and a MIME (Multipurpose Internet Mail Exchange)-aware e-mail program. At first glance, it may appear similar to one of the several web-to-mail software interfaces; but the www4mail program introduces new features not previously available. In short, e-mail messages containing filtered HTML pages are automatically passed to the www4mail server when links to other web sites are selected while browsing.
Written in modular Perl, the program allows retrieval of web pages, searching of arbitrary databases, filling out of web forms (GET and POST conduct web database searches) and following of links (on-line browsing), all by e-mail. It is multi-lingual, easy to manage and supports current Internet standards (MIME, HTML 4.0, etc.).
Developed from scratch on the Linux platform, www4mail has been used successfully on the BSD platform and contains some optional optimisations that are Linux-specific. For example, www4mail can monitor the system load average, directly from the Linux /proc file system and, at high load averages, queue requests for later processing.
Here are some major features of www4mail:
sends replies as e-mail attachments or in the body of an e-mail message, depending on the type of request options sent by the e-mail client through the web browser
supports scripting, once the browser can display it
handles dynamic contents, parsing text HTML and source HTML
preserves the original layout of requested web pages
retrieves information from FTP sites and Usenet news servers
handles meta tags; that is, if a web page is redirected or relocated by the use of a meta statement, www4mail automatically warns about the possible relocation of the information and provides suitable links for the new location at the top of the reply page
handles frames, inserting suitable links to each framed document
supports user authentication for password-protected web/FTP sites
traps error messages and sends them back to the user
provides support for text-only access for compatibility with the alternative “Agora” and “GetWeb” web-mail servers
serves filtered requests to reduce bandwidth
supports the transfer of binary data
allows web pages to be downloaded as PostScript files, to be viewed or printed locally (see for manuals)
4.23.00 - It was in the C-edit directory as of May 1.
www4mail (see logo in Figure 1) was developed mainly to help researchers from developing countries browse the Web using only e-mail and slow Internet links. While the amount of information on the Web has grown exponentially in the last few years, there is still a large community of Internet users who have access to only e-mail, or their Internet providers do not offer full Internet connections (some of them still use UUCP) or who cannof afford to have an expensive account with full Internet capabilities. Many of these users live in rural areas of developing countries, and rely on e-mail to access essential medical and business information as well as for interpersonal communication and world news. Having the ability to query available databases (such as AltaVista, HotBot, etc.) or preprint repositories with one simple e-mail and receive the output in a few minutes (or hours) could help them tremendously with their scientific work.
At present, www4mail can be tested by sending an e-mail message to firstname.lastname@example.org, or to any other place where the gateway is installed (e.g., Bellanet-Canada, www.bellanet.org/email.htm), listing the requested URL(s) in the body of the message.
Over 50 server configuration options are currently available for setting parameters such as maximum quota per user, gateway administrators, maximum size of each request, or to split sizes for large files. (Type help in the body of the e-mail message for further details).
The installation procedure of the server is simple. For example, under Red Hat Linux, create a user account called www4mail (adduser www4mail), log on as user www4mail (su - www4mail), extract the tar archive in the home directory for www4mail (tar zxvf www4mail.tar.gz) and perform a few extra operations (e.g., to enable forwarding). It is necessary to create a link from the executable /home/www4mail/bin/www4mail to the /etc/smrsh subdirectory in order to keep the sendmail MTA (mail transfer agent) happy. To optimize its configuration, some preliminary monitoring is necessary.
www4mail has been very useful for many people from many different countries, often receiving over 12,000 requests per day. You can view weekly statistics at http://web.bellanet.org/www4mail/).
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July 20, 2016 12:00 pm CDT
One of the best things about the UNIX environment (aside from being stable and efficient) is the vast array of software tools available to help you do your job. Traditionally, a UNIX tool does only one thing, but does that one thing very well. For example, grep is very easy to use and can search vast amounts of data quickly. The find tool can find a particular file or files based on all kinds of criteria. It's pretty easy to string these tools together to build even more powerful tools, such as a tool that finds all of the .log files in the /home directory and searches each one for a particular entry. This erector-set mentality allows UNIX system administrators to seem to always have the right tool for the job.
Cron traditionally has been considered another such a tool for job scheduling, but is it enough? This webinar considers that very question. The first part builds on a previous Geek Guide, Beyond Cron, and briefly describes how to know when it might be time to consider upgrading your job scheduling infrastructure. The second part presents an actual planning and implementation framework.
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This ebook takes a look at some of the practical applications of the Linux on Power platform and ways you might bring all the performance power of this open architecture to bear for your organization. There are no smoke and mirrors here—just hard, cold, empirical evidence provided by independent sources. I also consider some innovative ways Linux on Power will be used in the future.Get the Guide