Newsgroup: it.comp.os.linux.iniziare
Titolo: perchè dovrei usare linux?

http://blogs.computerworld.com/london_stock_exchange_to_abandon_failed_windows_platform

  Strepitoso.  Fantastico.  Incredibile.
Per coloro che l'inglese non lo conoscono? Cosa e' successo?
Please!

 Please!
Nulla di particolarmente eclatante.
In estrema sintesi: la borsa di Londra (LSE) un po' di tempo fa aveva 
annunciato in pompa magna di aver deciso di adottare per la gestione del 
processo di trading un nuovo sistema sviluppato da Microsoft e Accenture 
basato su Windows (TradElect). Da notare che il sistema � particolarmente 
critico e necessita di tempi di elaborazione delle transazioni molto 
ristretti, sotto i 10ms oltre che ovviamente dover garantire disponibilit� 
almeno a 4 9.
Dopo aver avuto un blackout di servizio particolarmente importante e dopo 
che si sono resi conto che l'obiettivo di efficienza per quanto riguarda i 
tempi di elaborazione non � nemmeno lontanamente raggiunto, la CEO se ne � 
andata (o � stata cacciata?) e a quanto pare getteranno alle ortiche tutto 
il sistema che � costato un fottio di soldi.
Si riporta come altri utenti con esigenze simili oggi utilizzino 
proficuamente soluzioni di trading basate su Linux e si citano Chi-X, CME e 
NYSE e ci si augura che LSE faccia lo stesso.
-- 
Flavio Visentin
Scientists have finally discovered what's wrong with the female brain:
On the left side, there is nothing right, and on the right side, there
is nothing left.

 eclatante, invece!
Continuo a non vedere nulla di eclatante.... non � accaduto nulla di pi� di 
quanto mi aspettassi quando lessi la notizia dell'accordo.
Forse sar� che ho toccato con mano i sistemi "mission critical" messi in 
piedi dall'azienda piccola e morbida che non mi sembra affatto strano.


 to_abandon_failed_windows_platform
Be si sapeva da tempo che finche' ci giochi e, quando funziona, ci fai
qualche lavoretto, va bene, ma quando vengono richieste prestazioni.
Gia' nel 1999 Linux era stato scelto per la stazione orbitale
http://www.linuxjournal.com/article/3024
per doti di :
[...]
Linux to the Rescue
To overcome these and other issues, ESA built two products: GOAS and
RACSI. GOAS is the Ground Operator Assistant System for the rendezvous
operations of ATV. Used on ground, GOAS is a software tool to monitor
the ATV mission and intervene in case of a problem. GOAS provides
complex command and control capabilities to replan the entire mission if
necessary. RACSI is the remote ATV control at ISS. RACSI is a laptop
computer running a software package operated by an astronaut onboard the
station. RACSI double monitors and checks the ATV mission and provides
two simple command capabilities: temporarily interrupt the mission or
command a collision-avoidance maneuver.
Currently, both the GOAS and RACSI developments run under Linux.
Although GOAS was developed on Solaris (using versions 1 and 2), the
software was ported to Linux without difficulties. RACSI was originally
programmed entirely under Linux. For both systems, Linux was chosen as
the underlying operating system because it provides four basic features
required by up-to-date space applications: reliability, performance,
portability and affordability. Reliability is crucial to space
applications. The feature of reliability is guaranteed by the robustness
of Linux: both applications run dozens of processes concurrently, using
extensively shared memories and semaphores. The software never crashes
or misbehaves, despite the fact that both systems were designed to run
nonstop for weeks or even months.
Performance is the definitive factor in measuring real-time critical
software. Although Linux is not used in real-time mode (the RT-Linux
module is not loaded), the applications run in real time. That is, they
receive data from the spacecraft, display it and send it back to the
satellite, all in real time. Everything runs within the specified
communications rate between craft.
Software portability is of vital importance for upgrades and
applications enhancement. Portability among UNIX flavors can be done
quickly, preserving expandability and keeping manpower costs down. This
is not true for other non-UNIX operating systems. In addition, Linux is
available for an enormous range of hardware platforms, making the change
between platforms as simple as recompiling (in most cases).
Nowadays, space applications often lack the funds needed to buy costly
licenses. Linux is a zero-cost operating system, which provides true
affordability. It can be copied as many times as desired, keeping
license costs and royalties low. This is true not only for the operating
system but also for the tools (compilers, debuggers, editors,
development environments, etc.) which come with it.
GOAS on the Ground
The native GOAS system runs on a Sun workstation, Ultra-SPARC 5, with
64MB of RAM and 300MB of hard disk space. A color monitor is mandatory.
(See Figure 4.) This configuration runs under Solaris (version 2.5). It
uses the X (X11R6) graphical user interface, with Sun OpenLook as the
window manager.
The Linux version was developed from this initial system; the Linux GOAS
runs on a 233MHz Pentium with 48MB of RAM. This system also uses X11R6,
with Linux OpenLook as the window manager. The pointing device is a
mouse, although using keystrokes is allowed.
GOAS was programmed in the C and C++ languages. C is used for
programming the applications, C++ for programming the graphical
interface. GOAS uses a collection of commercial off-the-shelf software
routines (ILOG views) to build certain parts of the man-machine
interface.
GOAS can run with two or three monitors at the same time, allowing the
viewing of many spacecraft parameters. It is possible to configure a
different monitor to display the man-machine interface of the
monitoring, failure detection, replanning modules, etc. Like RACSI, the
software of GOAS is subdivided into several modules (see Figure 5),
according to a modular architecture compliant with ESA software
standards. However, GOAS is much more complex in terms of mission
planning capabilities, trajectory prediction and failure detection and
recovery.
[...]