Free acquire software for linux

Crashtest simulates car crashes. Crashtest is an educational tool that can be used to acquire much insight into this complex process.

The user can learn about the relation between speed and stopping distance. Also, many physical properties can be studied.

Crashtest is developed by Bram Stolk, SARA, and was commissioned by NWO for the Weten Week 2006 in the Netherlands.

Wackamole is an application that helps with making a cluster highly available. The project manages a bunch of virtual IPs, that should be available to the outside world at all times. Wackamole ensures that a single machine within a cluster is listening on each virtual IP address that Wackamole manages.
If it discovers that particular machines within the cluster are not alive, it will almost immediately ensure that other machines acquire these public IPs. At no time will more than one machine listen on any virtual IP. Wackamole also works toward achieving a balanced distribution of number IPs on the machine within the cluster it manages.
Wakamole operates on a cluster of tightly connected machines (all on the same LAN). It works by managing a pool of IP addresses that you expect to be available at all times. These IP addresses are virtual (meaning no machine has any of those IPs as its default IP address). Wackamole will work to ensure that all of the IP addresses in the pool are assigned as virtual IPs to the machines in the cluster. No IP address is held by more than one machine and every IP address is available.
This allows you to run a service using multiple DNS RR records without the worry of one of the machines crashing -- if the machine crashes, the virtual IP addresses it was responsible for will be managed by the remaining machines in the cluster.
There is no other software like Wackamole. Wackamole is quite unique in that it operates in a completely peer-to-peer mode within the cluster. Other products that provide the same high-availability guarantees use a "VIP" method. A networking appliance assumes a single virtual IP address and "maps" requests to that IP address to the machines in the cluster. This networking appliance is a single point of failure by itself, so most industry accepted solutions incorporate classic master-slave failover or bonding between two identical appliances. These networking appliances can be:
- simple commodity servers running user applications to provide high availability,
- operating system features like IPVS under Linux or similar such features under Windows 2000 and FreeBSD,
- hardware networking component like Foundry ServerIron, Cisco LocalDirector or other content-aware switch, Cisco Arrowpoint content switched, Extreme Networks load-balancers and other such hardware products.
Enhancements:
- Many changes were made.

Contextual::Return is a Perl module to create context-senstive return values.

SYNOPSIS

use Contextual::Return;
use Carp;

sub foo {
return
SCALAR { thirty-twelve }
BOOL { 1 }
NUM { 7*6 }
STR { forty-two }

LIST { 1,2,3 }

HASHREF { {name => foo, value => 99} }
ARRAYREF { [3,2,1] }

GLOBREF { *STDOUT }
CODEREF { croak "Dont use this result as code!"; }
;
}

# and later...

if (my $foo = foo()) {
for my $count (1..$foo) {
print "$count: $foo is:n"
. " array: @{$foo}n"
. " hash: $foo->{name} => $foo->{value}n"
;
}
print {$foo} $foo->();
}

Usually, when you need to create a subroutine that returns different values in different contexts (list, scalar, or void), you write something like:

sub get_server_status {
my ($server_ID) = @_;

# Acquire server data somehow...
my %server_data = _ascertain_server_status($server_ID);

# Return different components of that data,
# depending on call context...
if (wantarray()) {
return @server_data{ qw(name uptime load users) };
}
if (defined wantarray()) {
return $server_data{load};
}
if (!defined wantarray()) {
carp Useless use of get_server_status() in void context;
return;
}
else {
croak q{Bad context! No biscuit!};
}
}

That works okay, but the code could certainly be more readable. In its simplest usage, this module makes that code more readable by providing three subroutines--LIST(), SCALAR(), VOID()--that are true only when the current subroutine is called in the corresponding context:

use Contextual::Return;

sub get_server_status {
my ($server_ID) = @_;

# Acquire server data somehow...
my %server_data = _ascertain_server_status($server_ID);

# Return different components of that data
# depending on call context...
if (LIST) { return @server_data{ qw(name uptime load users) } }
if (SCALAR) { return $server_data{load} }
if (VOID) { print "$server_data{load}n" }
else { croak q{Bad context! No biscuit!} }
}

Contextual returns

Those three subroutines can also be used in another way: as labels on a series of contextual return blocks (collectively known as a context sequence). When a context sequence is returned, it automatically selects the appropriate contextual return block for the calling context. So the previous example could be written even more cleanly as:

use Contextual::Return;

sub get_server_status {
my ($server_ID) = @_;

# Acquire server data somehow...
my %server_data = _ascertain_server_status($server_ID);

# Return different components of that data
# depending on call context...
return (
LIST { return @server_data{ qw(name uptime load users) } }
SCALAR { return $server_data{load} }
VOID { print "$server_data{load}n" }
DEFAULT { croak q{Bad context! No biscuit!} }
);
}

The context sequence automatically selects the appropriate block for each call context.

Useful Traffic Accounting Dragon is a traffic accounter that actually gives useful information about traffic instead of stupidly counting incoming/outgoing packets.
Dragon accounts traffic by user, program and timestamp and puts this information into useful correlation.
Dragon is implemented as a Perl script for the backend, using /etc/passwd to automatically get information about user accounts, /proc/net/ to get information about open connections and /proc/ to get information about running processes and which processes currently use which network connection.
All this information can be combined so you can actually see what user caused which traffic using what program and when it happened.
All this information is acquired automatically so the minimal configuration necessary is to tell dragon where it can find its MySQL database.
Enhancements:
Features:
- cleanup on CTRL-C
- add patch for Linux Kernel 2.6.17.7
- for now, graphs are disabled in the webfrontend
- webfrontend has now Total, User and Program tabs
Bugfixes:
- forgot to close a filedescriptor fixed
- use leading zeroes on port numbers in messages about connections that no longer exist
- really fix wait for next minute

Alvis::Pipeline is a Perl extension for passing XML documents along the Alvis pipeline.

SYNOPSIS

use Alvis::Pipeline;
$in = new Alvis::Pipeline::Read(host => "harvester.alvis.info",
port => 16716,
spooldir => "/home/alvis/spool");
$out = new Alvis::Pipeline::Write(port => 29168);
while ($xml = $in->read(1)) {
$transformed = process($xml);
$out->write($transformed);
}

This module provides a simple means for components in the Alvis pipeline to pass documents between themselves without needing to know about the underlying transfer protocol. Pipe objects may be created either for reading or writing; components in the middle of the pipeline will create one of each. Pipes support exactly one method, which is either read() or write() depending on the type of the pipe. The granularity of reading and writing is the XML document; neither smaller fragments nor larger aggregates can be transferred.

The documents expected to pass through this pipeline are those representing documents acquired for, and being analysed by, Alvis. These documents are expressed as XML contructed according to the specifications described in the Metadata Format for Enriched Documents. However, while this is the motivating example pipeline that led to the creation of this module, there is no reason why other kinds of documents should not also be passed through pipeline using this software.

The pipeline protocol is described below, to facilitate the development of indepedent implementations in other languages.