I have recently released Remote::Use at CPAN, which
addresses the problem of loading modules from a binary compatible Perl Module Server. It is in partially in debt
with this node and idsfa comment.
There was an actual motivation to have - as
idsfa remarks - a solution
that does not install the module (as Module::AutoINC), but one that
only requires limited knowledge and
no privileges.
At the institution I work the student
laboratories contain hundreds of computers
that can be started in Linux or Windows. The
OS is replicated from a master copy in a
server.
The administrators are reluctant
to install all the Perl Modules I need
for teaching. The problem is that I keep
discovering interesting new modules and
introducing them in my lectures, which
means I am continuously bothering them,
asking for a new module to be introduced
in the master copy/computer.
However, I can
still install that modules in a machine that
is accesible to the students.
Remote::Use
helps to solve these sort of problems. It
provides ways to run a Perl
program even if some libraries aren't
availables at start time. The libraries
will be downloaded from a specified server
using a specified application that runs on
top of some protocol. The clients must be
binary compatibles with the server if binary
libraries - See Remote::Use::Tutorial
for examples -
are
involved. Typical downloaders are "Rsync"
and "Wget" but any suitable alternative like
lwp-mirror or "CURL" can be used. This means
that many different protocols can be used
for the transference: SSH, SFTP, HTTP, HTTPS,
FTP, etc. This way, my students can download
the modules their programs use to a scratch
directory. Once the modules are downloaded
they will not be downloaded again, unless the
modules are removed from the scratch disk.
Read Remote::Use::Tutorial
if you want to know more.
The way to make it work is simple.
Consider the following program:
$ cat -n prime3.pl
1 #!/usr/bin/perl -I../lib -w
2 # The module Math::Prime::XS isn't installed in the machine
3 # but will be downloaded from some remote server
4 use Math::Prime::XS qw{:all};
5
6 @all_primes = primes(9);
7 print "@all_primes\n";
8
9 @range_primes = primes(4, 9);
10 print "@range_primes\n";
The client machine does not have installed
Math::Prime::XS. As the name suggest, the modules
involves some binary libraries. By declaring the use
of Remote::Use first,
the libraries will be downloaded and
the program can complete its execution:
$ time perl -MRemote::Use=config,rsyncconfig prime3.pl
receiving file list ... done
>f+++++++++ XS.so
sent 42 bytes received 16141 bytes 10788.67 bytes/sec
total size is 16043 speedup is 0.99
receiving file list ... done
>f+++++++++ XS.bs
sent 42 bytes received 94 bytes 90.67 bytes/sec
total size is 0 speedup is 0.00
receiving file list ... done
>f+++++++++ XS.pm
sent 42 bytes received 5733 bytes 11550.00 bytes/sec
total size is 5635 speedup is 0.98
2 3 5 7
5 7
real 0m2.349s
user 0m0.116s
sys 0m0.060s
The libraries are stored in a cache directory.
consequently succesive executions don't pay extra
overhead:
$ time perl -MRemote::Use=config,rsyncconfig prime3.pl
2 3 5 7
5 7
real 0m0.066s
user 0m0.056s
sys 0m0.008s
The programmer has however to set
a configuration file rsyncconfig
setting the parameters that govern the
downloading process:
$ cat rsyncconfig
package rsyncconfig;
sub getarg {
my ($class, $self) = @_;
return (
host => 'orion:',
prefix => '/tmp/perl5lib/',
command => 'rsync -i -vaue ssh',
ppmdf => '/tmp/perl5lib/.orion.installed.modules',
);
}
1;
Casiano
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