CDLUC3/n2t-eggnog - Githubissues

        EGGNOG INSTALLATION INSTRUCTIONS

INSTALLATION

If not already unpacked, unpack with

tar xzf ...

after adjusting the version number as needed.

To install the modules and scripts locally, type the following

mkperl make make test make install

where "mkperl" is an alias for something similar to

perl Makefile.PL INSTALL_BASE=~/local

that works for N2T.

EGGNOG QUIRKS -- HISTORICAL ARTIFACTS

This code is a direct descendant from the NOID package available from CPAN. It splits the binding (egg) away from the minting (nog), and is compatible with noid's minter templates and check digit computations.

It's written in Perl, so it's unfashionable, but it's also fast, compact, and secure, and it runs everywhere.

The architecture betrays the age of the code base, born in 2002. Originally written for an embedded database with no dependency on an externally running daemon, it used BerkeleyDB. To meet the demands of high availability, support is being added for an external database, in this case MongoDB. The code will support either or both models at once. The press of deadlines have not made it possible in to avoid coding in platform-specific assumptions in this first phase (another phase will be required to make the DB connections more generic).

Morever, the original CGI-based architecture that kept pace with server loads until about 2013, is also in transition (to the Mojolicious web framework).

The marriage in eggnog and noid between binding and minting has always been rocky. In honor of the union, even after the break up, the code relied on the metaphor of a "minder", an object that could be either a minter or a binder. That metaphor worked in the early days but became increasingly strained with the realization that (a) binders tend to be few and minters numerous, (b) a formal non-embedded database solution was right for binders, and (c) a lightweight, non-database solution was right for minters (eg, JSON blobs instead of separate key-value stores).

In 2002 the code needed a serialization for metadata, and for want of an alternative to heavyweight and boring XML, I chose to pursue ANVL (A Name Value Language). Without development and promotion energy, ANVL was not destined to catch on as once hoped. As JSON and YAML have come to the fore, YAML is a first priority alternative because metadata activities significantly involve non-technical humans (the original target of ANVL) that would be put off by JSON.

...

PERL STYLE NOTE

This code often uses big boolean expressions instead typical if-elsif-else structures because entering a { block } is relatively expensive. It looks strange if you're not used to it, but this is how it works. Instead of

if ( e1 && e2 && e3 ) {
    s1;
    s2;
    ...;
}
elsif ( e4 || e5 && e6 ) {
    s3;
}
else {
    s4;
    s5;
}

we can write this series of conditional expressions and statements as

e1 && e2 && e3 and
    s1,
    s2,
1 or
e4 || e5 && e6 and
    s3,
1 or
    s4,
    s5,
1;

That's the rigorous form, where the "1 or" makes sure that the list of statements ends with a "true" and stops ("closes the brace") the processing of the next boolean "or" clause. The whole mess ends at the ";".

Riskier to maintain but shorter is to omit the "1 or". We can do this if we KNOW that the immediately preceding statements in the "," separated list will evaluate to "true" or if we're at the last statement before ";". For example, if s2 and s3 always return "true", we can shorten the above to

e1 && e2 && e3 and
    s1,
    s2
or
e4 || e5 && e6 and
    s3
or
    s4,
    s5
;

For this big boolean form to work along with list processing, it's common to parenthsize argument lists (so Perl know where the statement ends) as well as an entire assignment statements (so Perl knows where the RHS ends). If you don't do this, the commas terminating the boolean statements have a tendency to get swallowed up by Perl functions preceding them.

ACKNOWLEDGEMENTS

Thanks to Greg Janee, Joan Starr, Brian Tingle, Martin Haye, and Paul Fogel for their contributions.

xxx modernize this block

Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:

* Redistributions of source code must retain the above copyright
  notice, this list of conditions and the following disclaimer.
* Redistributions in binary form must reproduce the above copyright
  notice, this list of conditions and the following disclaimer in the
  documentation and/or other materials provided with the distribution.
* Neither the name of the University of California nor the names of
  its contributors may be used to endorse or promote products derived
  from this software without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OF THE UNIVERSITY OF CALIFORNIA BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

CDLUC3 / n2t-eggnog

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