NAME
FAIR::Accessor - all this does is assign the HTTP call to the correct routine
VERSION
version 0.216
SYNOPSIS
The following code is a complete implementation of a 'Hello, World!' FAIR Accessor
#!/usr/bin/perl -w
package HelloWorld_Accessor; # this should be the same as your filename!
use strict;
use warnings;
use JSON;
#-----------------------------------------------------------------
# Configuration and Daemon
#-----------------------------------------------------------------
use base 'FAIR::Accessor';
my $config = {
title => 'Hello World Data Accessor',
serviceTextualDescription => 'Server for some Helloworld Data',
textualAccessibilityInfo => "The information from this server requries no authentication", # this could also be a $URI describing the accessibiltiy
mechanizedAccessibilityInfo => "", # this must be a URI to an RDF document
textualLicenseInfo => "CC-BY", # this could also be a URI to the license info
mechanizedLicenseInfo => "", # this must be a URI to an RDF document
baseURI => "", # I don't know what this is used for yet, but I have a feeling I will need it!
ETAG_Base => "HelloWorld_Accessor_For_Greetings", # this is a unique identificaiton string for the service (required by the LDP specification)
localNamespaces => {hw => 'http://hello.world.org/some/items/',
hw2 => 'http://another.hello.world.org/some/predicates/'}, # add a few new namespaces to the list of known namespaces....
localMetadataElements => [qw(hw:Greeting hw2:grusse) ], # things that we use in addition to common metadata elements
};
my $service = HelloWorld_Accessor->new(%$config);
# start daemon
$service->handle_requests;
#-----------------------------------------------------------------
# Accessor Implementation
#-----------------------------------------------------------------
=head2 get_all_meta_URIs
Function: REQUIRED SUBROUTINE - returns the first-stage LD Platform list of contained URIs and the dataset metadata.
Args : $starting_at_record : this will be passed-in to tell you what record to start with (for paginated responses)
$path : the webserver's PATH_INFO environment value (used to modify the behaviour of REST services)
Returns : JSON encoded listref of 'meta URIs' representing individual records
Note : meta URIs are generally URIs that point back to this same server; calling GET on a meta URI will
return an RDF description of the set of DCAT distributions for that record.\
this can be handled by the
=cut
sub get_all_meta_URIs {
my ($starting_at_record, $path_info) = @_;
$path_info ||="";
my %result = ( # NOTE THAT ALL OF THESE ARE OPTIONAL! (and there are more fields.... see DCAT...)
'dc:title' => "Hello World Accessor Server",
'dcat:description' => "the prototype Accessor server for Hello World",
'dcat:identifier' => "handle:HelloWorld1234567",
'dcat:keyword' => ["greetings", "friendly", "welcome", "Hi"],
'dcat:landingPage' => 'http://hello.world.net/homepage.html',
'dcat:language' => 'en',
'dcat:publisher' => 'http://hello.world.net',
'dcat:temporal' => 'http://reference.data.gov.uk/id/quarter/2006-Q1', # look at this!! It doesn't have to be this complex, but it can be!
'dcat:theme' => 'http://example.org/ConceptSchemes/HelloWorld.rdf', # this is the URI to a SKOS Concept Scheme
);
my $BASE_URL = "http://" . $ENV{'SERVER_NAME'} . $ENV{'REQUEST_URI'} . $path_info;
# you may chose to return no record IDs at all, if you only want to serve repository-level metadata
my @known_records = ($BASE_URL . "/hello",
$BASE_URL . "/world",
# ... you need to generate this list of record URIs here... somehow
);
$result{'void:entities'} = scalar(@known_records); # THE TOTAL *NUMBER* OF RECORDS THAT CAN BE SERVED
$result{'ldp:contains'} = \@known_records; # the listref of record ids
return encode_json(\%result);
}
=head2 get_distribution_URIs
Function: REQUIRED IF get_all_meta_URIs list of URIs point back to this script.
returns the second-stage LD Platform metadata describing the DCAT distributions, formats, and URLs
for a particular record
Args : $ID : the desired ID number, as determined by the Accessor.pm module
$PATH_INFO : the webserver's PATH_INFO environment value (in case the $ID best-guess is wrong... then you're on your own!)
Returns : JSON encoded hashref of 'meta URIs' representing individual DCAT distributions and their formats (format is key)
The format for this response is:
{"metadata":
{"rdf:type": ["edam:data_0006","sio:SIO_000088"]
},
"distributions":
{"application/rdf+xml":"http://myserver.org/ThisScript/record/479-467-29X.rdf",
"text/html":"http://myserver.org/ThisScript/record/479-467-29X.html"
}
}
=cut
sub get_distribution_URIs {
my ($self, $ID, $PATH_INFO) = @_;
my %response;
my %formats;
my %metadata;
$formats{'text/html'} = 'http://myserver.org/ThisScript/helloworld.html';
$formats{'application/rdf+xml'} = 'http://myserver.org/ThisScript/helloworld.rdf';
# set the ontological type for the record (optional)
$metadata{'rdf:type'} = ['edam:data_0006', 'sio:SIO_000088'];
# and whatever other metadata you wish (also optional)
# extractMetaDataFromSpreadsheet(\%metadata, $ID);
$response{distributions} = \%formats;
$response{metadata} = \%metadata if (keys %metadata); # only set it if you can provided something
my $response = encode_json(\%response);
return $response;
}DESCRIPTION
FAIR Accessors are an implementation of the W3Cs Linked Data Platform. FAIR Accessors follow a two-stage interaction model, where the first stage retrieves a series of URLs representing meta-records for every record in that repository (or whatever slice of the repository is being served). This is accomplished by the get_all_meta_URIs subroutine. These URLs will generally point back at this same Accessor script (e.g. with the record number appended to the URL: http://this.host/thisscript/12345).
This script then expresses metadata about that record, including the available DCAT distributions and their file formats. This is accomplished by the get_distribution_URIs subroutine.
The two subroutine names - get_all_meta_URIs and get_distribution_URIs - are not flexible, as they are called by the underlying libraries.
NAME
FAIR::Accessor - Module for creating Linked Data Platform Accessors for the FAIR Data projectAUTHOR
Mark Denis Wilkinson (markw [at] illuminae [dot] com)
COPYRIGHT AND LICENSE
This software is Copyright (c) 2015 by Mark Denis Wilkinson.
This is free software, licensed under:
The Apache License, Version 2.0, January 2004