NAME
Metabase::Resource - factory class for Metabase resource descriptors
VERSION
version 0.025
SYNOPSIS
my $resource = Metabase::Resource->new(
'cpan:///distfile/RJBS/Metabase-Fact-0.001.tar.gz',
);
my $resource_meta = $resource->metadata;
my $typemap = $resource->metadata_types;
DESCRIPTION
Metabase is a framework for associating metadata with arbitrary resources. A Metabase can be used to store test reports, reviews, coverage analysis reports, reports on static analysis of coding style, or anything else for which Metabase::Fact types are constructed.
Resources in Metabase are URI's that consist of a scheme and scheme specific information. For example, a standard URI framework for a CPAN distribution is defined by the URI::cpan class.
cpan:///distfile/RJBS/URI-cpan-1.000.tar.gz
Metabase::Resource is a factory class for resource descriptors. It provide a common interface to extract scheme-specific indexing metadata from a scheme-specific resource subclass.
For example, the Metabase::Resource::cpan class will deconstruct the example above this into a Metabase resource metadata structure with the following elements:
type => Metabase-Resource-cpan-distfile
dist_file => RJBS/URI-cpan-1.000.tar.gz
cpan_id => RJBS
dist_name => URI-cpan
dist_version => 1.000
Only the type
field is mandatory for all resources. The other fields are all specific to Metabase::Resource::cpan.
COMMON METHODS
new
my $resource = Metabase::Resource->new(
'cpan:///distfile/RJBS/Metabase-Fact-0.001.tar.gz',
);
Takes a single resource string argument and constructs a new Resource object from a resource subtype determined by the URI scheme. Throws an error if the required resource subclass is not available.
resource
Returns the string used to initialize the resource object.
scheme
Returns a string containing the scheme.
_cache (private)
Returns a hash reference for subclasses to use to store data derived from the content
string.
OVERLOADING
Resources have stringification overloaded to call content
. Equality (==) and inequality (!=) are overloaded to perform string comparison instead.
SUBCLASSING AND SUBCLASS METHODS
Metabase::Resource relies on subclasses to implement scheme-specific parsing of the URI into relevant index metadata.
Subclasses SHOULD NOT implement a new
constructor, as the Metabase::Resource constructor will load the subclass, construct the object, bless the object into the subclass, and then call validate
on the object. Subclasses MAY store structured data derived from the content string during validation.
Subclasses SHOULD use the content
method to access the resource string and the scheme
method to access the scheme. Subclasses MAY use the _cache
accessor to store derived metadata data. Subclasses MUST provide a metadata_types
method to return data types for all elements stored in _cache
.
All subclasses MUST implement the validate
, metadata
and metadata_types
methods, as described below.
All methods MUST throw an exception if an error occurs.
validate
$resource->validate
This method is called by the constructor. It SHOULD return true if the resource string is valid according to scheme-specific rules. It MUST die if the resource string is invalid.
metadata
$meta = $resource->metadata;
This method MUST return a hash reference with resource-specific indexing metadata for the Resource. The key MUST be the name of the field for indexing. The scheme
key MUST be present and the scheme
value MUST be identical to the string from the scheme
accessor. Other keys SHOULD provide dimensions to differentiate one resource from another in the context of scheme
. If a scheme has subcategories, the key type
SHOULD be used for the subcategory. Values MUST be simple scalars, not references.
Here is a hypothetical example of a metadata
function for a metabase user resource like 'metabase:user:ec2726a4-070c-11df-a2e0-0018f34ec37c':
sub metadata {
my $self = shift;
my ($uuid) = $self =~ m{\Ametabase:user:(.+)\z};
return {
scheme => 'metabase',
type => 'user',
user => $uuid,
}
}
Field names should be valid perl identifiers, consisting of alphanumeric characters or underscores. Hyphens and periods are allowed, but are not recommended.
metadata_types
my $typemap = $resource->metadata_types;
This method is used to identify the datatypes of keys in the data structure provided by metadata
. It MUST return a hash reference. It SHOULD contain a key for every key that could appear in the data structure generated by metadata
and provide a value corresponding to a datatype for each key. It MAY contain keys that do not always appear in the result of metadata
.
Data types are loosely based on Data::RX. Type SHOULD be one of the following:
'//str' -- indicates a value that should be compared stringwise
'//num' -- indicates a value that should be compared numerically
Here is a hypothetical example of a metadata_types
function for a metabase user resource like 'metabase:user:ec2726a4-070c-11df-a2e0-0018f34ec37c':
sub metadata_types {
return {
scheme => '//str',
type => '//str',
user => '//str',
}
}
Consumers of metadata_types
SHOULD assume that any metadata
key not found in the result of metadata_types
is a '//str' resource.
BUGS
Please report any bugs or feature using the CPAN Request Tracker. Bugs can be submitted through the web interface at http://rt.cpan.org/Dist/Display.html?Queue=Metabase-Fact
When submitting a bug or request, please include a test-file or a patch to an existing test-file that illustrates the bug or desired feature.
AUTHORS
David Golden <dagolden@cpan.org>
Ricardo Signes <rjbs@cpan.org>
H.Merijn Brand <hmbrand@cpan.org>
COPYRIGHT AND LICENSE
This software is Copyright (c) 2016 by David Golden.
This is free software, licensed under:
The Apache License, Version 2.0, January 2004