NAME¶
Metabase::Fact - base class for Metabase Facts
VERSION¶
version 0.022
SYNOPSIS¶
# defining the fact class
package MyFact;
use Metabase::Fact::Hash;
our @ISA = qw/Metabase::Fact::Hash/;
# using the fact class
my $fact = TestReport->new(
resource => 'RJBS/Metabase-Fact-0.001.tar.gz',
content => {
status => 'FAIL',
time => 3029,
},
);
$client->send_fact($fact);
DESCRIPTION¶
Metabase is a framework for associating content and 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 datatypes are constructed.
Metabase::Fact is a base class for Facts (really opinions or analyses) that can
be sent to or retrieved from a Metabase repository.
Structure of a Fact object¶
A Fact object associates a "content" attribute with a
"resource" attribute and a "creator" attribute.
The "resource" attribute must be in a URI format that can be validated
via a Metabase::Resource subclass. The "content" attribute is an
opaque scalar with subclass-specific meaning. The "creator"
attribute is a URI with a "metabase:user" scheme and type (see
Metabase::Resource::metabase).
Facts have three sets of metadata associate with them. Metadata are generally
for use in indexing, searching and managing Facts.
- •
- "core metadata" describe universal properties of all Facts and
are used to submit, store, manage and retrieve Facts within the Metabase
framework.
- •
- "resource metadata" describe index properties derived from the
"resource" attribute. (As these can be regenerated from the
"resource" -- which is part of "core metadata" -- they
are not stored with a serialized Fact.)
- •
- "content metadata" describe index properties derived from the
"content" attribute. (As these can be regenerated from the
"content" -- which is part of "core metadata" -- they
are not stored with a serialized Fact.)
Each of the three metadata sets has an associated accessor:
"core_metadata", "resource_metadata" and
"content_metadata".
Each of the three sets also has an accessor that returns a hashref with a data
type for each possible element in the set: "core_metadata_types",
"resource_metadata_types" and "content_metadata_types".
Data types are loosely based on Data::RX. For example:
'//str' -- indicates a value that should be compared stringwise
'//num' -- indicates a value that should be compared numerically
'//bool' -- indicates a valut that is true or false
When searching on metadata, you must join the set name to the metadata element
name with a period character. For example:
core.guid
core.creator
core.resource
resource.scheme
content.size
content.score
ATTRIBUTES¶
Unless otherwise noted, all attributes are read-only and are either provided as
arguments to the constructor or are generated during construction. All
attributes (except "content") are also part of "core
metadata".
Arguments provided to new¶
content (required)
A reference to the actual information associated with the fact. The exact form
of the content is up to each Fact class to determine.
resource (required)
The canonical resource (URI) the Fact relates to. For CPAN distributions, this
would be a "
cpan:///distfile/..." URI. (See URI::cpan.) The
associated accessor returns a Metabase::Resource subclass.
creator (optional)
A Metabase::User::Profile URI that indicates the creator of the Fact. If not set
during Fact creation, it will be set by the Metabase when a Fact is submitted
based on the submitter Profile. The "set_creator" mutator may be
called to set "creator", but only if it is not previously set. The
associated accessor returns a Metabase::Resource subclass or "undef"
if the creator has not been set.
guid (optional)
The Fact object's Globally Unique IDentifier. This is generated automatically if
not provided. Generally, users should not provide a "guid" argument,
but it is permitted for use in special cases where a non-random
"guid" is necessary.
Generated during construction¶
These attributes are generated automatically during the call to "new".
type
The class name, with double-colons converted to dashes to be more URI-friendly.
e.g. "Metabase::Fact" would be "Metabase-Fact".
schema_version
The "schema_version" of the Fact subclass that created the object.
This may or may not be the same as the current "schema_version" of
the class if newer versions of the class have been released since the object
was created.
creation_time
Fact creation time in UTC expressed in extended ISO 8601 format with a
"Z" (Zulu) suffix. For example:
2010-01-10T12:34:56Z
update_time
When the fact was created, stored or otherwise updated, expressed an ISO 8601
UTC format as with "creation_time". The "touch" method may
be called at any time to update the value to the current time. This attribute
generally only has local significance within a particular Metabase repository.
For example, it may be used to sort Facts by when they were stored or changed
in a Metabase.
valid
A boolean value indicating whether the fact is considered valid. It defaults to
true. The "set_valid" method may be called to change the
"valid" property, for example, to mark a fact invalid rather than
deleting it. The value of "valid" is always normalized to return
"1" for true and "0" for false.
CONSTRUCTOR¶
new¶
$fact = MyFact->new(
resource => 'AUTHORID/Foo-Bar-1.23.tar.gz',
content => $content_structure,
);
Constructs a new Fact. The "resource" and "content"
attributes are required. No other attributes should be provided to
"new" except "creator".
CLASS METHODS¶
type¶
$type = MyFact->type;
The "type" accessor may also be called as a class method.
class_from_type¶
$class = MyFact->class_from_type( $type );
A utility function to invert the operation of the "type" method.
upgrade_fact¶
MyFact->upgrade_fact( $struct );
This method will be called when initializing a fact from a data structure that
claims to be of a schema version other than the schema version reported by the
loaded class's "default_schema_version" method. It will be passed
the hashref of args being used to initialized the fact object (generally the
output of "as_struct" from an older version), and should alter that
hash in place.
default_schema_version¶
$version = MyFact->default_schema_version;
Defaults to 1. Subclasses should override this method if they make a
backwards-incompatible change to the internals of the content attribute.
Schema version numbers should be monotonically-increasing integers. The
default schema version is used to set an objects schema_version attribution on
creation.
PERSISTENCE METHODS¶
The following methods are implemented by Metabase::Fact and subclasses generally
should not need to override them.
save¶
$fact->save($filename);
This method writes out the fact to a file in JSON format. If the file cannot be
written, an exception is raised. If the save is successful, a true value is
returned. Internally, it calls "as_json".
load¶
my $fact = Metabase::Fact->load($filename);
This method loads a fact from a JSON format file and returns it. If the file
cannot be read or is not valid JSON, and exception is thrown. Internally, it
calls "from_json".
as_json¶
This returns a JSON string containing the serialized object. Internally, it
calls "as_struct".
from_json¶
This method regenerates a fact from a JSON string generated by
"as_json". Internally, it calls "from_struct".
as_struct¶
This returns a simple data structure that represents the fact and can be used
for transmission over the wire. It serializes the content and core metadata,
but not other metadata, which should be recomputed by the receiving end.
from_struct¶
my $fact = Metabase::Fact->from_struct( $struct );
This takes the output of the "as_struct" method and reconstitutes a
Fact object. If the class the struct represents is not loaded,
"from_struct" will attempt to load the class or will throw an error.
OBJECT METHODS¶
The following methods are implemented by Metabase::Fact and subclasses generally
should not need to override them.
This returns a hashref containing the fact's core metadata. This includes things
like the guid, creation time, described resource, and so on.
This returns a hashref of types for each core metadata element
This method returns metadata describing the resource.
This returns a hashref of types for each resource metadata element
set_creator¶
$fact->set_creator($profile_uri);
This method sets the "creator" core metadata for the core metadata for
the fact. If the fact's "creator" is already set, an exception will
be thrown.
set_valid¶
$fact->set_valid(0);
This method sets the "valid" core metadata to a boolean value.
touch¶
$fact->touch
This method sets the "update_time" core metadata for the core metadata
for the fact to the current time in ISO 8601 UTC format with a trailing
"Z" (Zulu) suffice.
ABSTRACT METHODS¶
Methods marked as
required must be implemented by a Fact subclass. (The
version in Metabase::Fact will die with an error if called.)
In the documentation below, the terms
must,
must not,
should, etc. have their usual RFC 2119 meanings.
These methods MUST throw an exception if an error occurs.
content_as_bytes¶
required
$string = $fact->content_as_bytes;
This method MUST serialize a Fact's content as bytes in a scalar and return it.
The method for serialization is up to the individual fact class to determine.
Some common subclasses are available to handle serialization for common data
types. See Metabase::Fact::Hash and Metabase::Fact::String.
content_from_bytes¶
required
$content = $fact->content_from_bytes( $string );
$content = $fact->content_from_bytes( \$string );
Given a scalar, this method MUST regenerate and return the original content data
structure. It MUST accept either a string or string reference as an argument.
It MUST NOT overwrite the Fact's content attribute directly.
content_metadata¶
optional
$content_meta = $fact->content_metadata;
If provided, this method MUST return a hash reference with content-specific
indexing metadata. The key MUST be the name of the field for indexing and
SHOULD provide dimensions to differentiate one set of content from another.
Values MUST be simple scalars, not references.
Here is a hypothetical example of "content_metadata" for an image
fact:
sub content_metadata {
my $self = shift;
return {
width => _compute_width ( $self->content ),
height => _compute_height ( $self->content ),
caption => _extract_caption( $self->content ),
}
}
Field names should be valid perl identifiers, consisting of alphanumeric
characters or underscores. Hyphens and periods are allowed, but are not
recommended.
content_metadata_types¶
optional
my $typemap = $fact->content_metadata_types;
This method is used to identify the datatypes of keys in the data structure
provided by "content_metadata". If provided, it MUST return a hash
reference. It SHOULD contain a key for every key that could appear in the data
structure generated by "content_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 "content_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
'//bool' -- indicates a boolean value where "1" is true and "0" is false
Here is a hypothetical example of "content_metadata_types" for an
image fact:
sub content_metadata_types {
return {
width => '//num',
height => '//num',
caption => '//str',
}
}
Consumers of "content_metadata_types" SHOULD assume that any
"content_metadata" key not found in the result of
"content_metadata_types" is a '//str' resource.
validate_content¶
required
eval { $fact->validate_content };
This method SHOULD check for the validity of content within the Fact. It MUST
throw an exception if the fact content is invalid. (The return value is
ignored.)
validate_resource¶
optional
eval { $fact->validate_resource };
This method SHOULD check whether the resource type is relevant for the Fact
subclass. It SHOULD use Metabase::Resource to create a resource object and
evaluate the resource object scheme and type. It MUST throw an exception if
the resource type is invalid. Otherwise, it MUST return a valid
Metabase::Resource subclass. For example:
sub validate_resource {
my ($self) = @_;
# Metabase::Resource->new dies if invalid
my $obj = Metabase::Resource->new($self->resource);
if ($obj->scheme eq 'cpan' && $obj->type eq 'distfile') {
return $obj;
}
else {
my $fact_type = $self->type;
Carp::confess("'$resource' does not apply to '$fact_type'");
}
}
The default "validate_resource" accepts any resource that can
initialize a "Metabase::Resource" object.
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.
SUPPORT¶
Bugs / Feature Requests¶
Please report any bugs or feature requests through the issue tracker at
<
https://github.com/dagolden/Metabase-Fact/issues>. You will be notified
automatically of any progress on your issue.
Source Code¶
This is open source software. The code repository is available for public review
and contribution under the terms of the license.
<
https://github.com/dagolden/Metabase-Fact>
git clone https://github.com/dagolden/Metabase-Fact.git
AUTHORS¶
- •
- David Golden <dagolden@cpan.org>
- •
- Ricardo Signes <rjbs@cpan.org>
- •
- H.Merijn Brand <hmbrand@cpan.org>
CONTRIBUTORS¶
- •
- Nathan Gary Glenn <nglenn@cpan.org>
- •
- Randy Stauner <rwstauner@cpan.org>
COPYRIGHT AND LICENSE¶
This software is Copyright (c) 2013 by David Golden.
This is free software, licensed under:
The Apache License, Version 2.0, January 2004