Metadata Quality Assessment Framework API

This project is the central piece of the Metadata Quality Assurance Framework, every other project is built on top of it. It provides a general framework for measuring metadata quality in different digital collections.

Quality dimensions
Running as command-line application
Using the library
Defining schema with a configuration file
- Rules
Defining MeasurementConfiguration with a configuration file
Using an experimental version
More info

Quality dimensions

The framework measures the following features:

completeness: it says how complete your records, i.e. what ratio of data elements defined in the metadata schema is available in the records. It can also collect information about the extistence of the field, and their cardinality (how many times they occur in a record)
uniqueness and TF-IDF score: it calculates the TF-IDF scores for field values. It is useful to learn how unique or how frequent the data values.
rule catalogue: one can set different rules or constraints against the data values. It checks if these rules are followed. One can set scores for failure and success cases.
multilingual saturation: how multilingual your records. It requires XML or RDF based multilingual annotation. It reports the number of tagged literals, number of distinct language tags, number of tagged literals per language tag, average number of languages per property for which there is at least one language-tagged literal
language extractor: it extracts the language tag of data elements if any.

above these there are some helper calculators:

extractor: extracts and outputs values from the record
annotator: injects metadata into the output (e.g. some values, which helps further processings, such as file name, date, identifier or other information about the measurement, which are not available within the records)
indexer: index particular data elements with Solr before measurement. It is a necessary step for measuring TF-IDF or uniqueness

Running as command-line application

usage:

./mqa -i <file> -s <file> -m <file>
      [-f <format>] [-h <arg>] [-o <file>] [-r <path>] [-v <format>] [-w <format>] [-z]

-i,--input <file> Input file.
-s,--schema <file> Schema file describing the metadata structure to run assessment against.
-v,--schemaFormat <format> Format of schema file: json, yaml. Default: based on file extension, else json.
-m,--measurements <file> Configuration file for measurements.
-w,--measurementsFormat <format> Format of measurements config file: json, yaml. Default: based on file extension, else json.
-o,--output <file> Output file.
-f,--outputFormat <format> Format of the output: json, ndjson (new line delimited JSON), csv, csvjson (json encoded in csv; useful for RDB bulk loading). Default: ndjson.
-r,--recordAddress <path> An XPath or JSONPath expression to separate individual records in an XML or JSON files.
-z,--gzip Flag to indicate that input is gzipped.
-h,--headers <arg> Headers to copy from source

Using the library

If you want to implement it to your collection you have to define a schema, which presentats an existing metadata schema, and configure the basic facade, which will run the calculation.

First, add the library into your project's pom.xml file:

<dependencies>
  ...
  <dependency>
    <groupId>de.gwdg.metadata</groupId>
    <artifactId>metadata-qa-api</artifactId>
    <version>0.9.4</version>
  </dependency>
</dependencies>

Define a configuration:

MeasurementConfiguration config = new MeasurementConfiguration()
  // we will measure completeness now
  .enableCompletenessMeasurement();

You can create a configuration file.

Define a schema:

Schema schema = new BaseSchema()
  // this schema will be used for a CSV file
  .setFormat(Format.CSV)
  // DataELement represents a data element, which might have 
  // a number of properties
  .addField(
    new DataELement("url", Category.MANDATORY)
        .setExtractable()
  )
  .addField(new DataELement("name"))
  .addField(new DataELement("alternateName"))
  ...
  .addField(new DataELement("temporalCoverage"));

Build a CalculatorFacade object:

CalculatorFacade calculator = new CalculatorFacade(config) // use configuration
  .setSchema(schema)   // set the schema which describes the source
  .configure();        // finalize the configuration

If you have a CSV source and you would like to reuse the headers use setCsvReader():

CalculatorFacade calculator = new CalculatorFacade(config) // use configuration
  .setSchema(schema)   // set the schema which describes the source
  .setCsvReader(       // optional, if it is a CSV source
    new CsvReader()
      .setHeader(((CsvAwareSchema) schema).getHeader()))
  .configure();        // finalize the configuration

These are the two important requirements for the start of the measuring. The measuring is simple:

String csv = calculator.measure(input)

The input should be a string formatted as JSON, XML or CSV. The output is a comma separated line. The calculator.getHeader() returns the list of the column names.

There are a couple of alternatives, if you would like to receive a List or a Map:

String measure(String record) throws InvalidJsonException Returns a CSV string

"0.352941,1.0,1,1,0,1,0,0,0,0,1,0,0,1,1,0,0,0,0,1,1,0,1,0,0,0,0,1,0,0,1,1,0,0,0,0"

List<String> measureAsList(String record) throws InvalidJsonException Returns a list of strings.

List.of("0.352941", "1.0", "1", "1", "0", "1", "0", "0", "0", "0", "1", "0", "0", "1", "1",
        "0", "0", "0", "0", "1", "1", "0", "1", "0", "0", "0", "0", "1", "0", "0", "1", "1",
        "0", "0", "0", "0");

List<Object> measureAsListOfObjects(String record) throws InvalidJsonException Returns a list of objects

List.of(0.35294117647058826, 1.0, true, true, false, true, false, false, false, false, true,
        false, false, true, true, false, false, false, false, 1, 1, 0, 1, 0, 0, 0, 0, 1, 0,
        0, 1, 1, 0, 0, 0, 0);

Map<String, Object> measureAsMap(String record) throws InvalidJsonException Returns a map of objects. The keys of the map are the names of the metrics.

Map.of(
  "completeness:TOTAL", 0.35294117647058826,
  "completeness:MANDATORY", 1.0,
  "existence:url", true,
  "existence:name", true,
  "existence:alternateName", false,
  "existence:description", true,
  "existence:variablesMeasured", false,
  "existence:measurementTechnique", false,
  "existence:sameAs", false,
  "existence:doi", false,
  "existence:identifier", true,
  "existence:author", false,
  "existence:isAccessibleForFree", false,
  "existence:dateModified", true,
  "existence:distribution", true,
  "existence:spatialCoverage", false,
  "existence:provider", false,
  "existence:funder", false,
  "existence:temporalCoverage", false,
  "cardinality:url", 1.
  "cardinality:name", 1,
  "cardinality:alternateName", 0,
  "cardinality:description", 1,
  "cardinality:variablesMeasured", 0,
  "cardinality:measurementTechnique", 0,
  "cardinality:sameAs", 0,
  "cardinality:doi", 0,
  "cardinality:identifier", 1,
  "cardinality:author", 0,
  "cardinality:isAccessibleForFree", 0,
  "cardinality:dateModified", 1,
  "cardinality:distribution", 1,
  "cardinality:spatialCoverage", 0,
  "cardinality:provider", 0,
  "cardinality:funder", 0,
  "cardinality:temporalCoverage", 0
)

String measureAsJson(String inputRecord) throws InvalidJsonException Returns a JSON representation

{
  "completeness":{
    "completeness":{
      "TOTAL":0.35294117647058826,
      "MANDATORY":1.0
    },
    "existence":{
      "url":true,
      "name":true,
      "alternateName":false,
      "description":true,
      "variablesMeasured":false,
      "measurementTechnique":false,
      "sameAs":false,
      "doi":false,
      "identifier":true,
      "author":false,
      "isAccessibleForFree":false,
      "dateModified":true,
      "distribution":true,
      "spatialCoverage":false,
      "provider":false,
      "funder":false,
      "temporalCoverage":false
    },
    "cardinality":{
      "url":1,
      "name":1,
      "alternateName":0,
      "description":1,
      "variablesMeasured":0,
      "measurementTechnique":0,
      "sameAs":0,
      "doi":0,
      "identifier":1,
      "author":0,
      "isAccessibleForFree":0,
      "dateModified":1,
      "distribution":1,
      "spatialCoverage":0,
      "provider":0,
      "funder":0,
      "temporalCoverage":0
    }
  }
}

Map<String, List<MetricResult>> measureAsMetricResult(String inputRecord) throws InvalidJsonException Returns a map with a "raw" format. The keys of the map are the individual calculators. The values are list of MetricResult objects. Each has a name (use getName() method), and a map of metrics (use getResultMap() method). Since it is rather difficult to illustrate, let me give you some assertions here:

assertTrue(metrics instanceof Map);
assertEquals(1, metrics.size());
assertEquals("completeness", metrics.keySet().iterator().next());
// the calculator produced three metrics
assertEquals(3, metrics.get("completeness").size());

// first: completeness
assertEquals("completeness", metrics.get("completeness").get(0).getName());
assertEquals(
  Map.of("TOTAL", 0.35294117647058826, "MANDATORY", 1.0),
  metrics.get("completeness").get(0).getResultMap());

// second: existence
assertEquals("existence", metrics.get("completeness").get(1).getName());
assertEquals(
  Set.of("url", "name", "alternateName", "description", "variablesMeasured", "measurementTechnique",
        "sameAs", "doi", "identifier", "author", "isAccessibleForFree", "dateModified",
        "distribution", "spatialCoverage", "provider", "funder", "temporalCoverage"),
  metrics.get("completeness").get(1).getResultMap().keySet());
assertEquals(
  List.of(true, true, false, true, false, false, false, false, true, false, false, true, true,
          false, false, false, false),
  new ArrayList(metrics.get("completeness").get(1).getResultMap().values()));

// third: cardinality
assertEquals("cardinality", metrics.get("completeness").get(2).getName());
assertEquals(
  Set.of("url", "name", "alternateName", "description", "variablesMeasured", "measurementTechnique",
        "sameAs", "doi", "identifier", "author", "isAccessibleForFree", "dateModified",
        "distribution", "spatialCoverage", "provider", "funder", "temporalCoverage"),
  metrics.get("completeness").get(2).getResultMap().keySet());
assertEquals(
  List.of(1, 1, 0, 1, 0, 0, 0, 0, 1, 0, 0, 1, 1, 0, 0, 0, 0),
  new ArrayList(metrics.get("completeness").get(2).getResultMap().values()));

If your input is a CSV file, and you already processed the lines into list of cells, you could use the same methods:

String measure(List<String> record) throws InvalidJsonException
List<String> measureAsList(List<String> record) throws InvalidJsonException
List<Object> measureAsListOfObjects(List<String> record) throws InvalidJsonException
Map<String, Object> measureAsMap(List<String> record) throws InvalidJsonException
String measureAsJson(List<String> inputRecord) throws InvalidJsonException
Map<String, List<MetricResult>> measureAsMetricResult(List<String> inputRecord) throws InvalidJsonException

An example which collects output into a StringBuffer (you can persist lines into a CSV file or into a database):

// collect the output into a container. The output is a CSV file
StringBuffer output = new StringBuffer();

// get the header of the output CSV
output.append(calculator.getHeader())

// The input could be JSON, XML or CSV. 
// You can set any kind of datasource, as long it returns a String
Iterator iterator = ...;
while (iterator.hasNext()) {
  try {
    // measure the input
    String csv = calculator.measure(iterator.next());
    // save csv
    output.append(csv);
  } catch (InvalidJsonException e) {
    // handle exception
  }
}

// get the output
String metrics = output.toString();

Defining schema with a configuration file

It is possible to define the schema with a YAML or JSON configuration file.

Schema schema = ConfigurationReader
  .readSchemaYaml("path/to/some/configuration.yaml")
  .asSchema();

A YAML example:

format: json
fields:
  - name: edm:ProvidedCHO/@about
    path:  $.['providedCHOs'][0]['about']
    indexField: id
    extractable: true
    rules:
      - and:
        - minCount: 1 
        - maxCount: 1
        failureScore: -10
      - pattern: ^https?://.*$
        successScore: 3
    categories:
      - MANDATORY
  - name: Proxy/dc:title
    path: $.['proxies'][?(@['europeanaProxy'] == false)]['dcTitle']
    categories:
      - DESCRIPTIVENESS
      - SEARCHABILITY
      - IDENTIFICATION
      - MULTILINGUALITY
      - CUSTOM
  - name: Proxy/dcterms:alternative
    path: $.['proxies'][?(@['europeanaProxy'] == false)]['dctermsAlternative']
    categories:
      - DESCRIPTIVENESS
      - SEARCHABILITY
      - IDENTIFICATION
      - MULTILINGUALITY
groups:
  - fields:
      - Proxy/dc:title
      - Proxy/dc:description
    categories:
      - MANDATORY

The same in JSON:

{
  "format": "json",
  "fields": [
    {
      "name": "edm:ProvidedCHO/@about",
      "path":  "$.['providedCHOs'][0]['about']",
      "indexField": "id",
      "extractable": true,
      "rules": [
        {
          "and": [
            {"minCount": 1},
            {"maxCount": 1}
          ],
          "failureScore": -10
        },
        {
          "pattern": "^https?://.*$",
          "successScore": 3
        }
      ],
      "categories": ["MANDATORY"]
    },
    {
      "name": "Proxy/dc:title",
      "path": "$.['proxies'][?(@['europeanaProxy'] == false)]['dcTitle']",
      "categories": [
        "DESCRIPTIVENESS",
        "SEARCHABILITY",
        "IDENTIFICATION",
        "MULTILINGUALITY"
      ]
    },
    {
      "name": "Proxy/dcterms:alternative",
      "path": "$.['proxies'][?(@['europeanaProxy'] == false)]['dctermsAlternative']",
      "categories": [
        "DESCRIPTIVENESS",
        "SEARCHABILITY",
        "IDENTIFICATION",
        "MULTILINGUALITY"
      ]
    }
  ],
  "groups": [
    {
      "fields": [
        "Proxy/dc:title",
        "Proxy/dc:description"
      ],
      "categories": [
        "MANDATORY"
      ]
    }
  ]
}

The central piece is the fields array. Each item represents the properties of a single data elements (a DataELement in the API). Its properties are:

name (String): the name or label of the data element
path (String): a address of the data element. If the format is XML, it should be an XPath expression. If format is JSON, it should be a JSONPath expression. If the format is CSV, it should be the name of the column.
categories (List): a list of categories this field belongs to. Categories can be anything, in Europeana's use case these are the core functionalities the field supports
extractable (boolean): whether the field can be extracted if field extraction is turned on
rules (List): a set of rules or constraints which will be checked against
indexField (String): the name which can be used in a search engine connected to the application (at the time of writing Apache Solr is supported)

Optionaly you can set the "canonical list" of categories. It provides two additional functionalities

if a field contains a category which is not listed in the list, that will be excluded (with a warning in the log)
the order of the categories in the output follows the order set in the configuration.

Here is an example (in YAML):

format: json
...
categories:
  - MANDATORY
  - DESCRIPTIVENESS
  - SEARCHABILITY
  - IDENTIFICATION
  - CUSTOM
  - MULTILINGUALITY

Rules

One can add constraints to the fields. There are content rules, which the tool will check. In this version the tool mimin SHACL constraints.

Cardinality

One can specify with this properties how many occurrences of a data elemens a record can have.

`minCount <number>`

Specifies the minimum number of field occurence (API: setMinCount() or withMinCount())

Example: the field should have at least one occurrence

- name: about
  path:  $.['about']
  rules:
  - minCount: 1

`maxCount <number>`

Specifies the maximum number of field occurence (API: setMaxCount() or withMaxCount())

Example: the field might have maximum one occurrence

- name: about
  path:  $.['about']
  rules:
  - maxCount: 1

Value Range

You can set a range of value within which the field's value should remain. You can set a lower and higher bound with boolean operators. You can specify either integers or floating point numbers.

`minExclusive <number>`

The minimum exclusive value ([field value] > limit, API: setMinExclusive(Double) or withMinExclusive(Double))

`minInclusive <number>`

The minimum inclusive value ([field value] >= limit, API: setMinInclusive(Double) or withMinExclusive(Double))

`maxExclusive <number>`

The maximum exclusive value ([field value] < limit, API: setMaxExclusive(Double) or withMaxExclusive(Double))

`maxInclusive <number>`

The maximum inclusive value ([field value] <= limit, API: setMaxInclusive(Double) or withMaxInclusive(Double))

Example: 1.0 <= price <= 2.0

- name: price
  path:  $.['price']
  rules:
    - and:
      - minInclusive: 1.0
      - maxInclusive: 2.0

Example: 1.0 < price < 2.0

- name: price
  path:  $.['price']
  rules:
    - and:
      - minExclusive: 1
      - maxExclusive: 2

Note: integers will be interpreted as floating point numbers.

String constraints

`minLength <number>`

The minimum string length of each field value (API: setMinLength(Integer) or withMinLength(Integer))

Example: the field value should not be empty

- name: about
  path:  $.['about']
  rules:
    - minLength: 1

`maxLength <number>`

The maximum string length of each field value (API: setMaxLength(Integer) or withMaxLength(Integer))

Example: the value should be 3, 4, or 5 characters long.

- name: about
  path:  $.['about']
  rules:
    - and:
      - minLength: 3
      - maxLength: 5

`hasValue <String>`

The value should be equal to the provided value (API: setHasValue(String) or withHasValue(String))

Example: the status should be "published".

- name: status
  path:  $.['status']
  rules:
    - hasValue: published

`in [String1, ..., StringN]`

The string value should be one of the listed values (API: setIn(List<String>) or withIn(List<String>))

Example: the value should be either "dataverse", "dataset" or "file".

- name: type
  path:  $.['type']
  rules:
    - in: [dataverse, dataset, file]

`pattern <regular expression>`

A regular expression that each field value matches to satisfy the condition. The expression can match a a part of the whole string (see the Java Matcher object's find method). (API: setPattern(String) or withPattern(String))

Example: the field value should start with http:// or https:// and end with .jpg, .jpeg, .jpe, .jfif, .png, .tiff, .tif, .gif, .svg, .svgz, or .pdf.

- name: thumbnail
  path: oai:record/dc:identifier[@type='binary']
  rules:
    - pattern: ^https?://.*\.(jpg|jpeg|jpe|jfif|png|tiff|tif|gif|svg|svgz|pdf)$

`minWords <number>`

The minimum word count of each field value (API: setMinWords(Integer) or withMinWord(Integer))

Example: the field value should have at least one words

- name: about
  path:  $.['about']
  rules:
    - minWords: 1

`maxWords <number>`

The maximum string length of each field value (API: setMaxWords(Integer) or withMaxWords(Integer))

Example: the value should be at least 3 character long, but should not contain more than 2 words.

- name: about
  path:  $.['about']
  rules:
    - and:
      - minLength: 3
      - maxWords: 2

Comparision of properties

`equals <field label>`

The set of all values of a field is equal to the set of all values of another field (API: setEquals(String) or withEquals(String))

Example: The ID should be equal to the ISBN number.

fields:
  - name: id
    path:  $.['id']
    rules:
      - equals: isbn
  - name: isbn
    path:  $.['isbn']

`disjoint <field label>`

The set of values of a field is disjoint (not equal) with the set of all values of another field (API: setDisjoint(String) or withDisjoint(String))

Example: The title should be different from description.

fields:
  - name: title
    path:  $.['title']
    rules:
      - equals: description
  - name: description
    path:  $.['description']

`lessThan <field label>`

Each values of a field is smaller than each values of another field (API: setLessThan(String) or withLessThan(String))

Example: the date of birth is less than the date of death

- name: birthDate
  path: oai:record/dc:date[@type='birth']
  rules:
    - lessThan: deathDate

`lessThanOrEquals <field label>`

Each values of a field is smaller than or equals to each values of another field (API: setLessThanOrEquals(String) or withLessThanOrEquals(String))

Example: the starting page of the article should be less than or equal to the ending page:

- name: startingPage
  path: startingPage
  rules:
    - lessThan: endingPage

Logical operators

With logical operators you can build complex rules. Each component should fit to its own rules.

`and [<rule1>, ..., <ruleN>]`

Passes if all the rules in the set passed. (API: setAnd(List<Rule>) or withAnd(List<Rule>))

Example: The ID should have one and only one occurrence, and is should not be an empty string.

- name: id
  path: oai:record/dc:identifier[@type='providerItemId']
  rules:
    - and:
      - minCount: 1
      - maxCount: 1
      - minLength: 1

`or [<rule1>, ..., <ruleN>]`

Passes if at least one of the rules in the set passed. (API: setOr(List<Rule>) or withOr(List<Rule>))

Example: The thumbnail should either end with a known image extension or its content type should be one of the provided MIME image types.

- name: thumbnail
  path: oai:record/dc:identifier[@type='binary']
  rules:
    - or:
      - pattern: ^.*\.(jpg|jpeg|jpe|jfif|png|tiff|tif|gif|svg|svgz)$
      - contentType: [image/jpeg, image/png, image/tiff, image/tiff-fx, image/gif, image/svg+xml]

`not [<rule1>, ..., <ruleN>]`

Passes if none of the rules in the set passed. (API: setNot(List<Rule>) or withNot(List<Rule>))

Example: make sure that the title and the description is different.

- name: title
  path:  $.['title']
  rules:
    - not:
      - equals: description

Other constraints

These rules don't have parallel in SHACL.

`contentType [type1, ..., typeN]`

This rule interprets the value as a URL, fetches it and extracts the HTTP header's content type, then checks if it is one of those allowed.

Example: The HTTP content type should be image/jpeg, image/png, image/tiff, image/tiff-fx, image/gif, or image/svg+xml.

- name: thumbnail
  path: oai:record/dc:identifier[@type='binary']
  rules:
    - contentType: [image/jpeg, image/png, image/tiff, image/tiff-fx, image/gif, image/svg+xml]

`unique <boolean>`

(since v0.9.0)

This rule checks if the value of the field is unique. Prerequisite: the field should have indexField property, and the content should be indexed with Apache Solr.

`dependencies [id1, id2, ..., idN]`

(since v0.9.0)

This rule checks if other rules has already checked and passed. It passes if all dependent rules has passed or resulted NA, otherwise fail. The ids should be valid, and the dependent rule should take place after the ones from which it depends.

`dimension [criteria1, criteria2, ..., criteriaN]`

(since v0.9.0)

This checks if a linked image fits to some dimension constraints (unit in pixel) - if the value is an URL for an image. One can check the minimum and maximum size of width, height and shorter or longer sides (in case it is not important if width or height is the shorter). The criteria:

minWidth: the minimum width
maxWidth: the maximum width
minHeight: minimum height
maxHeight: maximum height
minShortside: minimum length of the shorter side of the image
maxShortside: maximum length of the shorter side of the image
minLongside: minimum length of the longer side of the image
maxLongside: minimum length of the longer side of the image

example:

format: csv
fields:
- name: thumbnail
  path: oai:record/dc:identifier[@type='binary']
  rules:
  - id: 3.1
    failureScore: -9
    dimension:
      minWidth: 200
      minHeight: 200

General properties

`id <String>`

You can define an identifier to the rule, which will be reflected in the output. If you miss it, the system will assign a count number. ID might also help if you transform a human readable document such as cataloguing rules into a configuration file, and you want to keep linkage between them. (API setId(String) or withId(String))

`description <String>`

Provide a description to document what the particular rule is doing. It can be anything reasonable, it does not play a role in the calculation.

`failureScore <integer>`

A score which will be calculated if the validation fails. The score should be a negative or positive integer (including zero). (API setFailureScore(Integer) or withFailureScore(Integer))

`successScore <integer>`

A score which will be calculated if the validation passes. The score should be a negative or positive integer (including zero). (API setSuccessScore(Integer) or withSuccessScore(Integer))

`naScore <integer>`

A score which will be calculated if the value is missing (there is no such data element). The score should be a negative or positive integer (including zero). (API setNaScore(Integer) or withNaScore(Integer))

Example: set of rules with IDs and scores.

- name: providerid
  path: oai:record/dc:identifier[@type='providerid']
  rules:
  - and:
    - minCount: 1
    - minLength: 1
      failureScore: -6
      id: 2.1
  - pattern: ^(DE-\d+|DE-MUS-\d+|http://id.zdb-services.de\w+|\d{8}|oai\d{13})$
    failureScore: -3
    naScore: 0
    id: 2.2
  - pattern: ^(DE-\d+|DE-MUS-\d+|http://id.zdb-services.de\w+)$
    successScore: 6
    naScore: 0
    id: 2.4
  - pattern: ^http://id.zdb-services.de\w+$
    successScore: 3
    naScore: 0
    id: 2.5
  - pattern: ^http://d-nb.info/gnd/\w+$
    successScore: 3
    naScore: 0
    id: 2.6

`hidden <boolean>`

(since v0.9.0)

If the rule is hidden it will be calculated, but its output will not be present in the overall output. It can be used together width dependencies to set up compound conditions.

`skip <boolean>`

(since v0.9.0)

This rule prevents a particular rule to be part of calculation. This could be useful in development phase when you started to create a complex rule but haven't yet finished, or when the execution of the rule takes long time (e.g. checking content type or image dimension), and temporary you would like to turn it off.

`debug <boolean>`:

(since v0.9.0)

If set, the tool logs the rule identifier, its value and the rule's result.

Set rules via Java API

Schema schema = new BaseSchema()
  .setFormat(Format.CSV)
  .addField(
    new DataELement("title", "title")
      .setRule(
        new Rule()
          .withDisjoint("description")
      )
  )
  .addField(
    new DataELement("url", "url")
      .setRule(
        new Rule()
          .withMinCount(1)
          .withMaxCount(1)
          .withPattern("^https?://.*$")
      )
  )
  ;

Via configuration file (a YAML example):

format: csv
fields:
  - name: title
    categories: [MANDATORY]
    rules:
      disjoint: description
  - name: url
    categories: [MANDATORY]
    extractable: true
    rules:
      minCount: 1
      maxCount: 1
      pattern: ^https?://.*$

In both cases we defined two fields. title has one constraints: it should not be equal to the value of description field (which is masked out from the example). Note: if this hypothetical description field is not available the API drops an error message into the log. url should have one and only one instance, and its value should start with "http://" or "https://".

As you can see there are two types of setters in the API: setSomething and withSomething. The difference is that setSomething returs with void, but withSomething returns with the Rule object, so you can use it in a chain such as new Rule().withMinCount(1).withMaxCount(3) (while new Rule().setMinCount(1).setMaxCount(3) doesn't work, because setMinCount() does returns nothing, and one can not apply setMaxCount(3) on that nothing).

Defining MeasurementConfiguration with a configuration file

MeasurementConfiguration can be created from JSON or YAML configuration files with the following methods:

ConfigurationReader.readMeasurementJson(String filePath): reading configuration from JSON
ConfigurationReader.readMeasurementYaml(String filePath): reading configuration from YAML

an example:

MeasurementConfiguration configuration = ConfigurationReader
  .readMeasurementJson("path/to/some/configuration.json");

An example JSON file:

{
  "fieldExtractorEnabled": false,
  "fieldExistenceMeasurementEnabled": true,
  "fieldCardinalityMeasurementEnabled": true,
  "completenessMeasurementEnabled": true,
  "tfIdfMeasurementEnabled": false,
  "problemCatalogMeasurementEnabled": false,
  "ruleCatalogMeasurementEnabled": false,
  "languageMeasurementEnabled": false,
  "multilingualSaturationMeasurementEnabled": false,
  "collectTfIdfTerms": false,
  "uniquenessMeasurementEnabled": false,
  "completenessCollectFields": false,
  "saturationExtendedResult": false,
  "checkSkippableCollections": false
}

fieldExtractorEnabled: Flag whether or not the field extractor is enabled (default: false). (API calls: setters: enableFieldExtractor(), disableFieldExtractor(), getter: isFieldExtractorEnabled())
fieldExistenceMeasurementEnabled: Flag whether or not run the field existence measurement (default: true). (API calls: setters: enableFieldExistenceMeasurement(), disableFieldExistenceMeasurement(), getter: isFieldExistenceMeasurementEnabled())
fieldCardinalityMeasurementEnabled: Flag whether or not run the field cardinality measurement (default: true). (API calls: setters: enableFieldCardinalityMeasurement(), disableFieldCardinalityMeasurement(), getter: isFieldCardinalityMeasurementEnabled())
completenessMeasurementEnabled: Flag whether or not run the completeness measurement (default: true). (API calls: setters: enableCompletenessMeasurement(), disableCompletenessMeasurement(), getter: isCompletenessMeasurementEnabled())
tfIdfMeasurementEnabled: Flag whether or not run the uniqueness measurement (default: false). (API calls: setters: enableTfIdfMeasurement(), disableTfIdfMeasurement(), getter: isTfIdfMeasurementEnabled())
problemCatalogMeasurementEnabled: Flag whether or not run the problem catalog (default: false). (API calls: setters: enableProblemCatalogMeasurement(), disableProblemCatalogMeasurement(), getter: isProblemCatalogMeasurementEnabled())
ruleCatalogMeasurementEnabled: Flag whether or not run the rule catalog (default: false). (API calls: setters: enableRuleCatalogMeasurement(), disableRuleCatalogMeasurement(), getter: isRuleCatalogMeasurementEnabled())
languageMeasurementEnabled: Flag whether or not run the language detector (default: false). (API calls: setters: enableLanguageMeasurement(), disableLanguageMeasurement(), getter: isLanguageMeasurementEnabled())
multilingualSaturationMeasurementEnabled: Flag whether or not run the multilingual saturation measurement (default: false). (API calls: setters: enableMultilingualSaturationMeasurement(), disableMultilingualSaturationMeasurement(), getter: isMultilingualSaturationMeasurementEnabled())
collectTfIdfTerms: Flag whether or not collect TF-IDF terms in uniqueness measurement (default: false). (API calls: setters: collectTfIdfTerms(boolean), getter: collectTfIdfTerms())
uniquenessMeasurementEnabled: Flag whether or not to run in uniqueness measurement (default: false). (API calls: setters: enableUniquenessMeasurement(), disableUniquenessMeasurement(), getter: isUniquenessMeasurementEnabled())
completenessCollectFields: Flag whether or not run missing/empty/existing field collection in completeness (default: false). (API calls: setters: enableCompletenessFieldCollecting(boolean), getter: isCompletenessFieldCollectingEnabled())
saturationExtendedResult: Flag whether or not to create extended result in multilingual saturation calculation (default: false). (API calls: setters: enableSaturationExtendedResult(boolean), getter: isSaturationExtendedResult())
checkSkippableCollections: Flag whether or not to check skipable collections (default: false). (API calls: setters: enableCheckSkippableCollections(boolean), getter: isCheckSkippableCollections())
String solrHost: The hostname of the Solr server. (API calls: setters: setSolrHost(String), withSolrHost(String):MeasurementConfiguration, getter: getSolrHost())
String solrPort: The port of the Solr server. (API calls: setters: setSolrPort(String), withSolrPort(String):MeasurementConfiguration, getter: getSolrPort())
String solrPath: The path part of of the Solr server URL. (API calls: setters: setSolrPath(String), withSolrPath(String):MeasurementConfiguration, getter: getSolrPath())
String onlyIdInHeader: the Rules should return the ID in the header instead of a generated value. (API calls: setters: setOnlyIdInHeader(boolean), withOnlyIdInHeader(boolean):MeasurementConfiguration, getter: isOnlyIdInHeader())

Using an experimental version

If you want to try an experimental version (which has SNAPSHOT in its version name), you have to enable the retrieval of those versions in the pom.xml file:

<repositories>
  <repository>
    <id>sonatypeSnapshots</id>
    <name>Sonatype Snapshots</name>
    <url>https://oss.sonatype.org/content/repositories/snapshots</url>
    <releases>
     <enabled>false</enabled>
    </releases>
    <snapshots>
      <enabled>true</enabled>
    </snapshots>
  </repository>
</repositories>

<dependencies>
  ...
  <dependency>
    <grroupId>de.gwdg.metadata</grroupId>
    <artifactId>metadata-qa-api</artifactId>
    <version>0.9-SNAPSHOT</version>
  </dependency>
</dependencies>

Thanks to Miel Vander Sande (@mielvds) for the hint!

More info

Since version 0.8-SNAPSHOT the project requires Java 11.

For the usage and implementation of the API see https://github.com/pkiraly/europeana-qa-api.

Java doc for the actual development version of the API: https://pkiraly.github.io/metadata-qa-api.

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src		src
.codeclimate.yml		.codeclimate.yml
.gitignore		.gitignore
.travis.yml		.travis.yml
CHANGELOG.md		CHANGELOG.md
LICENSE.md		LICENSE.md
README.md		README.md
mqa		mqa
pom.xml		pom.xml

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Metadata Quality Assessment Framework API

Quality dimensions

Running as command-line application

Using the library

Defining schema with a configuration file

Rules

Cardinality

minCount <number>

maxCount <number>

Value Range

minExclusive <number>

minInclusive <number>

maxExclusive <number>

maxInclusive <number>

String constraints

minLength <number>

maxLength <number>

hasValue <String>

in [String1, ..., StringN]

pattern <regular expression>

minWords <number>

maxWords <number>

Comparision of properties

equals <field label>

disjoint <field label>

lessThan <field label>

lessThanOrEquals <field label>

Logical operators

and [<rule1>, ..., <ruleN>]

or [<rule1>, ..., <ruleN>]

not [<rule1>, ..., <ruleN>]

Other constraints

contentType [type1, ..., typeN]

unique <boolean>

dependencies [id1, id2, ..., idN]

dimension [criteria1, criteria2, ..., criteriaN]

General properties

id <String>

description <String>

failureScore <integer>

successScore <integer>

naScore <integer>

hidden <boolean>

skip <boolean>

debug <boolean>:

Set rules via Java API

Defining MeasurementConfiguration with a configuration file

Using an experimental version

More info

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`minCount <number>`

`maxCount <number>`

`minExclusive <number>`

`minInclusive <number>`

`maxExclusive <number>`

`maxInclusive <number>`

`minLength <number>`

`maxLength <number>`

`hasValue <String>`

`in [String1, ..., StringN]`

`pattern <regular expression>`

`minWords <number>`

`maxWords <number>`

`equals <field label>`

`disjoint <field label>`

`lessThan <field label>`

`lessThanOrEquals <field label>`

`and [<rule1>, ..., <ruleN>]`

`or [<rule1>, ..., <ruleN>]`

`not [<rule1>, ..., <ruleN>]`

`contentType [type1, ..., typeN]`

`unique <boolean>`

`dependencies [id1, id2, ..., idN]`

`dimension [criteria1, criteria2, ..., criteriaN]`

`id <String>`

`description <String>`

`failureScore <integer>`

`successScore <integer>`

`naScore <integer>`

`hidden <boolean>`

`skip <boolean>`

`debug <boolean>`: