GitHub - networknt/json-schema-validator: A fast Java JSON schema validator that supports draft V4, V6, V7, V2019-09 and V2020-12

This is a Java implementation of the JSON Schema Core Draft v4, v6, v7, v2019-09 and v2020-12 specification for JSON schema validation. This implementation supports Customizing Dialects, Vocabularies, Keywords and Formats.

The JSON parser used is the Jackson parser.

OpenAPI 3 request/response validation is supported with the use of the appropriate dialect.

As it is a key component in our light-4j microservices framework to validate request/response against OpenAPI specification for light-rest-4j and RPC schema for light-hybrid-4j at runtime, performance is the most important aspect in the design.

JSON Schema Specification compatibility

Information on the compatibility support for each version, including known issues, can be found in the Compatibility with JSON Schema versions document.

Since Draft 2019-09 the format keyword only generates annotations by default and does not generate assertions.

This behavior can be overridden to generate assertions by setting the formatAssertionsEnabled to true in SchemaRegistryConfig or ExecutionConfig.

Upgrading to new versions

This library can contain breaking changes in minor version releases that may require code changes.

Information on notable or breaking changes when upgrading the library can be found in the Upgrading to new versions document.

The Releases page will contain information on the latest versions.

Comparing against other implementations

The JSON Schema Validation Comparison project from Creek has an informative Comparison of JVM based Schema Validation Implementations which compares both the functional and performance characteristics of a number of different Java implementations.

The Bowtie project has a report that compares functional characteristics of different implementations, including non-Java implementations, but does not do any performance benchmarking.

Why this library

Performance

The following is the benchmark results from the JSON Schema Validator Perftest project that uses the Java Microbenchmark Harness.

Note that the benchmark results are highly dependent on the input data workloads and schemas used for the validation.

In this case this workload is using the Draft 4 specification and largely tests the performance of the evaluating the properties keyword. You may refer to Results of performance comparison of JVM based JSON Schema Validation Implementations for benchmark results that use the JSON Schema Test Suite.

If performance is an important consideration, the specific sample workloads should be benchmarked, as there are different performance characteristics when certain keywords are used. For instance the use of the unevaluatedProperties or unevaluatedItems keyword will trigger annotation collection in the related validators, such as the properties or items validators, and annotation collection will adversely affect performance.

Special attention should also be made for inefficient schemas using deeply nested oneOf or anyOf that do not have a condition to short-circuit the evaluation using if and then. The validator has no choice but to perform all the evaluations, and the error messages would be typically very confusing as it will return all the messages from the children.

NetworkNT 2.0.0

Benchmark                                     Mode  Cnt       Score     Error   Units
NetworkntBenchmark.basic                     thrpt   10    5297.105 ± 290.078   ops/s
NetworkntBenchmark.basic:gc.alloc.rate       thrpt   10    1618.328 ±  88.626  MB/sec
NetworkntBenchmark.basic:gc.alloc.rate.norm  thrpt   10  320360.020 ±   0.002    B/op
NetworkntBenchmark.basic:gc.count            thrpt   10     365.000            counts
NetworkntBenchmark.basic:gc.time             thrpt   10     130.000                ms

Everit 1.14.6

Benchmark                                     Mode  Cnt       Score     Error   Units
EveritBenchmark.basic                        thrpt   10    4615.637 ± 151.195   ops/s
EveritBenchmark.basic:gc.alloc.rate          thrpt   10    2097.810 ±  68.708  MB/sec
EveritBenchmark.basic:gc.alloc.rate.norm     thrpt   10  476592.023 ±   0.001    B/op
EveritBenchmark.basic:gc.count               thrpt   10     521.000            counts
EveritBenchmark.basic:gc.time                thrpt   10     170.000                ms

Functionality

This implementation is tested against the JSON Schema Test Suite. As tests are continually added to the suite, these test results may not be current.

Implementations	Overall	DRAFT_03	DRAFT_04	DRAFT_06	DRAFT_07	DRAFT_2019_09	DRAFT_2020_12
NetworkNt	pass: r:4840 (100.0%) o:2421 (100.0%) fail: r:0 (0.0%) o:0 (0.0%)		pass: r:610 (100.0%) o:255 (100.0%) fail: r:0 (0.0%) o:0 (0.0%)	pass: r:829 (100.0%) o:322 (100.0%) fail: r:0 (0.0%) o:0 (0.0%)	pass: r:913 (100.0%) o:554 (100.0%) fail: r:0 (0.0%) o:0 (0.0%)	pass: r:1227 (100.0%) o:639 (100.0%) fail: r:0 (0.0%) o:0 (0.0%)	pass: r:1261 (100.0%) o:651 (100.0%) fail: r:0 (0.0%) o:0 (0.0%)

Note that this uses the JoniRegularExpressionFactory for the pattern and format regex tests.

Jackson Parser

This library uses Jackson which is a Java JSON parser that is widely used in other projects. If you are already using the Jackson parser in your project, it is natural to choose this library over others for schema validation.

YAML Support

The library works with JSON and YAML on both schema definitions and input data.

OpenAPI Support

The OpenAPI 3.0 specification is using JSON schema to validate the request/response. The library has support for the OpenAPI 3.0 and OpenAPI 3.1 dialects.

Minimal Dependencies

Following the design principle of the Light Platform, this library has minimal dependencies to ensure there are no dependency conflicts when using it.

Required Dependencies

The following are the dependencies that will automatically be included when this library is included.

<dependency>
    <!-- Used for logging -->
    <groupId>org.slf4j</groupId>
    <artifactId>slf4j-api</artifactId>
    <version>${version.slf4j}</version>
</dependency>

<dependency>
    <!-- Used to process JSON -->
    <groupId>com.fasterxml.jackson.core</groupId>
    <artifactId>jackson-databind</artifactId>
    <version>${version.jackson}</version>
</dependency>

<dependency>
    <!-- Used to process YAML -->
    <groupId>com.fasterxml.jackson.dataformat</groupId>
    <artifactId>jackson-dataformat-yaml</artifactId>
    <version>${version.jackson}</version>
</dependency>

<dependency>
    <!-- Used to validate RFC 3339 date and date-time -->
    <groupId>com.ethlo.time</groupId>
    <artifactId>itu</artifactId>
    <version>${version.itu}</version>
</dependency>

Optional Dependencies

The following are the optional dependencies that may be required for certain options.

These are not automatically included and setting the relevant option without adding the library will result in a ClassNotFoundException.

<dependency>
    <!-- Used to validate ECMA 262 regular expressions -->
    <!-- Approximately 50 MB in dependencies -->
    <!-- GraalJSRegularExpressionFactory -->
    <groupId>org.graalvm.js</groupId>
    <artifactId>js</artifactId>
    <version>${version.graaljs}</version>
</dependency>

<dependency>
    <!-- Used to validate ECMA 262 regular expressions -->
    <!-- Approximately 2 MB in dependencies -->
    <!-- JoniRegularExpressionFactory -->
    <groupId>org.jruby.joni</groupId>
    <artifactId>joni</artifactId>
    <version>${version.joni}</version>
</dependency>

Excludable Dependencies

The following are required dependencies that are automatically included, but can be explicitly excluded if they are not required.

The YAML dependency can be excluded if this is not required. Attempting to process schemas or input that are YAML will result in a ClassNotFoundException.

<dependency>
    <groupId>com.networknt</groupId>
    <artifactId>json-schema-validator</artifactId>
    <exclusions>
        <exclusion>
            <groupId>com.fasterxml.jackson.dataformat</groupId>
            <artifactId>jackson-dataformat-yaml</artifactId>
        </exclusion>
    </exclusions>
</dependency>

The Ethlo Time dependency can be excluded if accurate validation of the date-time format is not required. The date-time format will then use java.time.OffsetDateTime to determine if the date-time is valid .

<dependency>
    <groupId>com.networknt</groupId>
    <artifactId>json-schema-validator</artifactId>
    <exclusions>
        <exclusion>
            <groupId>com.ethlo.time</groupId>
            <artifactId>itu</artifactId>
        </exclusion>
    </exclusions>
</dependency>

Community

This library is very active with a lot of contributors. New features and bug fixes are handled quickly by the team members. Because it is an essential dependency of the light-4j framework in the same GitHub organization, it will be evolved and maintained along with the framework.

Prerequisite

The library supports Java 8 and up. If you want to build from the source code, you need to install JDK 8 locally. To support multiple version of JDK, you can use SDKMAN

Usage

Adding the dependency

This package is available on Maven central.

Maven:

<dependency>
    <groupId>com.networknt</groupId>
    <artifactId>json-schema-validator</artifactId>
    <version>2.0.0</version>
</dependency>

Gradle:

dependencies {
    implementation(group: 'com.networknt', name: 'json-schema-validator', version: '2.0.0');
}

Validating inputs against a schema

The following example demonstrates how inputs are validated against a schema. It comprises the following steps.

Creating a configuration for controlling validator behavior.
Creating a schema registry with the default schema dialect and how the schemas can be retrieved.
- Configuring mapping the $id to a retrieval IRI using schemaIdResolvers.
- Configuring how the schemas are loaded using the retrieval IRI. For instance a Map<String, String> schemas containing a mapping of retrieval URI to schema data as a String can by configured using builder.schemas(schemas). This also accepts a Function<String, String> schemaRetrievalFunction.
Loading a schema from a schema location.
Using the schema to validate the data along with setting any execution specific configuration like for instance the locale or whether format assertions are enabled.

/*
 * The SchemaRegistryConfig can be optionally used to configure certain aspects
 * of how the validation is performed.
 *
 * By default the JDK regular expression implementation which is not ECMA 262
 * compliant is used. The GraalJSRegularExpressionFactory.getInstance() offers
 * the best compliance followed by JoniRegularExpressionFactory.getInstance()
 * but both require additional optional dependencies.
 */
SchemaRegistryConfig schemaRegistryConfig = SchemaRegistryConfig.builder()
        .regularExpressionFactory(JoniRegularExpressionFactory.getInstance()).build();

/*
 * This creates a schema registry that supports all the standard dialects for
 * cross-dialect validation and will use Draft 2020-12 as the default if $schema
 * is not specified in the schema data. If $schema is specified in the schema
 * data then that schema dialect will be used instead and this version is
 * ignored.
 */
SchemaRegistry schemaRegistry = SchemaRegistry.withDefaultDialect(SpecificationVersion.DRAFT_2020_12,
        builder -> builder.schemaRegistryConfig(schemaRegistryConfig)
                /*
                 * This creates a mapping from $id which starts with
                 * https://www.example.org/schema to the retrieval IRI classpath:schema.
                 */
                .schemaIdResolvers(schemaIdResolvers -> schemaIdResolvers
                        .mapPrefix("https://www.example.com/schema", "classpath:schema")));

/*
 * Due to the mapping the schema will be retrieved from the classpath at
 * classpath:schema/example-main.json. If the schema data does not specify an
 * $id the absolute IRI of the schema location will be used as the $id. If the
 * schema data does not specify a dialect using $schema the default dialect
 * specified when creating the schema registry.
 */
Schema schema = schemaRegistry.getSchema(SchemaLocation.of("https://www.example.com/schema/example-main.json"));
String input = "{\r\n"
 + "  \"main\": {\r\n"
 + "    \"common\": {\r\n"
 + "      \"field\": \"invalidfield\"\r\n"
 + "    }\r\n"
 + "  }\r\n"
 + "}";

List<Error> errors = schema.validate(input, InputFormat.JSON, executionContext -> {
    /*
     * By default since Draft 2019-09 the format keyword only generates annotations
     * and not assertions.
     */
    executionContext.executionConfig(executionConfig -> executionConfig.formatAssertionsEnabled(true));
});

Validating a schema against a meta-schema

The following example demonstrates how a schema is validated against a meta-schema of a dialect.

This is actually the same as validating inputs against a schema except in this case the input is the schema and the schema used is the meta-schema.

Note that the meta-schemas for Draft 4, Draft 6, Draft 7, Draft 201 9-09 and Draft 2020-12 are bundled with the library and these classpath resources will be used by default.

SchemaRegistry schemaRegistry = SchemaRegistry.withDialect(Dialects.getDraft202012());
/*
 * Due to the mapping the meta-schema for the dialect will be retrieved from the
 * classpath at classpath:draft/2020-12/schema.
 */
Schema schema = schemaRegistry.getSchema(SchemaLocation.of(Dialects.getDraft202012().getId()));
String input = "{\r\n"
    + "  \"type\": \"object\",\r\n"
    + "  \"properties\": {\r\n"
    + "    \"key\": {\r\n"
    + "      \"title\" : \"My key\",\r\n"
    + "      \"type\": \"invalidtype\"\r\n"
    + "    }\r\n"
    + "  }\r\n"
    + "}";
List<Error> errors = schema.validate(input, InputFormat.JSON, executionContext -> {
    /*
     * By default since Draft 2019-09 the format keyword only generates annotations
     * and not assertions.
     */
    executionContext.executionConfig(executionConfig -> executionConfig.formatAssertionsEnabled(true));
});

Results and output formats

Results

The following types of results are generated by the library.

Type Description

Assertions Validation errors generated by an assertion keyword on a particular input data instance. This is generally described in an Error or in a OutputUnit. Note that since Draft 2019-09 the format keyword no longer generates assertions by default and instead generates only annotations unless configured otherwise using a configuration option or by using a dialect that uses the appropriate vocabulary.

Annotations Additional information generated by an annotation keyword for a particular input data instance. This is generally described in a OutputUnit. Annotation collection and reporting is turned off by default. Annotations required by keywords such as unevaluatedProperties or unevaluatedItems are always collected for evaluation purposes and cannot be disabled but will not be reported unless configured to do so.

The following information is used to describe both types of results.

Type	Description
Evaluation Path	This is the set of keys from the root through which evaluation passes to reach the schema for evaluating the instance. This includes `$ref` and `$dynamicRef`. eg. `/properties/bar/$ref/properties/bar-prop`
Schema Location	This is the canonical IRI of the schema plus the JSON pointer fragment to the schema that was used for evaluating the instance. eg. `https://json-schema.org/schemas/example#/$defs/bar/properties/bar-prop`
Instance Location	This is the JSON pointer fragment to the instance data that was being evaluated. eg. `/bar/bar-prop`

Assertions contains the following additional information

Type	Description
Message	The validation error message.
Message Key	The message key used for generating the message for localization.
Arguments	The arguments used for generating the message.
Keyword	The keyword that generated the message.
Schema Node	The `JsonNode` pointed to by the Schema Location. This is the schema data that caused the input data to fail. It is possible to get the location information by configuring the `SchemaRegistry` with a `NodeReader` that uses the `LocationJsonNodeFactoryFactory` and using `JsonNodes.tokenStreamLocationOf(schemaNode)`.
Instance Node	The `JsonNode` pointed to by the Instance Location. This is the input data that failed validation. It is possible to get the location information by configuring the `SchemaRegistry` with a `NodeReader` that uses the `LocationJsonNodeFactoryFactory` and using `JsonNodes.tokenStreamLocationOf(instanceNode)`.
Error	The error.
Details	Additional details that can be set by custom keyword validator implementations. The library will set the `property` and `index` details for certain errors. For instane the `required` keyword will set the `property`. Note that this is not part of the instance location as that points to the instance node.

Annotations contains the following additional information

Type	Description
Value	The annotation value generated

Line and Column Information

The library can be configured to store line and column information in the JsonNode instances for the instance and schema nodes. This will adversely affect performance and is not configured by default.

This is done by configuring a NodeReader that uses the LocationJsonNodeFactoryFactory on the SchemaRegistry. The JsonLocation information can then be retrieved using JsonNodes.tokenStreamLocationOf(jsonNode).

String schemaData = "{\r\n"
                + "  \"$id\": \"https://schema/myschema\",\r\n"
                + "  \"properties\": {\r\n"
                + "    \"startDate\": {\r\n"
                + "      \"format\": \"date\",\r\n"
                + "      \"minLength\": 6\r\n"
                + "    }\r\n"
                + "  }\r\n"
                + "}";
String inputData = "{\r\n"
                + "  \"startDate\": \"1\"\r\n"
                + "}";
SchemaRegistry schemaRegistry = SchemaRegistry.withDialect(Dialects.getDraft202012(),
        builder -> builder.nodeReader(nodeReader -> nodeReader.locationAware()));

Schema schema = schemaRegistry.getSchema(schemaData, InputFormat.JSON);
List<Error> errors = schema.validate(inputData, InputFormat.JSON, executionContext -> {
    executionContext.executionConfig(executionConfig -> executionConfig.formatAssertionsEnabled(true));
});
Error format = errors.get(0);
JsonLocation formatInstanceNodeTokenLocation = JsonNodes.tokenStreamLocationOf(format.getInstanceNode());
JsonLocation formatSchemaNodeTokenLocation = JsonNodes.tokenStreamLocationOf(format.getSchemaNode());
Error minLength = errors.get(1);
JsonLocation minLengthInstanceNodeTokenLocation = JsonNodes.tokenStreamLocationOf(minLength.getInstanceNode());
JsonLocation minLengthSchemaNodeTokenLocation = JsonNodes.tokenStreamLocationOf(minLength.getSchemaNode());

assertEquals("format", format.getKeyword());
assertEquals("date", format.getSchemaNode().asText());
assertEquals(5, formatSchemaNodeTokenLocation.getLineNr());
assertEquals(17, formatSchemaNodeTokenLocation.getColumnNr());
assertEquals("1", format.getInstanceNode().asText());
assertEquals(2, formatInstanceNodeTokenLocation.getLineNr());
assertEquals(16, formatInstanceNodeTokenLocation.getColumnNr());
assertEquals("minLength", minLength.getKeyword());
assertEquals("6", minLength.getSchemaNode().asText());
assertEquals(6, minLengthSchemaNodeTokenLocation.getLineNr());
assertEquals(20, minLengthSchemaNodeTokenLocation.getColumnNr());
assertEquals("1", minLength.getInstanceNode().asText());
assertEquals(2, minLengthInstanceNodeTokenLocation.getLineNr());
assertEquals(16, minLengthInstanceNodeTokenLocation.getColumnNr());
assertEquals(16, minLengthInstanceNodeTokenLocation.getColumnNr());

Output formats

This library implements the Flag, List and Hierarchical output formats defined in the Specification for Machine-Readable Output for JSON Schema Validation and Annotation.

The List and Hierarchical output formats are particularly helpful for understanding how the system arrived at a particular result.

Output Format	Description
Default	Generates the list of assertions.
Boolean	Returns `true` if the validation is successful. Note that the fail fast option is turned on by default for this output format.
Flag	Returns an `OutputFlag` object with `valid` having `true` if the validation is successful. Note that the fail fast option is turned on by default for this output format.
List	Returns an `OutputUnit` object with `details` with a list of `OutputUnit` objects with the assertions and annotations. Note that annotations are not collected by default and it has to be enabled as it will impact performance.
Hierarchical	Returns an `OutputUnit` object with a hierarchy of `OutputUnit` objects for the evaluation path with the assertions and annotations. Note that annotations are not collected by default and it has to be enabled as it will impact performance.

The following example shows how to generate the hierarchical output format with annotation collection and reporting turned on and format assertions turned on.

SchemaRegistry schemaRegistry = SchemaRegistry.withDialect(Dialects.getDraft202012());
Schema schema = schemaRegistry.getSchema(SchemaLocation.of("https://json-schema.org/schemas/example"));

OutputUnit outputUnit = schema.validate(inputData, InputFormat.JSON, OutputFormat.HIERARCHICAL, executionContext -> {
    executionContext.executionConfig(executionConfig -> executionConfig
            .annotationCollectionEnabled(true)
            .annotationCollectionFilter(keyword -> true)
            .formatAssertionsEnabled(true));
});

The following is sample output from the Hierarchical format.

{
  "valid": false,
  "evaluationPath": "",
  "schemaLocation": "https://json-schema.org/schemas/example#",
  "instanceLocation": "",
  "droppedAnnotations": {
    "properties": ["foo", "bar"],
    "title": "root"
  },
  "details": [
    {
      "valid": false,
      "evaluationPath": "/properties/foo/allOf/0",
      "schemaLocation": "https://json-schema.org/schemas/example#/properties/foo/allOf/0",
      "instanceLocation": "/foo",
      "errors": {
        "required": "required property 'unspecified-prop' not found"
      }
    },
    {
      "valid": false,
      "evaluationPath": "/properties/foo/allOf/1",
      "schemaLocation": "https://json-schema.org/schemas/example#/properties/foo/allOf/1",
      "instanceLocation": "/foo",
      "droppedAnnotations": {
        "properties": ["foo-prop"],
        "title": "foo-title",
        "additionalProperties": ["foo-prop", "other-prop"]
      },
      "details": [
        {
          "valid": false,
          "evaluationPath": "/properties/foo/allOf/1/properties/foo-prop",
          "schemaLocation": "https://json-schema.org/schemas/example#/properties/foo/allOf/1/properties/foo-prop",
          "instanceLocation": "/foo/foo-prop",
          "errors": {
            "const": "must be a constant value 1"
          },
          "droppedAnnotations": {
            "title": "foo-prop-title"
          }
        }
      ]
    },
    {
      "valid": false,
      "evaluationPath": "/properties/bar/$ref",
      "schemaLocation": "https://json-schema.org/schemas/example#/$defs/bar",
      "instanceLocation": "/bar",
      "droppedAnnotations": {
        "properties": ["bar-prop"],
        "title": "bar-title"
      },
      "details": [
        {
          "valid": false,
          "evaluationPath": "/properties/bar/$ref/properties/bar-prop",
          "schemaLocation": "https://json-schema.org/schemas/example#/$defs/bar/properties/bar-prop",
          "instanceLocation": "/bar/bar-prop",
          "errors": {
            "minimum": "must have a minimum value of 10"
          },
          "droppedAnnotations": {
            "title": "bar-prop-title"
          }
        }
      ]
    }
  ]
}

Configuration

Execution Configuration

Name	Description	Default Value
`annotationCollectionEnabled`	Controls whether annotations are collected during processing. Note that collecting annotations will adversely affect performance.	`false`
`annotationCollectionFilter`	The predicate used to control which keyword to collect and report annotations for. This requires `annotationCollectionEnabled` to be `true`.	`keyword -> false`
`locale`	The locale to use for generating messages in `Error`. Note that this value is copied from `SchemaRegistryConfig` for each execution.	`Locale.getDefault()`
`failFast`	Whether to return failure immediately when an assertion is generated. Note that this value is copied from `SchemaRegistryConfig` for each execution but is automatically set to `true` for the Boolean and Flag output formats.	`false`
`formatAssertionsEnabled`	The default is to generate format assertions from Draft 4 to Draft 7 and to only generate annotations from Draft 2019-09. Setting to `true` or `false` will override the default behavior.	`null`
`readOnly`	Used to indicate that the property should not be sent as part of the request payload, but only in the response payload. This affects the `readOnly` keyword used for the OpenAPI dialect.	`null`
`writeOnly`	Used to indicate that the property should not be sent as part of the response payload, but only in the request payload. This affects the `writeOnly` keyword used for the OpenAPI dialect.	`null`

Schema Registry Configuration

Name	Description	Default Value
`cacheRefs`	Whether the schemas loaded from refs will be cached and reused for subsequent runs. Setting this to `false` will affect performance.	`true`
`errorMessageKeyword`	The keyword to use for custom error messages in the schema. If not set this features is disabled. This is typically set to `errorMessage` or `message`.	`null`
`executionContextCustomizer`	This can be used to customize the `ExecutionContext` generated by the `Schema` for each validation run.	`null`
`failFast`	Whether to return failure immediately when an assertion is generated.	`false`
`formatAssertionsEnabled`	The default is to generate format assertions from Draft 4 to Draft 7 and to only generate annotations from Draft 2019-09. Setting to `true` or `false` will override the default behavior.	`null`
`locale`	The locale to use for generating messages in `Error`.	`Locale.getDefault()`
`losslessNarrowing`	Whether lossless narrowing is used for the `type` keyword. Since Draft 6 a value of `1.0` is interpreted as an integer whether or not this is enabled.	`false`
`messageSource`	This is used to retrieve the locale specific messages.	`DefaultMessageSource.getInstance()`
`pathType`	The path type to use for reporting the instance location and evaluation path. Set to `PathType.JSON_PATH` to use JSON Path.	`PathType.JSON_POINTER`
`preloadSchema`	Whether the schema will be preloaded before processing any input. This will use memory but the execution of the validation will be faster.	`true`
`regularExpressionFactory`	The factory to use to create regular expressions for instance `JoniRegularExpressionFactory` or `GraalJSRegularExpressionFactory`. This requires the dependency to be manually added to the project or a `ClassNotFoundException` will be thrown.	`JDKRegularExpressionFactory.getInstance()`
`schemaIdValidator`	This is used to customize how the `$id` values are validated. Note that the default implementation allows non-empty fragments where no base IRI is specified and also allows non-absolute IRI `$id` values in the root schema.	`JsonSchemaIdValidator.DEFAULT`
`strict`	This is set whether keywords are strict in their validation. What this does depends on the individual validators.
`typeLoose`	Whether types are interpreted in a loose manner. If set to true, a single value can be interpreted as a size 1 array. Strings may also be interpreted as number, integer or boolean.	`false`

Walk Configuration

Name	Description	Default Value
`applyDefaultsStrategy`	The strategy for applying defaults when walking when missing or null nodes are encountered.	`ApplyDefaultsStrategy.EMPTY_APPLY_DEFAULTS_STRATEGY`
`keywordWalkHandler`	The `WalkHandler` triggered for keywords.	`NoOpWalkHandler.getInstance()`
`propertyWalkHandler`	The `WalkHandler` triggered for properties.	`NoOpWalkHandler.getInstance()`
`itemWalkHandler`	The `WalkHandler` triggered for items.	`NoOpWalkHandler.getInstance()`

Performance Considerations

Special attention should be made for inefficient schemas using deeply nested oneOf or anyOf that do not have a condition to short-circuit the evaluation using if and then. The validator has no choice but to perform all the evaluations, and the error messages would be typically very confusing as it will return all the messages from the children.

Instances for SchemaRegistry and the Schema created from it are designed to be thread-safe provided its configuration is not modified and should be cached and reused. Not reusing the Schema means that the schema data needs to be repeated parsed with validator instances created and references resolved. When references are resolved, the validators created will be cached.

Collecting annotations will adversely affect validation performance.

The earlier draft specifications contain less keywords that can potentially impact performance. For instance the use of the unevaluatedProperties or unevaluatedItems keyword will trigger annotation collection in the related validators, such as the properties or items validators.

This does not mean that using a schema with a later draft specification will automatically cause a performance impact. For instance, the properties validator will perform checks to determine if annotations need to be collected, and checks if the dialect contains the unevaluatedProperties keyword and whether the unevaluatedProperties keyword exists adjacent the evaluation path.

Security Considerations

The library assumes that the schemas being loaded are trusted. This security model assumes the use case where the schemas are bundled with the application on the classpath.

Issue	Description	Mitigation
Schema Loading	The library by default will load schemas from the classpath and over the internet if needed.	The `SchemaLoader` can be configured to block or allow certain IRIs for schema retrieval.
Schema Caching	The library by default preloads and caches references when loading schemas.	Set `cacheRefs` option in `SchemaRegistryConfig` to false.
Regular Expressions	The library does not validate if a given regular expression is susceptable to denial of service (ReDoS).	An `AllowRegularExpressionFactory` can be configured to perform validation on the regular expressions that are allowed.
Validation Errors	The library by default attempts to return all validation errors. The use of applicators such as `allOf` with a large number of schemas may result in a large number of validation errors taking up memory.	Set `failFast` option in `SchemaRegistryConfig` to immediately return when the first error is encountered. The `OutputFormat.BOOLEAN` or `OutputFormat.FLAG` also can be used.

Quick Start

Customizing Schema Retrieval

Customizing Dialects, Vocabularies, Keywords and Formats

OpenAPI Specification

Schema Walkers

Regular Expressions

Custom Error Messages

Multiple Language

MetaSchema Validation

Projects

The light-rest-4j, light-graphql-4j and light-hybrid-4j use this library to validate the request and response based on the specifications. If you are using other frameworks like Spring Boot, you can use the OpenApiValidator, a generic OpenAPI 3.0 validator based on the OpenAPI 3.0 specification.

If you have a project using this library, please submit a PR to add your project below.

mpenet/legba - OpenAPI service library for clojure, adhering to the RING spec

Contributors

Thanks to the following people who have contributed to this project. If you are using this library, please consider to be a sponsor for one of the contributors.

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Name		Name	Last commit message	Last commit date
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.github/workflows		.github/workflows
doc		doc
src		src
.gitignore		.gitignore
CHANGELOG.md		CHANGELOG.md
LICENSE		LICENSE
NOTICE		NOTICE
README.md		README.md
pom.xml		pom.xml

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networknt/json-schema-validator

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